Atrial Fibrillation (AF) With Palpitations, Breathlessness and Chest Tightness: Why It Raises Stroke Risk, the CHA2DS2-VA Score, DOACs vs Warfarin, and Catheter Ablation

From a reader: admitted to hospital with palpitations, breathlessness and chest tightness, then told it is AF. What should we worry about?

Someone shared that they were admitted to hospital with palpitations, breathlessness, chest tightness and dizziness, and tests showed atrial fibrillation (AF).
Their doctors explained the risks of stroke, blood clots and heart failure, and talked about rate-control medicines, anticoagulants and catheter ablation. People around them wanted to know what each of these does.

Short answer: AF can be controlled, but two things need attention together: preventing clots from reaching the brain with an anticoagulant based on a risk score, and controlling palpitations and breathlessness with rate-control medicines, rhythm-control medicines or catheter ablation, alongside weight loss and stopping alcohol.
If an irregular-heartbeat alert on a blood pressure monitor is where your story started, read
Blood pressure monitor shows an irregular heartbeat but the ECG is normal

1. What AF is, and why it causes palpitations, breathlessness and chest tightness

Direct answer: normally the heartbeat starts in an orderly way at the sinus node (SA node). In AF, many chaotic electrical waves circle through the upper chambers, which quiver instead of contracting, and the lower chambers beat fast and irregularly, causing palpitations, breathlessness, chest tightness or dizziness.

AF usually starts at the openings of the pulmonary veins

A study of 45 people with frequent AF that did not respond to medicines found 69 abnormal trigger points, and 65 of them (94%) were inside the pulmonary veins.
AF started with a burst of firing at about 340 per minute, and after these points were ablated, 62% had no recurrence during follow-up
(Haïssaguerre 1998).
This discovery is the basis of today’s pulmonary vein isolation (PVI).

Why palpitations, breathlessness and chest tightness happen

When the upper chambers stop contracting, the lower chambers receive less blood, and when the lower chambers beat too fast they have less time to fill, so less blood is pumped out. This causes tiredness and dizziness.
A fast heart needs more oxygen, which can cause chest tightness. Some people have no symptoms and AF is found by chance on an ECG or a smartwatch.

Types of AF

By duration: episodes that stop on their own within 7 days (paroxysmal), episodes lasting more than 7 days (persistent), and permanent AF, where the doctor and patient agree to stop trying to restore rhythm.
Stroke risk depends on the risk score, not on whether AF is paroxysmal or permanent
(ESC 2024).

AF and heart failure

Framingham data showed heart failure developing in 33 per 1,000 person-years among people with AF, and AF developing in 54 per 1,000 person-years among people with heart failure.
Having both raised mortality (HR 2.7 in men and 3.1 in women when heart failure followed AF)
(Wang 2003).
Keeping the heart rate from staying too fast for long also protects the heart muscle.

2. Why AF raises stroke risk, and what the CHA2DS2-VA score tells you

Direct answer: slow blood flow in the left atrial appendage (LAA) lets clots form, and a clot that breaks loose can block a brain artery. Doctors use the CHA2DS2-VA score to judge whether the risk is high enough for an anticoagulant to help.

Most clots form in the left atrial appendage

A review of 23 studies found left atrial clots in 222 of 1,288 people with non-rheumatic AF, and in 201 of them (91%) the clot was in, or started from, the left atrial appendage
(Blackshear 1996).
Clots from the heart tend to be large, so they block large brain arteries and cause more severe strokes than other causes.

The CHA2DS2-VA score

The score was developed from CHA2DS2-VASc (Lip 2010).
The 2024 European guideline removed the point for female sex and recommends an anticoagulant at 2 points or more, and that one should be considered at 1 point
(ESC 2024).
The 2023 US guideline still uses CHA2DS2-VASc and recommends an anticoagulant when yearly stroke risk is 2% or more, which equals 2 points or more in men or 3 points or more in women
(ACC/AHA 2023).

Table: components of the CHA2DS2-VA score

Use this to prepare questions for your doctor. Decisions about medicines also weigh bleeding risk and other conditions.

Data from Thai patients with AF

The COOL-AF registry followed 3,405 Thai patients with AF for 3 years and found stroke or systemic embolism at 1.51 per 100 person-years.
CHA2DS2-VA predicted risk about as well as CHA2DS2-VASc, but women with 2 points or more had 1.72 times the risk of men, especially above age 70
(Krittayaphong 2025).

Why aspirin is not enough

A meta-analysis of 29 trials and 28,044 people found that warfarin cut stroke by 64%, antiplatelet drugs by 22%, and warfarin was 39% better than antiplatelet drugs
(Hart 2007).
Current guidelines therefore do not recommend aspirin to prevent stroke in AF.

3. Anticoagulants: DOACs vs warfarin, food and other medicines

Direct answer: direct oral anticoagulants (DOACs), namely apixaban, rivaroxaban, dabigatran and edoxaban, prevent stroke slightly better than warfarin, cut bleeding in the brain by about half, and need no INR blood tests. Warfarin is still needed for people with mechanical heart valves or moderate-to-severe mitral stenosis.

Evidence from four large trials

A pooled analysis of 71,683 people found that DOACs reduced stroke or systemic embolism by 19% (RR 0.81), bleeding in the brain by 52% (RR 0.48) and death from any cause (RR 0.90),
but increased gastrointestinal bleeding (RR 1.25)
(Ruff 2014).
European and US guidelines therefore recommend DOACs before warfarin for people who can take them.

Table: DOACs vs warfarin

Generic names only. Choice and dose depend on kidney function, age, weight and other medicines.

On warfarin: you do not need to give up green vegetables

Vitamin K helps make clotting proteins, which is where warfarin acts. Suddenly eating much more leafy greens can lower the INR; suddenly eating much less can raise it.
The key is to eat a similar amount each week and tell your doctor before a big change in diet.

• Dark leafy greens such as Chinese kale, spinach and broccoli are fine, in a steady amount.
• Large amounts of strong green tea, some fruit juices and vitamin K supplements: ask a pharmacist first.
• Heavy alcohol raises bleeding risk and makes the INR swing.

Medicines and herbs reported to interact with warfarin

A review of 181 articles covering 120 drugs or foods found that 72% of reports described a stronger warfarin effect.
Consistent reports involved azole antifungals, macrolide and quinolone antibiotics, NSAID painkillers, SSRI antidepressants, omeprazole, lipid-lowering drugs and amiodarone,
and herbs such as green tea and danshen were also reported
(Holbrook 2005).

Lower bleeding risk without stopping the medicine yourself

• Take it at the same time every day using a pill box or calendar. If you miss a dose, follow the advice for that medicine or ask a pharmacist; do not double up on your own.
• Tell your dentist and doctors before tooth extraction, endoscopy or surgery.
• Use paracetamol instead of NSAIDs when possible, and keep blood pressure controlled.
• Carry a card or list with the name of your anticoagulant and the time of the last dose.

4. Rate control, rhythm control or catheter ablation

Direct answer: rate-control medicines keep the lower chambers from beating too fast. Rhythm-control medicines and catheter ablation try to restore a normal rhythm, which relieves symptoms well, but every option still needs an anticoagulant according to the risk score.

Rate control

Medicines include beta-blockers, the calcium channel blockers diltiazem and verapamil, and digoxin.
The RACE II trial in 614 people with permanent AF found that lenient control (resting pulse below 110 beats per minute) was no worse than strict control (below 80 beats per minute), with major events in 12.9% vs 14.9% over 3 years
(Van Gelder 2010).

Early rhythm control

The EAST-AFNET 4 trial in 2,789 people diagnosed with AF within the past year who also had cardiovascular conditions found that early rhythm control lowered cardiovascular death, stroke, or hospitalization for heart failure or acute coronary syndrome
to 3.9 vs 5.0 per 100 person-years (HR 0.79). The rhythm-control group mainly used antiarrhythmic drugs, or ablation, and had serious rhythm-control side effects in 4.9% vs 1.4%
(Kirchhof 2020).

Catheter ablation

A doctor passes a catheter through a vein in the groin and uses heat or cold around the openings of the pulmonary veins (PVI) to stop abnormal signals from entering the upper chambers.

• As first treatment: in EARLY-AF, among 303 people with paroxysmal AF, recurrence at 1 year was 42.9% after cryoballoon ablation vs 67.8% with medicines (Andrade 2021).
• General patients: in CABANA, among 2,204 people, ablation did not significantly reduce the combined outcome of death, disabling stroke, serious bleeding or cardiac arrest (8.0% vs 9.2%), but it reduced recurrence (49.9% vs 69.5%) (Packer 2019).
• Heart failure with weak pumping: in CASTLE-AF, among 363 people, ablation reduced death or hospitalization for heart failure, 28.5% vs 44.6% (Marrouche 2018).

For fear, pain and recovery after ablation, read
Afraid of cardiac ablation: pain, risks and recovery

Do you still need an anticoagulant after ablation?

Yes, for at least 2 months afterwards. After that, European and US guidelines base the decision on the stroke risk score, not on whether the rhythm is back to normal,
because AF can return without symptoms
(ESC 2024).

If you cannot take long-term anticoagulants

Closing the left atrial appendage with a catheter-delivered device (LAAC) is an option for some people. Pooled data from 2 trials of 1,114 people followed for 5 years showed stroke prevention similar to warfarin
and less bleeding in the brain (HR 0.20), although ischemic stroke trended slightly higher without reaching significance (HR 1.71)
(Reddy 2017).

5. Weight, alcohol and coffee: what has evidence

Direct answer: weight loss and stopping alcohol reduced AF in research studies; moderate coffee intake was not found to increase AF.

Losing 10% of body weight

The LEGACY study of 355 overweight people with AF found that those who lost 10% or more of their weight were about 6 times more likely to stay free of AF than the other groups,
but weight swings of more than 5% reduced the benefit
(Pathak 2015).

Stopping alcohol

A trial in 140 people drinking 10 or more drinks a week found AF returned in 53% of those who stopped drinking vs 73% of those who continued, over 6 months
(Voskoboinik 2020).

Coffee

A study of 386,258 adults found each additional daily cup of coffee was linked to a 3% lower risk of arrhythmia (HR 0.97), including AF
(Kim 2021).
If coffee clearly brings on palpitations for you, cut back, but there is no need to stop it to prevent AF. Read more at
Palpitations after quitting coffee: caffeine and arrhythmia

• Aim to lose weight gradually until you reach 10%, then keep it off.
• Stop or sharply cut alcohol, especially if you take an anticoagulant.
• Keep blood pressure and diabetes on target.
• If you snore loudly and are sleepy in the day, get tested for sleep apnea.
• Do regular brisk walking or moderate exercise once a doctor says it is safe.

6. Notes for Buddhist monks with AF and the laypeople who offer them meals

Direct answer: monks do not choose their own food and eat only before noon, so anticoagulant plans need to be worked out with the doctor and pharmacist. Laypeople can help a great deal by offering suitable food and not offering medicines or herbs without asking first.

Non-communicable diseases among Thai monks

A review of 22 studies found that obesity and high blood pressure were the most common non-communicable diseases among Thai Buddhist monks, who make up about 0.3% of the population,
and that religious practices, such as receiving food from others, shape health behaviors
(Jeamjitvibool 2022).
Both conditions are risk factors for AF and stroke.

When to take medicines

Medicines can be taken at the times the doctor prescribes. Medicines that must be taken with food, such as rivaroxaban 15–20 mg, should be timed with the morning or late-morning meal.
Twice-daily apixaban and dabigatran can be taken in the evening without food. Ask a pharmacist to fit the schedule to the daily routine.

How laypeople can help

• Offer meals with vegetables, fish, tofu and whole grains; offer fewer fried foods, sweets and very sweet drinks.
• For monks taking warfarin, meals that change every day can make vitamin K intake swing, so tell the doctor about the meal routine; the doctor may adjust the dose or INR checks.
• Do not offer painkillers, herbal pills, herbal liquor tonics or other herbs without asking a doctor or pharmacist, because they can increase bleeding.
• Help keep a note of the anticoagulant’s name and the time of the last dose nearby; this matters a great deal in emergency stroke treatment.
• Watch for F.A.S.T. signs and call emergency services right away if they appear.

Healthcare coverage

In Thailand, monks and novices can use the Universal Coverage Scheme at their registered hospital; call the 1330 hotline to check entitlements.

7. F.A.S.T.: when stroke is suspected, every minute counts

Direct answer: if F.A.S.T. signs appear, call emergency services right away without waiting to see if they pass, and tell the responders which anticoagulant is taken and when the last dose was, because this affects treatment choices.

• F (Face): face drooping, one corner of the mouth dropping when smiling
• A (Arm): weakness of an arm or leg on one side
• S (Speech): slurred speech or inability to speak
• T (Time): note the last time the person was seen well, then call emergency services

Why speed matters

Pooled data on 6,756 people from 9 trials showed that clot-busting medicine given through a vein (alteplase) helps when given within 4.5 hours, and the earlier the better;
within 3 hours, 32.9% recovered without significant disability vs 23.1%
(Emberson 2014).
For selected people with a large brain artery blocked, removing the clot through a catheter helps up to 6–24 hours, with 49% vs 13% functionally independent among 206 people
(Nogueira 2018).
Some people on anticoagulants cannot receive clot-busting medicine but can still have the clot removed, so they need to reach a hospital with a stroke team quickly.
Read more warning signs at
Early warning signs of stroke and heart disease

Table: comparing treatment and prevention options in AF

Generic names and drug classes only. Treatment choices must be supervised by a doctor.

Common beliefs versus the evidence

Anticoagulants are clot-dissolving drugs

Not true. They prevent new clots. Dissolving a clot that has already blocked a brain artery uses a different medicine given only in hospital.

Everyone with AF must take an anticoagulant for life

It depends on the risk score. People with a low score may not need one, while people with a high score usually need it long term, with regular review.

After ablation you can stop the medicine right away

No. The medicine continues for at least 2 months, and after that the decision follows the stroke risk score.

On warfarin you must give up green vegetables

Not needed. The key is eating a similar amount each week so the INR stays steady.

Aspirin is enough

It is not. Aspirin prevents far fewer strokes than anticoagulants, and current guidelines do not recommend it for this.

Coffee sets off AF, so you must stop it

Large studies have not found that moderate coffee raises AF. Alcohol, by contrast, has trial evidence of increasing recurrence.

Frequently asked questions (FAQ)

What is atrial fibrillation (AF), and why does it cause palpitations and breathlessness?

AF is a condition in which electrical signals in the upper chambers of the heart become chaotic, so the upper chambers quiver instead of contracting and the lower chambers beat fast and irregularly. Less blood is pumped out, causing palpitations, breathlessness, chest tightness or dizziness. Most triggers start at the openings of the pulmonary veins.

Why are people with AF at risk of stroke?

Blood flows slowly in the left atrial appendage and forms clots there; about 91% of left atrial clots in AF sit in this appendage. A clot that breaks loose can block a brain artery. The Framingham Study found that AF raises stroke risk nearly fivefold.

Who should take an anticoagulant, and what is the CHA2DS2-VA score?

CHA2DS2-VA gives points for heart failure, high blood pressure, age, diabetes, previous stroke or TIA, and vascular disease. The 2024 European guideline recommends an anticoagulant at 2 points or more and says one should be considered at 1 point. Doctors also weigh bleeding risk and kidney function.

How do DOACs differ from warfarin, and do I need to watch my diet?

DOACs prevent 19% more strokes than warfarin, cut bleeding in the brain by about half and need no INR tests, but slightly increase gastrointestinal bleeding. People on warfarin do not need to give up green vegetables but should eat a similar amount each week and ask a pharmacist before using a new medicine or herb.

How is catheter ablation done, and who is it for?

A doctor passes a catheter through a groin vein and uses heat or cold around the openings of the pulmonary veins. It suits people who still have symptoms on medicines, people who do not want long-term rhythm-control drugs, and people with heart failure. As a first treatment, recurrence at 1 year was 42.9% vs 67.8% with medicines.

Can I stop my anticoagulant after ablation?

It continues for at least 2 months afterwards. After that, guidelines base the decision on the stroke risk score, not on whether the rhythm is back to normal, because AF can return without symptoms.

How should monks who eat only before noon take anticoagulants?

Medicines that must be taken with food, such as rivaroxaban 15–20 mg, should be timed with the morning or late-morning meal. Twice-daily apixaban or dabigatran can be taken in the evening without food. Monks on warfarin should tell the doctor that meals change every day, and laypeople should not offer medicines or herbs without asking first.

What should I do if stroke is suspected in someone with AF?

If the face droops, one side of the body is weak, or speech is slurred, call emergency services right away, note the last time the person was seen well, and tell the responders which anticoagulant is taken and when the last dose was. Clot-busting medicine works within 4.5 hours, and earlier is better.

Scientific mechanism

Triggers and substrate: heart muscle sleeves extending into the pulmonary veins fire early beats (triggers). When the upper chambers stretch and scar from high blood pressure, obesity or age (substrate),
the signals circle in many loops and AF becomes sustained, and AF itself keeps remodeling the upper chambers
(Haïssaguerre 1998).

Clots: all three parts of Virchow’s triad are present: slow flow in the appendage, a changed atrial wall, and blood that clots more easily
(Blackshear 1996).

Medicines: warfarin blocks the recycling of vitamin K, lowering production of several clotting factors. DOACs directly block factor Xa (apixaban, rivaroxaban, edoxaban) or thrombin (dabigatran),
so their effect is steadier and independent of vitamin K
(Ruff 2014).

Ablation: creates a ring of scar around the pulmonary vein openings so triggers cannot send signals into the upper chambers. It works better before the substrate has changed much, which is the reasoning behind early treatment
(Andrade 2021).

Written and reviewed by Asst. Prof. Dr. Norawit Raatpiboon

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