Effects of cisapride on corrected QT interval, heart rate, and rhythm in infants undergoing polysomnography

Objective. To evaluate the effects of cisapride, a prokinetic gastrointesti nal drug, on the electrocardiographic QT interval, heart rate, and rhythm i n infants during routine 8-hour polysomnography. Reported electrocardiogram (ECG) and rhythm disturbances in a small number of patients with the use o f cisapride provided the impetus for this prospective study. Study Design. Two hundred fifty-two infants born at term were enrolled. Of these, 134 were on cisapride therapy for suspected gastroesophageal reflux and 118 were not on cisapride and served as controls. Cisapride-treated and control infants were from the outset divided into 3 age groups; group 1: u nder 3 months of age; group 2: between 3 and 6 months of age; and group 3: >6 months of age. Continuous ECG bipolar limb lead I recording, saturation monitoring, and electroencephalography were conducted. QT intervals and hea rt rate were measured at hourly intervals. Results. Cisapride doses were: group 1 mean, 0.80 mg/kg/day (range: 0.38-1. 55); group 2 mean, 0.80 mg/kg/ day (range: 0.23-1.38); and group 3 mean, 0. 72 mg/kg/ day (range: 0.32-1.41). Heart rate was higher in the younger infa nts, with a gradual decrease with age. No difference in heart rate was dete cted between the cisapride and control groups. The QTc interval in patients in group 1 was statistically longer than the controls, when applying both Bazett's and Hodges' formulae for QT correction. The other age groups did n ot differ. No arrhythmia or atrioventricular conduction abnormalities were observed. Conclusion. Infants under 3 months of age on cisapride treatment had signif icantly longer QTc intervals (with Bazett's formula, the 98th percentile wa s 504 ms in the cisapride group vs 447 ms in controls). The clinical signif icance and risk of the increased QTc interval in these infants are unclear and need further evaluation and risk stratification. Meanwhile, cisapride s hould be judiciously prescribed in infants <3 months of age.