Unstable angina, myocardial infarction and sudden death after an exercise stress test.

We performed coronary angiography within 95 minutes of the onset of symptoms in seven patients with an acute coronary event after an exercise stress test. The test was normal in six patients. Previous angiography in four patients revealed no evident or moderate obstructive coronary arterial disease. After the test, unstable angina developed in two patients, acute myocardial infarction in four and ventricular fibrillation in one, who was successfully resuscitated. At acute angiography the coronary artery involved was occluded in four and sub-totally obstructed in three. In three cases, coronary occlusion was due to thrombosis, vasospasm, or both. In six vessels there was an eccentric lesion, which is consistent with a ruptured plaque. These findings show that physical exercise can unexpectedly provoke an acute coronary event with sub-total or total occlusion of a previous angiographically normal or moderately obstructed coronary artery. The mechanism is probably related to exercise-induced plaque rupture which can produce coronary (sub)occlusion by coronary thrombosis, spasm, or both.