BACKGROUND Owing to the unique structure and function of the heart, tumor metastasis in the heart is rare. Accordingly, no unique symptoms have yet been identified for cardiac metastasis. A patient presented with cardiac metastasis 3 years after surgical resection of alveolar soft tissue sarcomas in their late stage. METHODS Ultrasonography showed a middle-high echo clump on the left surface of the mid-upper interventricular septum, which had an unclear boundary with the myocardium. Meanwhile, blood flow was found in the clump, with no blockage of blood flow having been observed. CONCLUSIONS Although cardiac metastasis in terminal cancer patients always carries a poor prognosis, there is still no effective treatment for cardiac metastasis. In the clinic, it is important to improve the patient's quality of life, reduce symptoms and signs, and extend the duration of survival.