Atrial fibrillation

A supraventricular tachyarrhythmia caused by chaotic atrial electrical activity leading to ineffective atrial contraction and an irregularly irregular ventricular rhythm (no distinct P waves on ECG).

• Most common sustained arrhythmia; associated with ≈5× higher stroke risk (atrial clots can embolize) and increased mortality. Can also cause heart failure (tachycardia-mediated cardiomyopathy) if uncontrolled. Frequent exam topic linking arrhythmia to stroke prevention.

• Symptoms range from palpitations, anxiety, shortness of breath, or lightheadedness to syncope – or even asymptomatic (incidental). Pulse is classically irregularly irregular; apex heart rate may exceed peripheral pulse rate (pulse deficit).
• Often in older patients with hypertension or structural heart disease (coronary artery disease, heart failure, valvular disease like rheumatic mitral stenosis). Other triggers: acute illness or infection, thyrotoxicosis (new AF + weight loss/tremor → check TSH), alcohol binge ('holiday heart'), surgery, pulmonary embolism.

1. Confirm diagnosis with ECG (absent P waves, irregularly spaced QRS complexes). Evaluate for precipitating causes: check TSH (hyperthyroidism), electrolytes, etc.
2. Assess stability: if hemodynamic instability (hypotension, acute heart failure, angina) → immediate synchronized cardioversion.
3. If stable: initiate rate control (e.g., IV beta blocker or diltiazem for rapid AF; digoxin if hypotensive or in systolic HF). Consider rhythm control (antiarrhythmics or elective cardioversion) for persistent symptoms, difficulty controlling rate, or in younger patients.
4. Estimate stroke risk with CHA₂DS₂-VASc score and decide on anticoagulation. Generally, ≥2 (men) or ≥3 (women) → chronic anticoagulation indicated (barring contraindications).
5. Perform a transthoracic echocardiogram to identify structural heart disease (e.g., valve stenosis, left atrial enlargement) and help guide management. If AF duration >48 h before planned cardioversion, patient needs 3 weeks of anticoagulation or a transesophageal echo to exclude atrial clot.

1. Rate control: β-blockers (e.g., metoprolol) or non-dihydropyridine calcium channel blockers (diltiazem) to slow AV conduction (goal <110 bpm at rest). Add digoxin in refractory cases or if concomitant HFrEF.
2. Rhythm control: consider cardioversion (electrical or pharmacologic) for new-onset or symptomatic AF. Antiarrhythmics (e.g., flecainide, sotalol, amiodarone) or catheter ablation can be used to maintain sinus rhythm in recurrent AF, especially in younger patients.
3. Anticoagulation: indicated for stroke prevention in eligible patients (per CHA₂DS₂-VASc). DOACs (direct oral anticoagulants like apixaban) are first-line for non-valvular AF. Use warfarin in valvular AF (e.g., mechanical valve or rheumatic MS).

• Clue: Hyperthyroidism often presents as new-onset AF – always check a TSH level.
• Mnemonic: CHA₂DS₂-VASc for stroke risk factors in AF: CHF, Hypertension, Age ≥75 (2 points), Diabetes, Stroke/TIA (2), Vascular disease, Age 65–74, Sex Category (female).
• Irregularly irregular pulse with no P waves = atrial fibrillation until proven otherwise.

• AF with hemodynamic instability (hypotension, pulmonary edema, chest pain) → emergency synchronized cardioversion is required.
• AF with WPW (Wolff-Parkinson-White): irregular wide-complex tachycardia → avoid AV nodal blockers (risk of VF); use procainamide or immediate cardioversion.

1. Irregularly irregular pulse → get ECG to confirm AF (no P waves).
2. Unstable patient (hypotension, etc) → immediate cardioversion.
3. Stable → control rate (AV nodal blocker); consider rhythm control if needed (e.g., cardioversion).
4. Assess CHA₂DS₂-VASc stroke risk → if elevated, start anticoagulation (prefer DOACs).
5. Investigate underlying causes: check TSH, echo for structural heart disease; manage reversible triggers (e.g., stop alcohol).

• Elderly patient with long-standing hypertension and diabetes, now with palpitations, an irregularly irregular heartbeat, and absent P waves on ECG → Atrial fibrillation (rate control and anticoagulate as indicated).
• Middle-aged patient with weight loss, tremor, and tachycardia is found to have AF → AF secondary to thyrotoxicosis (check TSH; treat the hyperthyroidism and use beta blockers).
• Otherwise healthy adult with an episode of AF after heavy alcohol intake (holiday celebration) → 'Holiday heart' syndrome (paroxysmal AF triggered by alcohol binge).