Coronary artery embolism and acute coronary syndrome: A critical appraisal of existing data

The occurrence of coronary artery embolism (CE) has been associated with various clinical conditions, including aortic and mitral prosthetic heart valve implantation, atrial fibrillation (AF), dilated cardiomyopathy, neoplasia, infective endocarditis, atrial septal defect, cardiac tumors, and hypercoagulable states. CE is also a rare cause of myocardial infarction (MI), with a prevalence of about 5%, a figure probably underestimated. The purpose of this article was to determine the current state of knowledge on acute coronary syndrome (ACS) related to CE. We thus performed a comprehensive structured literature search of the MEDLINE database for articles published between 1 January 1990 and 31 December 2021. The diagnosis of CE remains difficult despite the currently used Shibata classification, which is based on major criteria, including angiographic characteristics: globular filling defects, saddle thrombi or multiple filling defects and absence of atherosclerosis in the coronary arteries. Suspected or confirmed CE requires the identification of an etiology. There are only two published series on CE, including about 50 cases each. The three main causes in these series were: 1) atrial fibrillation (73% vs 28.3%), 2) cardiomyopathy (9.4% vs 25%) and 3) malignancy (9.6% vs 15.1%). Finally, 26.3% of the MI patients with CE had no identifiable cause of CE. When anatomically possible, analyzing the thrombus after thrombectomy may help. MI due to CE requires systematic assessment of other locations, i.e. multiple coronary and extracardiac locations. Simultaneous systemic embolization to the brain (67%), limbs (25%), kidneys (25%) or spleen (4%) is frequent, occurring in approximately 25% of CE-related MI. In the setting of acute MI, CE is associated with significant morbidity and mortality. Coronary artery thromboembolism is a rare, non-atherosclerotic, cause of ACS, and prospective studies are needed to evaluate a systematic diagnostic approach and personalized therapeutic strategies.