Five days after an inferior myocardial infarction, a 68-year-old man develops sudden pulmonary edema with a new holosystolic murmur at the apex. He dies despite emergency surgery. Which autopsy finding best explains the decompensation?

• A Rupture of the interventricular septum
• B Rupture of the posteromedial papillary muscle ✓
• C Acute free wall rupture with hemopericardium
• D Extension of infarct into the right ventricle

Explanation

Papillary muscle rupture complicates infarcts 2 to 7 days old and causes fulminant mitral regurgitation with pulmonary edema. The posteromedial papillary muscle is preferentially involved because it has a single blood supply from the posterior descending artery, whereas the anterolateral muscle has dual supply. Septal rupture gives a harsh left-to-right shunt murmur at the left sternal border, not an apical regurgitant murmur.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.