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Post-MI Papillary Muscle Rupture — EECC MCQ

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ModerateCoronary Artery DiseasePost-MI Papillary Muscle RuptureEECC

A 65-year-old man presents 4 days after an inferior STEMI with sudden severe breathlessness, a new pansystolic murmur at the apex radiating to the axilla, and pulmonary oedema. Echo shows a flail posterior mitral valve leaflet with severe MR. What is the mechanism?

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Correct answer: B — Papillary muscle rupture (posteromedial papillary muscle, supplied by the PDA/RCA) causing acute flail MR — this is a surgical emergency requiring urgent mitral valve surgery

Papillary muscle rupture is a mechanical complication of MI typically occurring 2-7 days post-infarction. The posteromedial papillary muscle is more vulnerable (single blood supply from the PDA) compared with the anterolateral papillary muscle (dual supply from LAD and LCx). It presents with sudden severe MR, pulmonary oedema, and cardiogenic shock. Unlike post-MI VSD (which has a thrill), papillary muscle rupture causes a pansystolic murmur radiating to the axilla without a thrill. Emergency mitral valve surgery (repair or replacement) is life-saving. Medical stabilisation with vasodilators (to reduce MR severity) and IABP may be needed as a bridge. Mortality without surgery approaches 70-80% within 24 hours.

Reference: ESC (2023): Guidelines for the Management of Acute Coronary Syndromes