Initiation of Anticoagulation in Atrial Fibrillation
Anticoagulation is recommended for patients with non‑valvular atrial fibrillation whose CHA₂DS₂‑VASc score indicates elevated stroke risk. High‑risk is defined as a score ≥ 2 in men or ≥ 3 in women [1][2][3]. Direct oral anticoagulants are the preferred first‑line agents over warfarin for most patients [1][2][3].
Risk Stratification
- CHA₂DS₂‑VASc scoring
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Points: Congestive heart failure = 1, Hypertension = 1, Age ≥ 75 = 2, Diabetes = 1, Stroke/TIA/thromboembolism = 2, Vascular disease = 1, Age 65‑74 = 1, Sex female = 1 [1][2][3].
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Thresholds for anticoagulation
- Men: initiate anticoagulation at score ≥ 2 [1][2].
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Women: initiate anticoagulation at score ≥ 3 [1][2].
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Low‑risk patients (men ≤ 1, women ≤ 2) may be managed without anticoagulation, with consideration of aspirin only in selected cases [2][3].
Preferred Anticoagulant Choice
- Direct oral anticoagulants (DOACs) are first‑line therapy for eligible patients [1][2][3].
- Warfarin may be used when DOACs are contraindicated, in severe renal impairment, or when cost/access issues arise [1][2].
Clinical Considerations and Contraindications
- Evaluate bleeding risk using tools such as the HAS‑BLED or ATRIA scores; high bleeding risk does not automatically preclude anticoagulation but warrants shared decision‑making [1].
- Absolute contraindications include active major bleeding, recent intracranial hemorrhage, and severe thrombocytopenia [2][3].
- Relative contraindications include uncontrolled hypertension, recent gastrointestinal bleeding, and severe liver disease; modify therapy accordingly [2][3].
Monitoring and Follow‑up
- For DOACs, routine laboratory monitoring is not required; assess renal and hepatic function at least annually [2][3].
- For warfarin, maintain INR in the therapeutic range (2.0–3.0) with regular monitoring [2][3].
- Re‑assess CHA₂DS₂‑VASc and bleeding risk periodically, especially after clinical events that alter risk status [2][3].