Isolated left cor triatriatum: a rare cause of effort dyspnoea in the adult.

Left cor triatriatum is a congenital heart disease characterized by an intra-atrial membrane determining obstruction and pressure gradient. We report an unusual case of cor triatriatum in a nonprofessional athlete presenting with effort dyspnoea. Although frequently diagnosed in the infant, it may also be a rare cause of effort dyspnoea in the adult.