Pediatric cardiac tumors are rare. Among these, cardiac fibroma is the second most common. Its clinical manifestations depend on size and location of the tumor and include arrhythmia or obstruction to blood flow. Symptomatic cardiac fibroma is generally treated with surgical resection or cardiac transplantation. We present the case of a 12-year-old boy with a lethal ventricular arrhythmia induced by a remnant tumor that was previously partially resected. An implantable cardioverter defibrillator was inserted as the arrhythmia was resistant to medical treatment. He was discharged in stable condition with an implantable cardioverter defibrillator generator and followed up in the outpatient clinic.