A 52-year-old man with a history of myocardial infarction 6 months ago now presents with recurrent episodes of angina at rest and on minimal exertion. His resting heart rate is 72 bpm, blood pressure is 128/82 mmHg, and he is already on aspirin, atorvastatin, and lisinopril. He has no contraindications to beta-blockers. What is the drug of choice to add for antianginal efficacy and secondary prevention?

Explanation

## Drug of Choice: Metoprolol (Beta-Blocker) **Key Point:** In post-MI angina with no contraindications, a beta-blocker is the first-line agent for both antianginal efficacy and secondary prevention (cardioprotection). ### Why Metoprolol in Post-MI Angina? 1. **Dual benefit: Antianginal + cardioprotective** - Reduces myocardial oxygen demand (↓ HR, contractility, BP) - Decreases sudden cardiac death risk post-MI - Reduces reinfarction rate 2. **Evidence-based in secondary prevention** - Beta-blockers are Class I recommendation post-MI (ESC, ACC/AHA guidelines) - Improve survival in post-MI patients - Reduce angina frequency and severity 3. **Mechanism in angina** - Negative chronotropic effect → ↓ HR - Negative inotropic effect → ↓ contractility - Negative dromotropic effect → ↓ conduction velocity - Net result: ↓ myocardial O₂ demand ### Comparison with Alternatives | Drug | Antianginal Efficacy | Post-MI Cardioprotection | Why Not First-Line Here | | --- | --- | --- | --- | | **Metoprolol** | ✓✓ | ✓✓ (Class I) | — | | **Diltiazem** | ✓ | ✗ (may worsen HF; no survival benefit) | Non-dihydropyridine CCB; not indicated post-MI | | **Ranolazine** | ✓ (adjunctive) | ✗ (no cardioprotection) | Adjunctive only; no secondary prevention benefit | | **Isosorbide mononitrate** | ✓ (symptomatic) | ✗ (no cardioprotection) | Adjunctive for symptom relief; not first-line | **Clinical Pearl:** Non-dihydropyridine CCBs (diltiazem, verapamil) are **contraindicated or used with extreme caution** in post-MI patients with reduced ejection fraction because they can worsen heart failure and have no survival benefit. **High-Yield:** **MNEMONIC: ABCDE of post-MI therapy** - **A**spirin - **B**eta-blocker (e.g., metoprolol) - **C**holestin (statin) - **D**iuretic (if HF) - **E**ACE inhibitor Beta-blockers are foundational in post-MI management. **Warning:** Do not confuse antianginal efficacy (which diltiazem and ranolazine have) with post-MI cardioprotection (which only beta-blockers and ACE inhibitors provide in this context). [cite:Harrison 21e Ch 297]