Severe QT Prolongation Common in Users of Antipsychotic Medications

In a recent study, severe QT prolongation occurred in 13.0 percent of quetiapine and 14.2 percent of haloperidol users

By Lori Solomon HealthDay Reporter

TUESDAY, Jan. 23, 2024 (HealthDay News) — More than one in eight patients receiving quetiapine or haloperidol therapy appear to develop severe QT prolongation (SQTP), according to a study published online Jan. 14 in Heart Rhythm.

Chun-Li Wang, M.D., from the Linkou Medical Center in Taoyuan, Taiwan, and colleagues examined the incidences, risk factors, and outcomes of SQTP in quetiapine and haloperidol users. The analysis included electronic health records from adult patients who ever used quetiapine (8,832 individuals) or haloperidol (2,341 individuals) with baseline and follow-up electrocardiograms.

The researchers found that mean increases in the posttreatment-corrected QT (QTc) interval were +8.3 and +8.9 ms after the administration of quetiapine and haloperidol, respectively. SQTP occurred in 13.0 percent of quetiapine and 14.2 percent of haloperidol users. For SQTP, common risk factors included old age, heart failure, hypokalemia, amiodarone use, and baseline QTc interval. There were significant associations for SQTP in quetiapine users and ventricular arrhythmias (odds ratio, 2.84) and sudden cardiac death (odds ratio, 2.29).

“Of the 41 drugs on the market in the United States that are listed as having a known risk of torsades de pointes, five are antipsychotic drugs, the mainstay of treatment of schizophrenia and psychosis,” write the authors of an accompanying editorial. “The use of antipsychotic drugs is associated with an approximately twofold increased risk of sudden cardiac death. If we cannot eliminate this risk, then at the least we need to minimize the risk by identifying those patients who are at highest risk and managing them more closely.”