DOI: https://doi.org/10.36347/sasjm.2025.v11i04.018

Pages: 358-361

Background: Thromboembolic events are common in gastrointestinal malignancies, particularly in the context of Trousseau's syndrome. However, left ventricular (LV) thrombus as an initial presentation of gastric adenocarcinoma is extremely rare. Case Summary: We report the case of a 67-year-old man with a history of chronic smoking and chronic obstructive pulmonary disease, who presented with dyspnea, dry cough, fatigue and weight loss. Diagnostic imaging revealed a mobile thrombus in the left ventricle, without underlying cardiomyopathy or arrhythmia. Further investigation, prompted by the unexplained thrombus, revealed elevated tumor markers and an antral gastric wall thickening. Upper gastrointestinal endoscopy with biopsy confirmed the diagnosis of gastric adenocarcinoma. Anticoagulation therapy with low-molecular-weight heparin was initiated, followed by long-term anticoagulation. Echocardiographic follow-up demonstrated partial regression of the thrombus. Conclusion: This case highlights the importance of considering occult malignancy, particularly gastric cancer, in patients presenting with unexplained cardiac thrombi. A multidisciplinary approach is essential for timely diagnosis and optimized management.