Cardiovascular magnetic resonance in mild to moderate clozapine-induced myocarditis: is there a role in the absence of electrocardiographic and echocardiographic abnormalities?

Clozapine is an atypical, neuroleptic medication that can cause myocarditis. While the "gold standard" for diagnosis of myocarditis is perceived to be via myocardial biopsy, cardiovascular magnetic resonance (CMR) has also proven its utility in this respect, primarily through its ability to detect myocardial scar by late-gadolinium enhancement (LGE). Until recently, however, clozapine-induced myocarditis specifically has not been known to be associated with LGE on CMR. In that particular case, LGE was demonstrated in a patient with clozapine-induced myocarditis. However, quite important, that patient also had specific abnormalities on the electrocardiogram (ECG) and echocardiogram that corresponded to the area of LGE demonstrated by CMR. We highlight a case series of three patients with clozapine-induced myocarditis and provide a literature review to discuss and critically appraise the true incremental diagnostic value of CMR in such patients with normal ECG and echocardiography.