Abstract 17127: Rapid Progression of Conduction System Disease in Suspected Fulminant Nivolumab Myocarditis

Abstract

Background: Immune checkpoint inhibitors (ICI) have shown efficacy in treating a wide spectrum of malignancies, but have a known risk of cancer therapy related cardiac toxicity. We present a case that demonstrates how conduction system disease can rapidly progress in a patient with suspected nivolumab (PD1) induced fulminant myocarditis. Case: An 82-year-old male with a history of esophageal carcinoma presented with agonal breathing and altered mental status. He had received his second dose of PD1 therapy three days prior. He was intubated and admitted for hypoxic respiratory failure and elevated troponin. His initial EKG demonstrated new marked 1st degree AV block with right bundle branch block (RBBB) morphology. A stat echocardiogram noted an EF of 60-65% with no wall motion abnormalities. Decision-making: On Day 2, Mobitz Type I block was appreciated on telemetry. The patient met criteria for acute myocarditis with his clinical presentation, new conduction system disease, and high sensitivity troponin of 13,000. Given recent PD1 therapy, lack of infectious prodrome, and lack of prior heart disease, suspicion for ICI induced myocarditis was high. High dose steroid therapy was initiated. On Day 3, the patient was noted to have alternating left bundle branch block and RBBB. On Day 4, he progressed to complete heart block, prompting transvenous pacemaker (PM) placement with subsequent permanent PM placement. A repeat echo showed global hypokinesis with an EF of 40-45% and reduced RV function. He also required vasopressor support meeting criteria for fulminant myocarditis. Due to his hemodynamic instability and low clinical suspicion, he did not receive cardiac catheterization. Cardiac MRI and cardiac biopsy were not readily available in this institution. Conclusion: The clinical findings, lack of infectious prodrome, and worsening arrhythmia requiring pacing and vasopressor support, in patient with recent PD1 treatment suggests nivolumab induced fulminant myocarditis. In institutions without advanced testing infrastructure, rapid recognition of progressive conduction system disease may be used as an early marker for diagnosis, treatment initiation, and referral to tertiary care centers for advanced management of fulminant ICI myocarditis.