Coronary thrombosis induced by intracoronary acetylcholine injection in a patient with normal coronary myocardial infarction.

A 67-year-old male was admitted with acute myocardial infarction. Coronary thrombolysis was carried out because complete occlusion of the obtuse marginal branch (OM) in the circumflex artery was detected in emergent coronary angiography, and recanalization of the OM was obtained at 3 hours after the onset of chest pain. No significant stenosis of the OM was found in coronary angiography performed at the recovery stage. After intracoronary acetylcholine injection to the left coronary artery, coronary spasm was induced and coronary thrombosis was observed in the left anterior descending artery thereafter. These findings indicate the possibility that the etiology of myocardial infarction is coronary thrombosis induced by coronary spasm.