A 68-year-old man with hypertension and diabetes mellitus presents with palpitations and dyspnea for 2 days. On examination, pulse is irregularly irregular at 110 bpm, BP 145/92 mmHg. ECG shows absent P waves, irregular RR intervals, and a ventricular rate of 115 bpm. Troponin I is normal. Echocardiography shows normal LV function and no structural heart disease. Which of the following is the most appropriate initial management?

Explanation

## Clinical Context This patient presents with new-onset atrial fibrillation (AF) with rapid ventricular response (RVR) in a hemodynamically stable state. The key clinical features are: - Irregularly irregular pulse - Absent P waves on ECG - Normal troponin and LV function - Hemodynamic stability (BP 145/92, conscious) ## Management Strategy for Stable AF with RVR **Key Point:** In hemodynamically stable AF with RVR, the immediate goal is rate control, not rhythm control. Rate control is achieved with AV nodal blocking agents. **High-Yield:** The 2019 AHA/ACC/HRS Focused Update emphasizes that rate control is non-inferior to rhythm control for symptom relief in AF without structural heart disease. ## Why Intravenous Diltiazem or Verapamil? 1. **Rapid onset:** IV calcium channel blockers achieve rate control within 5–15 minutes 2. **Safety profile:** No proarrhythmic risk; safe in normal LV function 3. **Dual benefit:** Provides both rate control and symptom relief (dyspnea, palpitations) 4. **Anticoagulation:** Must be initiated concurrently based on CHA₂DS₂-VASc score ## Rate Control Targets in AF | Clinical Scenario | Target HR | Method | |---|---|---| | Hemodynamically stable, no HF | 60–100 bpm at rest, <110 bpm on exertion | IV CCB or beta-blocker | | Acute RVR with HF | <110 bpm (lenient control acceptable) | IV digoxin or amiodarone | | Hemodynamic instability | Immediate cardioversion | Synchronized DC shock | **Clinical Pearl:** "Lenient rate control" (target <110 bpm) is now preferred over strict rate control (<80 bpm) in stable AF, as it reduces medication burden without compromising outcomes [cite:Harrison 21e Ch 226]. ## Anticoagulation Consideration This patient's CHA₂DS₂-VASc score = 3 (age ≥65, hypertension, diabetes), indicating high stroke risk. Anticoagulation with DOAC or warfarin must be started unless contraindicated. ```mermaid flowchart TD A["AF with RVR"]:::outcome --> B{"Hemodynamically stable?"}:::decision B -->|"Yes"| C["Rate control first"]:::action B -->|"No"| D["Immediate cardioversion"]:::urgent C --> E{"Structural heart disease?"}:::decision E -->|"No"| F["IV CCB or beta-blocker"]:::action E -->|"Yes/HF"| G["IV digoxin or amiodarone"]:::action F --> H["Assess CHA₂DS₂-VASc"]:::decision G --> H H --> I["Anticoagulation if score ≥1"]:::action ```