Adverse cardiac events in out-patients initiating clozapine treatment: a nationwide register-based study

Area of Science:

• Psychiatry
• Cardiology
• Pharmacovigilance

Background:

• Clozapine is an effective antipsychotic but carries a risk of cardiac adverse events.
• Estimating the incidence of clozapine-associated cardiac events, particularly myocarditis, is crucial for patient safety.
• Understanding these risks in real-world settings is essential for clinical decision-making.

Purpose of the Study:

• To estimate the rates of clozapine-associated cardiac adverse events in Danish outpatients.
• To compare these rates with those of other antipsychotic treatments.
• To assess the incidence of undiagnosed myocarditis by examining mortality data.

Main Methods:

• Utilized nationwide Danish health registers from 1996 to 2015.
• Identified outpatients initiating clozapine or other antipsychotics.
• Analyzed rates of myocarditis, pericarditis, and cardiomyopathy within specific timeframes post-initiation.

Main Results:

• Of 7932 patients, 3262 initiated clozapine. Myocarditis (0.03%) and pericarditis (0%) occurred within 2 months; cardiomyopathy occurred in 0.06% (1 year) and 0.12% (2 years).
• Rates of these cardiac events were similar for other antipsychotics.
• The maximum estimated rate of clozapine-associated fatal myocarditis was 0.28%.

Conclusions:

• Cardiac adverse effects associated with clozapine initiation in Danish outpatients are rare.
• The observed rates are comparable to those of other antipsychotic drugs.
• This suggests a favorable cardiac safety profile for clozapine in this population when monitored appropriately.