Multimodality Cardiac Imaging and Multidisciplinary Collaboration in Monitoring Intracardiac Sarcoma Response to Immunotherapy

BACKGROUND: Intracardiac metastases causing right ventricular outflow tract obstruction are rare and carry a dismal prognosis. Immune checkpoint inhibitor (ICI) therapy risks immune-mediated pseudoprogression that could worsen hemodynamic obstruction. CASE SUMMARY: A 40-year-old man with metastatic alveolar soft part sarcoma presented with dyspnea, pericardial effusion, and intracardiac masses causing significant right ventricular outflow tract obstruction. Cardiac magnetic resonance tissue characterization established a noninvasive diagnosis without endomyocardial biopsy. ICI therapy was delivered as an inpatient in a coronary care unit with continuous cardiology monitoring. Serial echocardiography demonstrated progressive reduction in mass size with relief of obstruction, and Cardiac magnetic resonance confirmed treatment response. More than 2 years later, he achieved complete metabolic response on positron emission tomography-computed tomography and remains well in active surveillance. DISCUSSION: Multimodality imaging provides complementary hemodynamic, tissue-level, and metabolic surveillance essential for detecting pseudoprogression and confirming true treatment response in hemodynamically significant intracardiac tumors. TAKE-HOME MESSAGE: Multidisciplinary cardio-oncology collaboration can enable safe ICI delivery and durable complete response in hemodynamically significant intracardiac metastatic disease.