Lessons Learned and Questions Raised by an Atypical Case of Clozapine-Induced Myocarditis

A Caucasian male in his early twenties suffering from treatment resistant schizophrenia was started on clozapine. After three days he developed tachycardia, a common side effect of clozapine induction. He had one temperature spike (38.9°C) on day ten after induction but remained clinically well. An ECG and blood tests were normal. Due to persistent tachycardia and an episode of collapse whilst seated on day 12, he was admitted to hospital for further investigation. A diagnosis of myocarditis was confirmed as a result of elevated cardiac enzyme levels and an echocardiogram. Following withdrawal of clozapine, supportive management, and initiation of cardiac medication, the patient made a successful recovery. He will be followed up with the cardiology team to ensure that his heart function returns to normal. Given the incidence of clozapine-induced myocarditis, the associated mortality risk, and diagnostic difficulties, this case raises questions about whether a formal system for identifying myocarditis should be adopted.