A massive left atrium in the context of severe mitral regurgitation: a case report.

Mitral regurgitation (MR) is among the most common heart conditions. Untreated, severe MR may result in adverse cardiac remodeling, atrial fibrillation (AF), and heart failure. A 45-year-old male with a history of AF presented with heart failure symptoms. Transesophageal echocardiogram revealed a myxomatous mitral valve with anterior leaflet prolapse, severe MR, and massively dilated left atrium (LA). A computerized tomography scan found severe LA dilation up to 17.8 cm. The patient underwent mitral valve replacement, tricuspid valve repair, and LA reduction. MR is known to result in LA dilation due to increased LA volume and pressure. While large LA sizes have been reported, they are often related to congenital conditions and rarely grow to the size identified in this case. AF and LA dilation both predict adverse outcomes, increasing the risk of thrombus formation in such a large chamber.