A patient in her early 20s presented with blood-stained sputum and shortness of breath. Initially, she was treated for pneumonia. Later, upon exacerbation of symptoms, further investigations were done which exhibited a left atrial mass causing compression of contralateral atrium. She underwent surgical resection of the mass, which was initially mistaken as myxoma. However, histopathological correlation revealed spindle cell sarcoma with focal myogenic differentiation. This case report highlights the role of Radiation Therapy in adjuvant setting with promising impact on improving local control after R2 resection. Cardiac spindle cell sarcoma, being one of the rarest cardiac tumours reported to date, warrants establishment of a Rare Tumour Multidisciplinary Team for management of such malignancies.