446 Cor-Triatriatum Dexter: An Incidental Finding in an Adult with Rheumatic Heart Disease

Introduction Cor-triatriatum dexter (CTD) is an extremely rare congenital anomaly, accounting for 0.025% of congenital heart defects. It typically presents in childhood; however this case describes incidental finding of CTD in an asymptomatic 49-year old male with rheumatic heart disease. Case Presentation A 49-year-old male presented with 2–3-month history of exertional dyspnea (NYHA grade II), orthopnea, pedal edema, and occasional palpitations. He had a prior diagnosis of rheumatic heart disease with severe mitral regurgitation. Examination revealed elevated jugular venous pressure, bilateral basal crepitations, soft S1, pansystolic murmur in mitral area, loud non-palpable S2, and right ventricular heave. Investigations showed right ventricular hypertrophy with strain on ECG, severe mitral and tricuspid regurgitation on echo, and CTD characterized by a membrane dividing the right atrium into two chambers with an 8.6mm defect. Coronary angiography revealed atherosclerotic disease. Right heart structures were otherwise normal with no pulmonary artery stenosis or Ebstein anomaly. The CTD was likely present since birth but non-obstructive, allowing the patient to remain asymptomatic until presenting with sequelae of longstanding mitral regurgitation. Treatment and Outcome: The patient underwent MVR, TR and resection of the CTD membrane. Post-operative echo showed normally functioning prosthetic mitral valve, mild TR and no residual CTD membrane. The patient was discharged in stable condition on warfarin. Conclusion CTD may remain undiagnosed well into adulthood due to non-obstructive membranous anatomy. Incidental diagnosis prompted successful surgical resection alongside repair of symptomatic valvular disease. Clinicians should have high index of suspicion for detecting rare congenital anomalies in adults with acquired heart disease.