Incidence and significance of early and late left ventricular thrombus after ST-elevation myocardial infarction

Background Left ventricular thrombus (LVT) may develop in patients with acute myocardial infarction and increases the risk of thromboembolic events. The incidence of LVT decreased since the introduction of primary percutaneous coronary intervention (PCI). However, limited studies have investigated the current incidence and clinical significance of LVT in these patient group. Purpose To assess the incidence of LVT in ST-elevation myocardial infarction (STEMI) visualized with cardiac magnetic resonance imaging (CMR) at 1 week and 3 months after primary PCI, and evaluate its prognostic significance. Methods A post-hoc analysis of the EUROpean Intracoronary Cooling Evaluation in ST-elevation myocardial infarction (EURO-ICE) trial was performed. The presence of LVT was assessed for both baseline CMR and final CMR. Furthermore, standard CMR imaging outcomes, anticoagulation strategy, and major adverse cardiovascular and cerebrovascular events (MACCE) were assessed and compared between patients with and without LVT. Results In total 188 patients were included in this study. LVT was present at week 1 in 27 patients (14.4%) and at 3 months in 12/184 (6.5%). Baseline characteristics between patients with and without LVT were similar. Patients with LVT had lower left ventricular ejection fraction (LVEF) and larger infarct size than patients without LVT, respectively 38.1% vs 45.6% (p<0.001) and 36.2% vs 27.8% of left ventricular mass (p=0.003). Oral anticoagulation was started in 16 of 27 patients (59.3%). At 3 months LVT resolved in 22 of 27 patients (81.5%). In 7 patients (4.5%), LVT was present at 3 months while no LVT was observed at 1 week. These patients with a new late LVT specifically did not show improvement of LVEF at 3 months compared to baseline, (ΔLVEF -3.4% ±7.2) while in all other patients LVEF improved significantly. The incidence of MACCE was 7.4% in the patients with LVT at 1 week and 1.3% in patients without LVT (p=0.09). There was 1 patient with a stroke in the LVT group (3.7%). Conclusion Even after primary percutaneous coronary intervention, the incidence of left ventricular thrombus in patients with ST-elevation myocardial infarction remains high. In most patients, LVT resolved at 3 months and oral anticoagulation could then be interrupted. This strategy seems safe as clinical outcomes were comparable in patients with and without LVT.