Published: December 2011

M² Logo update: Quetiapine and cardiomyopathy - an emerging safety signal

Prescriber Update 32(4): 31
December 2011

M² logo is a new medicines monitoring scheme that aims to stimulate adverse reaction reports for specific medicines and reactions; this helps Medsafe and CARM to investigate these safety signals and decide if any action needs to be taken.

The first medicine and reaction of interest added to the M² logo scheme was quetiapine and cardiomyopathy. Over a six month period Medsafe and CARM monitored reports received for the combination and further investigated this emerging safety signal.

Quetiapine is approved for use in New Zealand for the treatment of acute and chronic psychoses (including schizophrenia), and bipolar affective disorder. Quetiapine is structurally related to clozapine and olanzapine; clozapine has previously been associated with cases of myocarditis and cardiomyopathy.

Cardiomyopathy is a heart muscle disorder that can result in congestive heart failure.* Dilated cardiomyopathy (DCM) is the most common form and is also commonly associated with the use of medicines. Up to two thirds of cases are considered to be idiopathic; however identification of a precipitating cause is important. There is some evidence that DCM may be partially reversible if the precipitating cause is withdrawn.1

CARM has received 7 reports of cardiomyopathy associated with the use of quetiapine. These reports describe quetiapine being used for depression (3), bipolar disorder (2), and schizophrenia (2). The age range of patients was 20-52 years, and duration of quetiapine use was 6 months to 5 years. A total of 2 reports were confounded (1 by clozapine use and 1 by excessive alcohol consumption) and one patient’s symptoms improved despite continuing quetiapine.

A biologically plausible mechanism for this association is yet to be confirmed; however some authors have suggested that, as with clozapine, a hypersensitivity myocarditis is the likely mechanism. Quetiapine may also have an indirect effect on the development of cardiomyopathy by causing obesity and diabetes.

The New Zealand quetiapine data sheets are in the process of being updated to indicate that cardiomyopathy has been reported in patients taking quetiapine.

Health professionals are advised to consider quetiapine as a possible cause in patients presenting with unexplained cardiomyopathy. Specialist advice should be sought and consideration given to discontinuing quetiapine treatment if cardiomyopathy occurs.

Please continue to report all suspected cases of cardiomyopathy associated with the use of quetiapine to CARM. This will help Medsafe to further explore this signal.

Your support of  M² logo and New Zealand’s spontaneous reporting scheme helps Medsafe to monitor and improve the safety of medicines in New Zealand.

* Excludes cardiac dysfunction resulting from structural heart disease, such as coronary artery disease, primary valve disease or severe hypertension.

  1. Stevenson LW, Loscalzo J. Chapter 238. Cardiomyopathy and Myocarditis. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson JL, Loscalzo J, eds. Harrison’s Principles of Internal Medicine. 18th ed. New York: McGraw-Hill; 2011. Accessed November 16, 2011.