Patient: Male, 73-year-old Final Diagnosis: Pseudoaneurysm • thrombus Symptoms: Chest pain • sycope Medication: — Clinical Procedure: — Specialty: General and Internal Medicine Objective: Unusual clinical course Background:ST-elevation myocardial infarction (STEMI), when associated with acute left ventricular (LV) free-wall rupture, is often a lethal complication, and if not followed by sudden death, the rupture may be contained by the parietal pericardium and a local thrombus, leading to the formation of a left ventricular (LV) pseudoaneurysm. The incidence of LV pseudoaneurysm after STEMI is ~ 0.3%.Case Report:A 73-year-old man who presented with an acute syncopal episode and intermittent chest pain for 7 days was found to have an anterolateral myocardial infarction (MI) with lateral wall rupture and pseudoaneurysm formation. He had an LV thrombosis in the LV aneurysm. While this increased his risk of thromboembolic events, it likely stopped the evolution of the rupture and stabilized the pericardial effusion size. The patient underwent coronary artery bypass grafting (CABG), thrombectomy, and lateral wall repair.Conclusions:Left ventricular pseudoaneurysm and left ventricular thrombus in a patient presenting with an acute ST-elevation myocardial infarction is a rare complication of myocardial infraction, with an incidence of <1%. It is often a lethal complication and requires stabilization and repair if not followed by sudden death.