A 58-year-old man with hypertension and type 2 diabetes presents to the emergency department with palpitations and dyspnea for 3 hours. On examination, pulse is irregularly irregular at 128/min, BP 145/92 mmHg, and JVP is normal. ECG shows absent P waves, irregular ventricular rhythm, and a ventricular rate of 120–140 bpm. Troponin is negative. Chest X-ray is normal. What is the most appropriate immediate management?

Explanation

## Clinical Presentation & Diagnosis This patient has **acute-onset atrial fibrillation with rapid ventricular response** (RVR). The ECG findings (absent P waves, irregular rhythm, rate >120) confirm AF. The patient is hemodynamically stable (normal JVP, no pulmonary edema on CXR, negative troponin). ## Management Strategy for Stable AF with RVR **Key Point:** In hemodynamically stable AF with RVR, the immediate priority is **rate control**, not rhythm control. Acute rhythm conversion is reserved for unstable patients or those with acute heart failure. **High-Yield:** The choice of rate-control agent depends on: - Presence of heart failure or LV dysfunction - Presence of accessory pathway (WPW) - Comorbidities (asthma, COPD, bradycardia) ## Why Diltiazem is Correct 1. **Non-dihydropyridine calcium channel blocker** — effective for rapid AV nodal blockade 2. **Rapid onset** — IV diltiazem achieves rate control within 2–5 minutes 3. **Hemodynamically stable patient** — diltiazem is safe in this context (no cardiogenic shock, normal BP) 4. **No contraindications** — no evidence of acute HF, no accessory pathway, no asthma/COPD 5. **Guideline-recommended** — IV diltiazem or verapamil are first-line for stable AF-RVR [cite:Harrison 21e Ch 226] ## Mechanism ```mermaid flowchart TD A[Acute AF with RVR]:::outcome --> B{Hemodynamically stable?}:::decision B -->|Yes| C{Acute HF or LV dysfunction?}:::decision B -->|No| D[DC cardioversion ± sedation]:::urgent C -->|No| E[IV rate control agent]:::action C -->|Yes| F[IV digoxin or amiodarone]:::action E --> G{Accessory pathway?}:::decision G -->|No| H[IV diltiazem or verapamil]:::action G -->|Yes| I[Avoid AV nodal blockers<br/>Use IV amiodarone or flecainide]:::urgent H --> J[Target HR 60-80 at rest]:::outcome ``` ## Why Not the Other Options? | Option | Why Not Preferred | |--------|-------------------| | **Amiodarone 300 mg IV** | Amiodarone is reserved for hemodynamically unstable AF or when rate control fails with standard agents. It is not first-line for stable AF-RVR due to risk of hypotension and proarrhythmia. | | **Digoxin 500 mcg stat** | Digoxin has a slow onset (30–60 min for IV dose) and is less effective for acute RVR. It is now rarely used as monotherapy for AF-RVR. Better suited for chronic rate control in sedentary patients. | | **DC cardioversion** | Cardioversion is indicated only if the patient is hemodynamically unstable (hypotension, acute pulmonary edema, altered mental status, chest pain). This patient is stable. | **Clinical Pearl:** The "ABCDE" mnemonic for AF management: - **A**ntithrombotic (anticoagulation based on CHA₂DS₂-VASc score) - **B**eta-blocker or rate-control agent - **C**ardioversion (if unstable) - **D**isease management (treat underlying cause) - **E**lectrolyte correction **Tip:** Always assess hemodynamic stability first. Stable AF-RVR → rate control. Unstable AF → immediate cardioversion.