We report the case of a 66-year-old woman with no significant past medical history who presented to the Emergency Department at Houston Methodist Hospital with 24 hours of chest pain. An electrocardiogram was done, an electrocardiogram confirmed a posterolateral ST elevation myocardial infarction. An immediate and successful percutaneous coronary intervention of a totally occluded ramus intermedius was performed. Six hours later she developed pulmonary edema, cardiogenic shock, severe acidosis, and anuria. Echocardiography showed severe mitral regurgitation due to a ruptured anterolateral papillary muscle, and emergency surgery revealed necrosis of this muscle. A bioprosthetic mitral valve was placed, and extracorporeal membrane oxygenation was needed for 3 days. This is a rare mechanical complication of myocardial infarction, which usually affects the posteromedial papillary muscle. The patient subsequently made a good recovery. One month later, just prior to discharge home, the patient developed pneumonia and sepsis, and she expired from multiorgan failure.