Cor triatriatum sinister (CTS) is a rare congenital defect in which the left atrium divided into two chambers by fenestrated fibromuscular septum. It found less than 0.1% of clinically diagnosed cardiomyopathy and 0.4% autopsies heart disease patients. Dyspnea was reported as most common symptom atrial fibrillation (AF) described 30% published cases CTS. We report young patient with CTS who had...