Coronary embolism is a potential cause of reduced myocardial perfusion and ischaemia, which may clinically manifest as myocardial infarction. Data on the incidence of coronary embolism as a mechanism underlying acute coronary syndrome are limited. Coronary embolism should be suspected as a cause of acute coronary syndrome in patients without coronary angiographic evidence of atherosclerosis, but with risk factors for intracardiac thrombus formation. The most important of these are atrial fibrillation and dilated cardiomyopathy. We present a case of a patient in whom the diagnosis of myocardial infarction was justified by the coexisting dilated cardiomyopathy, and where coronary artery occlusion most likely occurred through the embolic mechanism. Differential diagnosis of the aetiology of acute coronary syndrome should be performed in patients with myocardial infarction without coronary atherosclerosis. This allows to implement individualised causative treatment, which may differ from standard management in myocardial infarction.

myocardial infarction, coronary embolism, atrial fibrillation, dilated cardiomyopathy, coronary angiography