A 68-year-old man develops severe mitral regurgitation with pulmonary edema 4 days after anterior STEMI. Echocardiography reveals a flail posterior mitral leaflet. The MOST likely underlying mechanism is:
- A Papillary muscle rupture ✓
- B Rheumatic calcification of the mitral annulus
- C Aortic root dilatation causing annular dilatation
- D Infective endocarditis with vegetation on posterior leaflet
Correct answer: A. Papillary muscle rupture
Explanation
Papillary muscle rupture is the classic mechanical complication of MI causing acute severe mitral regurgitation, typically occurring 2–7 days post-infarct. The posteromedial papillary muscle has a single blood supply (RCA) making it more susceptible; however, anterior MI can affect the anterolateral papillary muscle. The resulting flail leaflet produces an acute regurgitant murmur and rapid hemodynamic deterioration requiring urgent surgical repair.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.