The deceased was a 44-year-old male who was treated for a suspected Ebstein's anomaly observed using transthoracic echocardiogram. He was found dead in his bed at home. Autopsy revealed that the septal tricuspid leaflet was intact; however, a large anterior tricuspid leaflet cleft and right atrioventricular cavity dilation were observed. Pathological examination revealed a normal tricuspid valve, except for the presence of a cleft with local fibrosis of the left ventricle papillary muscle and hemosiderin-containing macrophages at both lungs. There were no other abnormalities that may have led to death. It was concluded that he died a cardiac death based on the right heart overload associated with the anterior tricuspid leaflet cleft. This case indicates the possibility that the anterior tricuspid leaflet cleft can cause death and also highlights the necessity of a detailed autopsy to accurately diagnose the cause of death.