A 58-year-old male recovering from a myocardial infarction shows persistent ST segment elevation. What is the most likely diagnosis?

The diagnosis of left ventricular aneurysm is supported by the presence of persistent ST segment elevation in a patient recovering from a myocardial infarction (MI). Following an MI, especially one involving substantial myocardial necrosis, the heart may remodel structurally. An aneurysm can develop in the area of the damaged myocardium, leading to bulging during systole. This change can manifest as ST segment elevation on an electrocardiogram (ECG), even after the acute phase of the MI has resolved.

In contrast, postinfarction ischemia typically presents with angina and may lead to changes in the ST segment, but it usually does not cause persistent elevation in the absence of ongoing ischemic changes. Ischemic cardiomyopathy refers to chronic heart failure stemming from prolonged ischemia and is characterized by ventricular dysfunction rather than isolated ST segment elevations. Constrictive pericarditis can cause diastolic dysfunction and may lead to other ECG changes, but it is not primarily associated with persistent ST segment elevation following an MI.

Thus, in the context of the clinical scenario, persistent ST segment elevation after an MI is most consistent with the development of a left ventricular aneurysm.