Myocardial infarction (MI) results from what condition?

Myocardial infarction (MI), commonly known as a heart attack, primarily results from the complete occlusion of one or more coronary arteries. This blockage prevents blood flow to a part of the heart muscle, leading to tissue ischemia and eventual necrosis if blood flow is not restored quickly. The heart muscle relies on a continuous supply of oxygenated blood delivered through the coronary arteries; when these arteries are obstructed, the affected portion of the heart can suffer irreversible damage, resulting in the clinical picture associated with MI.

The other options reflect conditions that can impact heart function but do not directly cause a myocardial infarction. Stiffness of the left ventricle is associated with conditions like left ventricular hypertrophy or heart failure, which can lead to or exacerbate ischemic heart disease, but do not in themselves cause an MI. Similarly, reduced ability to exercise and pulmonary circulation failure pertain to overall cardiac efficiency and functional capacity rather than the acute event of myocardial infarction, which is specifically tied to coronary artery obstruction leading to blood flow disruption.