Association of autonomic dysfunction and clozapine. Heart rate variability and risk for sudden death in patients with schizophrenia on long-term psychotropic medication.

Background: Antipsychotic medications cause a wide range of adverse effects and have been associated with sudden death in psychiatric patients.

Aims: To supply power spectral analysis of heart rate variability as a tool to examine the arrythmogenic effects of neuroleptics.

Method: Heart rate analysis was carried out in patients with schizophrenia on standard doses of neuroleptic monotherapy -- 21 were on clozapine, 18 on haloperidol and 17 on olanzapine -- and in 53 healthy subjects.

Results: Patients with schizophrenia on clozapine had significantly higher heart rate, lower heart rate variability and lower high-frequency and higher low-frequency components compared with patients on haloperidol or olanzapine and matched control subjects. Prolonged QTc intervals were more common in patients than controls.

Conclusions: Patients treated with neuroleptic medications, especially clozapine, showed autonomic dysregulation and cardiac repolarisation changes. Physicians should be aware of this adverse reaction.