A case of "acquired" cor triatriatum.

Cor triatriatum sinister is a rare congenital cardiac anomaly. It consists of a fibro-muscular membrane that separates the left atrium into two chambers resulting in a tri-atrial heart. It is often found in association with other structural cardiac anomalies. The "acquired" form is extremely rare and only anecdotal reports are found in literature. We describe a case of acquired cor triatriatum following surgical repair of coronary sinus type of total anomalous pulmonary venous connection (TAPVC), which presented 11 years after initial repair of TAPVC. © Indian Association of Cardiovascular-Thoracic Surgeons 2021.