Arrhythmic markers and clozapine in patients with schizophrenia: effect of 10 weeks clozapine treatment on heart rate variability, late potentials and QT dispersion

Objective: Clozapine is a well-known atypical antipsychotic agent which is especially useful in patients with treatment-resislant schizophrenia, but there is still debate on its potential to cause arrhythmia and sudden death. To explore the effect of clozopine on arrhythmic markers in patients with schizophrenia, heart rate variability, QT dispersion and late potentials were measured before and after 10 weeks' treatment. Method: Heart rate variability and QT dispersion were measured by electrocardiography. Signal averaged electrocardiography was used to measure late potentials. Heart rate variability, QT dispersion and late potentials were measured at baseline with at least 2-7 days wash-out period and after 10 weeks of clozapine treatment. Results: No significant differences were found in late potentials and QT dispersion domains or Or corrected values between pretreatment and posttreatment parameters of clozopine. Heart rate variability measures seemed to be significantly decreased after the treatment. This difference was more prominent in female patients and patients who were under 35 years. Change in mean heart rate variability value was found to be significantly correlated with the dosage of clozopine but not with autonomous side effects such as, dizziness, hypertension, and decreased perspiration. Conclusion: Clozapine decreases heart rate variability after 10 weeks of treatment and this effect may be dose dependent. In this study, clozopine did not effect late potentials and QT dispersion as markers of drug-induced arrhythmia.