In which adult patients with non‑valvular atrial fibrillation or atrial flutter should the CHA₂DS₂‑VASc score be used to assess stroke risk and guide anticoagulation decisions?

When to Use CHA₂DS₂-VASc Score

Use the CHA₂DS₂-VASc score in all adult patients with non-valvular atrial fibrillation or atrial flutter to assess stroke risk and guide anticoagulation decisions. 1

Patient Population for CHA₂DS₂-VASc Application

Apply the CHA₂DS₂-VASc score to patients with non-valvular AF, defined as atrial fibrillation in the absence of moderate-to-severe mitral stenosis or mechanical heart valves. 2 This definition is critical because:

• Patients with mechanical heart valves (any position) require immediate warfarin therapy regardless of any stroke risk score—the CHA₂DS₂-VASc score is invalid and potentially unsafe in this population 2
• Patients with moderate-to-severe rheumatic mitral stenosis require warfarin (INR 2.0-3.0) independent of CHA₂DS₂-VASc scoring, as their stroke risk is approximately 20-fold higher than the general population 2
• All CHA₂DS₂-VASc validation studies explicitly excluded these two groups 2

Patients with non-valvular AF eligible for CHA₂DS₂-VASc scoring include those with:

• Bioprosthetic heart valves 2
• Mild mitral stenosis 2
• Other non-severe valvular diseases (aortic stenosis, mitral regurgitation) 2, 3
• Paroxysmal, persistent, or permanent AF patterns—the stroke risk is identical at the same CHA₂DS₂-VASc score regardless of AF type 4, 5

Patients to EXCLUDE from CHA₂DS₂-VASc Assessment

Do not use the CHA₂DS₂-VASc score in the following situations: 1

• Mechanical prosthetic heart valve (any position)
• Moderate-to-severe mitral stenosis
• Transient or reversible causes of AF (pneumonia, hyperthyroidism, pregnancy, cardiac surgery)
• Patients on comfort care measures only
• Patients with another indication for anticoagulation
• Planned or present left atrial appendage occlusion or ligation 1

Anticoagulation Thresholds Based on CHA₂DS₂-VASc Score

For men with CHA₂DS₂-VASc ≥2 or women with CHA₂DS₂-VASc ≥3, oral anticoagulation is mandated (Class I recommendation). 1, 4 The sex-adjusted threshold accounts for female sex adding 1 point to the score. 1

For men with CHA₂DS₂-VASc = 1 or women with CHA₂DS₂-VASc = 2, consider oral anticoagulation through shared decision-making. 4 This intermediate-risk group has an annual stroke rate of 1.61-2.75%, which exceeds the theoretical threshold for novel oral anticoagulants (0.9%) but falls below the traditional warfarin threshold (1.7%). 6, 7 Research demonstrates that not all risk factors carry equal weight—age 65-74 years confers the highest stroke rate (3.34-3.50%/year), while vascular disease or hypertension alone confer lower rates (1.91-1.96%/year). 6

For men with CHA₂DS₂-VASc = 0 or women with CHA₂DS₂-VASc = 1, no oral anticoagulation is recommended (Class I). 4 The annual stroke risk is ≤0.6-0.68%. 4, 7

Preferred Anticoagulant Selection

Direct oral anticoagulants (DOACs)—dabigatran, rivaroxaban, apixaban, or edoxaban—are recommended over warfarin as first-line therapy (Class I, Level A). 1, 4, 5 DOACs demonstrate at least non-inferiority and in some trials superiority to warfarin for stroke prevention with lower serious bleeding risks. 5

Warfarin (target INR 2.0-3.0) is mandatory only for mechanical heart valves or moderate-to-severe mitral stenosis. 4, 2 DOACs are contraindicated in mechanical valve patients (Class III Harm recommendation) after dabigatran trials showed increased thromboembolic and bleeding events. 2

Critical Pitfalls to Avoid

Never substitute antiplatelet therapy (aspirin) for anticoagulation—this is contraindicated (Class III, Level A) as it provides minimal stroke protection with similar bleeding risk. 4

Do not withhold anticoagulation based solely on a high HAS-BLED score (≥3). 4, 5 A high bleeding risk score indicates the need for closer monitoring and modifiable risk factor management, not contraindication to anticoagulation. 4

Do not differentiate anticoagulation decisions based on AF pattern (paroxysmal vs. persistent vs. permanent)—stroke risk is identical at the same CHA₂DS₂-VASc score. 4, 5

Avoid underdosing DOACs out of bleeding concerns, as this increases stroke risk without proven safety benefits. 4

Periodically reevaluate anticoagulation need (Class I, Level C) as risk factors evolve over time. 4 Assess renal function before initiating DOACs and reassess at least annually. 5