On the third day after an acute anterior STEMI treated with primary PCI, a patient develops sudden severe dyspnoea, a new loud pan-systolic murmur at the left sternal border, and rapid haemodynamic deterioration. Echocardiography shows a left-to-right shunt. What is the MOST likely diagnosis?
- A Acute severe mitral regurgitation from papillary muscle rupture
- B Ventricular septal rupture (post-infarction VSR) ✓
- C Free wall rupture with tamponade
- D Right ventricular infarction
Correct answer: B. Ventricular septal rupture (post-infarction VSR)
Explanation
Post-infarction ventricular septal rupture classically presents 2–7 days after STEMI with a new harsh pan-systolic murmur loudest at the left sternal border, step-up of oxygen saturation in the right ventricle, and left-to-right shunting on echo. Anterior STEMI causes apical/anterior VSR. Papillary muscle rupture causes severe MR with pulmonary oedema but the echo shunt is mitral regurgitation, not left-to-right. Free wall rupture presents with tamponade and typically no murmur.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.