What it is
Atrial fibrillation (AF) is an irregular, disorganized atrial rhythm causing an irregularly irregular pulse. The atria do not contract effectively, and the ventricles respond irregularly depending on AV node conduction.
- Paroxysmal AF: self-terminates (usually <7 days, often <48 hours).
- Persistent AF: lasts >7 days or requires cardioversion.
- Long-standing persistent: continuous >12 months.
Genetics
- AF can cluster in families; common genetic variants (e.g., PITX2, ZFHX3) contribute risk alongside age and comorbidities.
- Rare monogenic forms involve ion-channel genes (e.g., SCN5A, KCNQ1) and may present earlier.
Risk factors and causes
Major risk factors
- Age (strongest risk factor)
- Hypertension
- Obesity / metabolic syndrome
- Diabetes
- Sleep apnoea
- Heart failure / cardiomyopathy
- Valvular disease
- Alcohol excess
- Hyperthyroidism
Mechanisms (simplified)
- Triggers (often pulmonary veins)
- Substrate: atrial stretch, enlargement, fibrosis, inflammation
- Remodeling: “AF begets AF” (electrical + structural changes over time)
Symptoms
Common
- Palpitations
- Breathlessness
- Fatigue
- Reduced exercise tolerance
- Dizziness / “washed out” feeling
Sometimes silent
Some people have no symptoms, and AF is detected incidentally or after a stroke. If symptoms are minimal, the focus is often on stroke prevention and rate control.
Investigations
- ECG (diagnostic): irregularly irregular rhythm, no consistent P waves.
- Ambulatory monitoring: Holter / patch monitor / event recorder if intermittent.
- Echocardiogram: left atrial size, LV function, valves.
- Bloods: thyroid function, electrolytes, renal function; consider iron studies if clinically indicated.
- Consider sleep apnoea screening if suggestive symptoms.
Stroke risk — CHA₂DS₂-VASc
AF increases stroke risk. The CHA₂DS₂‑VASc score estimates annual stroke risk and helps guide anticoagulation decisions.
CHA₂DS₂‑VASc Calculator (with estimated annual stroke risk)
Approximate annual stroke risk table (untreated)
| Score | Estimated stroke risk (%/year) |
|---|---|
| 0 | 0% |
| 1 | 1.3% |
| 2 | 2.2% |
| 3 | 3.2% |
| 4 | 4.0% |
| 5 | 6.7% |
| 6 | 9.8% |
| 7 | 9.6% |
| 8 | 12.5% |
| 9 | 15.2% |
Typical guideline approach: anticoagulation is generally recommended at higher scores (often ≥2 in men or ≥3 in women), and considered at intermediate scores depending on bleeding risk and patient preference.
Treatments (overview)
Core goals
- Prevent stroke (anticoagulation when indicated)
- Control heart rate (reduce symptoms and prevent cardiomyopathy)
- Restore/maintain sinus rhythm when appropriate
- Treat drivers (weight, BP, sleep apnoea, alcohol, thyroid disease)
Common medications
- Rate control: beta blockers; diltiazem/verapamil; digoxin (selected)
- Rhythm control: flecainide/propafenone (selected); sotalol/dofetilide (selected); amiodarone (effective but toxicity)
- Stroke prevention: DOACs or warfarin where indicated
Rhythm control vs rate control
Rate control
Accept AF but keep the ventricular rate controlled. This can work well if symptoms are mild and stroke risk is addressed.
- A common lenient target is <110 bpm at rest in stable patients.
- If rates remain high, risk of tachycardia‑induced cardiomyopathy rises.
Rhythm control
Try to restore and maintain sinus rhythm (cardioversion, antiarrhythmics, ablation). This is often favored when symptoms persist, AF is early, or when AF worsens heart failure.
- Rhythm control can improve quality of life and exercise capacity.
- It may reduce cardiovascular events in selected patients when used early.
Cardioversion and sinus rhythm durability
Short‑term
- Electrical cardioversion often restores sinus rhythm immediately, but early recurrence is common if the atria are irritable or enlarged.
- Stroke prevention rules still apply: if risk is high, anticoagulation is usually continued even after restoring sinus rhythm.
Long‑term
- Recurrence risk rises with longer AF duration, larger left atrium, obesity, sleep apnoea, and untreated hypertension.
- Antiarrhythmic drugs and risk‑factor treatment can increase durability.
Ablation outcomes (AF vs flutter)
AF ablation is usually pulmonary vein isolation. This differs from typical atrial flutter ablation, which targets a single circuit (CTI) and is often more “curative.”
After AF ablation
- Short term: “blanking period” recurrences can occur in the first ~3 months.
- Long term: AF can recur; repeat procedures are sometimes needed.
- Stroke prevention decisions are still based on CHA₂DS₂‑VASc, not just rhythm status.
Life expectancy and long‑term complications
AF is associated with a higher risk of death and major cardiovascular disease. Importantly, much of the risk is driven by the things that travel with AF (hypertension, heart failure, diabetes, vascular disease) and by complications such as stroke and heart failure.
Relative risk of major outcomes (meta‑analysis)
| Outcome | Relative risk associated with AF (approx.) | Why it matters |
|---|---|---|
| All‑cause mortality | ~1.46× | AF is associated with a substantially higher risk of death over time. |
| Cardiovascular mortality | ~2.03× | Higher risk of fatal cardiovascular events. |
| Stroke | ~2.42× | AF-related strokes are often more severe; prevention is central. |
| Heart failure | ~4.99× | AF and heart failure worsen each other; rate control and rhythm strategies may help selected patients. |
| Ischaemic heart disease | ~1.61× | Shared risk factors; AF can unmask underlying disease. |
| Chronic kidney disease | ~1.64× | AF is linked with cardio‑renal disease progression. |
Practical “what changes prognosis most” table
| Modifiable driver | Effect on AF burden / outcomes | Examples |
|---|---|---|
| Uncontrolled heart rate | Higher risk of tachycardia‑induced cardiomyopathy and heart failure | Persistent resting HR >110–120, exertional HR very high |
| Hypertension | Promotes atrial enlargement and stroke risk | BP control, reduce salt, treat sleep apnoea |
| Obesity / sleep apnoea | Higher recurrence after cardioversion/ablation; more AF progression | Weight loss, CPAP where indicated |
| Alcohol excess | Increases AF episodes and triggers | Reduction or abstinence in frequent AF |
Bottom line: AF is not “benign,” but outcomes improve substantially when stroke risk is treated, rates are controlled, and the underlying drivers are addressed.
Anticoagulants (blood thinners) — risks and trade‑offs
Anticoagulants reduce stroke risk but increase bleeding risk. The decision is usually individualized using stroke risk (CHA₂DS₂‑VASc) and bleeding risk factors (e.g., prior bleeds, kidney disease, interacting medications).
Deep dive: BloodThinnersRisks.com
Emergency warning signs
- Chest pain/pressure, fainting, severe breathlessness
- Stroke symptoms (face droop, arm weakness, speech difficulty)
- Very fast heart rate with lightheadedness or low blood pressure symptoms
If you suspect a medical emergency, call local emergency services immediately.
Educational video
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