228: CARDIOGENIC SHOCK SECONDARY TO PEMBROLIZUMAB MYOCARDITIS IN A PATIENT WITH MELANOMA: A CASE REPORT

Introduction: Immune-checkpoint inhibitors (ICIs) have revolutionized cancer treatment but can rarely lead to cardiac toxicities, including myocarditis. We present a case of a 75-year-old female with right upper extremity melanoma (pT4BN) who developed cardiogenic shock and multisystem organ failure after receiving adjuvant pembrolizumab therapy. Description: Two weeks after pembrolizumab initiation, the patient experienced dyspnea, cough, and decreased performance status, prompting suspension of treatment. Elevated troponin I levels (6.3 ng/mL) necessitated emergency department (ED) referral, where she exhibited dyspnea, lower extremity edema, generalized weakness, left bundle branch block, and ST segment depression on ECG. Elevated troponin (peak 18.4 ng/mL), B-type natriuretic peptide (BNP) (1139 pg/mL), and leukocytosis (16.6 × 10^3/μL) indicated non-ST segment elevation myocardial infarction (NSTEMI). Cardiac catheterization revealed no obstructive coronary disease and the patient ultimately deteriorated with worsening cardiac indices and cardiogenic shock. She had associated unstable bradycardia thought to be secondary to myocarditis. Echocardiography and hemodynamics showed improvement after initiation of aspirin and high dose methylprednisolone. Temporary transvenous pacer placement was utilized to bridge recovery of shock until further steroids were given. We propose pembrolizumab-induced myocarditis as the etiology of cardiogenic shock in this patient. Cardiac MRI was deferred due to the patient's instability. Discussion: ICIs are a major advancement in cancer treatment and are used in increasing prevalence. The lower immune tolerance with ICIs results in rare but fatal immune-related adverse events and cardiotoxicity, most common being myocarditis. This case underscores the importance of considering ICI-induced myocarditis in the differential diagnosis of cardiogenic shock in cancer patients receiving immunotherapy. Prompt recognition and intervention are vital for optimizing outcomes. As ICIs gain prominence in cancer treatment, further research and awareness are warranted to best identify and manage these rare but potentially life-threatening complications.