Leiomyosarcomas are uncommon malignancies of soft tissue associated with a poor prognosis due to local and metastatic disease. We describe an example of metastatic pulmonary leiomyosarcoma with intracardiac extension in a patient who had previously undergone resection of a primary retroperitoneal mass. Distinguishing metastatic malignancy within the heart from a primary tumour, such as atrial myxoma, may be difficult, with the use of various imaging modalities assisting in diagnosis and management. In this case, the patient's course was complicated by dramatic progression with widespread emboli resulting in peripheral arterial occlusion and stroke.