Mechanisms of coronary artery spasm.

Coronary artery spasm, the pathogenic mechanism most frequently observed in the syndrome of Prinzmetal's variant angina, appears to be caused by a local, nonspecific smooth muscle hyperreactivity. The relationship between coronary atherosclerosis, endothelial dysfunction, and coronary artery spasm is still speculative. Coronary artery spasm should be distinguished from other forms of coronary vasoconstriction, which may also play a role in angina pectoris. Occlusive coronary spasm causes complete interruption of coronary blood flow and may contribute to thrombus formation. Segmental coronary hyperreactivity may also be a component of acute coronary syndromes.