Prinzmetal Vasospastic Angina

Prinzmetal angina is rest angina caused by focal epicardial coronary vasospasm with transient ST elevation. It is a form of vasospastic angina.

Commoner in East Asian populations, in younger patients (40 to 70 years) and in smokers.

Mechanisms are vascular smooth muscle hyperreactivity (Rho kinase), endothelial dysfunction and autonomic imbalance.

Triggers are cocaine, amphetamines, cannabis, 5 fluorouracil and capecitabine, triptans, ergot, alcohol withdrawal, hyperventilation and cold.

Complications include infarction, high grade AV block, ventricular tachycardia and fibrillation, and sudden death.

Prognosis is good with calcium channel blockers (cardiac event rates under 5% yearly), but poor in those with VF at presentation or multivessel spasm.

• Pain at rest, typically from midnight to early morning, lasting 5 to 15 minutes, often clustered, and relieved by nitrates.
• Exercise tolerance is usually preserved, with variable threshold exertional angina in some.
• Syncope or palpitations reflect spasm related arrhythmia.
• Associations include migraine and Raynaud phenomenon.
• Red flags are syncope, VF or aborted sudden death, and prolonged ST elevation unresponsive to nitrates (infarction).

• ECG during pain shows transient ST elevation that resolves with nitroglycerin. Holter monitoring captures episodes.
• Coronary angiography often shows nonobstructive or mildly obstructive disease.
• Provocative testing at angiography: intracoronary acetylcholine 20, 50, 100 micrograms (up to 200) or ergonovine 10 to 60 micrograms, positive with 90% or greater focal constriction plus symptoms and ECG change. Reverse with intracoronary nitroglycerin 100 to 200 micrograms. Perform only in experienced centres with pacing available.
• Exclude cocaine use, thyrotoxicosis and drug triggers.

• Calcium channel blockers are first line: diltiazem 120 to 360 mg daily or amlodipine 5 to 10 mg, up to nifedipine 30 to 90 mg daily. Use high doses, titrated to suppress attacks.
• Long acting nitrates (isosorbide mononitrate 30 to 120 mg daily) added if spasm persists. Sublingual nitroglycerin for acute attacks.
• Avoid nonselective beta blockers, which can provoke spasm. Avoid triptans and ergots.
• Add nicorandil 10 to 20 mg twice daily, or a statin, for refractory cases.
• Smoking cessation is essential. Stop cocaine and other triggers.
• Aspirin only if concomitant atherosclerosis, and low dose.
• ICD for survivors of ventricular fibrillation or sustained VT despite optimal medical therapy.
• Continue calcium channel blocker for at least 6 to 12 months before cautious tapering. Abrupt withdrawal can cause rebound spasm.
• Stenting is reserved for fixed stenosis at the spastic site.