Left main coronary artery to biatrial fistula associated with severe functional mitral valve regurgitation.

A 67-year-old woman had progressive dyspnea, a loud murmur of mitral regurgitation, and a separate, continuous cardiac murmur suggesting shunt. Electrocardiographygated computed tomography demonstrated a 7-cm aneurysm of the left main coronary artery with possible connection to the right atrium (Figure, A), along with a thin tissue boundary between the aneurysm (Figure, B) and left atrium, raising the possibility of secondary erosion (Figure, C, arrow). Echocardiography revealed severe functional mitral regurgitation, presumably due to volume overload (Figure, D and Movie I in the online-only Data Supplement). Flow was seen between the aneurysm and the left atrium (Figure, E and Movie II in the online-only Data Supplement). Intraoperative evaluation identified a large fistula at the left main coronary artery trifurcation (Figure, F), multiple erosions into the left atrium dome (Figure, G), and a communication to the right atrium (Figure, H) near the superior vena cava–right atrium junction. The origin of the fistula was identified, resected, and patched with bovine pericardium. The mitral valve was repaired, and communications to the left atrium/right atrium were closed. Postoperative transesophageal echocardiography (Figure, I and Movie III in the online-only Data Supplement) and computed tomography (Figure, J) demonstrated the absence of aneurysm and fistulous connections. The patient’s postoperative course was uneventful.