Left ventricular thrombus (LVT) is a rare complication of ST-elevation myocardial infarction (STEMI) and its management is based on low-evidence recommendations. LVT is also underdiagnosed because of low routine use of cardiac Myocardial Resonance (CMR) imaging after STEMI.

To describe the prevalence, the management and the 12-month follow-up of LVT in a contemporary acute STEMI population.

Consecutive STEMI patients were enrolled in a monocentric, observational, prospective study (HIBISCUS cohort). They all underwent a trans-thoracic echocardiography (TTE) at Intensive Care Unit (ICU) discharge and at one month. A CMR was also performed at one month. All CMR were re-analyzed a posteriori by a core lab, this assessment was the gold standard for LVT diagnosis. Medical treatment, follow-up by medical imaging and adverse events were collected at 12 months prospectively.

A total of 247 STEMI patients were included. LVT was present in 30 (12.1%) patients. For eight of them clinicians were not aware of the diagnosis as LVT was not seen upon first CMR reading.

LVT was diagnosed before ICU discharge in 16.7% of cases. In patients with initial diagnosis (n=22), vitamin K Antagonist (VKA) treatment was prescribed in (n=15) 76.7% and a direct oral anticoagulant (DOAC) in (n=7) 23.3%.

A LVT follow-up imaging was specifically requested in 77.8% cases within 12-months. It was based on TTE in n=9 (64.3%), CMR in n=3 (21.4%) and MDCT in n=2 (14.3%). Follow-up imaging showed a persistent LVT in 28.6% of cases.

At 12months follow-up there was no ischemic stroke but one (3%) severe hemorrhage and one (3%) stent thrombosis.

This observational study shows a 12% prevalence of LVT in a contemporary STEMI population and confirms the significant underdiagnosis by TTE. There was an important heterogeneity in the management and monitoring of LVT with a low rate of ischemic or hemorrhagic events.