The pathophysiologic basis of acute coronary insufficiency. Observations favoring the hypothesis of intermittent reversible coronary obstruction.

Clinical, coronary angiographic, and myocardial metabolic data were analyzed to test alternative hypotheses for the pathophysiologic basis of acute coronary insufficiency. The initial incidence of coronary collaterals was not low in relation to coexisting coronary obstructive disease; the early subsequent coronary occlusion rate was high; and in asymptomatic intervals during the acute illness, myocardial hypoxia was infrequent and coronary reserve substantial. These observations support the hypothesis that the acute coronary insufficiency syndrome is caused by reversible coronary ischemic episodes rather than by a new permanent atherosclerotic lesion.