Quick Overview
Atrial fibrillation (AF) is the most common sustained arrhythmia, affecting 2-3% of the UK population. Management centres on stroke prevention via anticoagulation (using CHA₂DS₂-VASc scoring) and rate/rhythm control strategies. NICE NG196 emphasises structured anticoagulation decision-making and DOAC preference over warfarin in eligible patients.
Core Facts & Concepts
CHA₂DS₂-VASc Score (annual stroke risk assessment):
- Congestive heart failure (1 point)
- Hypertension (1 point)
- Age ≥75 years (2 points)
- Diabetes (1 point)
- Stroke/TIA/thromboembolism (2 points)
- Vascular disease (MI, PAD, aortic plaque) (1 point)
- Age 65-74 years (1 point)
- Sex category (female) (1 point)
📊 Anticoagulation thresholds:
- Score 0 (men) or 1 (women): No anticoagulation
- Score ≥1 (men) or ≥2 (women): Offer anticoagulation
DOAC vs Warfarin Selection:
- DOACs preferred (apixaban, rivaroxaban, edoxaban, dabigatran) unless contraindicated
- Warfarin if: mechanical heart valve, moderate-severe mitral stenosis, CrCl <15 ml/min
- No routine monitoring needed for DOACs (vs INR 2-3 for warfarin)
Bleeding Risk Assessment (ORBIT/HAS-BLED):
- HAS-BLED ≥3: High bleeding risk (does NOT contraindicate anticoagulation-identify modifiable factors)
- Components: Hypertension, Abnormal renal/liver function, Stroke, Bleeding history, Labile INR, Elderly (>65), Drugs/alcohol
Problem-Solving Approach
Step-by-step anticoagulation decision:
- Confirm AF diagnosis (ECG showing irregularly irregular rhythm, absent P waves)
- Calculate CHA₂DS₂-VASc score → Anticoagulate if ≥1 (men) or ≥2 (women)
- Assess bleeding risk (HAS-BLED/ORBIT) → Address modifiable factors (BP control, alcohol cessation)
- Select anticoagulant:
- First-line: DOAC (check renal function, drug interactions)
- Warfarin: if DOAC contraindicated or valvular AF
- Review annually for stroke/bleeding risk changes
🚩 Red flags requiring immediate action:
- Haemodynamic instability → DC cardioversion
- Fast ventricular rate (>110 bpm) with symptoms → Rate control urgently
- Stroke/TIA while on anticoagulation → Review adherence, consider switching agent
Analysis Framework
Rate vs Rhythm Control Strategy:
| Rate Control | Rhythm Control |
|---|---|
| First-line for most patients | Symptomatic despite rate control |
| Target: <110 bpm (lenient) if asymptomatic | New-onset AF (<48h) or younger patients |
| Drugs: β-blocker, diltiazem/verapamil, digoxin | Cardioversion ± antiarrhythmics (amiodarone, flecainide) |
| No anticoagulation difference | Requires TOE if >48h (exclude thrombus) |
DOAC Comparison (key differences):
| Drug | Dosing | Renal threshold | Reversal agent |
|---|---|---|---|
| Apixaban | 5mg BD | Avoid if CrCl <15 | Andexanet alfa |
| Rivaroxaban | 20mg OD | Avoid if CrCl <15 | Andexanet alfa |
| Edoxaban | 60mg OD | Avoid if CrCl <15 or >95 | Andexanet alfa |
| Dabigatran | 150mg BD | Avoid if CrCl <30 | Idarucizumab |
Visual Aid
Key Points Summary
✓ Anticoagulate if CHA₂DS₂-VASc ≥1 (men) or ≥2 (women)-stroke prevention is paramount
✓ DOACs preferred over warfarin unless mechanical valve, mitral stenosis, or CrCl <15 ml/min
✓ HAS-BLED ≥3 = high bleeding risk but NOT a contraindication-address modifiable factors
✓ Rate control (target <110 bpm) is first-line for most; rhythm control if symptomatic or young
✓ β-blockers or rate-limiting CCBs for rate control; digoxin only if sedentary/heart failure
✓ Cardioversion requires 3 weeks anticoagulation pre/4 weeks post OR TOE to exclude thrombus if >48h
✓ Annual review essential-reassess stroke risk, bleeding risk, and anticoagulation appropriateness
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