The CHA₂DS₂-VASc score is the international standard for estimating annual stroke risk in patients with non-valvular atrial fibrillation (NVAF). It refines the older CHADS₂ score by including additional risk factors (vascular disease, age 65-74, female sex) that improve risk stratification — particularly in patients previously classified as "low risk" by CHADS₂.

The score ranges from 0 to 9 points. A higher score indicates higher annual stroke risk and a stronger indication for oral anticoagulation.

• C — Congestive heart failure or LV dysfunction (1 point)
• H — Hypertension (1 point)
• A₂ — Age ≥75 (2 points)
• D — Diabetes mellitus (1 point)
• S₂ — Prior stroke/TIA/thromboembolism (2 points)
• V — Vascular disease (MI, PAD, aortic plaque) (1 point)
• A — Age 65-74 (1 point)
• Sc — Sex category (female) (1 point)

• Score 0: No antithrombotic therapy. Annual reassessment.
• Score 1 (female sex alone): No anticoagulation needed.
• Score 1 (other than female): Consider oral anticoagulation — shared decision with patient.
• Score ≥2: Oral anticoagulation recommended.
• Choice: DOAC preferred over warfarin in most patients (except mechanical valve, moderate-severe mitral stenosis). Always pair with HAS-BLED bleeding risk assessment.

• Valvular AF (mechanical valve, moderate-severe mitral stenosis) — anticoagulation indicated regardless of score
• Atrial flutter without AF — same stroke risk, but ablation often curative
• Acute AF in setting of reversible cause (hyperthyroidism, alcohol, sepsis) — treat underlying cause
• Subclinical AF on CIED <5 minutes/day — risk uncertain