How is stroke risk managed in patients with non-rheumatic atrial fibrillation using the CHA2DS2-VASc (Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes, Stroke or transient ischemic attack, Vascular disease, Age 65-74 years, Sex category) score?

CHA₂DS₂-VASc Scoring for Stroke Risk Management in Atrial Fibrillation

How to Calculate the Score

The CHA₂DS₂-VASc score assigns points for specific risk factors to stratify stroke risk in patients with non-valvular atrial fibrillation, with higher scores mandating oral anticoagulation. 1, 2

The scoring system assigns points as follows:

• Congestive heart failure: 1 point (signs/symptoms of heart failure with objective evidence of cardiac dysfunction) 1, 2
• Hypertension: 1 point (BP >140/90 mmHg or on antihypertensive treatment) 1, 2
• Age ≥75 years: 2 points 1, 2
• Diabetes mellitus: 1 point (fasting glucose ≥126 mg/dL or on hypoglycemic agents) 1, 2
• Prior Stroke/TIA/thromboembolism: 2 points 1, 2
• Vascular disease: 1 point (prior MI, peripheral artery disease, or aortic plaque) 1, 2
• Age 65-74 years: 1 point 1, 2
• Female sex: 1 point 1, 2

The maximum possible score is 9 points. 1, 2

Annual Stroke Risk by Score

The CHA₂DS₂-VASc score directly correlates with annual stroke risk:

• Score 0: 0% annual stroke risk 1, 2
• Score 1: 1.3% annual stroke risk 1, 2
• Score 2: 2.2% annual stroke risk 1, 2
• Score 3: 3.2% annual stroke risk 1, 2
• Score 4: 4.0% annual stroke risk 1, 2
• Score 5: 6.7% annual stroke risk 1, 2
• Score 6: 9.8% annual stroke risk 1, 2
• Score 7: 9.6% annual stroke risk 1, 2
• Score 8: 6.7% annual stroke risk 1, 2
• Score 9: ≥15.2% annual stroke risk 1, 2

Treatment Algorithm Based on Score

For men with a score ≥2 or women with a score ≥3, oral anticoagulation is mandatory. 1, 2, 3

Score 0 (men) or 1 (women only due to sex point):

• No anticoagulation recommended - these patients have truly low risk (0-0.6% annual stroke rate) 1, 2, 3
• No antithrombotic therapy needed 2, 3

Score 1 (men) or 2 (women):

• Consider oral anticoagulation - annual stroke risk is 1.3-2.2% 1, 2, 3
• The 2019 ESC guidance emphasizes this is a grey area requiring careful assessment of bleeding risk versus stroke prevention benefit 1
• Calculate HAS-BLED score to assess bleeding risk 1, 3
• If HAS-BLED ≥2, anticoagulation may not provide net clinical benefit 3
• If HAS-BLED <2, initiate oral anticoagulation 2, 3

Score ≥2 (men) or ≥3 (women):

• Oral anticoagulation is required - annual stroke risk exceeds 2.2% 1, 2
• Preferentially use NOACs (apixaban, rivaroxaban, dabigatran, edoxaban) over warfarin 2
• Apixaban 5 mg twice daily (or 2.5 mg twice daily if ≥2 of: age ≥80 years, weight ≤60 kg, creatinine ≥1.5 mg/dL) demonstrated superiority to warfarin in the ARISTOTLE trial 4
• Rivaroxaban 20 mg once daily (or 15 mg once daily if CrCl 30-50 mL/min) demonstrated non-inferiority to warfarin in the ROCKET AF trial 5

Advantages Over CHADS₂ Score

The CHA₂DS₂-VASc score is superior to the older CHADS₂ score because it identifies truly low-risk patients more accurately. 1, 2, 3

Key advantages include:

• Broader score range (0-9 vs 0-6) allowing more refined risk stratification 2, 3
• Includes additional risk factors (female sex, age 65-74, vascular disease) that CHADS₂ omits 1, 2, 3
• Better discriminates stroke risk among patients with low CHADS₂ scores (0-1), with C-statistic of 0.606-0.67 versus 0.561 for CHADS₂ 1, 2
• Many patients with CHADS₂ score of 0 actually have CHA₂DS₂-VASc scores of 2-3 with annual stroke rates up to 3.2% 3

Bleeding Risk Assessment

Always assess bleeding risk using the HAS-BLED score before initiating anticoagulation. 1, 3

The HAS-BLED score assigns 1 point each for:

• Hypertension (systolic BP >160 mmHg) 1
• Abnormal renal or liver function 1
• Stroke history 1
• Bleeding history or predisposition 1
• Labile INR (if on warfarin) 1
• Elderly (age >65 years) 1
• Drugs (antiplatelet agents, NSAIDs) or alcohol excess 1

A HAS-BLED score ≥3 indicates high bleeding risk requiring closer monitoring, but is not an absolute contraindication to anticoagulation. 1, 3

Critical Pitfalls to Avoid

Do not rely solely on CHADS₂ scoring - it misclassifies many patients as low-risk who actually have significant stroke risk when assessed by CHA₂DS₂-VASc. 3

Women cannot achieve a CHA₂DS₂-VASc score of 0 due to the sex category point, but women <65 years without other risk factors remain truly low-risk and do not require anticoagulation. 1, 3

High bleeding risk should not automatically exclude anticoagulation - instead, address modifiable bleeding risk factors including uncontrolled hypertension, concomitant aspirin use, and alcohol excess. 6

The score applies only to non-valvular atrial fibrillation - exclude patients with moderate-to-severe mitral stenosis or mechanical prosthetic heart valves, as these patients require anticoagulation regardless of CHA₂DS₂-VASc score. 1