Continuation of clozapine following mild myocarditis

DOI: 10.1177/0004867411433970 In the course of a study of clozapine and myocarditis, we have documented five individuals who met our case definition of myocarditis but yet continued clozapine without long-term cardiac injury. The case definition required clinical evidence, together with cardiac specific diagnostic evidence of myocarditis (Ronaldson et al., 2010). Each of the five (four men and one woman, aged 28–52 years) met the criteria, having tachycardia together with troponin I or T more than twice the upper limit of normal (Table 1). Three also had clinical symptoms of illness. Three had echocardiography around the time of the raised troponin and the result was normal for all three, as was follow-up echocardiography in two individuals. Each of these cases had only mild disease, as measured by troponin concentrations which were between twice and four times the upper limit of normal. However, the degree of the rise in eosinophils for Case 4 and in CRP for Case 5 was suggestive of more severe illness. Two of the cases continued clozapine with no interruption; one had a reduction in dose from 300 to 200 mg/day and two missed 1 or 1.5 days of clozapine and then continued. Acute clozapine-induced myocarditis, including in cases for whom it is asymptomatic or whose laboratory parameters give no indication of severe illness, can be fatal (Ronaldson et al., 2011a). Nevertheless, in some cases it is clearly safe to continue clozapine. Not only is it safe, but continuation of clozapine might also be highly desirable for the long-term mental health of the individual. The data available do not permit a demarcation between truly mild cases