A 62-year-old woman with a history of stable angina and asthma is prescribed a beta-blocker for symptom control. Within 48 hours, she develops severe bronchospasm and wheezing. Her cardiologist decides to switch to an alternative antianginal agent. Which drug would be the safest choice in this patient with asthma?

## Clinical Context This patient has developed beta-blocker-induced bronchospasm, a contraindication to all beta-blockers (even cardioselective ones at higher doses). An alternative antianginal class is required. ## Why Diltiazem is the Safest Choice **Key Point:** Non-dihydropyridine calcium channel blockers (diltiazem, verapamil) are the preferred alternative antianginal agents in patients with contraindications to beta-blockers, including asthma and COPD [cite:Harrison 21e Ch 297]. **Mechanism of Action:** 1. Inhibit L-type calcium channels in vascular smooth muscle and cardiac tissue 2. Cause coronary vasodilation → increased coronary blood flow 3. Reduce cardiac contractility and heart rate → decreased myocardial oxygen demand 4. Reduce afterload → decreased left ventricular wall stress **Advantages in Asthma:** - **No bronchospasm risk:** Calcium channel blockers do not cause airway constriction - Diltiazem has mild negative inotropic and chronotropic effects (similar to beta-blockers in efficacy) - Suitable for dual therapy: diltiazem + long-acting nitrate is an acceptable alternative regimen - Additional blood pressure control **High-Yield:** Non-dihydropyridine CCBs (diltiazem, verapamil) are the first-line alternative to beta-blockers in asthma/COPD with angina [cite:KD Tripathi 8e Ch 29]. ## Comparison of Calcium Channel Blockers in Angina | Class | Agent | Coronary Vasodilation | Negative Inotrope | Negative Chronotrope | Use in Angina | |-------|-------|----------------------|-------------------|----------------------|---------------| | **Non-DHP** | Diltiazem | ++ | + | + | **First-line alternative to β-blockers** | | **Non-DHP** | Verapamil | ++ | ++ | ++ | Alternative; more negative inotropic effect | | **DHP** | Nifedipine | +++ | − | − (reflex ↑HR) | Not monotherapy; causes reflex tachycardia | | **DHP** | Amlodipine | ++ | − | − | Hypertension + angina; less negative inotrope | **Warning:** Dihydropyridine CCBs (nifedipine, amlodipine) cause reflex tachycardia and increased myocardial oxygen demand; they are not suitable as monotherapy for angina and should not be used in asthma patients without a rate-limiting agent. **Clinical Pearl:** Verapamil has stronger negative inotropic effects than diltiazem; diltiazem is preferred if there is any concern about left ventricular dysfunction or conduction abnormalities.