QTc-interval abnormalities in a forensic population

Prevalence of QTc interval prolongation and its associated risk factors among psychiatric patients: a prospective observational study

BACKGROUND

QT interval prolongation is a growing concern worldwide, posing psychiatric patients to life-threatening fatal arrhythmias i.e., torsade de pointes. This study aimed to identify the prevalence of QT interval prolongation, its associated risk factors and prescribing patterns of QT prolonging drugs among psychiatric patients.

METHOD

A prospective observational study was conducted that included psychiatric patients from a tertiary care hospital and a psychiatry clinic in Peshawar, Khyber Pakhtunkhwa, Pakistan. Electrocardiogram was recorded of those patients who were using psychotropic medications for ≥7 days, aged 18 years or more, and of either gender, male or female. The Fredericia correction formula was used for measuring QTc values (corrected QT). Chi-square test was applied to estimate differences between patients with or without prolonged QTc interval whereas, logistic regression analysis was performed to identify various predictors of QT interval prolongation.

RESULTS

Out of 405 patients, the QTc interval was prolonged in 23 (5.7%) patients including 1 (0.2%) patient with highly abnormal prolonged QTc interval (> 500 ms). QT drugs (91.6%), female sex (38.7%) and hypertension (10.6%) were the most common QT prolonging risk factors. Prolonged QTc interval was significantly higher among male patients (p = 0.007).

CONCLUSION

In the present study, QT interval prolongation was observed in a considerable number of psychiatric patients. While, the high prevalence of QT prolonging risk factors among these patients warrants the increased risk of fatal arrhythmias. Therefore, risk assessment and electrocardiographic monitoring, and prescription of safer alternatives are highly recommended.

QTc interval in a sample of long-term schizophrenia inpatients

This naturalistic study attempted to determine the prevalence of prolonged QTc interval in a relatively large population of inpatients hospitalized with chronic schizophrenia, and to explore QTc relationship with demographic variables, metabolic parameters and prescribed treatments. All inpatients from a Spanish long-term psychiatric hospital were cross-sectionally investigated to determine the prevalence of QTc prolongation and metabolic syndrome. The sample with a DSM-IV diagnosis of schizophrenia included 171 Caucasian inpatients, all of Spanish origin. A prolonged QTc interval was defined as >450 ms in men and >470 ms in women. The relationships between QTc and other continuous variables were assessed using a linear regression model with QTc as the dependent variable. Only 10 patients (6%) had a prolonged QTc interval; one case was possibly explained by hypokalemia. Three patients (2%) had a QTc > 500 ms. Gender, old age (> or = 50 years old), current smoking, systolic blood pressure, HDL cholesterol and history of arrhythmia were found to have significant effects on QTc interval in a linear regression analysis. After controlling for significant variables, the mean QTc interval was not significantly influenced by antipsychotic dose, type of antipsychotic treatment, the use of depot antipsychotics, or the number of different antipsychotics prescribed. Our study focused on long-term schizophrenia inpatients with frequent antipsychotic polypharmacy and high antipsychotic doses, and suggested that after excluding the case with hypokalemia length of QTc was associated with history of arrhythmias and with metabolic factors, while the effects of antipsychotic compound or class were not so evident.