Severity of mitral regurgitation may be underestimated in the presence of a left atrial myxoma.

It is well known that mobile or large left atrial myxoma may lead to valve obstruction and insufficiency, and affect transmitral valve flow. The case is reported of a 47-year-old woman with severe mitral regurgitation (MR) and huge left atrial myxoma (6?4?3 cm). Preoperatively, the MR appeared related to the myxoma and was classified as moderate. Following extirpation of the myxoma, intraoperative transesophageal echocardiography (TEE) revealed a severe mitral regurgitant jet. After mitral valve repair by ring implantation, the MR was reduced to minor insufficiency. Hence, a large atrial tumor may mask the severity of concomitant unrelated MR in routine echocardiography. Intraoperative TEE helped in assessing correct mitral valve function after tumor extirpation. Preoperative echocardiography should focus on mitral valve dysfunction in order to separate tumor-related and -unrelated valvular pathologies.