A 58-year-old man with a 10-year history of hypertension presents to the emergency department with palpitations and dyspnea for 6 hours. His wife reports he has been increasingly fatigued over the past 2 weeks. On examination, his heart rate is 142 bpm and irregular, blood pressure is 128/82 mmHg, and respiratory rate is 22/min. Chest X-ray shows mild pulmonary congestion. ECG reveals an irregular rhythm with absent P waves and a ventricular rate of 130–150 bpm. Troponin I is negative. What is the most appropriate immediate management for this patient?

Explanation

## Clinical Presentation Analysis This patient presents with **symptomatic atrial fibrillation with rapid ventricular response** (RVR). The key clinical features are: - Irregular rhythm with absent P waves on ECG (diagnostic of AF) - Ventricular rate 130–150 bpm - Hemodynamic stability: BP 128/82 mmHg, no signs of shock - Symptoms: palpitations, dyspnea (but not cardiogenic shock) - Pulmonary congestion suggesting possible heart failure ## Management Strategy **Key Point:** In hemodynamically stable AF with RVR, the immediate goal is **rate control**, not rhythm conversion. **High-Yield:** The choice of rate-control agent depends on: 1. Hemodynamic stability (this patient is stable) 2. Presence of heart failure or LV dysfunction 3. Contraindications to specific agents ## Why Diltiazem? | Agent | Onset | Use Case | Caution | |-------|-------|----------|----------| | **Diltiazem IV** | 2–5 min | Stable AF + RVR; effective rate control | Avoid in decompensated HF | | Amiodarone IV | 5–10 min | Unstable AF; also converts rhythm | Hypotension risk; slower onset | | Digoxin oral | 30–60 min | Chronic AF; HF with reduced EF | Slow onset; not for acute RVR | | DC cardioversion | Immediate | Hemodynamic instability or cardiogenic shock | This patient is stable | **Clinical Pearl:** Diltiazem (a non-dihydropyridine calcium channel blocker) is preferred in acute AF with RVR in hemodynamically stable patients because it: - Rapidly slows AV nodal conduction - Achieves rate control within 2–5 minutes - Does not require loading with digoxin (which takes 30–60 min) - Maintains blood pressure better than IV amiodarone in this context ## Why Not the Other Options? **Amiodarone:** While effective, it is reserved for: - Hemodynamically unstable AF (cardiogenic shock, syncope) - AF with hemodynamic compromise - Rhythm conversion when rate control alone fails This patient is hemodynamically stable, so amiodarone is not first-line. **Digoxin:** Oral digoxin has a **slow onset (30–60 minutes)** and is unsuitable for acute RVR. It is used for chronic rate control in AF, especially in sedentary patients or those with HF and reduced EF. **DC Cardioversion:** Indicated only when: - Hemodynamic instability (hypotension, cardiogenic shock, altered mental status) - Acute coronary syndrome with AF This patient has stable vital signs and no signs of shock. ## Next Steps After Rate Control 1. Achieve target HR < 110 bpm at rest (lenient control per recent guidelines) 2. Assess for stroke risk (CHA~2~DS~2~-VASc score) → anticoagulation 3. Investigate underlying cause (hypertension, thyroid disease, structural heart disease) 4. Plan rhythm control strategy if indicated (flecainide, sotalol, amiodarone for chronic management)