Myxomatous mitral valve degeneration complicating asymptomatic cor triatriatum.

Cor triatriatum presenting in adulthood is extremely rare. This paper reports a case of cor triatriatum initially masquerading as mitral stenosis, which was later complicated by myxomatous mitral valve degeneration with severe regurgitation, which necessitated mitral valvular replacement. To the authors' knowledge, such a combination has not been reported in the literature.