A 70-year-old man is found collapsed 5 days after an anterior STEMI. He was asymptomatic until sudden loss of consciousness. Monitor shows a slow wide-complex rhythm with a palpable femoral pulse absent despite organized electrical activity. Immediate bedside echocardiography shows a small pericardial effusion. What is the most likely mechanism?

• A Rupture of the interventricular septum
• B Reocclusion of the infarct-related artery with reinfarction
• C Acute severe mitral regurgitation from papillary muscle rupture
• D Rupture of the ventricular free wall with hemopericardium ✓

Explanation

Free wall rupture typically occurs 3 to 7 days after transmural infarction, often in hypertensive elderly women with a first infarction. Blood escapes into the pericardium causing tamponade and pulseless electrical activity, where organized electrical activity persists without a mechanical pulse. Septal rupture presents with a murmur and shock rather than sudden collapse, and papillary muscle rupture presents with pulmonary edema and a new apical pansystolic 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.