Primary cardiac angiosarcoma is a rare, aggressive malignancy that commonly metastasizes to various organs. The presenting symptoms are typically nonspecific, so a comprehensive examination is required to confirm the diagnosis promptly. This case report describes the presentation of an older patient with a history of neoplasms. Echocardiography and biopsy were performed, but despite surgical intervention to resect a large right atrial mass, the patient died. A final diagnosis of primary angiosarcoma was made based on the resected specimen.