Abstract Body (Do not enter title and authors here): Background: Limited data exist on the incidence of severe QT prolongation (SQTP) in patients using antipsychotics or antidepressants and the associated risk of ventricular arrhythmias (VA) and sudden cardiac death (SCD).
Aims: This study aimed to investigate the incidence, risk factors, and outcomes of SQTP in patients using antipsychotics or antidepressants.
Methods: Electronic medical records from a multicenter healthcare system in Taiwan were analyzed to identify patients using antipsychotics or antidepressants with baseline and follow-up electrocardiograms. SQTP was defined as a corrected QT interval exceeding 500 ms post-treatment or an increase of >60 ms compared to baseline. Risk factors for SQTP development and associated risks of VA and SCD were assessed using multivariate logistic regression.
Results: Following antipsychotic use (n = 28,892) and antidepressant use (n = 14,634), mean corrected QT interval increases were +7.7 ± 39.0 ms and +6.7 ± 36.1 ms, respectively. Over 10% of patients using haloperidol, amisulpride, olanzapine, quetiapine, or risperidone experienced SQTP. Antipsychotics with a known or conditional risk of torsades de pointes and antidepressants with a known risk of torsades de pointes had a higher likelihood of SQTP compared to alprazolam control. Risk factors for SQTP included age >65 years, electrolyte imbalances, renal insufficiency, amiodarone use, left ventricular ejection fraction <50%, and the use of drugs with known torsades de pointes risk. In antipsychotic users, SQTP was significantly associated with increased risks of VA (odds ratio 2.91; 95% CI 2.29–3.70) and SCD (odds ratio 2.16; 95% CI 1.50–3.12). Similarly, in antidepressant users, SQTP was significantly linked to VA risks (odds ratio 2.78; 95% CI 1.63–4.74). Subgroup analyses for females and patients aged 18-50 years yielded consistent results.
Conclusions: Over 10% of patients on certain antipsychotics experienced SQTP, often with related risk factors. SQTP was significantly associated with elevated risks of VA and SCD in antipsychotic users, and increased VA risk in antidepressant users. Clinicians should be alert to SQTP in patients taking antipsychotics or antidepressants.