Anticoagulation Strategy Using CHA₂DS₂-VASc and HAS-BLED Scores in Atrial Fibrillation
Use CHA₂DS₂-VASc to identify who needs anticoagulation (score ≥1 in males or ≥2 in females warrants oral anticoagulation), then use HAS-BLED to identify modifiable bleeding risk factors and flag patients needing closer monitoring—but a high HAS-BLED score (≥3) is NOT a reason to withhold anticoagulation. 1
Step 1: Stroke Risk Assessment with CHA₂DS₂-VASc
Calculate the CHA₂DS₂-VASc score for all AF patients, including those with paroxysmal AF: 1, 2
- Congestive heart failure or LVEF ≤40%: 1 point
- Hypertension: 1 point
- Age ≥75 years: 2 points
- Diabetes mellitus: 1 point
- Prior stroke, TIA, or thromboembolism: 2 points
- Vascular disease (prior MI, peripheral artery disease, aortic plaque): 1 point
- Age 65-74 years: 1 point
- Female sex: 1 point 2, 3
Treatment decisions based on score: 1, 2
- Score = 0 in males or 1 in females (lone AF, age <65): No antithrombotic therapy recommended 1
- Score ≥1 in males or ≥2 in females: Oral anticoagulation definitively recommended 1, 2, 3
The CHA₂DS₂-VASc score has superior sensitivity compared to older CHADS₂ scoring and reliably identifies truly low-risk patients who can safely avoid anticoagulation. 1 This applies equally to paroxysmal, persistent, and permanent AF—the stroke risk is identical regardless of AF pattern. 3
Step 2: Bleeding Risk Assessment with HAS-BLED
Calculate HAS-BLED score for all AF patients at every patient contact: 1, 2
- Hypertension (uncontrolled, >160 mmHg systolic): 1 point
- Abnormal renal function (dialysis, transplant, creatinine >2.6 mg/dL): 1 point
- Abnormal liver function (cirrhosis or bilirubin >2x normal or AST/ALT >3x normal): 1 point
- Stroke history: 1 point
- Bleeding history or predisposition (anemia, prior major bleed): 1 point
- Labile INR (if on warfarin, time in therapeutic range <60%): 1 point
- Elderly (age >65 years): 1 point
- Drugs (antiplatelet agents, NSAIDs) or alcohol excess (≥8 drinks/week): 1 point each 1, 2
Interpretation and action: 1
- HAS-BLED ≥3: Identifies patients at higher bleeding risk who warrant more frequent review and follow-up, with aggressive attention to modifiable risk factors 1, 2
- Critical point: A high HAS-BLED score is rarely a reason to avoid anticoagulation—it serves to identify modifiable bleeding risk factors that should be addressed 1
The HAS-BLED score outperforms stroke risk scores (CHADS₂ and CHA₂DS₂-VASc) for predicting serious bleeding and should be used specifically for bleeding risk assessment. 4 However, stroke and bleeding risks are correlated but not exchangeable—most patients have equal or lower bleeding risk compared to their stroke risk category. 5
Step 3: Anticoagulant Selection
Direct oral anticoagulants (DOACs) are recommended as first-line therapy over warfarin: 2, 3
- Preferred DOACs: Apixaban, rivaroxaban, dabigatran, or edoxaban 2, 3
- Rationale: DOACs have predictable pharmacodynamics, similar or lower major bleeding rates, and significant reduction in hemorrhagic stroke compared to warfarin 2, 6
Warfarin is preferred over DOACs only for: 2, 7
For warfarin therapy (if used): 7
- Target INR 2.0-3.0 (target 2.5) for most AF patients 1, 7
- Time in therapeutic range should be ≥65% for optimal efficacy 1
Step 4: Address Modifiable Bleeding Risk Factors
At every patient contact, actively manage modifiable bleeding risk factors: 1
- Control hypertension (target <160/90 mmHg)
- Discontinue concomitant NSAIDs or aspirin in anticoagulated patients (unless specific indication like recent ACS/PCI)
- Reduce alcohol consumption to <8 drinks/week
- Optimize renal and liver function where possible
- Treat underlying bleeding predispositions (e.g., gastric ulcer, anemia) 1
- For warfarin patients with labile INR, consider switching to DOAC or implementing self-monitoring 1
Common Pitfalls to Avoid
Do not use HAS-BLED as a contraindication to anticoagulation. The score identifies patients who need closer monitoring and modification of risk factors, not patients who should be denied stroke prevention therapy. 1, 2 The benefit of stroke prevention outweighs bleeding risk in almost all patients with CHA₂DS₂-VASc ≥1 (males) or ≥2 (females). 1, 2
Do not use stroke risk scores (CHADS₂ or CHA₂DS₂-VASc) to predict bleeding risk. While these scores correlate with bleeding, HAS-BLED demonstrates significantly better discriminatory performance for bleeding events and should be used specifically for bleeding risk assessment. 4, 8
Do not withhold anticoagulation due to fear of falls. A patient would need to fall approximately 300 times per year for the risk of intracranial hemorrhage to outweigh the stroke prevention benefit. 1
Schedule patients with HAS-BLED ≥3 for more frequent follow-up (every 3-6 months rather than annually) to reassess bleeding risk factors and ensure adherence, as bleeding risk is highly dynamic. 1