Case ReportIn January 2013, a 41-year-old man, a heavy smoker who had little medical or surgical history, presented with New York Heart Association functional class III-IV dyspnea, which had worsened progressively over the preceding week and had been associated with subjective fevers, chills, and infrequent episodes of chest pain. On physical examination, the patient had a blood pressure of 96/45 mmHg, a pulse rate of 124 beats/ min, a respiratory rate of 24 breaths/min, and a temperature of 102.5 °F. Cardiac examination revealed the point of maximum impulse to be in the left 5th intercostal space at the mid-clavicular line; auscultation revealed an S 3 gallop at the mitral area, with a grade 4/6 holosystolic murmur best heard over the apex. The electrocardiogram showed sinus tachycardia without evidence of ischemic ST-T changes. The chest radiograph showed a normal cardiac silhouette with signs of pulmonary venous congestion.A 2-dimensional (2D) transthoracic echocardiogram (TTE) showed a membranelike structure extending from the superior LA wall to the base of the posterior mitral leaflet, creating a false lumen that partly occluded the true LA chamber-a picture consistent with LA free-wall dissection. Attached to the lower end of this membrane was a large mass with multiple finger-like projections (Fig. 1). Color-flow Doppler mode revealed a central jet of moderate mitral regurgitation caused by lack of coaptation of the mitral valve leaflets. Additional moderate-to-severe systolic flow was detected-this from the left ventricle into the false lumen, through a perforated posterior mitral leaflet (Fig. 2). Mild pericardial effusion was also noted. These findings were confirmed by a transesophageal echocardiogram (TEE) (Fig. 3). The dissection membrane caused no pulmonary vein obstruction.On the basis of the patient's clinical presentation, we obtained blood cultures and began broad-spectrum antibiotic therapy; however, within one hour of his presentation (and before surgical intervention), the patient died of cardiogenic shock refractory to medical treatment. Three blood cultures grew methicillin-sensitive Staphylococcus aureus.Although no definitive pathologic diagnosis by autopsy was available, the positive blood cultures, together with the 2D TTE and TEE findings in a patient with such a clinical presentation, are highly consistent with the diagnosis of infective endocarditis of the mitral valve. The formation of a large mitral valve vegetation appears to have