A 68-year-old man with hypertension and diabetes mellitus type 2 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, pulse is irregularly irregular at 110 bpm, blood pressure 145/92 mmHg, and bibasal crackles are heard. ECG shows absent P waves, irregular RR intervals, and a ventricular rate of 105–115 bpm. Troponin is negative. Chest X-ray shows mild pulmonary edema. What is the most appropriate immediate management?

Explanation

## Clinical Presentation & Diagnosis This patient has **new-onset atrial fibrillation with rapid ventricular response (RVR)** complicated by **acute decompensated heart failure** (pulmonary edema on CXR, bibasal crackles, dyspnea). The irregularly irregular pulse, absent P waves, and irregular RR intervals on ECG confirm AF. ## Why IV Amiodarone is the Correct Choice **Key Point:** In AF with RVR and hemodynamic compromise (pulmonary edema), the dual goal is **rate control AND rhythm control simultaneously**. IV amiodarone is the agent of choice in this setting. **High-Yield:** Amiodarone is preferred here because: - Provides **rapid rate control** (IV onset ~30–60 min) via AV nodal blockade - Offers **rhythm conversion** (Class III antiarrhythmic — prolongs action potential duration) - Has **minimal negative inotropic effect** compared to beta-blockers or non-dihydropyridine CCBs, making it safe in acute decompensated HF - Standard IV protocol: **300 mg over 20–60 minutes**, followed by 150 mg if needed, then maintenance infusion (Harrison's Principles of Internal Medicine, 21e, Ch. 226) ## Why Other Options Are Incorrect **Option A — IV Digoxin:** Digoxin is now considered **second-line** for rate control in AF. It has a slow onset (hours), narrow therapeutic index, and is not appropriate as the sole immediate agent in acute RVR with hemodynamic compromise. The dosing regimen listed (500 mcg + 250 mcg at 6 hours) reflects older practice; modern guidelines reserve digoxin for rate control in patients with HF who are refractory to other agents. **Option C — Immediate electrical cardioversion without anticoagulation:** Electrical cardioversion is indicated for hemodynamically *unstable* AF (hypotension, shock, severe ischemia). This patient is borderline but not in cardiogenic shock (BP 145/92 mmHg). More critically, cardioversion without anticoagulation in AF of **unknown duration (>48 hours cannot be excluded)** carries a significant risk of **thromboembolic stroke**. Anticoagulation or TEE-guided cardioversion is required unless the patient is in extremis. **Option D — Oral metoprolol 50 mg twice daily:** Oral beta-blockers have a **delayed onset** and are inappropriate for acute RVR management. Furthermore, beta-blockers are **relatively contraindicated in acute decompensated heart failure** due to their negative inotropic and chronotropic effects, which can worsen hemodynamics acutely (KD Tripathi, Essentials of Medical Pharmacology, 8e). ## Clinical Pearl **Clinical Pearl:** Beta-blockers and non-dihydropyridine CCBs (verapamil, diltiazem) are avoided in acute decompensated HF because their negative inotropy can precipitate cardiogenic shock. IV amiodarone uniquely combines rate control, rhythm conversion, and hemodynamic safety in this scenario. **Anticoagulation note:** Anticoagulation (DOAC or warfarin) must be initiated once AF is confirmed, but is not the *immediate* intervention for RVR with hemodynamic compromise — it is a concurrent priority, not a replacement for rate/rhythm control. [cite: Harrison's Principles of Internal Medicine, 21e, Ch. 226; ESC Guidelines on AF Management 2020]