A 72-year-old woman with a history of paroxysmal atrial fibrillation, hypertension, and diabetes mellitus type 2 is seen in the outpatient clinic. She is currently on metoprolol 50 mg twice daily for rate control and aspirin 75 mg daily. Her last episode of AF was 4 months ago and was self-limiting. Today, she is in sinus rhythm with a heart rate of 68 bpm and blood pressure 138/86 mmHg. She reports no symptoms. What is the most appropriate next step in her anticoagulation management?

Explanation

## Stroke Risk Stratification in Atrial Fibrillation This patient requires anticoagulation assessment using the **CHA₂DS₂-VASc score**, regardless of whether she is currently in sinus rhythm. ### CHA₂DS₂-VASc Score Calculation | Component | Points | This Patient | |-----------|--------|---------------| | **C**ongestive heart failure | 1 | 0 | | **H**ypertension | 1 | 1 | | **A**ge ≥75 years | 2 | 0 | | **A**ge 65–74 years | 1 | 1 | | **D**iabetes mellitus | 1 | 1 | | **S**troke/TIA/thromboembolism | 2 | 0 | | **V**ascular disease | 1 | 0 | | **A**ge 65–74 years (female) | 1 | 1 | | **Sc** (female sex) | 1 | 1 | | **TOTAL** | — | **5** | **High-Yield:** A CHA₂DS₂-VASc score of ≥2 in men or ≥3 in women warrants anticoagulation. This patient scores **5**, indicating **high stroke risk** [cite:Harrison 21e Ch 226]. ### Key Point: Sinus Rhythm Does NOT Eliminate Need for Anticoagulation **Key Point:** Even though this patient is currently in sinus rhythm, she has **paroxysmal atrial fibrillation** — a documented arrhythmia with recurrent episodes. The 2019 AHA/ACC Guidelines recommend anticoagulation for all patients with AF and CHA₂DS₂-VASc ≥2 (men) or ≥3 (women), **regardless of rhythm status** [cite:AHA/ACC 2019]. ### DOAC vs Warfarin ```mermaid flowchart TD A["Indication for anticoagulation<br/>in AF established"]:::outcome --> B{"First-line agent?"}:::decision B -->|"DOAC preferred"|C["Apixaban, dabigatran,<br/>edoxaban, rivaroxaban"]:::action B -->|"Warfarin if DOAC<br/>contraindicated"|D["Target INR 2–3"]:::action C --> E["Advantages: No monitoring,<br/>better GI tolerability,<br/>lower intracranial bleed risk"]:::outcome D --> F["Advantages: Reversible,<br/>cheaper in resource-limited settings"]:::outcome ``` **High-Yield:** DOACs (direct oral anticoagulants) are now **first-line** for AF anticoagulation in most patients, including elderly patients, because they: - Have predictable pharmacokinetics (no INR monitoring needed) - Show superior efficacy vs warfarin in major trials (ARISTOTLE, RE-LY, ROCKET-AF) - Have lower rates of intracranial hemorrhage - Offer better gastrointestinal tolerability than warfarin **Clinical Pearl:** Apixaban and dabigatran have the most evidence in elderly patients (>75 years) and are preferred in this age group [cite:Harrison 21e Ch 226]. ### Why Aspirin Alone Is Inadequate **Warning:** Aspirin is **NOT** recommended as monotherapy for stroke prevention in AF. It is inferior to anticoagulation and is only used if anticoagulation is absolutely contraindicated. A CHA₂DS₂-VASc score of 5 mandates anticoagulation, not aspirin.