A 62-year-old man with a 10-year history of hypertension and diabetes mellitus type 2 presents to the emergency department with palpitations and dyspnea for 6 hours. On examination, heart rate is 145 bpm, blood pressure 128/82 mmHg, and the pulse is irregularly irregular. Chest X-ray shows no pulmonary edema. ECG reveals atrial fibrillation with a rapid ventricular response. Troponin I is normal. Which of the following is the most appropriate immediate management?

Explanation

## Initial Management of Haemodynamically Stable AF with RVR ### Clinical Context This patient has atrial fibrillation with rapid ventricular response (RVR) but is haemodynamically stable (BP 128/82, no pulmonary edema, normal troponin). The key discriminator is **haemodynamic stability**. ### Approach to Rate Control **Key Point:** In haemodynamically stable AF with RVR, the goal is rapid ventricular rate control using AV nodal blocking agents. IV calcium channel blockers (diltiazem, verapamil) or IV beta-blockers are first-line. **High-Yield:** Diltiazem and verapamil achieve rate control within 2–5 minutes IV, making them ideal for acute settings. They reduce AV nodal conduction and are superior to digoxin in AF with RVR because digoxin has a slower onset (30–60 min) and less predictable rate control in the acute setting. ### Why IV Diltiazem/Verapamil? 1. **Rapid onset:** 2–5 minutes 2. **Predictable AV nodal blockade:** Slows conduction through the AV node 3. **Haemodynamic stability maintained:** No negative inotropic effect in this patient 4. **Safe in acute MI:** Troponin is normal; these agents are safe ### Comparison of Rate Control Agents | Agent | Onset | Route | Use in Stable AF-RVR | Notes | |-------|-------|-------|----------------------|-------| | **IV Diltiazem/Verapamil** | 2–5 min | IV | **First-line** | Rapid, predictable | | **IV Beta-blocker** (metoprolol) | 5–10 min | IV | First-line alternative | Slower than CCB | | **Digoxin** | 30–60 min | IV/oral | Not acute RVR | Slow, unreliable in AF | | **Amiodarone** | 5–10 min | IV | Haemodynamic instability | Antiarrhythmic, not rate control | **Clinical Pearl:** Amiodarone is reserved for haemodynamically unstable AF or when rate control fails. It is an antiarrhythmic (rhythm control), not a rate control agent, and carries risk of proarrhythmia and organ toxicity. **Warning:** Digoxin is NOT appropriate for acute AF-RVR because its onset is too slow (30–60 minutes) and rate control is unpredictable, especially in high sympathetic states (acute illness, stress). It is useful for chronic rate control in sedentary patients. ### Rhythm vs. Rate Control - **Rate control** (diltiazem, verapamil, beta-blockers) is the initial strategy in haemodynamically stable AF. - **Rhythm control** (amiodarone, flecainide, sotalol) or **cardioversion** is reserved for haemodynamic instability, acute heart failure, or failed rate control. **Key Point:** Synchronized DC cardioversion is indicated only if the patient is haemodynamically unstable (hypotension, shock, acute pulmonary edema, altered mental status) — this patient is stable. [cite:Harrison 21e Ch 226]