Out-of-hospital cardiac arrest due to acute myocardial infarction possibly caused by coronary vasospasm

A 60-year-old man with out-of-hospital cardiac arrest was transported to our hospital by an emergency medical service. Ventricular fibrillation was finally terminated after the initiation of circulation support by percutaneous cardiopulmonary support device. Although acute myocardial infarction was suspected, emergency coronary angiography could not identify the culprit lesion of myocardial infarction while there were multiple intermediate stenotic lesions. Since re-elevation of troponin I was recorded on the 4th day after admission, coronary angiography was performed again, and diffuse severe stenosis in the right coronary artery and total occlusion in the left circumflex coronary artery that disappeared by the injection of isosorbide dinitrate was detected. Therefore, we reached the diagnosis of acute myocardial infarction due to coronary vasospasm. It is very rare that emergency coronary angiogram reveals coronary vasospasm at the culprit lesion of myocardial infarction. The guideline recommends calcium channel antagonist and long-acting nitrates for vasospastic angina; however, it would be really difficult to make correct diagnosis of coronary vasospasm among the patients with acute myocardial infarction or out-of-hospital cardiac arrest. Repeated measurements of troponin and coronary angiography identified the cause of acute myocardial infarction as coronary vasospasm in the present case.