Vasospasm-induced acute myocardial infarction—Thrombus formation without thrombogenic lesion at the culprit

Although plaque rupture is the major cause of acute myocardial infarction, vasospasm is also known as a potential cause of acute myocardial infarction. However, it is very rare and is sometimes difficult to diagnose correctly. A 30-year-old male patient with suspected unstable angina pectoris who received catheterization in 1999 had normal coronary artery but positive result in the provocation test of vasospasm. Although his angina had been suppressed by medications, he suffered ST-elevation acute myocardial infarction after the discontinuation of medication. The initial angiogram showed total occlusion of the proximal left anterior descending coronary artery. Thrombolysis and nitroglycerin achieved recanalization of the culprit lesion with only mild residual stenosis. Angioscopy revealed normal white luminal wall without any thrombogenic lesion. Therefore, the cause of coronary occlusion was diagnosed as vasospasm. However, since the repeated vasospastic occlusion of the culprit lesion regardless of repeated intra-coronary injection of nitroglycerin was observed, a stent was implanted and vasospasm was successfully prevented. It is not easy to judge from the angiogram that the cause of coronary occlusion in the patients with acute myocardial infarction is vasospasm. It is important to think routinely about the possibility of vasospasm as a cause of acute myocardial infarction.