Ten days after an anterior MI, a 66-year-old man develops a new holosystolic murmur at the left sternal border with a thrill, worsening dyspnea, and a prominent V wave on wedge pressure tracing. Echocardiography shows a left-to-right shunt. What is the most likely diagnosis?

• A Acute mitral regurgitation due to papillary muscle rupture
• B Left ventricular free wall rupture
• C Dressler's syndrome
• D Ventricular septal defect (VSD) ✓

Explanation

Ventricular septal defect is a mechanical complication of MI occurring 3–7 days post-infarction (range up to 2 weeks) and presents with a new harsh holosystolic murmur with thrill at the left lower sternal border and step-up of oxygen saturation in the right ventricle. The prominent V wave described here in wedge pressure is more characteristic of mitral regurgitation, but the presence of a left-to-right shunt on echocardiography confirms VSD. Acute MR from papillary muscle rupture also produces a holosystolic murmur but with pulmonary edema and no shunt.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.