QTc-interval abnormalities and psychotropic drug therapy in psychiatric patients.
BACKGROUND
Sudden unexplained death in psychiatric patients may be due to drug-induced arrhythmia, of which lengthening of the rate-corrected QT interval (QTc) on the electrocardiogram is a predictive marker. We estimated the point prevalence of QTc lengthening in psychiatric patients and the effects of various psychotropic drugs.


METHODS
Electrocardiograms were obtained from 101 healthy reference individuals and 495 psychiatric patients in various inpatient and community settings and were analysed with a previously validated digitiser technique. Patients with and without QTc lengthening, QTc dispersion, and T-wave abnormality were compared by logistic regression to calculate odds ratios for predictive variables.


RESULTS
Abnormal QTc was defined from the healthy reference group as more than 456 ms and was present in 8% (40 of 495) of patients. Age over 65 years (odds ratio 3.0 [95% CI 1.1-8.3]), use of tricyclic antidepressants (4.4 [1.6-12.1]), thioridazine (5.4 [2.0-13.7]), and droperidol (6.7 [1.8-24.8]) were robust predictors of QTc lengthening, as was antipsychotic dose (high dose 5.3 [1.2-24.4]; very high dose 8.2 [1.5-43.6]). Abnormal QT dispersion or T-wave abnormalities were not significantly associated with antipsychotic treatment, but were associated with lithium therapy.


CONCLUSIONS
Antipsychotic drugs cause QTc lengthening in a dose-related manner. Risks are substantially higher for thioridazine and droperidol. These drugs may therefore confer an increased risk of drug-induced arrhythmia.
Reilly
J G
JG
Academic Department of Psychiatry, University of Newcastle Upon Tyne, UK.
Ayis
S A
SA
Ferrier
I N
IN
Jones
S J
SJ
Thomas
S H
SH
D000293:Adolescent; D000328:Adult; D000368:Aged; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000627:therapeutic use; D002423:Cause of Death; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography / Q000187:drug effects*; D004739:England; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000175:diagnosis / Q000401:mortality; D008297:Male; D001523:Mental Disorders / Q000188:drug therapy* / Q000401:mortality; D008875:Middle Aged; D016017:Odds Ratio; D011619:Psychotropic Drugs / Q000009:adverse effects* / Q000627:therapeutic use; D012307:Risk Factors
D014150:Antipsychotic Agents; D011619:Psychotropic Drugs