A 70-year-old man who had an anterior STEMI 3 weeks ago develops increasing dyspnea and a loud pansystolic murmur at the apex radiating to the axilla. Echo shows an ejection fraction of 30% with no VSD. What is the most likely complication?
- A Post-infarction VSD
- B Papillary muscle rupture causing acute mitral regurgitation ✓
- C Left ventricular free wall rupture
- D Dressler's syndrome
Correct answer: B. Papillary muscle rupture causing acute mitral regurgitation
Explanation
Papillary muscle rupture (or dysfunction) causing acute-to-subacute mitral regurgitation is a mechanical complication of STEMI that typically presents 2–7 days post-infarction but can be delayed. The posteromedial papillary muscle (supplied by PDA) is more vulnerable due to single blood supply, unlike the anterolateral papillary muscle. It causes a harsh pansystolic murmur at the apex radiating to the axilla with flash pulmonary edema and reduced EF. VSD produces a murmur radiating to the right sternal border with a step-up in oxygen saturation in the RV.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.