What is the most common cause of acute myocardial infarction?

The most common cause of acute myocardial infarction (AMI) is thrombus development at a site of vascular injury. This occurs typically due to the rupture of an atherosclerotic plaque in the coronary arteries. When a plaque ruptures, it exposes its contents to the bloodstream, which activates the coagulation cascade, leading to the formation of a thrombus (blood clot). This thrombus can occlude the coronary artery, thus restricting blood flow to the myocardium and causing ischemia or infarction.

This mechanism of thrombus formation is a fundamental aspect of coronary artery disease, which is a leading cause of cardiovascular events. While other options may lead to myocardial ischemia, such as coronary microemboli, congenital abnormalities, or severe coronary artery spasm, these are far less common in the context of acute myocardial infarction. The prevalence and significance of plaque rupture and subsequent thrombus formation make it the primary cause in the majority of AMI cases.