In this study, we report a case of a healthy, 25-year-old male patient with presyncope during a football match divergent blood pressure, and a grade 3/6 aortic diastolic murmur. The echocardiogram showed a rounded structure in the basal area of the interventricular septum adjacent to the aortic valve, which causes inadequate commissural support, communicating with the left ventricle (LV). There was moderate secondary aortic insufficiency and dilated LV with preserved contractility. MRI revealed myocardial density in the structure without delayed enhancement. After follow-up, the LV increased further in size and syncope on exertion. The patient underwent surgery and the anatomic pathologist diagnosed left ventricular diverticulum. The diverticulum, a congenital protrusion in the myocardial wall of the LV, differs from an aneurysm by its close connection to the chamber and presence of myocardial fibers in the composition of the wall. It most often affects the LV or right ventricular apex and is rare in the septum.