QT interval prolongation from antipsychotics in schizophrenia and acute psychosis - A prospective study.

Background: Antipsychotic drugs have the potential to cause QT-interval prolongation (QTIP), which may lead to Torsades de Pointes and sudden cardiac death. Thus, it is important to know about the incidence and risk factors for QTIP.

Aim: The primary objective of the study was to find out the incidence of QTIP due to the use of antipsychotic drugs in patients with schizophrenia and acute psychosis after two weeks of drug use. The secondary objective was to find the risk factors for QTIP.

Materials and methods: The study included 160 consenting patients, aged ≥18 years, either sex, diagnosed with schizophrenia or acute psychosis, who had not taken oral/water-based injectable antipsychotics during the last 15 days or any long-acting antipsychotic injectable during the previous 6 months. Patients with other psychiatric disorders, substance use other than nicotine/caffeine, low serum levels of potassium/calcium/magnesium, congenital long QT syndrome, history of cardiac conditions, or those taking drugs with high risk to cause QTIP were excluded. ECG was recorded before starting treatment and after at least 2 weeks of treatment with antipsychotic drugs. Corrected QT interval (QTc) was calculated using Fridericia's and Bazett's formulae. QTc >450 ms in males and >460 ms in females was considered prolonged.

Results: The mean age of study participants was 35.88 years (SD: 13.32), and 88 (55%) were males; 138 (86.3%) suffered from schizophrenia. Seventy-one (44.4%) and 74 (46.3%) received risperidone and olanzapine, respectively. Twelve (7.5%) developed QTIP (QTc calculated using Fridericia's formula). Twenty-five (15.6%) were seen to develop QTIP (QTc calculated using Bazett's formula). Additional risk factors for QTIP could not be identified in the study sample.

Conclusion: QTIP is present in a reasonable number of participants. Careful screening and assessment for risk factors that could increase the chances of QTIP must be done regularly in patients getting antipsychotic drugs.