At what CHADS-VASc (Cardiac failure, Hypertension, Age >= 75, Diabetes, Stroke/TIA/thromboembolism, Vascular disease, Age 65-74, Sex category) score should anticoagulation therapy be initiated?

Anticoagulation Recommendations Based on CHA₂DS₂-VASc Score

Oral anticoagulation should be initiated in patients with atrial fibrillation who have a CHA₂DS₂-VASc score ≥2 in men or ≥3 in women, while patients with a score of 0 can safely omit anticoagulation therapy. 1

Risk Stratification Using CHA₂DS₂-VASc Score

The CHA₂DS₂-VASc score is the recommended tool for assessing stroke risk in patients with atrial fibrillation, with points assigned as follows:

• Congestive heart failure/LV dysfunction: 1 point
• Hypertension: 1 point
• Age ≥75 years: 2 points
• Diabetes mellitus: 1 point
• Stroke/TIA/thromboembolism (previous): 2 points
• Vascular disease (prior MI, PAD, aortic plaque): 1 point
• Age 65-74 years: 1 point
• Sex category (female): 1 point

Anticoagulation Recommendations by Score

CHA₂DS₂-VASc Score = 0 (Men) or 1 (Women, where the only point is for female sex)

• No anticoagulation therapy is recommended 2, 1
• Studies show these patients have a very low annual stroke risk (0.49-0.64% per year) 3, 4
• Anticoagulation does not provide significant benefit in this truly low-risk group 3

CHA₂DS₂-VASc Score = 1 (Men) or 2 (Women, where one point is for female sex)

• Consider oral anticoagulation 1, 5
• Annual stroke risk is significantly higher (1.55-2.75% per year) compared to score = 0 5, 4
• Not all risk factors carry equal weight; age 65-74 years confers the highest risk (3.50% annual stroke rate) 5
• The American College of Cardiology guidelines indicate anticoagulation may be considered (Class IIb recommendation) 2

CHA₂DS₂-VASc Score ≥2 (Men) or ≥3 (Women)

• Oral anticoagulation is strongly recommended 2, 1
• Class I recommendation from the American College of Cardiology 2
• DOACs (dabigatran, rivaroxaban, apixaban, or edoxaban) are preferred over warfarin in eligible patients 1

Choice of Anticoagulant

1. Direct Oral Anticoagulants (DOACs):

   • Preferred for non-valvular atrial fibrillation due to:
     • No need for regular INR monitoring
     • Fewer food and drug interactions
     • Lower risk of intracranial hemorrhage
     • At least equivalent efficacy for stroke prevention

2. Warfarin:

   • Recommended for patients with:
     • Mechanical heart valves
     • Moderate to severe mitral stenosis
     • End-stage renal disease (CrCl <15 mL/min) or on dialysis
   • Target INR: 2.0-3.0
   • Time in therapeutic range (TTR) should be >65-70%

Important Considerations

• Renal function should be evaluated before initiating DOACs and at least annually 2, 1
• Antiplatelet monotherapy is not recommended for stroke prevention in AF, regardless of stroke risk 1
• For patients with nonvalvular AF unable to maintain therapeutic INR with warfarin, a DOAC is recommended 2
• Patients with mechanical heart valves should only use warfarin; dabigatran is specifically contraindicated 2
• The risk of bleeding should be assessed using tools like the HAS-BLED score, but high bleeding risk should prompt closer monitoring rather than withholding anticoagulation 1

Clinical Pitfalls to Avoid

1. Do not use antiplatelet therapy alone for stroke prevention in AF patients with elevated stroke risk
2. Do not withhold anticoagulation solely based on bleeding risk; instead, address modifiable risk factors
3. Do not use DOACs in patients with mechanical heart valves
4. Do not fail to reassess stroke and bleeding risks periodically, as risk factors may develop over time
5. Avoid undertreatment of patients with a CHA₂DS₂-VASc score of 1 (men) or 2 (women), as they have a significant stroke risk that warrants consideration of anticoagulation