Coronary artery spasm.

Variant angina with ST elevation indicates transmural myocardial ischaemia and is due to spasm of a large epicardial coronary artery. Spasm occurs in arteries with varying degrees of fixed obstruction, giving rise to different clinical profiles of variant angina. However, coronary angiography is required to differentiate between those with minor coronary disease, and those with significant (greater than 70%) obstruction. In patients with minor coronary disease or normal arteries, beta-blockers are contraindicated, and treatment with calcium antagonist vasodilators should be commenced after documentation of spontaneous or ergonovine induced spasm. Patients with significant fixed coronary obstructions require bypass grafting if technically feasible. The role of coronary spasm is not confined to variant angina, as it causes angina at rest with ST depression, and may also cause myocardial infarction and sudden death.