Incidence and Outcomes of Early Left Ventricular Thrombus Formation Following ST-Elevation Myocardial Infarction Treated with Primary Percutaneous Coronary Intervention

Background:
Since the advent of primary percutaneous coronary intervention (PCI) for the treatment of ST-elevation myocardial infarction (STEMI), studies have reported a declining incidence of left ventricular thrombus (LVT) following STEMI. The majority of LVT were found prior to hospital discharge. The goal of this study was to report the incidence and outcomes of early LVT in the contemporary era of PCI practice in a large cohort of patients.

Methods:
We retrospectively studied 2040 consecutive STEMI patients between October 2007 and April 2016 who underwent successful primary PCI with stent implantation. Screening echocardiography was performed within 24-48 hours of admission. Patients with anterior STEMI and reduced ejection fraction (EF<40%) had a repeat test before discharge. Patients with anterior STEMI were treated with intravenous heparin for 24-48 hours until a first echocardiography test was performed. Heparin was continued in case of significant left ventricular dysfunction (EF<35%) and apical akinesis or dyskinesis until a second test ruled out LVT.

Results:
LVT was diagnosed before hospital discharge in 31/2040 patients (1.5%). Only 2/31 patients with LVT (6.5%) developed embolic events before discharge and 1/31 (3.2%) had an episode of upper gastrointestinal bleeding. 28/31 patients (90%) had anterior STEMI. Patients who developed LVT after STEMI had lower EF, higher CPK levels, prolonged symptoms to emergency room time, and prolonged time to reperfusion. There was no difference between the two groups in 30-day mortality and in hospital STEMI-related complications.

Conclusions:
We report a low incidence of early LVT following STEMI, a low incidence of pre-discharge embolic events, and no difference in 30-day mortality. The low incidence of LVT is possibly related to improvements in PCI practice over the last decades but could also be ascribed to our anticoagulation policy. Further studies are needed to weigh the risks and benefits of a limited in-hospital anticoagulation protocol.