An Unusual Case of Metastatic Gastric Cancer Presenting with Right Heart Failure and Cardiac Metastasis.

Cardiac metastasis is rarely detected in oncology practice. Herein we present a rare case of metastatic gastric cancer that metastasized to the right atrium and presented with right heart failure. A 51-year-old male patient with no known chronic disease presented with fatigue, abdominal distension and leg edema for 3 weeks. Physical examination revealed abdominal ascites, tachycardia and pretibial edema. Transthoracic echocardiography (TTE) revealed a hypoechoic, less-mobile mass that almost completely filled the right atrium. Moreover, 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) showed metastatic lesions and a primary tumor-suspicious area in the esophagogastric component. Upper GI endoscopic evaluation performed on the patient revealed an ulcerovegetating mass consistent with gastric adenocarcinoma. A human epidermal growth factor receptor 2 (HER-2) was positiveand programmed death-ligand 1 (PD-L1) combined positive score (CPS) was detected as 15 in immunohistochemistry (IHC). Thereafter, an anticoagulant treatment was started including pembrolizumab and trastuzumab every three weeks, and an oxaliplatin and 5-FU-based chemotherapy regimen was started every two weeks. There was no regression in the cardiac lesion during follow-up; thereafter, there was a significant risk of cardioembolic complications, and a 10 × 7 cm mass filling the right atrium and adhering to the inferior vena cava was resected. The pathology results of the excision material reported gastric carcinoma metastasis. Systemic evaluation performed 3 months later showed regression in primary and metastatic lesions. Cardiac metastases are rare and may not be discovered until autopsy due to the prominence of primary disease findings. Cardiac metastasis, although rare, should be kept in mind in gastric cancer patients presenting with heart failure.