Progressive Right-Sided Heart Failure and Secondary Tricuspid Valve Disease in Pediatric Lutembacher Syndrome: A Case Report.

Background: Lutembacher syndrome (LS) is a rare condition characterized by the coexistence of mitral stenosis (MS) and an atrial septal defect (ASD). Clinical manifestations vary according to the severity of MS and the size of the ASD. Case Presentation: We report a 13-year-old female with congenital MS and a secundum ASD who presented with decompensated right heart failure after being lost to follow-up for 10 years. Progressive worsening of MS and enlargement of the ASD resulted in significant left-to-right shunting, severe right heart volume overload, pulmonary hypertension, tricuspid annular dilation, and severe tricuspid regurgitation. Cardiac catheterization demonstrated low cardiac output, pulmonary overcirculation, and postcapillary pulmonary hypertension. The patient underwent mechanical mitral valve replacement, ASD closure, and tricuspid annuloplasty. Outcome: Postoperatively, the patient experienced transient left ventricular dysfunction that gradually improved with medical therapy. At 2-year follow-up, she demonstrated normal biventricular systolic function and complete resolution of heart failure symptoms. Conclusion: This case highlights how a large ASD may initially mask symptoms of severe MS while simultaneously promoting progressive right-sided heart failure and secondary tricuspid valve disease. Early surveillance and timely intervention are essential to prevent irreversible cardiac remodeling in patients with LS.