## Stroke Risk Stratification in Atrial Fibrillation ### Validated Risk Scores **Key Point:** Multiple validated risk stratification tools exist for estimating stroke risk in AF patients, but they serve different purposes. | Score | Purpose | Components | Clinical Use | | --- | --- | --- | --- | | **CHA₂DS₂-VASc** | Stroke risk assessment | Congestive heart failure, Hypertension, Age ≥75, Diabetes, Stroke/TIA, Vascular disease, Age 65–74, Sex (female) | Primary tool for anticoagulation decisions [cite:Harrison 21e Ch 226] | | **HAS-BLED** | Bleeding risk assessment | Hypertension, Abnormal renal/liver function, Stroke, Bleeding history, Labile INR, Elderly, Drugs/alcohol | Identifies patients at high bleeding risk; NOT for stroke prediction | | **ORBIT** | Bleeding risk assessment | Older age, Reduced hemoglobin, Bleeding history, Insufficient kidney function, Treatment with antiplatelet | Alternative bleeding risk score; NOT for stroke prediction | | **AFFIRM** | Trial name, NOT a risk score | N/A | The AFFIRM trial compared rate vs. rhythm control in AF; it is NOT a risk stratification tool | ### Why AFFIRM Is Incorrect **High-Yield:** The AFFIRM trial (Atrial Fibrillation Follow-up Investigation of Rhythm Management) was a landmark 2002 study comparing rhythm control versus rate control strategies in AF. It is a **clinical trial**, not a risk stratification score. It does not predict stroke or bleeding risk. **Clinical Pearl:** Students often confuse landmark trials with clinical tools. AFFIRM taught us that rate control is non-inferior to rhythm control for mortality and morbidity in most AF patients — but it is not used for risk stratification. ### Correct Risk Stratification Approach 1. **Calculate CHA₂DS₂-VASc** → determines need for anticoagulation 2. **Calculate HAS-BLED or ORBIT** → assesses bleeding risk; does NOT change anticoagulation decision but guides intensity of monitoring 3. **Anticoagulation decision:** If CHA₂DS₂-VASc ≥ 1 in men or ≥ 2 in women → anticoagulate (unless contraindicated) **Warning:** Do not confuse bleeding risk scores with stroke risk scores. A high HAS-BLED score does NOT mean you withhold anticoagulation; it means you monitor more closely and optimize modifiable bleeding risk factors.
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