A 62-year-old woman with vasospastic angina (Prinzmetal's angina) and hypertension presents with recurrent chest pain at rest, especially in the early morning hours. Which drug is the preferred first-line treatment?

Explanation

## Vasospastic Angina: Drug of Choice **Key Point:** Calcium channel blockers (particularly non-dihydropyridines like diltiazem or verapamil) are the first-line agents for vasospastic (Prinzmetal's) angina because they directly prevent coronary artery spasm and reduce vasomotor tone. ### Pathophysiology of Vasospastic Angina Vasospastic angina is characterized by: - **Episodic coronary artery spasm** (not atherosclerotic narrowing) - **Occurs at rest**, especially early morning or nocturnal - **ST elevation** on ECG during pain (unlike typical stable angina) - **Caused by excessive smooth muscle contraction** in coronary arteries ### Why Calcium Channel Blockers Are Superior | Feature | Mechanism | Benefit in Vasospasm | |---|---|---| | **Smooth muscle relaxation** | Block L-type Ca²⁺ channels → ↓ vascular tone | Directly prevents spasm | | **Vasodilation** | Preferential coronary vasodilation | Relieves acute spasm | | **Negative chronotropic effect** | (Non-DHP agents) | Reduces O₂ demand | | **No tolerance** | Sustained efficacy | Long-term control | **High-Yield:** Diltiazem and verapamil (non-dihydropyridine CCBs) are superior to dihydropyridines (amlodipine, nifedipine) in vasospastic angina because they also have negative chronotropic and inotropic effects, providing dual benefit. ### Why Beta-Blockers Are Contraindicated **Warning:** Beta-blockers are **NOT first-line** and may even **worsen vasospastic angina**: - Block β₂-mediated vasodilation → unopposed α-adrenergic vasoconstriction - Can precipitate or exacerbate coronary spasm - Increase spasm frequency and severity - If used, must combine with a calcium channel blocker ### Treatment Hierarchy for Vasospastic Angina ```mermaid flowchart TD A[Vasospastic Angina Diagnosed]:::outcome --> B[First-line: CCB]:::action B --> C{Symptom Control?}:::decision C -->|Yes| D[Continue monotherapy]:::action C -->|No| E[Add long-acting nitrate]:::action E --> F{Still inadequate?}:::decision F -->|Yes| G[Add second CCB or switch agent]:::action F -->|No| H[Maintenance therapy]:::action I[Beta-blocker alone]:::urgent --> J[AVOID - worsens spasm]:::urgent ``` **Clinical Pearl:** Patients with vasospastic angina often respond dramatically to CCBs, with complete symptom resolution in many cases. Long-acting nitrates can be added for refractory cases but are not first-line monotherapy. ### Diltiazem vs. Verapamil | Feature | Diltiazem | Verapamil | |---|---|---| | **Antianginal efficacy** | Excellent | Excellent | | **AV block risk** | Lower | Higher (more negative dromotropic) | | **Constipation** | Mild | Marked | | **Preferred in** | Most patients | Hypertension + angina | **Mnemonic:** **VASOSPASM = Verapamil/Amlodipine or diltiazem (calcium channel blocker) for Spasm** — remember CCBs, NOT beta-blockers.