Which of the following is NOT a cause of aortic regurgitation?

Myocardial infarction is not a direct cause of aortic regurgitation. Aortic regurgitation primarily occurs due to structural abnormalities affecting the aortic valve or the aortic root. Conditions such as aortic root disease can lead to dilatation of the aorta, which can eventually result in improper closure of the aortic valve. Rheumatic heart disease is known to cause damage to the aortic valve, leading to its inadequacy. Similarly, a congenitally bicuspid aortic valve predisposes individuals to regurgitation due to altered valve anatomy and function.

In contrast, a myocardial infarction typically results in damage to the heart muscle itself and can lead to complications such as cardiogenic shock or heart failure, but it does not inherently damage the aortic valve or its structure in a way that would lead to regurgitation. While myocardial infarction can affect cardiac function, its relationship to aortic regurgitation is not causal in nature.