Incidence and clinical relevance of QT prolongation caused by the new selective serotonin antagonist ketanserin.

ABSTRACT

Efficacy and safety of ketanserin were studied prospectively in a randomized, double-blind trial involving 221 patients treated for hypertension or coronary artery disease, or both. Since ketanserin has been suggested to cause QTc prolongation, the incidence and severity of this effect were investigated, as was the incidence of malignant ventricular arrhythmias during Holter monitoring. After a 1-week run-in period, all patients were examined blood pressure was measured and electrocardiograms and 24-hour Holter electrocardiograms were obtained. Two thirds of the patients (n = 147) were then randomized to receive ketanserin for 1 week (20 mg twice daily) followed by 3 weeks of 40 mg twice daily; one third of the patients (n = 74) received placebo (twice daily) for 4 weeks. After 4 weeks of treatment, blood pressure, electrocardiograms and 24-hour Holter electrocardiograms were repeated. In hypertensive patients, ketanserin significantly reduced systolic (mean reduction 17 +/- 2 mm Hg, p less than 0.0001) and diastolic blood pressure (12 +/- 1 mm Hg, p less than 0.0001) compared to baseline, and to the placebo group (p less than 0.005 for systolic and diastolic blood pressure). The QTc interval was prolonged with ketanserin (mean 400 to 418 ms, p less than 0.01) but not with placebo (399 vs 402 ms). In the ketanserin group 30% of patients and in the placebo group 8% of patients had QTc prolongation greater than 30 ms (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)