Which complication can occur from myocardial infarction involving the papillary muscles?

• A. Acute mitral regurgitation leading to pulmonary edema and shock
• B. Atrial fibrillation
• C. Ventricular septal defect
• D. Pericarditis

Answer: (A)

Damage to the papillary muscles during a myocardial infarction disrupts the mitral valve apparatus. The papillary muscles anchor the chordae tendineae to the mitral leaflets, helping them close properly in systole. If these muscles are infarcted or rupture, the leaflets can’t coapt, and mitral regurgitation occurs suddenly. The backflow into the left atrium raises left atrial and pulmonary venous pressures, leading to acute pulmonary edema and a drop in forward cardiac output, which can cause shock. Clinically, this presents as a new or rapidly worsening murmur with signs of heart failure after an MI.

Other post-MI complications like atrial fibrillation, ventricular septal defect, or pericarditis can occur, but they are not specifically caused by papillary muscle injury. Atrial fibrillation is an arrhythmia, ventricular septal defect results from interventricular septum rupture, and pericarditis is inflammation around the heart; none arise directly from papillary muscle disruption in the way acute mitral regurgitation does.