Letters
Cardiovascular diseases
Volume 198 - Issue 2

Echocardiographic monitoring for clozapine-associated cardiac toxicity — time for review?

Authors:  Stuart D Murch, David L Prior and David J Castle

Med J Aust 2013; 198 (2): 86-87. || doi: 10.5694/mja11.11394
Published online: 4 February 2013
To the Editor: Clozapine therapy is a recognised risk factor for myocarditis and cardiomyopathy; however, there are no national guidelines for cardiac monitoring. Similar to many centres in Australia, and consistent with the consensus view from major psychiatric facilities in Victoria,1 our institution’s policy is to monitor patients with a baseline echocardiogram before starting treatment with clozapine, at 6 months and 12 months after starting treatment, and ...
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To the Editor: Clozapine therapy is a recognised risk factor for myocarditis and cardiomyopathy; however, there are no national guidelines for cardiac monitoring. Similar to many centres in Australia, and consistent with the consensus view from major psychiatric facilities in Victoria,1 our institution’s policy is to monitor patients with a baseline echocardiogram before starting treatment with clozapine, at 6 months and 12 months after starting treatment, and once per year thereafter.

Clozapine-associated myocarditis usually occurs within the first month of treatment, whereas cardiomyopathy can occur at any time. It is not known whether either of these complications is dose related. Clozapine-associated cardiomyopathy is rare, with a reported incidence density rate of one case per 1941 patient-years on clozapine.2

We performed a retrospective audit of the medical records and all available echocardiograms for 159 consecutive patients who began treatment with clozapine at our institution from 1 January 2002 to 30 June 2009. Thirty-seven patients were excluded from analysis as their medical records were not available for review.

The patient group was predominantly male (71.3%), with a median age of 32 (interquartile range, 26–44 years). Overall, 73% of patients had a baseline echocardiogram, and 65% had at least one follow-up echocardiogram.

Myocarditis was identified in three patients. All three cases occurred within the first month of treatment with clozapine, and myocarditis was suspected on clinical grounds before an echocardiogram was performed. One case of cardiomyopathy was identified in a 24-year-old man, who was found to have a decline in left ventricular ejection fraction from 60% at baseline to 40% after 2 years of therapy. Clozapine weaning had already been initiated because of compliance issues, and the patient was asymptomatic.

Our findings suggest that routine echocardiography is not helpful in screening for clozapine-associated myocarditis. This adds weight to recent proposals that monitoring for this acute condition should focus on active clinical monitoring augmented with laboratory investigations, such as tests for C-reactive protein and troponin levels, in the first month of treatment.3 Echocardiography should be used as part of confirmatory testing if a case of clozapine-associated myocarditis is suspected. Further work is needed to clarify if routinely screening asymptomatic patients for cardiomyopathy is beneficial or cost-effective.

Authors

  • Stuart D Murch1
  • David L Prior1
  • David J Castle1
  • 1. St Vincent’s Hospital, Melbourne, VIC.

Correspondence: stuart.murch@svhm.org.au

Competing interests

St Vincent’s Hospital Melbourne has received an investigator-initiated grant from Hospira.

Acknowledgements

We thank Melissa Petrakis, Nga Tran and Danny Liew for assistance with data collection and review of the manuscript.

References

View this article on Wiley Online Library

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