What is atrial fibrillation?

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting over 400,000 Australians. In AF, the electrical impulses in the atria fire chaotically — up to 350–600 times per minute — causing the atria to quiver rather than contract in an organised rhythm. This produces an irregular, often fast ventricular response.

Types of AF

• Paroxysmal AF: Episodes that terminate spontaneously or with intervention within 7 days. Often recurrent.
• Persistent AF: AF lasting more than 7 days. Requires cardioversion to restore sinus rhythm.
• Long-standing persistent AF: Continuous AF lasting >12 months. Cardioversion may still be attempted.
• Permanent AF: AF where rhythm control is no longer pursued. Rate control and anticoagulation become the focus.

Symptoms

• Palpitations — irregular, often rapid heartbeat
• Breathlessness at rest or on exertion
• Fatigue and reduced exercise capacity
• Dizziness or presyncope
• Chest discomfort or pressure
• Reduced blood pressure in fast AF
• Asymptomatic — many patients have no symptoms (silent AF)

Causes & risk factors

• Advancing age — prevalence rises from <1% under 50 to >15% over 80
• Hypertension — most common modifiable risk factor
• Heart failure and left ventricular dysfunction
• Coronary artery disease
• Valvular heart disease (especially mitral valve disease)
• Obesity and obstructive sleep apnoea
• Hyperthyroidism
• Excessive alcohol (holiday heart syndrome)
• Diabetes mellitus

• 12-lead ECG: Confirms AF when the patient is in the arrhythmia. Shows absent P waves, irregular RR intervals.
• Holter monitor (24h–14 day): Essential for paroxysmal AF. Prolonged monitoring detects intermittent episodes not captured on a resting ECG.
• Echocardiogram: Assesses left atrial size (a marker of AF burden and ablation success), left ventricular function, and valve disease.
• Thyroid function tests: Hyperthyroidism is a reversible cause of AF.
• Sleep study: OSA is present in up to 30% of AF patients and, when treated, reduces AF recurrence.
• CHA₂DS₂-VASc score: Validated stroke risk scoring tool that guides anticoagulation decisions.

AF management follows the ABC pathway: Anticoagulation, Better symptom control, Cardiovascular risk factor management.

Anticoagulation (stroke prevention)

Direct oral anticoagulants (DOACs) — apixaban, rivaroxaban, dabigatran — are first-line therapy for stroke prevention in AF. They are superior to warfarin for most patients with non-valvular AF (CHA₂DS₂-VASc score ≥2 in men, ≥3 in women).

Rate control

Beta-blockers (metoprolol, bisoprolol) and calcium channel blockers (diltiazem, verapamil) reduce the heart rate during AF, improving symptoms without necessarily restoring normal rhythm. Target resting heart rate <110 bpm (lenient) or <80 bpm (strict).

Rhythm control

• Electrical cardioversion — DC shock under sedation to restore sinus rhythm
• Pharmacological cardioversion — flecainide, amiodarone
• Catheter ablation (pulmonary vein isolation) — now guideline-recommended early for symptomatic paroxysmal and persistent AF

Risk factor modification

Weight loss, blood pressure control, treatment of sleep apnoea, alcohol reduction and regular exercise all reduce AF burden and recurrence.

• AF is a major independent risk factor for stroke (5× higher risk)
• With appropriate anticoagulation, stroke risk is dramatically reduced
• AF is associated with a 2-fold increase in heart failure risk
• Rhythm control strategies (especially early ablation) improve quality of life and reduce hospitalisation
• AF management has improved significantly — most patients lead active lives with appropriate treatment

• Control blood pressure (most important modifiable risk factor)
• Weight loss — even 10% body weight reduction significantly reduces AF burden
• Treat obstructive sleep apnoea
• Limit alcohol — even moderate intake increases risk
• Regular moderate-intensity exercise
• Manage diabetes and metabolic syndrome