Which of the following is a mechanical complication that can occur after a myocardial infarction?

• A. Papillary muscle rupture
• B. Atrial fibrillation
• C. Pulmonary embolism
• D. Pericarditis

Answer: (A)

A key idea here is that some complications after a myocardial infarction involve actual structural damage to the heart, not just electrical or inflammatory processes. Papillary muscle rupture fits this, because it is a tear of the muscle that supports the mitral valve. When the papillary muscle ruptures, the mitral valve can’t close properly during systole, leading to acute mitral regurgitation. This causes a sudden rise in left atrial pressure and rapid pulmonary edema, often with hypotension and a new murmur, and it typically occurs several days after the MI when the infarcted tissue is weakest.

The other conditions are not mechanical failures of the heart’s structure. Atrial fibrillation is an electrical disturbance of the atria, not a structural rupture. A pulmonary embolism is a vascular blockage in the lungs, not a cardiac-valve failure. Pericarditis is inflammation of the pericardial sac, which is inflammatory rather than a rupture of a heart muscle that disrupts valve function.