Embolic myocardial infarction. Clinical characteristics, etiology, and prognosis

Abstract Introduction A small proportion of acute myocardial infarctions (AMI) are of embolic origin. There is limited information about the actual causes of these AMIs, the population they affect, and their prognosis. Purpose The purpose of this study is to describe the clinical characteristics of embolic myocardial infarction (EMB-AMI) and compare them with atherosclerotic myocardial infarction (ATH-AMI). Methods Retrospective observational study of patients admitted for AMI at our centre (2010-2022). Clinical characteristics, ethology, and prognosis are described, and the EMB-AMI cohort is compared with the ATH-AMI cohort. Results Out of 6046 AMIs, 75 (1.2%) were EMB-AMI. Cardiovascular risk factors were similarly distributed in both groups, except for a higher rate of smokers, males, and older age in the ATH-AMI group (figure 1). Additionally, EMB-AMIs more frequently presented as ST-elevation myocardial infarctions. Hospital mortality for EMB-AMI and ATH-AMI was 10.7% vs. 6.2% (p=0.177), and the rate of mechanical complications was higher in the EMB-AMI group (6.7% vs. 1.8%, p=0.009). Of the EMB-AMIs, 8 (10.7%) had other systemic emboli during admission, including a 5.3% of strokes (vs. 1.4% in the ATH-AMI group, p=0.021). In EMB-AMIs, coronary embolism was multivessel in 8 (10.7%) patients, 46 (61.3%) had distal vessel involvement, and 66 (88.0%) had initial TIMI 0 flow. Thrombectomy was performed in 51 (68%) patients, with 82% of them being successful. However, final TIMI was 0-1 in 36 (48%) patients and 3 in 32 (42.7%) patients. Angioplasty was performed in 12 (16.0%) patients. In 52 (67.5%) EMB-AMI patients, atrial fibrillation (AF) was diagnosed at some point during follow-up, and in 43 (57.3%), embolism was exclusively attributed to AF. Nine (12.0%) embolisms were attributed to prosthetic thrombosis, although thrombosis was confirmed by imaging in only one third of cases. Six (8%) embolisms were attributed to endocarditis, and 5 (6.7%) to patent foramen ovale. Rest of embolism causes detected are outlined in figure 2. During a mean follow-up of 44.8 months, 11 patients experienced new embolic events in the EMB-AMI cohort: 7 strokes, 2 probable coronary embolisms, and 2 systemic embolisms. Twenty-seven (36.0%) patients died during follow-up (38.4% of whom from cardiac causes), and 18 (24.0%) were admitted for heart failure. Conclusions EMB-AMI exhibits specific clinical characteristics distinct from ATH-AMI, with varied etiologies, with atrial fibrillation being the most common cause. These AMIs are associated with a higher incidence of complications, including mechanical complications of myocardial infarction and recurrence of embolic events.Characteristics and outcomesEmbolic source