Atrial Fibrillation

Atrial fibrillation (AF) is a supraventricular tachyarrhythmia with uncoordinated atrial activation and irregularly irregular ventricular response.

Prevalence about 2 to 4% of adults, increasing to 10% over age 80; lifetime risk about 1 in 3.

Classification: first diagnosed, paroxysmal (under 7 days), persistent (over 7 days), long standing persistent (over 12 months), permanent.

Risk factors: age, hypertension, heart failure, valvular disease, coronary disease, diabetes, obesity, sleep apnoea, alcohol, thyrotoxicosis, chronic kidney disease, athletic training, post operative state, genetic factors.

Complications: ischaemic stroke (5 times risk; CHA2DS2 VASc guides), heart failure, tachycardia cardiomyopathy, dementia, mortality.

• Palpitations, dyspnoea, fatigue, chest discomfort, presyncope; asymptomatic in up to one third.
• Irregularly irregular pulse, variable first heart sound, pulse deficit.
• Haemodynamic instability, acute heart failure, hypotension in rapid AF.
• Stroke or systemic embolism as first presentation.

• 12 lead ECG: absent P waves, irregular RR, fibrillatory waves. Prolonged monitoring (Holter, patch, implantable loop recorder) for paroxysmal AF; smartwatch alerts require ECG confirmation.
• Echocardiography: left atrial size, ventricular function, valve disease, thrombus (TOE).
• Laboratory: thyroid function, electrolytes, renal and liver function, CBC, glucose.
• Sleep study, coronary evaluation, and alcohol assessment as indicated.
• Stroke risk: CHA2DS2 VASc (heart failure, hypertension, age 75 or more 2 points, diabetes, stroke 2 points, vascular disease, age 65 to 74, female sex); anticoagulation for 2 or more in men, 3 or more in women. HAS BLED for modifiable bleeding risks.

Acute

• Unstable: synchronised direct current cardioversion (120 to 200 J biphasic).
• Stable rapid AF: rate control with metoprolol 2.5 to 5 mg IV or 25 to 100 mg orally, diltiazem 0.25 mg/kg IV then 5 to 15 mg/h (avoid in heart failure with reduced ejection fraction), digoxin 0.25 mg IV every 2 hours up to 1.5 mg, amiodarone 150 mg IV over 10 minutes then 1 mg/min for 6 hours.
• Rhythm control: electrical cardioversion after 3 weeks of anticoagulation or TOE exclusion of thrombus (if over 48 hours). Pharmacological: flecainide 200 to 300 mg orally (structurally normal heart), vernakalant, ibutilide 1 mg IV, amiodarone.

Stroke prevention

• DOAC preferred: apixaban 5 mg twice daily (2.5 mg if two of age 80 or more, weight 60 kg or less, creatinine 1.5 mg/dL or more), rivaroxaban 20 mg daily with food, edoxaban 60 mg daily, dabigatran 150 mg twice daily. Warfarin (INR 2 to 3) for mechanical valves and moderate to severe mitral stenosis.
• Left atrial appendage occlusion for patients with contraindication to long term anticoagulation.

Long term rhythm and rate control

• Early rhythm control improves outcomes (EAST AFNET 4). Antiarrhythmics: flecainide 50 to 150 mg twice daily or propafenone, sotalol 80 to 160 mg twice daily, dronedarone 400 mg twice daily (not in heart failure), amiodarone 200 mg daily.
• Catheter ablation (pulmonary vein isolation) for symptomatic paroxysmal or persistent AF, and first line in heart failure with reduced ejection fraction (CASTLE AF); success 60 to 80%.
• Rate control targets lenient (resting heart rate under 110) or strict (under 80) when symptomatic; atrioventricular node ablation with pacing for refractory cases.
• Risk factor modification: weight loss (10% or more), alcohol reduction, treat sleep apnoea, hypertension control, exercise.