Four days after an inferior STEMI, a 62-year-old woman suddenly develops flash pulmonary oedema with a new soft apical pansystolic murmur. Echocardiography shows severe mitral regurgitation with a flail posterior mitral leaflet and a hyperdynamic left ventricle. Which vessel's occlusion explains this complication?

• A Left anterior descending artery
• B Diagonal branch of the left circumflex
• C Left main coronary artery
• D Posterior descending artery ✓

Explanation

The posteromedial papillary muscle has a single blood supply from the posterior descending artery, making it vulnerable to rupture after inferior MI. The anterolateral papillary muscle receives a dual supply from the LAD diagonal branches and the circumflex obtuse marginal branches, so its rupture is far less common. This single-vessel anatomy is why papillary muscle rupture complicates inferior infarcts despite their smaller size.

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.