Left Ventricular Thrombus Formation after ST-Segment-Elevation Myocardial Infarction: Insights from a Cardiac Magnetic Resonance Multicenter Study

Data on left ventricular (LV) thrombus formation after primary percutaneous coronary intervention for ST-segment-elevation myocardial infarction (STEMI) are scarce. The aims of this study were to assess the (1) incidence of LV thrombi using cardiac magnetic resonance in a multicenter cohort of STEMI patients and (2) prognostic relevance of LV thrombi at 1-year follow-up. Methods and Results-In total, 738 STEMI patients reperfused by primary angioplasty were enrolled in 8 centers. Cardiac magnetic resonance was completed within 1 week after infarction. Central core laboratory-masked analyses for the presence of LV thrombi were performed. The primary clinical end point was the occurrence of major adverse cardiac events within 1 year. LV thrombi were detected in 26 patients (3.5%) in the overall cohort and in 7.1% in anterior STEMI patients. The presence of thrombi was associated with larger infarcts (P<0.001), less myocardial salvage (P<0.01), impaired LV ejection fraction (P<0.001), and more pronounced late microvascular obstruction (P=0.002). The presence of thrombi was independently associated with the incidence of major adverse cardiac events at 12 months (hazard ratio, 2.73; 95% confidence interval, 1.11-6.73; P=0.03). Conclusions-In this multicenter cohort of patients with STEMI, thrombus prevalence assessed by cardiac magnetic resonance was 3.5% and associated with decreased myocardial salvage, larger infarcts, and more pronounced reperfusion injury. Importantly, LV thrombus was independently associated with major adverse cardiac events at 1-year follow-up.