Surviving Adulthood with Rare Combined Congenital Heart Defects: Complete AV Canal Defect, Ebstein’s Anomaly, and Right Ventricular Hypoplasia

<b>Background/Objectives.</b> Ebstein's anomaly (EA), which accounts for fewer than 1% of congenital heart diseases, and atrioventricular canal defect (AVCD), present in approximately 4-5% of cases, exceptionally coexist, with this combination observed in fewer than 0.5% of patients with AVCD. We aim to report the oldest documented case of a 45-year-old female with the exceptionally rare combination of complete AVCD, EA, and right ventricular hypoplasia and to provide a concise review of these anomalies. <b>Case presentation.</b> Diagnosed in early childhood with a complete AVCD, pulmonary stenosis, and right ventricular (RV) hypoplasia, the patient underwent palliative surgical intervention with a modified Blalock-Taussig shunt at the age of 10 but did not receive subsequent regular follow-up. Over the ensuing 35 years, she remained largely untreated until presentation at 45 years of age with progressive exertional dyspnea, central cyanosis, and palpitations, corresponding to NYHA class III. Comprehensive multimodal imaging, including transthoracic echocardiography and cardiac magnetic resonance, revealed a complete AVCD with moderate-to-severe mitral regurgitation secondary to an anterior mitral leaflet cleft, severe tricuspid regurgitation, RV hypoplasia, and hallmark features of EA. Given the complex cardiac anatomy and the elevated surgical risk, the patient was considered inoperable, and a strategy of conservative management with multidisciplinary follow-up was implemented. <b>Conclusions.</b> This case highlights the exceptional longevity of a patient with the rare coexistence of complete AVCD, EA, and RV hypoplasia, surviving 45 years from diagnosis despite limited early intervention. It underscores the importance of lifelong follow-up in complex congenital heart disease and illustrates the role of multimodal imaging in assessing anatomy and guiding management when surgical options are high-risk or not feasible.