Abstract Body (Do not enter title and authors here): Case Presentation:
Clozapine is an antipsychotic used in treatment-resistant schizophrenia. Its use has been limited by adverse events, rarely including myocarditis. Here, we describe a rare case of clozapine-induced myocarditis and the improvement of cardiac function with avoidance of clozapine for one week and initiation of guideline-directed medical therapy (GDMT).

A 29-year-old man with schizophrenia on risperidone and paroxetine was admitted with schizophrenia decompensation and suicidal ideations. He was transitioned to clozapine with improvement in his psychiatric symptoms. Thirteen days after starting clozapine, he developed nausea, vomiting, tachycardia, and low-grade fever. He had leukocytosis but it was thought to be, in part, secondary to methylprednisolone before rituximab infusions for his multiple sclerosis. An electrocardiogram revealed sinus tachycardia, and troponin, which was taken in the setting of clozapine therapy, was 6.

Four days later, his fever and tachycardia with chills and dyspnea persisted; troponin was in the forties and increased to 235 within a few hours. Over the next 36 hours, troponin peaked at 3,600. C-reactive protein and erythrocyte sedimentation rates were elevated at 20.5 and 51, compared to 1.8 and 3 respectively upon initiation of symptoms a few days earlier. A respiratory viral panel, blood and urine cultures, human immunodeficiency virus, and an autoimmune workup were unrevealing. Clozapine was held. A transthoracic echocardiogram revealed a reduced systolic function with a left ventricular ejection fraction (LVEF) of 40%. A cardiac magnetic resonance imaging revealed acute myocarditis with LVEF 24%. He was started on GDMT and a repeat echocardiogram six days later revealed normalization of systolic function with LVEF 56% with clinical improvement. His last dose of clozapine was seven days earlier. He was discharged on GDMT and clozapine was added to his allergy list.

Discussion: Myocarditis is a serious and rare adverse event to clozapine therapy. Symptoms are non-specific and delays in diagnosis may lead to myocardial damage and fatal arrhythmias. In light of the patient’s presentation, unrevealing workup, and improvement with avoidance of clozapine, we believe that the individual had clozapine-induced myocarditis. It is important to highlight the occurrence of this rare outcome to consider this toxicity and initiate treatment in time.