About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- AF = irregularly irregular rhythm, absent P waves, narrow QRS (unless aberrant conduction)
- Classify: paroxysmal (<7 days, self-terminating), persistent (>7 days), permanent (accepted, no further rhythm control)
- Stroke risk assessment: CHA₂DS₂-VASc score → anticoagulate if ≥2 (men) or ≥3 (women)
- Rate control is first-line for most patients (beta-blocker or rate-limiting CCB)
- Anticoagulation: DOACs first-line (apixaban, rivaroxaban, edoxaban, dabigatran) — warfarin only if DOAC contraindicated or mechanical valve
Overview
Atrial fibrillation is a supraventricular tachyarrhythmia characterised by disorganised atrial electrical activity leading to ineffective atrial contraction. It is the commonest sustained cardiac arrhythmia worldwide and a major risk factor for ischaemic stroke. Management centres on two parallel decisions: rate vs rhythm control, and stroke risk assessment with anticoagulation.
Epidemiology
AF affects approximately 1.4 million people in the UK (2–3% of the adult population). Prevalence rises steeply with age — around 10% of people over 75. Risk factors include hypertension (most common modifiable risk factor), heart failure, valvular disease, obesity, obstructive sleep apnoea, thyrotoxicosis, excessive alcohol intake ("holiday heart"), and cardiothoracic surgery. AF independently increases stroke risk approximately 5-fold.
Clinical Features
Symptoms
Palpitations (often described as fast, irregular heartbeat)
Dyspnoea on exertion
Fatigue and reduced exercise tolerance
Dizziness or lightheadedness
Chest discomfort
Asymptomatic (incidental finding in up to 30%)
Stroke or TIA as the presenting feature
Acute pulmonary oedema or haemodynamic compromise
Signs
Irregularly irregular pulse — the hallmark finding
Pulse deficit (apical rate > radial rate)
Varying intensity of S1
Signs of underlying cause: thyrotoxicosis, valvular disease, heart failure
Tachycardia with haemodynamic instability
Investigations
First-line
12-lead ECGAbsent P waves, irregularly irregular QRS complexes, fibrillatory baseline. Confirms the diagnosis
BloodsTFTs (exclude thyrotoxicosis), FBC, U&Es, LFTs, coagulation screen
Second-line
EchocardiogramAssess for structural heart disease, LV function, left atrial size, valvular pathology
Ambulatory ECG monitoring24 h or 7-day Holter if paroxysmal AF suspected but not captured on resting ECG
CHA₂DS₂-VASc scoreStroke risk tool: C=CHF, H=HTN, A₂=Age≥75(2pts), D=DM, S₂=Stroke/TIA(2pts), V=Vascular disease, A=Age65-74, Sc=Sex(female)
Specialist
TOE (transoesophageal echo)Exclude left atrial appendage thrombus before cardioversion if duration >48 h and not adequately anticoagulated
Electrophysiology studyIf catheter ablation is being considered
1
Acute management
- If haemodynamically unstable → emergency DC cardioversion
- If stable and onset <48 h → consider pharmacological or electrical cardioversion
- If stable and onset >48 h (or unknown) → rate control + anticoagulate for ≥3 weeks before cardioversion (or TOE to exclude thrombus)
- Rate control: IV beta-blocker (metoprolol) or IV diltiazem; digoxin if sedentary
2
Long-term: Rate control (first-line per NICE)
- First-line: beta-blocker (bisoprolol) OR rate-limiting CCB (diltiazem/verapamil)
- Do NOT use rate-limiting CCB + beta-blocker together
- Second-line: digoxin (as monotherapy if sedentary, or add to beta-blocker/CCB)
- Target resting heart rate < 110 bpm (lenient control; stricter if symptomatic)
3
Long-term: Rhythm control (if rate control fails or symptomatic)
- Flecainide — if no structural heart disease (pill-in-pocket for paroxysmal AF)
- Amiodarone — if structural heart disease present (beware thyroid, liver, lung toxicity)
- DC cardioversion — electrical cardioversion under sedation
- Catheter ablation (pulmonary vein isolation) — increasingly offered as first-line rhythm control in suitable patients
4
Anticoagulation (all patients)
- Assess stroke risk: CHA₂DS₂-VASc ≥2 (men) or ≥3 (women) → offer anticoagulation
- DOACs are first-line: apixaban, rivaroxaban, edoxaban, or dabigatran
- Warfarin only if DOAC contraindicated or mechanical prosthetic valve
- Assess bleeding risk (ORBIT score) — not a reason to withhold anticoagulation, but guides monitoring
- Do NOT offer aspirin as stroke prophylaxis in AF (no longer recommended)
Complications
- Ischaemic stroke: 5-fold increased risk — the most feared complication. Cardioembolic strokes tend to be large and disabling
- Heart failure: Tachycardia-mediated cardiomyopathy from prolonged uncontrolled ventricular rate
- Systemic thromboembolism: Mesenteric ischaemia, limb ischaemia, renal infarction
- Bleeding: Anticoagulation-related — GI bleed, intracranial haemorrhage
- Reduced quality of life: Palpitations, anxiety, exercise intolerance
UKMLA Exam Tips
- 1Irregularly irregular pulse with no P waves = AF until proven otherwise
- 2CHA₂DS₂-VASc: remember that age ≥75 and prior stroke/TIA score 2 points each — everything else scores 1
- 3Aspirin is NO LONGER recommended for stroke prevention in AF — NICE dropped it
- 4Do NOT combine a beta-blocker with verapamil/diltiazem → risk of complete heart block
- 5Flecainide is contraindicated in structural heart disease (can cause fatal arrhythmia)
- 6"Pill-in-pocket" flecainide = self-administered flecainide for infrequent paroxysmal AF episodes
- 7If AF + WPW (delta wave on ECG) → avoid AV-nodal blocking drugs (digoxin, verapamil, beta-blockers) — they can facilitate VF via the accessory pathway
practicetest your knowledge on atrial fibrillationApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — cardiovascular and beyond.
open q-bank