Incidence and risk factors for clozapine-induced myocarditis and cardiomyopathy at a regional mental health service in Australia.

OBJECTIVE: To determine the incidence of clozapine-induced myocarditis and cardiomyopathy and identify risk factors.
METHOD: A cohort of 129 patients initiated on clozapine at Toowoomba Mental Health Service from year 2000 until 2011 was examined to evaluate cases of myocarditis and cardiomyopathy. Risk factors were analysed using multivariable logistic regression.
RESULTS: The incidence of clozapine-induced myocarditis and cardiomyopathy was 3.88% and 4.65% (or 2.26 per 100 patient years), respectively. A significant association was identified between clozapine-induced myocarditis and SSRI use (p = 0.043). Subclinical cardiomyopathy was identified in the absence of symptoms in the majority of cases.
CONCLUSIONS: These results illustrate a high incidence of clozapine-induced myocarditis as well as cardiomyopathy, reinforcing the need for a standardised, mandatory monitoring scheme. Concomitant SSRI use as one such potential predictor merits further study. © The Royal Australian and New Zealand College of Psychiatrists 2015.