(177) Myocarditis Leading to Cardiogenic Shock Caused by Immune Checkpoint Inhibitor

Introduction: Immune checkpoint inhibitors (ICI) target proteins on the surface of T cells. Myocarditis from ICI is a rare cardiotoxic side effect with high mortality. Mean time of presentation is 21 days after initiation of treatment. Various cardiac side effects included complete atrioventricular block, right bundle branch block, ventricular tachycardia (VT), sinus tachycardia.1 In extreme cases, can lead to cardiogenic shock. This is a rare case of Pembrolizumab use that led to cardiogenic shock.

Description: 75 year old female with renal cell carcinoma on ICI, was admitted for vision changes and headache. A week after admission, she went into cardiac arrest from ventricular fibrillation. Return of spontaneous circulation was achieved. Due to recurrent polymorphic VT, amiodarone and lidocaine infusions were initiated. Endomyocardial biopsy confirmed myocarditis. Diuresis was initiated. Since she was clinically well perfusing and high risk for VT, initiation of inotropes was first held. She was initiated on methylprednisolone 1g IV daily but did not have clinical improvement. Anti-thymocytes immunoglobulin (ATG) and mycophenolate were added. Cautiously low dose milrinone was initiated then weaned off after 3 day. Patient received ATG total dose 212 mg IV over 4 days, with prednisone taper, and mycophenolate 1000 mg PO twice daily.

Discussion: As incidences of malignancy are rising, there has been increasing focus on targeted therapies such as ICI. ICIs are monoclonal antibodies that target immune negative regulatory receptors such as cytotoxic T‐lymphocyte–associated protein 4 (CTLA‐4), programmed cell death receptor 1 (PD‐1), and programmed cell death ligand 1 (PD‐L1)2.2 ICIs are used in various cancer therapies as first line therapy or adjust therapy. Due to increased use, immune-related adverse events have been documented including ICI-induced myocarditis. Incidences of ICI-myocarditis is 0.04-1.14% with mortality of 25-50%3. Due to high mortality, even if mild grade suspicion of ICU-myocarditis was present, ICI therapy is stopped.

Our case constitutes a unique and rare situation of ICI induced myocarditis that led to cardiogenic shock. Use of mycophenolate and anti-thymocytes immunoglobulin helped recover from the myocarditis so that inotropic support was safely discontinued.