CASE PRESENTATION: A 27-year-old G4P4 female who had a spontaneous en-route vaginal delivery 4 days prior presented with productive cough and shortness of breath. She had a heart rate 170 bpm, temperature 39.4C, WBC 15K and circulatory collapse requiring aggressive fluid resuscitation and pressor support. Chest X-ray and chest computer tomography (fig 1) revealed multifocal patchy infiltrates suggestive of acute respiratory distress syndrome (ARDS). She was intubated and ventilated using lung protective ventilation strategy. Broad spectrum antibiotics were started. There was no evidence of endometritis and infectious workup failed to reveal any source. Bronchoscopy with bronchoalveolar lavage was without growth of bacteria or fungi. Transthoracic (TTE) and Transesophageal echocardiogram (TEE) revealed acute severe mitral regurgitation (MR) with normal left atrial and left ventricular (LV) size, preserved LV ejection fraction and no regional wall motion abnormality. There was no evidence of vegetation or ruptured chordae. The acute severe MR was thought to be of functional etiolgy. Erythrocyte sedimentation rate (>120 mm/hr) and C-reactive protein (141 mg/L) were elevated. Anti streptolysin-O titer was elevated (256 units/mL) but Anti-DNase B was negative, making acute rheumatic fever unlikely. Full rheumatologic workup was unremarkable. A pulmonary artery catheter (PAC) was placed on day 2 and showed a pulmonary artery wedge pressure of 15-16 mmHg. She was started on high dose aspirin (650 mg every 6 hours). She came off of pressors on day 3 and was extubated on day 4. High dose aspirin and antibiotics were continued for a total of 6 days. Repeat TTE on discharge showed improvement in severity of MR to mild-moderate degree. TEE 1 month post discharge revealed complete resolution of MR.