Objective: To investigate the effect of psychotropic drugs and their combinations on the QTc interval as well as the prevalence of long QTc (LQTc) among ambulatory patients with psychiatric illness in Jordan.
Methods: A cross-sectional study that included patients treated in an outpatient psychiatric clinic was conducted. The QTc duration was calculated using a combined QT correction (Bazett's formula for heart rate 60-100 and the Framingham formula for extremes of HR).
Results: Among 307 patients, about 60% received multiple psychotropic drugs. The LQTc frequency was 1.2%. QTc interval prolongation was observed in patients receiving selective serotonin reuptake inhibitors (SSRIs) (P = .011), tricyclic antidepressants (TCAs) (P = .033), citalopram (P = .044), or psychotropic polytherapy (P = .005). The addition of SSRIs to second-generation antipsychotics (SGAs) also lengthened the QTc interval (P = .029). There was a correlation between the number of psychotropic medications and the QTc length (P = .018). All patients with LQTc carried at least one risk factor for it other than the use of psychotropic medication(s), 3 of 4 patients had a combination therapy, all patients were prescribed SSRIs, and 2 of them had comorbid conditions.
Conclusion: There is a high prevalence of psychotropic drugs polytherapy, and it is clearly associated with LQTc. Citalopram, SSRIs, and TCAs prolong QTc interval. It is recommended to assess non-pharmacological factors for LQTc and, if necessary, to obtain an electrocardiogram before starting patients on psychotropic drugs known to prolong the QTc interval.
Keywords: Electrocardiography; antidepressive agents; antipsychotic agents; polypharmacy; psychotropic drugs; serotonin uptake inhibitors.
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