Heart rate variability in schizophrenic patients switched from typical antipsychotic agents to amisulpride and olanzapine: 3-Month follow-up

Schizophrenia is a severe mental disorder that requires lifelong treatment, and therefore information on the cardiovascular safety and tolerance of antipsychotics is of significant clinical importance. Atypical antipsychotics have been used to treat schizophrenia patients since the 1990s, and more and more patients have been switched to these from typical antipsychotics; however, there is still no accessible evaluation tool for assessing cardiovascular safety. In this study, we used a computer-assisted 5-min measurement of resting heart rate variability (HRV) in schizophrenia patients who were switched to atypical antipsychotic agents (amisulpride and olanzapine) due to severe side effects (tardive dyskinesia). In 15 patients who switched to amisulpride and 18 to olanzapine, HRV was evaluated before the medication was switched, and patients were followed up every month for 3 months after the switch. Frequency-domain analyses of short-term and stationary respiratory rate (RR) intervals were performed to evaluate low-frequency power (LF; 0.04-0.15 Hz), high-frequency power (HF; 0.15-0.40 Hz), the ratio of LF to HF (LF/HF), and LF in normalized units (LF%). Our results showed significant increases in the mean, variance and HF of RR intervals in the amisulpride group, but not in the olanzapine group. These results indicate that amisulpride has a more vagotonic effect, suggesting greater cardiovascular safety as compared with olanzapine when subjects are switched from typical antipsychotic agents.