SCMR 22nd Annual Scientific Sessions
Description of Clinical Presentation:
A 58 year-old man with history of localized melanoma status post wide excision, recent admission at an outside facility for an out of hospital arrest and secondary prevention implantable cardiac defibrillator (ICD) following a negative coronary angiogram. His suspected diagnosis was apical hypertrophic cardiomyopathy (HCM) based on echocardiography. Because of incessant ventricular (VT) and ICD shocks, he was referred to CMR for scar assessment prior to VT ablation.
Diagnostic Techniques and Their Most Important Findings:
Images were acquired using a 1.5T magnetic scanner (Avanto, Siemens, Erlangen, Germany). Steady-state free precession sequences (SSFP) cine images revealed two large intracardiac masses (Panel 1A) with normal biventricular function but focal hypokinetic anterior and apical segments at the location of the masses in the left ventricle. Both masses were isointense to myocardium on T1-weighted imaging (Panel 1B), hyperintense to myocardium on T2-weighted imaging (Panel 1C), and heterogeneously hypoperfused in relation to the myocardium. Late gadolinium enhancement imaging showed central low signal intensities concerning for central necrosis (Panel 1D). The CMR findings were concerning for cardiac tumors without evidence of HCM which prompted further workup.
The mass was biopsied via a transeptal approach using 3-dimensional guided intracardiac ultrasound. Pathology was consistent amelanotic melanoma. Whole body PET scan revealed extensive multiple focal cardiac metastases with probable pericardial involvement along with retroperitoneal metastasis suggesting peritoneal carcinomatosis. Oncology was consulted and the patient was initiated on pembrolizumab. For his VT, he was transitioned from intravenous amiodarone and lidocaine to oral amiodarone and mexiletine. He was arrhythmia-free for a week prior to discharge. He was maintained on pembrolizumab bimonthly infusions as an outpatient and tolerated therapy fairly well.
The patient was followed with serial surveillance CMR with evidence of tumor regression two months on therapy. Five months post follow-up, the CMR scan indicated the stigmata of treated tumor with regions of LGE and residual fibrotic changes (Panel 2). Follow-up whole body PET were also negative at 5 months.
Learning Points from this Case:
CMR-based diagnosis of cardiac malignancy critically altered the clinical management. The apical tumor was initially misinterpreted as apical HCM and a secondary prevention ICD was implanted. A MR non-conditional ICD was scanned using our institutional protocol involving pre and post scan device programing and continuous monitoring by a cardiologist. The CMR-based diagnosis lead to the timely initiation of the immune modulator pembrolizumab. Follow-up scans were used to monitor the patient’s clinical course and response to therapy.