Prof. Peter Barlis

Professor Peter Barlis (MBBS, MPH, PhD, FESC, FACC, FSCAI, FRACP) is an Interventional Cardiologist and the founding editor of Heart Matters. With expertise in coronary artery disease, advanced cardiac imaging, and interventional cardiology — and fellowships of the European Society of Cardiology, the American College of Cardiology, and the Royal Australasian College of Physicians — he brings the highest level of clinical authority to everything published on this site. Heart Matters was founded on Professor Barlis's belief that patients who understand their condition are less frightened and better equipped to make decisions about their care. Every article on this site reflects that commitment.

Racing Heart: Causes and Patterns Explained

racing heart
Key Points

  • A fast heart rate, known clinically as tachycardia, is defined as a resting rate above 100 beats per minute. Like a slow heart rate, it exists on a wide spectrum from entirely normal to clinically significant.
  • A racing heart felt suddenly and without obvious cause, particularly if it is regular, rapid, and accompanied by dizziness or breathlessness, is a common reason people seek cardiac assessment. An ECG recorded during the episode is one of the most useful pieces of information a clinician can have.
  • The most common causes of a persistently fast resting heart rate are dehydration, anaemia, thyroid overactivity, stimulant intake, anxiety, and fever. All are reversible once identified.
  • The main rhythm disturbances that produce a fast heart rate include atrial fibrillation, SVT, and atrial flutter. Each has a distinct pattern, and each is something a doctor can identify and discuss with you.
  • A very fast, regular, sudden-onset racing heart that does not settle with rest or simple measures is generally treated as urgent in standard clinical practice.

Almost everyone has experienced their heart racing at some point. After sprinting for a bus. During a frightening moment. After too much coffee. In those contexts it is entirely expected, entirely normal, and entirely self-limiting.

A racing heart that comes on unexpectedly, without obvious cause, and does not settle quickly, or one that is accompanied by dizziness, breathlessness, or chest discomfort, is worth understanding more carefully. The question is not just “is my heart beating fast?” but “why is it beating fast, and is this something that needs attention?”

The answer depends on several things: how fast, how regular, how sudden the onset, how long it lasts, and what else is happening at the same time.

What Is a Fast Heart Rate?

The numbers

A resting heart rate above 100 beats per minute is technically classified as tachycardia. Like most medical definitions, the threshold matters less than the context. A resting rate of 105 in someone who has just run upstairs is completely normal. A resting rate of 105 in someone sitting quietly who felt their heart suddenly accelerate is a different conversation entirely.

What your doctor will ask

When you describe a racing heart to a doctor, a few simple observations help guide the conversation more than almost anything else. Was the heartbeat regular or irregular, like a chaotic flutter? Did it come on suddenly, or build up gradually? Did it stop suddenly, or settle slowly? Were there any other symptoms at the same time, such as dizziness or breathlessness? How long did it last?

If you have a smartwatch that took an ECG or flagged an unusual rhythm at the time, that recording is genuinely useful, more useful than any description, and worth showing your doctor. A growing number of arrhythmias are now first picked up by smartwatch alerts, and clinicians take these seriously.

The most likely explanations for a fast heart rate fall into a few broad groups, all of which we cover in more detail elsewhere on Heart Matters. The non-cardiac causes listed below are by far the most common. The arrhythmia explainers cover the main rhythm disturbances in plain language, with links to dedicated guides on each.

Non-Cardiac Causes of a Fast Heart Rate

The majority of people with a persistently elevated resting heart rate have a reversible non-cardiac cause. These are important to identify because the underlying issue is usually straightforward to address once it is found.

Common Non-Cardiac Causes

Dehydration

Reduced blood volume causes the heart to beat faster to maintain output. One of the most common and easily corrected causes.

Anaemia

Reduced oxygen-carrying capacity in the blood prompts the heart to beat faster. Identified by a simple blood count.

Thyroid Overactivity

Hyperthyroidism raises the heart rate and increases arrhythmia risk. Identified by a thyroid function blood test.

Anxiety and Stress

Activation of the body’s stress response raises heart rate. Anxiety-related tachycardia is real, though cardiac causes are usually considered first.

Caffeine and Stimulants

Coffee, energy drinks, and some medications raise heart rate directly. Often underestimated as a contributor.

Fever and Infection

Every degree of temperature rise increases heart rate by around 10 beats per minute. Settles once the infection is treated.

Cardiac Arrhythmias: When the Racing Heart Is the Diagnosis

Three rhythm disturbances account for the great majority of arrhythmia-related racing heart episodes. Each has a distinctive pattern, and each is identifiable on an ECG.

SVT

Sudden onset, very regular, very fast. Starts and stops abruptly without warning. More frightening than dangerous in structurally normal hearts, and very treatable once identified.

Atrial Fibrillation

Irregular and often fast. Frequently described as a chaotic flutter rather than a steady racing. The most common sustained arrhythmia, and one of the most important to identify.

Atrial Flutter

Regular and fast, typically around 150 beats per minute. Feels like a steady rapid pounding. Similar to SVT in sensation but driven by a different mechanism in the upper chambers.

Supraventricular tachycardia (SVT)

SVT produces a sudden-onset, very regular, very fast racing heart, typically 150 to 220 beats per minute, that starts and stops abruptly without warning. It is more frightening than it is dangerous in people with structurally normal hearts, and it is one of the more treatable arrhythmias once identified. We have a dedicated article on SVT on Heart Matters.

Atrial fibrillation

AF produces an irregular, often fast racing sensation. The irregularity is one of its distinguishing features. It may feel like a chaotic fluttering rather than a regular racing. AF is the most common sustained cardiac arrhythmia and one of the most important to identify, partly because it carries an elevated stroke risk that is usually addressed with anticoagulation. Symptom management uses one of two strategies: rate control, which slows the heart down to a comfortable pace while the irregular rhythm continues, or rhythm control, which aims to restore a normal heart rhythm altogether. Which approach is chosen depends on the individual, and is a conversation with a cardiologist.

Atrial flutter

Atrial flutter typically produces a fast, regular racing heart at around 150 beats per minute, often described as a rapid but steady pounding. It can feel similar to SVT but has a different underlying mechanism. An ECG recorded during the episode is the key to telling the two apart, and the management approach is slightly different for each.

An ECG recorded during an episode of racing heart tells us more than any description afterwards. Even a smartwatch trace, shown to a doctor later, can be genuinely useful.

Prof. Peter Barlis, Interventional Cardiologist

Patterns of Presentation and How They Are Usually Approached

Most episodes of racing heart are self-limiting and not dangerous. The table below describes how different patterns are typically approached in clinical practice. It is not personalised advice. Decisions about seeking care for your own situation are best made in discussion with your doctor, or with the local emergency service if symptoms are severe.

Pattern Typical clinical approach
Racing heart with loss of consciousness or near-fainting Treated as a medical emergency, with people generally advised to call emergency services
Racing heart with chest pain or severe breathlessness Treated as a medical emergency, with people generally advised to call emergency services
Sustained fast racing heart not settling after 30 minutes Generally prompts urgent assessment. Driving oneself to hospital is usually advised against in this situation
First-ever episode of rapid irregular heart rate Same-day medical review is typical, to allow an ECG to be performed
Recurrent episodes previously investigated and confirmed benign Planned cardiology review, sometimes with a Holter monitor
Persistently fast resting rate above 100 without obvious cause Medical review within days is typical, including blood tests and an ECG
Questions Worth Raising at Your Next Appointment

  • If I have another episode, what is the best way to try to capture an ECG at the time?
  • Is my resting heart rate elevated, and has a reversible cause been considered?
  • Could my racing heart episodes be SVT, AF, or another arrhythmia?
  • Would a Holter monitor be useful in my case to try to capture the rhythm during symptoms?
  • Are there triggers I should be aware of in my own pattern, such as caffeine, alcohol, or poor sleep?

Heart Matters Resource

When in Doubt, Get Checked Out

A racing heart that is new, prolonged, irregular, or accompanied by dizziness or breathlessness is a common reason people seek assessment. An ECG recorded during the episode answers questions that no description can.

Read: When in Doubt, Get Checked Out →

Conclusion

A racing heart has many causes, most of them benign, and many of them correctable without any cardiac treatment at all. Dehydration, thyroid disease, anaemia, and anxiety all produce a fast heart rate that resolves once the underlying cause is addressed.

The pattern that more often leads to cardiac assessment is a racing heart that comes on suddenly without warning, feels rapid and regular, or is accompanied by dizziness or breathlessness, particularly if it has happened before. An ECG recorded during an episode is one of the most useful pieces of information available in working out what is going on. Most people who have their racing heart investigated come away with answers, often reassuring ones, and sometimes a diagnosis that is very treatable.

Related Reading

Stroke and TIA Explained

Brain MRI scans showing imaging used after stroke and TIA assessment
Key Points

  • A stroke happens when blood flow to part of the brain is cut off and brain cells begin to die. A TIA, or transient ischaemic attack, causes the same symptoms, but the blockage clears on its own before permanent damage occurs.
  • A TIA is a medical emergency, not a minor event. The risk of a full stroke is highest in the 48 hours that follow, so rapid assessment and treatment in that window makes an enormous difference.
  • Investigations after a stroke or TIA focus on finding the cause: narrowing in the neck arteries, an irregular heart rhythm called atrial fibrillation, a structural problem with the heart, or abnormal blood clotting.
  • The right medications started promptly after a TIA, including blood thinners, blood pressure treatment, and statins, significantly reduce the risk of a subsequent stroke.
  • A TIA is not a frightening endpoint. It is an opportunity. The evidence that acting quickly and comprehensively prevents stroke is among the strongest in all of vascular medicine.

A stroke or TIA can feel frightening when the symptoms first appear. One side of the face droops. A hand will not grip. Words come out wrong. Whether those symptoms last two minutes or two hours, they mean something important is happening that demands to be taken seriously.

A TIA is one of the most important medical events a person can experience, not because of the symptoms themselves, which resolve completely, but because of what they represent. The brain’s blood supply was briefly interrupted. The fact that it recovered fully this time does not mean the underlying cause has gone away.

The good news, and this is the central message, is that medicine now has highly effective ways to respond. The window between a TIA and a potential stroke is narrow, but it is also a genuine opportunity to intervene. The people who do best are those who engage with that opportunity quickly and completely.

What Is a Stroke?

A stroke happens when blood flow to part of the brain is suddenly interrupted. There are two main types. An ischaemic stroke occurs when a clot blocks one of the arteries supplying the brain. A haemorrhagic stroke occurs when there is bleeding from a blood vessel in or around the brain. In both situations, the affected area of the brain is at risk of injury, which is why time is so important in treatment.

The effects depend on which part of the brain is affected. Speech, movement, vision, balance, and memory can all be disrupted. Some effects improve significantly over time with rehabilitation, while others can be longer lasting or permanent. This is precisely why preventing a first stroke, or a second one, matters so much.

What Is a TIA?

A TIA, or transient ischaemic attack, produces exactly the same symptoms as a stroke, but the blockage clears on its own before permanent damage occurs. Symptoms appear suddenly, typically peak within seconds to a minute, and then resolve completely. In most cases this happens within minutes, though by definition it occurs within 24 hours.

Brain imaging after a true TIA shows no area of permanent damage. This is what distinguishes it from a minor stroke, though the immediate management of both is identical.

It is sometimes called a “mini-stroke”, but that name does it a serious disservice. A TIA is not a small event. It is a clear warning that the blood supply to the brain is not right, and that the risk of a full stroke in the days and weeks ahead is significantly elevated.

I never dismiss a TIA because the symptoms have passed. The fact that the brain recovered is exactly what gives us the best possible chance to prevent what could come next.

Prof. Peter Barlis, Interventional Cardiologist

1 in 10
people who have a TIA will go on to have a full stroke within 3 months without treatment, with the highest risk concentrated in the first 48 hours.
American Stroke Association

Recognising the Signs: FAST

The FAST acronym captures the most important warning signs of stroke and TIA. Knowing it can save a life. TIA symptoms are neurological. They reflect whichever part of the brain has been briefly deprived of blood. They come on suddenly and without warning. The key word is sudden.

⚠️
Recognise a Stroke: F.A.S.T.

If you see any of these signs, call 000 immediately. Do not wait. Do not drive to hospital. Every minute matters.

  • F — Face. Sudden drooping or weakness on one side. Ask the person to smile. Is it uneven?
  • A — Arms. Sudden weakness or numbness in one arm. Can they raise both arms and hold them there?
  • S — Speech. Slurred, confused, or absent speech, even briefly.
  • T — Time. Call emergency services immediately. Do not wait to see if symptoms resolve.

Other warning signs include sudden loss of vision in one eye, double vision, severe unexplained dizziness, or sudden loss of coordination. Even if everything resolves on the way to hospital, urgent assessment is still essential. A TIA that has passed is still a TIA.

What Investigations Will I Have?

The purpose of investigation after a stroke or TIA is not simply to confirm what happened. It is to find out why, because the answer determines the treatment. Your medical team will want to move through this quickly, often within the first 24 to 48 hours.

Brain imaging: MRI and CT

The first priority is imaging the brain. A CT scan is often performed first in the emergency setting because it is fast and widely available, and can quickly exclude a bleed in the brain. An MRI scan follows when possible, as it is more sensitive. MRI can identify whether any permanent damage has occurred, and can also reveal older areas of reduced blood flow that may point to the underlying cause.

When the MRI shows multiple small areas of damage scattered across different parts of the brain, this is a strong signal that clots are being released from somewhere into the circulation, often from the heart. Finding that source becomes the priority.

Carotid artery ultrasound

The carotid arteries run up either side of the neck and supply blood directly to the brain. A build-up of fatty plaque in these arteries, called carotid stenosis or narrowing, is one of the most common and treatable causes of stroke and TIA.

A carotid Doppler ultrasound is a simple, painless scan that measures blood flow through these arteries. If significant narrowing is found on the side corresponding to your symptoms, a procedure to clear or widen the artery may be recommended, and the evidence for doing this promptly after a TIA is strong.

Heart rhythm monitoring: finding atrial fibrillation

Atrial fibrillation, or AF, is responsible for approximately one in five strokes. AF is an irregular heart rhythm in which the heart beats chaotically rather than in a coordinated fashion. When this happens, blood can pool in a small pouch in the left side of the heart called the left atrial appendage, forming a clot that can then travel to the brain.

The challenge is that AF often comes and goes rather than being present all the time. This means a standard ECG, which records the heart rhythm for only a few seconds, may look entirely normal even in someone who has AF. Longer-term monitoring is often needed to catch it.

Monitor Type How Long It Records What It Detects
Standard ECG A few seconds AF present at the exact moment of recording
Holter monitor 24 to 48 hours AF that comes and goes over a day or two
Patch monitor Up to 14 days Infrequent AF that short monitoring misses
Implantable loop recorder Up to 3 years Very infrequent or hidden AF, highest sensitivity

When longer-term monitoring is needed

Sometimes a Holter or patch monitor comes back normal, but the clinical picture still strongly suggests the heart is the source of the problem. This is particularly the case when MRI has shown multiple small areas of damage in different parts of the brain, which points toward clots originating from a single source (often the heart) and being carried through the circulation.

In this situation, your specialist may recommend an implantable loop recorder. It is a small device, roughly the size of a USB stick, placed just beneath the skin of the chest under local anaesthetic in a minor procedure. It monitors the heart rhythm continuously for up to three years, transmitting data wirelessly to your cardiologist.

Studies have shown that prolonged monitoring with a loop recorder detects AF in a significant proportion of patients whose stroke initially had no clear cause. Finding AF months or even years after the original event still matters enormously, because it changes treatment from antiplatelet therapy to anticoagulation and substantially reduces the risk of a further stroke.

If your specialist has recommended a loop recorder, this reflects a thorough and proactive approach, not a sign that something has been missed.

Echocardiogram: imaging the heart

An echocardiogram is an ultrasound scan of the heart that shows its structure, function, and valves in detail. After a stroke or TIA, it helps identify whether the heart itself may be the source of a clot.

Conditions that can cause clots to form in the heart include reduced pumping function, valve disease, and a patent foramen ovale, or PFO. This is a small hole between the upper chambers of the heart that is present in around one in four people and that can allow clots to cross directly into the arterial circulation.

When a standard echocardiogram does not provide a clear enough view, a transoesophageal echocardiogram, or TOE, can be performed. A small probe is passed gently down the oesophagus, which sits directly behind the heart, giving a much closer and more detailed image of the heart and the large blood vessel that leaves it.

Blood tests

Blood tests assess cholesterol levels, including LDL, HDL, and triglycerides, along with blood glucose and HbA1c (a measure of your average blood sugar over the past three months) to screen for diabetes. A full blood count looks for conditions that increase the tendency to form clots, such as polycythaemia (an excess of red blood cells) or thrombophilia (an inherited tendency to form clots more readily than normal).

One marker worth asking about specifically is Lp(a), or lipoprotein(a). This is a lesser-known type of cholesterol-related particle that is not included in standard cholesterol tests. It is largely determined by genetics, and elevated levels independently raise the risk of both stroke and heart disease. As targeted therapies for elevated Lp(a) are now becoming available, identifying it early is increasingly meaningful. Read more in our article on lipoprotein(a) and inherited heart risk.

Medications That Reduce the Risk of a Future Stroke

The evidence base for stroke prevention after TIA is strong and well established. Several different classes of medication are used, and starting the right ones promptly is where much of the long-term risk reduction occurs.

The information below describes the main categories used in this setting and explains why each one matters. It is not a recommendation about your specific regimen. The choice of medication, combination, dose, and duration is an individual clinical decision that sits with your neurologist, cardiologist, and treating team.

Blood-thinning medications

Blood-thinning medications fall into two main groups, and they work in different ways. Antiplatelet medications, such as aspirin and clopidogrel, reduce the tendency of platelets (the tiny blood cells involved in clot formation) to stick together. Anticoagulants, such as warfarin and the newer direct oral anticoagulants (DOACs) including apixaban and rivaroxaban, work further along the clotting pathway and are more effective at preventing clots formed inside the heart.

Which group is used depends on the cause of the stroke or TIA. After a stroke or TIA not caused by atrial fibrillation, antiplatelet therapy is generally the cornerstone. In some situations, particularly the high-risk period immediately after a TIA, a second antiplatelet agent may be added for a defined period of time. Whether one or two agents are used, and for how long, is a careful clinical judgement made by your treating team based on the specific cause and your individual risk profile.

If atrial fibrillation is identified as the cause, the approach changes. Anticoagulants are generally more effective than antiplatelets in this setting because they target clots formed in the heart. Most patients with AF who would have once been treated with warfarin are now treated with a DOAC instead, since DOACs are generally easier to take, do not require regular blood tests for monitoring, and have a favourable safety profile. The choice of agent, the timing of starting it after the event, and the balance against any bleeding risk are decisions made by your specialist team.

Blood pressure treatment

High blood pressure is the single most important modifiable risk factor for stroke. Even modest, sustained reductions in blood pressure translate into meaningful reductions in the risk of a recurrent event.

ACE inhibitors are one class of blood pressure medication often used in this setting. The landmark PROGRESS trial showed a significant reduction in recurrent stroke with ACE inhibitor-based therapy after a first stroke or TIA, even in patients whose blood pressure was not markedly elevated. The benefit appeared to extend beyond simple blood pressure lowering. Several other classes of blood pressure medication are also effective, and the right combination for you depends on your other conditions and is a decision for your treating team.

Statins and cholesterol management

Statin therapy is often part of long-term care after a stroke or TIA, sometimes regardless of the baseline LDL cholesterol level. Statins do more than lower cholesterol. They stabilise arterial plaque, reduce inflammation in blood vessel walls, and lower the risk of future events through mechanisms that go beyond simple lipid reduction.

Lp(a) deserves specific mention here too. Standard lipid panels do not routinely include it, yet elevated Lp(a) is an independent risk factor for stroke and coronary artery disease. If your Lp(a) has not been checked, it is worth raising with your doctor, particularly as targeted therapies are becoming available.

Lifestyle Changes That Make a Meaningful Difference

Medications work best alongside genuine lifestyle change. The combination is more powerful than either alone.

Stop smoking

The single highest-impact change available, if relevant to you. Your doctor can help with cessation support and prescription options.

Move daily

Regular walking counts. Small and consistent beats occasional and intense, and 30 minutes most days is a realistic starting target.

Eat Mediterranean

A Mediterranean-style diet has the strongest evidence base for both heart and brain health. Olive oil, vegetables, legumes, oily fish, nuts.

Check your blood pressure

A home monitor is a small investment with a large payoff. Knowing your numbers makes the conversation with your doctor far more useful.

Stay engaged with your team

Long-term follow up matters. Knowing your medications, your targets, and what to ask at each appointment keeps you in control of the plan.

Protect your sleep

Poor sleep raises blood pressure and stress hormones. If snoring or daytime tiredness is significant, ask about obstructive sleep apnoea.

These do not all need to happen at once. Starting with the highest-impact change first, usually blood pressure control or smoking cessation if relevant, and building from there is both realistic and effective.

Heart Matters Resource

When in Doubt, Get Checked Out

If you or someone with you develops sudden facial drooping, arm weakness, speech difficulty, or any other sudden neurological symptom, even one that resolves quickly, call 000 immediately. Do not drive to hospital. Do not wait to see if things improve. A TIA that has passed is still a TIA, and the window for intervention is narrow.

Read: When in Doubt, Get Checked Out →

Questions to Discuss With Your Doctor

Knowing which questions to ask puts you in a much stronger position at every appointment. Here are the ones that matter most after a stroke or TIA:

  • What do you think caused my event, and what investigations are being arranged to find out?
  • Has my MRI shown any pattern that suggests clots from a cardiac source?
  • Do I need longer-term heart monitoring, and which type would you recommend?
  • Which medications am I starting, and what does each one do?
  • What are my blood pressure and LDL cholesterol targets?
  • Has my Lp(a) been checked, and if not, should it be?
  • What is the most important lifestyle change for me to prioritise first?

Conclusion

A stroke or TIA is serious, but it is also one of the most actionable events in medicine. The investigations that follow are not just about understanding what happened. They are about finding the specific, treatable causes that can be addressed.

The people who navigate this best are those who understand what happened, engage fully with the investigation process, and commit to the long-term prevention plan their team puts in place. That is not a passive role. It is an active one, and it makes a real and measurable difference.

Related Reading

Alcohol and the Heart: What the Evidence Actually Shows

heartmatters.com 2026 04 01T223832.942
Key Points

  • The evidence on alcohol and cardiovascular health has shifted significantly in recent years. The previously held view that moderate drinking was cardioprotective is now seriously questioned.
  • Alcohol raises blood pressure, is a significant trigger for atrial fibrillation, contributes to weight gain, and in higher quantities causes alcoholic cardiomyopathy, direct damage to the heart muscle.
  • Current evidence suggests there is no reliably “safe” level of alcohol consumption from a cardiovascular standpoint, though the absolute risk from light drinking remains low for most people.
  • The takeaway is not blanket abstinence. It is honest awareness of what alcohol does to the heart, and making informed choices about how much and how often.
  • For people with established AF, heart failure, hypertension, or cardiomyopathy, alcohol is a topic worth raising directly with their cardiologist.

Alcohol is one of the most common topics that comes up in cardiology consultations, and one where the advice has changed more than patients often realise. For years, the “J-curve” hypothesis held that moderate drinking, a glass or two of red wine a day, was actually protective for the heart. That idea shaped public perception deeply. Many patients arrive in clinic believing that their nightly glass of wine is, if anything, good for them.

The evidence base has shifted considerably. The J-curve has been substantially challenged by more rigorous epidemiological methods, and the current picture is more nuanced and more cautionary than the simple message that “moderate drinking is fine.” That does not mean the message is now blanket abstinence, but it does mean the conversation is worth more than a reassuring wave.

This article is about the honest picture: what alcohol actually does to the cardiovascular system, where the evidence is strong and where it is uncertain, and what that means practically for people who drink regularly and care about their heart health.

What Alcohol Does to the Cardiovascular System

Blood pressure

The most consistent cardiovascular effect of regular alcohol consumption is its impact on blood pressure. Even moderate regular drinking raises blood pressure, and the relationship is dose-dependent. This is not a small or theoretical effect. In someone with borderline hypertension, regular alcohol can be the difference between needing medication and not. In someone already on antihypertensive therapy, regular drinking can undermine the treatment.

Hypertension is one of the most important modifiable cardiovascular risk factors. Anything that reliably raises blood pressure is worth attention, and alcohol does this reliably.

Atrial fibrillation

The relationship between alcohol and atrial fibrillation is one of the strongest and most clinically important in cardiology. Alcohol is a direct trigger for AF episodes in susceptible individuals. The “holiday heart” phenomenon, in which AF occurs during or after heavier drinking, is well documented and reflects acute alcohol toxicity to the cardiac conduction system.

Beyond acute episodes, regular alcohol consumption is an independent risk factor for developing AF. It increases both the incidence of new AF and the recurrence rate in patients who have already been cardioverted or ablated. For patients with AF, this is not a peripheral concern. It is directly relevant to their arrhythmia burden and their stroke risk.

Weight and metabolic effects

Alcohol is energy-dense, approximately 7 calories per gram, almost as much as fat. It contributes to weight gain both directly and indirectly, by reducing dietary restraint and increasing appetite. Excess weight is itself a cardiovascular risk factor and a driver of sleep apnoea, insulin resistance, and dyslipidaemia. The contribution of alcohol to the metabolic picture is frequently underestimated by people who track their food intake but not their drinking.

Alcoholic cardiomyopathy

With sustained heavy drinking over years, direct toxic damage to the heart muscle produces alcoholic cardiomyopathy, a dilated and weakened left ventricle with reduced ejection fraction. This is reversible in its early stages with complete abstinence, but can progress to irreversible heart failure. It is one of the most important reversible causes of dilated cardiomyopathy, and is frequently under-recognised because drinking history is not always volunteered or asked about in detail.

The resveratrol myth

The specific cardioprotective reputation of red wine rested partly on resveratrol, a polyphenol in grape skins that showed promising cardiovascular effects in laboratory studies. The problem is that the concentrations needed to produce these effects in humans are orders of magnitude higher than what a glass of red wine provides. The resveratrol hypothesis has not held up in human trials. The cardiovascular benefits attributed to moderate red wine drinking are now more plausibly explained by confounding. Moderate drinkers tend to have healthier lifestyles overall, rather than the wine itself conferring any specific benefit.

The J-Curve: What It Was and Why It Has Been Challenged

The J-curve referred to the observation in older epidemiological studies that moderate drinkers had lower rates of cardiovascular events than both heavy drinkers and abstainers, suggesting a protective effect at low to moderate intake. This was the basis of the “a glass of wine is good for your heart” message.

The problem identified by more recent research using Mendelian randomisation, a method that uses genetic variants to eliminate confounding, is that the abstainer group in older studies was contaminated by “sick quitters”. These were people who had given up alcohol because of poor health, which made the abstainer group look sicker than it truly was. When this is corrected for, the J-curve largely disappears. The most rigorous current evidence suggests a linear or near-linear relationship between alcohol intake and cardiovascular risk, with no clearly protective threshold.

If you are drinking regularly and have high blood pressure or atrial fibrillation, the alcohol is not helping. In many cases it makes the underlying condition considerably harder to manage.

Professor Peter Barlis, Interventional Cardiologist

What This Means Practically

If you have… What alcohol does The conversation worth having
High blood pressure Raises BP directly, undermines medication Reducing alcohol may lower BP meaningfully without any other change
Atrial fibrillation Triggers episodes, increases recurrence after cardioversion or ablation Reducing or stopping alcohol is one of the most impactful AF management steps available
Heart failure Depresses heart muscle contractility acutely. Alcoholic cardiomyopathy if sustained Many cardiologists recommend abstinence in this setting. The specifics are worth discussing with your own doctor
No established cardiac disease Raises BP dose-dependently. Increases AF risk at higher intakes Awareness and moderation are the practical levers. Appropriate levels for your individual circumstances are a conversation with your doctor

A Note on Guidelines and Moderation

Alcohol guidelines exist across most countries but vary considerably by country, by sex, by age, and by individual health circumstances. Rather than quoting specific numbers that may not apply to your situation, the more useful message is this: moderation matters, and alcohol-free days matter.

A common practical starting point discussed in clinic is at least three alcohol-free days per week. Beyond that, the right level for any individual depends on their sex, weight, underlying health conditions, medications, and family history. This is why the more specific conversation belongs with your own doctor rather than in a general article.

If you drink regularly, an honest conversation with your healthcare professional about your drinking is one of the more useful discussions available to anyone managing a cardiovascular condition. Many people are surprised to find that reducing alcohol has a more significant impact on their blood pressure, their AF burden, or their weight than they expected, often more than other interventions they have been working hard on.

A note for people of East Asian background

An estimated 30 to 50 percent of people of East Asian heritage, including Japanese, Chinese, and Korean populations, carry a variant of the aldehyde dehydrogenase gene (ALDH2) that impairs alcohol metabolism. This produces the characteristic flushing reaction after alcohol (the “Asian flush”), and is associated with higher concentrations of the toxic intermediate acetaldehyde. Because acetaldehyde itself has direct effects on the cardiovascular system, the case for keeping intake low is particularly relevant for people who experience this flushing reaction.

Practical Steps Worth Considering

  • If you have hypertension, two to three alcohol-free weeks followed by a blood pressure check can be a useful experiment. The change is often meaningful and immediate.
  • If you have AF, keeping a diary of episodes and their relationship to drinking occasions can make the pattern clearer.
  • Building at least three alcohol-free days into each week, framed as a practical habit rather than deprivation, supports cardiovascular health.
  • Being honest about how much you are actually drinking matters. A restaurant pour of wine is typically considerably more than a standard drink measure, and the gap between perceived and actual intake is frequently significant.
  • For anyone concerned about their drinking or finding reduction difficult, a GP is a good starting point for a non-judgemental conversation.

Heart Matters Resource

When in Doubt, Get Checked Out

If you drink regularly and have high blood pressure, AF, or heart failure, a direct conversation with your cardiologist about alcohol is one of the more valuable discussions you can have. The impact on your condition may be greater than expected.

Read: When in Doubt, Get Checked Out →

Conclusion

The comfortable message that moderate drinking is heart-protective has not survived more rigorous scientific scrutiny. The current honest picture is that alcohol raises blood pressure reliably, triggers AF in susceptible individuals, and contributes to weight and metabolic risk, with no clearly protective threshold that modern evidence supports.

That does not mean the right answer for everyone is abstinence. For most people who drink lightly and have no established cardiovascular disease, the absolute risk is low and the conversation is about informed awareness rather than prohibition. For people managing hypertension, AF, or heart failure, alcohol is a modifiable factor that is frequently underestimated in its contribution to their condition.

The most useful thing this article can do is prompt that conversation. Honestly, without judgement, and with the clinical specificity it deserves.

Furosemide (Frusemide) Explained

furosemide, frusemide

Key Points

  • Furosemide is a powerful diuretic, a water or fluid tablet, used to remove excess fluid from the body in conditions such as heart failure, kidney disease and liver disease.
  • It works quickly and effectively, and is one of the most widely prescribed medications in cardiovascular medicine.
  • The most noticeable effect is a significant increase in urine output, which is the intended action of the medication.
  • Furosemide is typically taken in the morning, and sometimes again at midday if a second dose is needed. Taking it too late in the day can cause disruptive overnight urination.
  • The dose varies considerably between individuals. Some people need small doses while others require much larger amounts to achieve the same effect.
  • Regular monitoring of kidney function and electrolytes is an important part of long term furosemide use.

If you have been prescribed furosemide, you are in very good company. It is one of the most commonly used medications in cardiology and general medicine, and for good reason. It is highly effective at doing something that is genuinely important for many heart conditions: removing excess fluid from the body.

This article explains what furosemide is, why it is prescribed, what to expect when taking it, and what patients often find most surprising about this medication.

What Is Furosemide?

Furosemide is a diuretic, commonly known as a water or fluid tablet. It works by acting on the kidneys, specifically on a part of the kidney called the loop of Henle, which is why furosemide and medications like it are also called loop diuretics.

Its job is to tell the kidneys to excrete more salt and water into the urine than they otherwise would. The result is a significant increase in urine output, which reduces the total amount of fluid in the body. This is not a side effect, it is the intended action of the medication.

How furosemide works in the kidney, a three step diagram showing sodium, potassium and water being blocked from reabsorption and passing into urine
How furosemide works in the kidney tubule

Why Is It Prescribed?

Furosemide is prescribed whenever excess fluid has accumulated in the body and needs to be removed. This most commonly occurs in:

Heart failure. When the heart is not pumping as efficiently as it should, fluid can back up and accumulate in the lungs, the abdomen, and the legs. This congestion causes breathlessness, swollen ankles, and fatigue. Furosemide is a cornerstone of heart failure treatment because it directly addresses this fluid overload.

Kidney disease. Damaged kidneys do not excrete fluid as effectively, leading to fluid retention that furosemide can help manage.

Liver disease. Liver conditions such as cirrhosis can cause large amounts of fluid to accumulate in the abdomen, a condition called ascites. Furosemide is often used alongside another diuretic called spironolactone in this setting.

High blood pressure. Furosemide is occasionally used for blood pressure control, though other medications are more commonly chosen for this purpose.

Names Around the World

Furosemide is known by a number of different names depending on where you are and whether you are taking the generic or a branded version.

Generic name. Furosemide is the name used in Australia, the United Kingdom, the United States, Europe and most of the world. In some countries, and on older Australian and British prescriptions, it may be spelled frusemide. Both refer to exactly the same medication.

Common brand names include:

  • Lasix, the most widely recognised brand globally, used in Australia, the United States, the United Kingdom and many other countries
  • Frusid, used in Australia
  • Uremide, available in Australia
  • Frusehexal, available in Australia
  • Diural, used in some European countries
  • Seguril, used in Spain
  • Lasilix, used in France

Furosemide or Frusemide? They Are the Same Medication

If your doctor says frusemide, your old prescription says frusemide, or you have always known it by that name, you are not mistaken. Frusemide was the official approved name in Australia, the United Kingdom and most Commonwealth countries when the medication was first introduced in the 1960s.

In 2003 the United Kingdom and Australia officially adopted the international name furosemide, in line with the World Health Organization. Changing what an entire generation of clinicians had been saying and writing for decades takes considerably longer than a regulatory update, and you will hear both names used interchangeably in hospitals and clinics to this day.

If you travel internationally and need to continue your medication, the generic name furosemide will be understood by pharmacists in most countries, even if the brand name differs.

Available Formulations and Doses

Furosemide is available in several different forms, each suited to different clinical situations.

Tablets are the most commonly prescribed form for ongoing outpatient treatment. The standard tablet strengths available in Australia include:

  • 20mg, often used as a starting dose or for mild fluid retention
  • 40mg, the most commonly prescribed strength for heart failure and fluid management
  • 500mg, a high strength tablet sometimes known as Lasix 500. This strength is generally reserved for patients with advanced heart failure, significant diuretic resistance, or severe kidney disease, and is typically prescribed under the guidance of a cardiologist, heart failure specialist or nephrologist. It is not a first line dose and requires careful monitoring of kidney function and electrolytes.

Oral liquid preparations are available for patients who have difficulty swallowing tablets or who need a dose that falls between standard tablet strengths.

Intravenous and intramuscular injections are used in hospital settings when rapid or potent diuresis is needed. When someone is admitted with acute heart failure or severe fluid overload, furosemide given directly into a vein works within minutes and produces a much more immediate and powerful effect than the oral tablet. In hospital, furosemide can also be given as a continuous infusion through a drip when very large amounts of fluid need to be removed over a sustained period.

What to Expect When You Take It

The most immediate and noticeable effect of furosemide is a substantial increase in urination. This typically begins within 30 to 60 minutes of taking the medication and can produce a large volume of urine over several hours. For patients who are significantly fluid overloaded when they first start furosemide, the volume of urine produced can be quite striking.

This increase in urinary frequency and volume is not a problem. It is the medication working exactly as intended. The medical term for the passage of abnormally large volumes of urine is polyuria, and it is an expected feature of diuretic therapy, particularly in the early stages of treatment or after a dose increase.

As the excess fluid is removed from the body over days to weeks, the degree of diuresis typically settles to a more manageable level while the medication continues to prevent fluid from reaccumulating.

When to Take Furosemide

Timing matters with furosemide. Because the medication produces its diuretic effect within an hour of being taken, most doctors prescribe it to be taken in the morning. This way the period of increased urination occurs during waking hours rather than disrupting sleep.

When a larger total daily dose is needed, a second dose is typically prescribed at midday rather than in the afternoon or evening. Taking furosemide too late in the day means its peak diuretic effect will occur in the evening or overnight, which can significantly disrupt sleep with repeated trips to the bathroom.

If you are prescribed furosemide twice daily and find your sleep is being disrupted, it is worth discussing the timing of your second dose with your doctor. A simple adjustment in timing can make a considerable difference to quality of life without changing the total dose.

Why Doses Vary So Much Between Individuals

One of the things that surprises many patients is the wide range of doses that different people need. Furosemide doses can range from as little as 20 milligrams once daily to several hundred milligrams per day in some patients.

20mg → 500mg+
The range of daily furosemide doses used in clinical practice. The dose that is right for you depends on your kidney function, the severity of fluid overload, and how your body responds.

The reason for this variation is not simply about the severity of the underlying condition. Some people have what is called diuretic resistance, where the kidneys respond less efficiently to furosemide. This can occur in people with impaired kidney function, in those who have been on diuretics for a long time, and in some other clinical situations.

In these cases, larger doses are needed to achieve the same degree of fluid removal that a much smaller dose would produce in someone without resistance.

This is also why furosemide doses are sometimes changed over time. A dose that was very effective initially may need to be adjusted as circumstances change. Some patients find their dose increases during periods when their heart failure is less well controlled and then reduces again once things improve. This is entirely expected and is part of the way furosemide is used in clinical practice.

Monitoring While on Furosemide

Because furosemide affects the kidneys and the balance of electrolytes in the body, regular blood tests are an important part of long term treatment. The main things your doctor will monitor include:

Kidney function. Furosemide can sometimes reduce blood flow to the kidneys, particularly if the body becomes too dry from excessive diuresis. Regular checks ensure the kidneys are tolerating the medication well.

Potassium. Furosemide causes the kidneys to excrete potassium along with salt and water. Low potassium, called hypokalaemia, is one of the more common complications of long term furosemide use and can cause muscle cramps, weakness, and in more serious cases affect heart rhythm. Many patients on furosemide are also prescribed a potassium supplement or a potassium sparing diuretic such as spironolactone for this reason.

Sodium. Less commonly, furosemide can affect sodium levels, which your doctor will also keep an eye on.

What Patients Often Ask

Can I skip a dose if I am going out? This is one of the most common questions. Missing an occasional dose to manage a social commitment is understandable, but doing so regularly or skipping doses frequently can allow fluid to reaccumulate. It is worth having a conversation with your doctor about how to best manage furosemide around your lifestyle.

Will I always need it? This depends entirely on the underlying condition. Some patients take furosemide for a defined period and then stop. Others, particularly those with ongoing heart failure or chronic kidney disease, take it long term as part of their regular medication regimen.

What if I feel very thirsty or dizzy? These can be signs that the body has become too dry, sometimes called volume depletion. If you experience significant thirst, dizziness on standing, or a marked reduction in urine output, contact your doctor rather than simply drinking more fluid, as the dose may need adjustment.

The Importance of a Regular Medication Review

Furosemide does not work in isolation. Most people taking it are also prescribed several other medications for their heart, kidneys, or blood pressure, and many of these can interact with furosemide in ways that affect how the body responds.

A number of commonly prescribed medications can affect electrolyte levels, kidney function, or blood pressure when taken alongside furosemide. These include other blood pressure medications, certain pain relievers, some antibiotics, and a range of other cardiac medications. This is not a reason for concern, but it is a reason for awareness.

A regular medication review with your doctor and pharmacist is genuinely valuable for anyone taking furosemide long term. A pharmacist in particular is well placed to look across your entire medication list and identify any combinations that may warrant closer monitoring or a timing adjustment. This kind of review is not about finding problems, it is about making sure every medication you take is working as well as it possibly can.

It is also worth letting any new doctor, specialist or hospital team know that you are taking furosemide, particularly if you are prescribed a new medication, are unwell with vomiting or diarrhoea, or are preparing for a procedure. These are all situations where a temporary adjustment to your furosemide dose may be appropriate.

Heart Matters Resource

Ask About a Home Medicines Review

If you are taking furosemide alongside three or more other regular medications, you may be eligible for a Home Medicines Review with an accredited pharmacist, fully covered by Medicare. It is one of the most underused resources in Australian primary care and one of the most useful for people on long term cardiac medication.

Read: When in Doubt, Get Checked Out →

Conclusion

Furosemide is one of the most important and widely used medications in cardiovascular and kidney medicine. For many people it makes an enormous difference to daily comfort and quality of life, removing the excess fluid that makes breathing difficult and legs heavy.

If you are taking furosemide, the most important things to stay on top of are your regular blood tests, the timing of your doses, and an open conversation with your doctor or pharmacist whenever something changes. A medication review is not something to put off.

You are not alone in managing this. The team looking after you has prescribed furosemide many times and knows how to adjust it as your needs change. If something does not feel right, ask.

This article provides general information only and is not medical advice. Any decisions about your medication, dose or monitoring should be made in conversation with your cardiologist, GP or pharmacist.

More from Heart Matters

Smartwatches and Heart Health: What They Can and Cannot Detect

smartwatches smartwatch af detection

Key Points

  • Modern smartwatches can detect irregular heart rhythms, record a single-lead ECG, alert you to unusually high or low heart rates, and track heart rate variability. These are genuinely useful features, not marketing gimmicks.
  • Atrial fibrillation detection is the most clinically important capability. AF is often silent and the watch may be the first thing to flag it. This is already changing how cardiologists find and diagnose the condition.
  • A smartwatch ECG is a single-lead recording, equivalent to one view of your heart. A hospital ECG uses twelve leads. The watch cannot detect heart attacks, most structural problems, or many other arrhythmias.
  • An alert from your watch is a prompt to see your doctor, not a diagnosis. A positive AF notification needs to be confirmed with a proper clinical ECG before any treatment is considered.
  • False positives are common, particularly in younger people or those who move around during the recording. A notification does not mean you definitely have a heart problem.

Barely a week passes in a modern cardiology clinic without a patient walking in with their wrist extended, watch face up, ready to show their cardiologist something the device has picked up. Sometimes it is a graph. Sometimes it is a notification. Sometimes it is a recording that looks, unmistakably, like atrial fibrillation.

This is new. And it matters.

Consumer wearables have crossed a threshold in recent years. The technology is no longer novelty. For certain conditions, in certain patients, a smartwatch genuinely picks up things that would otherwise have gone undetected for months or years. For other conditions, it raises alarms that turn out to be nothing. Understanding the difference is what this article is about.

What Can a Smartwatch Actually Measure?

The sensors inside a modern smartwatch are more capable than most people realise. Here is what they are actually doing.

Optical Heart Rate (PPG)

Green LEDs shine into your skin and a sensor measures how light reflects off blood vessels. Changes in blood flow with each heartbeat allow the watch to calculate your heart rate and detect irregularities in the rhythm.

Single-Lead ECG

When you place your finger on the watch crown or back panel, an electrical circuit is completed through your body. The watch records the electrical activity of your heart for 30 seconds, producing a trace similar to Lead I of a standard ECG.

Heart Rate Alerts

Most watches can alert you when your resting heart rate goes above or below thresholds you set. An unexpected heart rate above 120 or below 40 at rest is worth knowing about and worth mentioning to your doctor.

Heart Rate Variability (HRV)

HRV measures the variation in time between heartbeats. It is a marker of recovery, stress, and autonomic nervous system function. Useful for general wellbeing tracking, though not a direct measure of heart disease.

The AF Detection Story

Atrial fibrillation is the most common sustained heart rhythm disorder. It affects millions of people worldwide, its prevalence rises sharply with age, and it significantly increases the risk of stroke. It is also, critically, often completely silent.

Many people live with paroxysmal AF, meaning AF that comes and goes, for months or years before it is ever detected. The Stroke Foundation estimates that AF is responsible for around one in five strokes in Australia. It is only found when a routine ECG happens to catch it, or when a stroke occurs, or when someone puts on a smartwatch.

That last possibility is what has changed the clinical landscape.

400,000+
participants enrolled in the Apple Heart Study, one of the largest cardiac screening studies ever conducted using consumer wearables to detect irregular pulse patterns suggesting atrial fibrillation
Perez MV et al. New England Journal of Medicine, 2019

The Apple Heart Study enrolled more than 400,000 participants and monitored them for irregular pulse patterns. Those who received a notification were sent a wearable ECG patch to confirm the finding. Of those who received notifications and wore the patch, 34 per cent had confirmed AF.

That sounds low. But consider the other side: these were people with no idea they might have AF, no symptoms, who would never have been referred for investigation without the watch. For those in whom AF was confirmed, the watch may genuinely have caught something that would otherwise have caused a stroke first.

The Fitbit Heart Study, published in 2021, found similar results. Using the optical sensor in Fitbit devices, the algorithm identified irregular rhythms in a large population, and those flagged were significantly more likely to have confirmed AF on subsequent testing.

I now see patients regularly who come in because their watch told them something was wrong with their heart rhythm. In several cases, it has been completely right. That is a genuinely new development in how we find atrial fibrillation.

The ECG on Your Wrist: What It Can and Cannot Do

The ECG feature on modern smartwatches is impressive technology. It is also frequently misunderstood.

A hospital 12-lead ECG records the electrical activity of your heart from twelve different angles simultaneously. It allows a cardiologist to assess rhythm, conduction, signs of previous heart attacks, and much more. A smartwatch ECG records from a single perspective for 30 seconds. Here is what that means in practice.

The smartwatch ECG CAN detect The smartwatch ECG CANNOT detect
Atrial fibrillation (irregular rhythm with absent P waves) Heart attacks, including STEMI (requires multiple leads)
Normal sinus rhythm (reassuring during symptoms) Most ischaemia or reduced blood flow to the heart
Some supraventricular arrhythmias if recorded during an episode Most structural heart abnormalities
Obvious bradycardia (very slow heart rate) Bundle branch blocks and conduction disorders reliably
Evidence prompting further investigation A normal result does not rule out heart disease

The most important line in that table is the last one. A normal ECG on your watch, recorded when you feel fine, does not mean your heart is healthy. It means your rhythm was normal at that moment, from that angle.

The Devices: What Each One Offers

Not all smartwatches are equal when it comes to cardiac monitoring. Here is where the main consumer devices currently stand.

Apple Watch

Series 4 and later

AF detection and single-lead ECG

Continuous background AF detection, on-demand 30-second ECG, and high and low heart rate alerts. Regulatory clearance in many countries including Australia. ECG results can be exported as PDF to share with your cardiologist.

Kardia by AliveCor

KardiaMobile and 6L

Dedicated ECG device

A purpose-built personal ECG device rather than a general smartwatch. Clips to a phone or watch band. The 6L version records six leads simultaneously. Worth discussing with your cardiologist if ongoing rhythm monitoring is a priority.

Samsung Galaxy

Series 4 and later

AF detection and single-lead ECG

Single-lead ECG and passive AF detection via the optical sensor. Regulatory clearance varies by country. A capable option for Android users who want cardiac rhythm monitoring in a general-purpose smartwatch.

Fitbit

Sense and Charge 6

Passive AF detection and ECG

Passive AF detection via the optical sensor and on-demand ECG recording. The Fitbit Heart Study provided good evidence for the AF detection capability. A lighter, more fitness-focused option for those who want cardiac monitoring without a full smartwatch.

When Your Watch Sends You an Alert: What to Do

This is where patients most often need guidance. An alert from your watch can feel alarming. Here is how to think about it.

You Have Received an Irregular Rhythm or AF Notification

Do not panic. A single notification, particularly in a younger person or one who was moving during the recording, has a meaningful false positive rate. It is a prompt to investigate, not a confirmed diagnosis.

Do not ignore it either. If your watch flags an irregular rhythm, particularly more than once, or if you also feel palpitations, breathlessness, or dizziness alongside it, contact your GP or cardiologist.

Save the recording. Export the ECG trace from your watch before your appointment if possible. Cardiologists can often see something useful in the raw trace even if the watch algorithm was uncertain.

A clinical ECG is needed for confirmation. No treatment for AF should begin based on a watch notification alone. A proper ECG, and in many cases a Holter monitor, is required to confirm the diagnosis and guide management.

The Limitations You Need to Understand

False positives are real. The optical sensor is susceptible to movement, a loose watch band, and poor skin contact. In younger, lower-risk populations, the majority of AF notifications may be false positives. Unnecessary anxiety and unnecessary investigations are real consequences.

False negatives also occur. Paroxysmal AF that comes and goes may simply not be happening at the moment you record. A normal reading does not mean AF is absent. Your cardiologist may still recommend a longer-duration cardiac monitor even after a normal watch ECG.

It cannot detect a heart attack. Chest pain or pressure that could represent a heart attack is a medical emergency. Call Triple Zero immediately. Do not try to record an ECG on your watch first.

It is not a substitute for clinical care. A smartwatch is a useful supplement to medical monitoring, not a replacement for it.

If You Think You Are Having a Heart Attack

Chest pain, pressure, tightness, pain spreading to the arm or jaw, sweating, or sudden severe breathlessness are potential symptoms of a heart attack. This is a medical emergency.

Call Triple Zero (000) in Australia immediately. Do not drive yourself to hospital. Do not attempt to record an ECG on your watch first. Time matters enormously and delays cost lives.

What Your Cardiologist Wants You to Know

Wear it consistently. Passive background monitoring is more valuable than on-demand recordings. Wearing it overnight, when resting heart rate is naturally lower, adds real diagnostic value.

Bring your data to appointments. Many watches allow you to export your heart rate history and ECG recordings. Having this at a consultation is genuinely useful.

Do not over-interpret every reading. A slight irregularity on one recording, a brief period of elevated heart rate during exercise, a single unusual-looking trace: these should be noted but not catastrophised. Context is provided by the clinical picture, not the watch alone.

Ask your cardiologist about dedicated ECG devices. If you have already been diagnosed with AF or another arrhythmia and your cardiologist wants you to monitor for episodes, a purpose-built ECG device may produce better-quality recordings. Your cardiologist can advise which approach suits your situation.

Conclusion

Can smartwatches detect heart problems? Yes, some of them, in some circumstances, with meaningful accuracy. The AF detection story in particular is genuinely compelling, and cardiologists are seeing its real-world impact every week.

But a smartwatch is not a cardiologist on your wrist. It is a screening tool with real limitations, a false positive rate that deserves respect, and a fundamental inability to diagnose the most time-critical cardiac emergencies.

Used well, with realistic expectations and a good relationship with a doctor who can contextualise what it finds, a modern smartwatch is a valuable addition to your heart health toolkit.

Related Articles

Does a Coffee a Day Keep AF at Bay?

coffee AF
Key Points

  • A new clinical trial published in JAMA found that patients with atrial fibrillation who continued drinking around one cup of coffee a day were 39% less likely to have a recurrence of AF compared to those who stopped completely.
  • This is the first randomised clinical trial to directly test whether coffee triggers AF episodes, overturning decades of routine clinical advice to avoid caffeine.
  • The finding does not mean patients should increase their coffee intake, and it does not apply to everyone. The trial involved patients who were already moderate coffee drinkers.
  • As with all research, there are limitations, and guidelines have not yet changed. Talk to your cardiologist before changing anything about your daily habits.

If you have been told you have atrial fibrillation, there is a good chance someone, whether a doctor, a nurse, or a well-meaning friend, has suggested you cut back on coffee. For years, caffeine has been viewed with suspicion in the context of heart rhythm disorders, and many patients with AF have quietly given up their morning cup out of caution. If you experience palpitations or an irregular heartbeat and are not sure whether it is related to AF, our dedicated article on palpitations explains what different sensations mean and when to seek help.

A major new clinical trial, published in JAMA in 2026 and conducted across five hospitals in Australia, the United States, and Canada, has now challenged that longstanding advice in a way that will be meaningful for many people living with AF.

The short version: in patients who already drank moderate amounts of coffee, continuing to drink around one cup a day after cardioversion was not harmful, and may actually have been protective against the return of irregular heart rhythm.

What is the DECAF trial?

DECAF stands for Does Eliminating Coffee Avoid Fibrillation, which neatly captures the question the researchers set out to answer. It is the first randomised clinical trial ever conducted on this specific question, which makes it a landmark study even by the standards of cardiology research.

The trial enrolled 200 adults with persistent AF who were all scheduled for cardioversion, the procedure that uses a controlled electrical impulse to reset the heart back into a normal rhythm. The average age of participants was 69 years and 71% were male. All were moderate coffee drinkers, consuming around seven cups per week, which is roughly one cup a day, at some point in the previous five years.

After successful cardioversion, patients were randomly assigned to one of two groups. One group was asked to continue drinking at least one cup of caffeinated coffee each day. The other group was asked to avoid all coffee and caffeine entirely, including decaffeinated coffee. Most participants were already being treated for AF with anticoagulation and some with antiarrhythmic or rate control medications, and these were continued throughout the trial. Both groups were then followed for six months to see whose heart rhythm stayed normal and whose returned to AF. The coffee group maintained their habit of around seven cups per week throughout the trial, while the abstinence group reduced to essentially none.

☕ Coffee group
47% of patients who continued drinking coffee had a recurrence of AF or atrial flutter within six months.

🚫 No coffee group
64% of patients who avoided all caffeine had a recurrence of AF or atrial flutter within six months.

📉 The difference
Patients who continued drinking coffee were 39% less likely to have a recurrence of AF compared to those who abstained entirely.

✅ Safety
Emergency visits and hospitalisations were similar between both groups. No deaths occurred in either group during the trial.

☕ What does this mean in practice?
For every 6 people with AF who continued drinking their daily coffee after cardioversion, approximately 1 avoided a recurrence that they would otherwise have had. That is a meaningful real-world benefit, and a number worth discussing with your cardiologist.

The result was statistically significant, meaning it is unlikely to be explained by chance alone. The lead investigator, Professor Christopher Wong of the University of Adelaide, described the results as astounding, noting that the trial suggests coffee is not only safe but potentially protective for patients with AF. Importantly, the DECAF trial was funded by the National Institutes of Health, with no pharmaceutical or industry sponsorship involved, which strengthens confidence in the independence of the findings.

Why might coffee help rather than hurt?

For decades, the assumption was that caffeine, as a stimulant, would make the heart more prone to irregular rhythms. The DECAF trial suggests the reality is more nuanced. The researchers and commentators offered several possible explanations for why moderate coffee consumption might actually be associated with fewer AF episodes.

Adenosine blockade
Caffeine blocks adenosine receptors in the heart. Adenosine can promote the conditions that allow AF to develop and persist, so blocking it may have a protective effect.

Anti-inflammatory effects
Coffee contains compounds beyond caffeine that have anti-inflammatory properties. Inflammation plays a role in the development of AF, so reducing it may help maintain normal rhythm.

Physical activity
Coffee is associated with increased physical activity, and exercise is known to reduce AF burden. Patients in the coffee group may have been more active as a result.

Caffeine withdrawal
Abruptly stopping caffeine causes physiological changes that may themselves be disruptive to heart rhythm. Regular moderate consumption avoids this stress on the body.

What are the limitations of this trial?

No single clinical trial, however well-designed, changes medical practice on its own, and the DECAF researchers themselves were careful to highlight several important limitations that patients should understand.

The trial enrolled 200 patients, which is a relatively modest number in the world of clinical cardiology. While the result was statistically significant, a larger study could either strengthen or modify these findings. The open-label design, meaning that both patients and researchers knew which group each person was in, could also influence how symptoms were reported or how often patients sought medical attention. There were also some differences in baseline characteristics between the two groups: the abstinence group was on average two years older and included more women, which may have influenced the results despite statistical adjustments.

The researchers also noted that AF episodes were detected through routine clinical care rather than a standardised monitoring schedule, which means some episodes in either group may not have been captured.

For years I have had the conversation in clinic about coffee and AF. Most patients ask about it, and until now the honest answer was that we did not have good randomised evidence either way. The DECAF trial changes that. For patients who are already moderate coffee drinkers, this is genuinely reassuring. But it is not a signal to start drinking more, and it is not a study of patients who never drank coffee. Context matters, and the conversation with your cardiologist still matters.

What does this mean for you?

If you have AF and you have been worried about your morning coffee, this trial offers genuine reassurance. For patients who are already moderate coffee drinkers, the best available evidence now suggests that continuing to drink around one cup a day is not harmful and may, if anything, be beneficial for heart rhythm stability after cardioversion.

However, it is important to understand what this trial does not tell us. It was not conducted in people who do not drink coffee at all, so it does not suggest that non-coffee-drinkers should start. It does not apply to large amounts of caffeine. It does not mean that every patient with AF should drink more coffee. And it does not override the advice of your own cardiologist, who knows your specific heart anatomy, medications, and circumstances.

Clinical guidelines have not yet been updated to reflect this trial, and further research will follow. In the meantime, the most sensible message is that you no longer need to feel guilty about your morning cup, but as always, any significant changes to your lifestyle or habits are worth discussing with your clinical team first.

Read More, Heart Matters

Our dedicated articles on atrial fibrillation cover what AF is, how it affects stroke risk, and the full range of treatment options available, explained in plain language.

Understanding AF and Stroke Risk →
AF Treatment Options →

A note before you refill the kettle
This trial is interesting and genuinely reassuring for moderate coffee drinkers with AF. But it is not a prescription to drink more coffee, and it is not a reason to change anything without speaking to your cardiologist first. Every patient is different, every heart is different, and the right conversation is the one you have with the clinician who knows your case. Bring this up at your next appointment and ask what it means for you specifically.

Conclusion

The DECAF trial is a genuinely important piece of research that challenges a longstanding assumption in cardiology. For decades, patients with AF have been advised, often without strong evidence, to avoid caffeine. The first properly conducted randomised trial on this question tells a different story: for moderate coffee drinkers, continuing to enjoy one cup a day after cardioversion appears to be safe and may reduce the likelihood of AF returning.

It is a finding worth knowing about. It is also a reminder that in medicine, advice that has been repeated for many years is not always grounded in the evidence we now have the tools to generate. This trial gave us that evidence, and it is genuinely good news for the many patients with AF who have been quietly missing their coffee.

More from Heart Matters

References

  • Wong CX, Cheung CC, Montenegro G, et al. Caffeinated Coffee Consumption or Abstinence to Reduce Atrial Fibrillation: The DECAF Randomized Clinical Trial. JAMA. 2026;335(4):317-325. doi:10.1001/jama.2025.21056
  • First presented by Christopher X. Wong, MBBS, MPH, PhD, at the American Heart Association Scientific Sessions 2025, New Orleans, LA, November 9, 2025. Published in print JAMA January 27, 2026
  • Funding: The DECAF trial was supported by the National Institutes of Health (NIH), National Heart, Lung and Blood Institute. No commercial or industry funding was involved in this research.

Stay Informed

The latest heart health news, research and resources — delivered to your inbox.