BackgroundLeft ventricular outflow tract stenosis and atrioventricular valve regurgitation are often problems encountered in adulthood after complete atrioventricular septal defect repair. The surgical approach and indications for managing long-term outcomes such as left atrioventricular valve regurgitation and left ventricular outflow tract stenosis after complete atrioventricular septal defect repair have been discussed.Case presentationA 23-year-old woman with intellectual disability was diagnosed with complete atrioventricular septal defect and underwent two-patch repair without cleft closure in childhood. Follow-up examination in adulthood demonstrated moderate left-sided atrioventricular valve regurgitation and left ventricular outflow tract stenosis with a circumferential ridge (peak velocity, 3.7 m/s; pressure gradient, 54 mmHg). Intraoperative findings showed a circumferential ridge under the aortic valve, and we removed the ridge. In addition, a cleft was present at the anterior leaflet, and we completely closed the cleft. Anticoagulation therapy was not initiated, and no embolic complications occurred. Follow-up echocardiography demonstrated no ridge under the aortic valve and only mild-range left AVVR.ConclusionsWe successfully performed surgical treatment without valve replacement or anticoagulation therapy in a patient with poor medical compliance. Delayed reoperation leads to degeneration of the valve structure and makes more difficult to repair. Atrioventricular valve regurgitation should be evaluated in combination with based on the etiology of the regurgitation especially cleft related or not, in addition to the dilatation annulus, cleft size, and depth of the leaflet coaptation depth, and associated other valve diseases.