Introduction: Synovial sarcomas are a common entity of soft tissue sarcomas, presenting in the extremities characterized by translocation t (X; 18)(p11.2;q11.2). Primary cardiac synovial sarcoma is a rare entity and has only been reported as case reports. Case presentation: A 26-year-old man presented to a cardiology clinic with signs and symptoms of acute heart failure. On echocardiogram, a left ventricular mass was found. He underwent heart surgery and on pathology assessment, a liposarcoma was diagnosed and was treated as such with doxorubicin and external radiotherapy. After six months, the tumor recurred locally and was referred to our institution. On pathologic review of the specimen, cardiac synovial sarcoma was diagnosed. He underwent a ventriculoplasty with an incomplete resection due to technical difficulties. onclusion: Cardiac neoplasms are a rare group of diseases, representing less than 0.3% of all neoplasms; moreover, cardiac synovial sarcoma has only been described as isolated case reports. We highlight the issues of the differential diagnosis of soft tissue sarcoma due to the different treatment options and prognosis. Although most primary heart masses are benign, we stress to not discard the malignant pathology, and the early referral to a high specialty center for treatment.