A 62-year-old man with STEMI undergoes primary PCI at 90 minutes. Post-PCI ECG shows >50% resolution of ST elevation and TIMI-3 flow. Six hours later he develops sudden hypotension, elevated JVP, clear lungs, and a new pansystolic murmur at the lower left sternal border. The most likely diagnosis is:
- A Acute mitral regurgitation due to papillary muscle rupture
- B Free wall rupture with tamponade
- C Dressler's syndrome
- D Ventricular septal defect (post-infarction VSD) ✓
Explanation
Post-infarction VSD typically occurs 3–7 days post-MI (but can be earlier with reperfusion injury) and presents with cardiogenic shock plus a loud, harsh pansystolic murmur at the lower sternal border with a palpable thrill. Acute mitral regurgitation from papillary muscle rupture is more commonly associated with inferior STEMI and produces pulmonary edema with an apical murmur. Free wall rupture presents as sudden cardiovascular collapse with pulseless electrical activity, not a murmur. The combination of clear lungs (right heart failure predominating) and lower sternal murmur points to VSD.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.