What is the main cause of myocardial infarction?

The main cause of myocardial infarction, commonly known as a heart attack, is the blockage of coronary arteries. This blockage often results from atherosclerosis, a condition where fatty deposits build up on the artery walls. As these plaques become unstable or rupture, they can lead to the formation of a thrombus (blood clot) that can significantly narrow or completely obstruct the coronary arteries. This obstruction deprives the heart muscle of oxygen and nutrients, leading to tissue damage or necrosis, which constitutes a myocardial infarction.

While factors like high blood pressure, obesity, and diabetes can contribute to the overall risk of developing coronary artery disease, they do so by promoting conditions that lead to the blockage of arteries. High blood pressure can damage blood vessels, obesity can increase the likelihood of atherosclerosis, and diabetes can lead to accelerated cardiovascular disease by causing increased blood sugar levels that damage blood vessels. However, the direct and immediate cause of a myocardial infarction is the blockage itself, making it the correct answer in this context.