A 76-year-old woman presented to our institution with shortness of breath, weakness, and syncope. Evaluation revealed severe mitral regurgitation and cardiogenic shock secondary to a flail posterior mitral valve leaflet. An emergency cardiac catheterization did not demonstrate significant coronary artery disease. The patient was sent for an emergency mitral valve replacement. Intraoperatively, the posteromedial papillary muscle was found to be transected. Histological analysis, clinical presentation, and a review of the literature of isolated papillary muscle infarction are presented.