The effect of varenicline on Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio in healthy smokers and nonsmokers

Background: Varenicline could affect the T wave and QT interval. The interval from the peak to the end of the electrocardiographic (ECG) T wave (Tp-e) may correspond to the transmural dispersion of repolarization, and increased Tp-e interval and Tp-e/QT ratio are associated with malignant ventricular arrhythmias. In this study, we assessed the effects of varenicline on Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio. Methods: Thirty healthy volunteers (15 healthy non-smokers [NS] and 15 healthy smokers [S]) were included in the randomized, double-blind, placebo-controlled, crossover study. Varenicline (2 mg single dose) or placebo was administered in two different testing sessions (5 days after the first period, performed the second period). Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio were assessed in the supine position and during handgrip exercise before and after the participants were given placebo or varenicline. Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio were calculated from continuous ECG recordings and averages were used in the final analysis. Result: There were no statistically significant differences among any of the Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio before and after placebo administration in both groups (S and NS). In the S group, Tp-e and QTc interval, and Tp-e/QT and Tp-e/QTc ratio were significantly increased after varenicline administration (Tp-e: 64.28 +/- 8.78 vs. 70.42 +/- 13.12; p = 0.02, QTc: 409.57 +/- 28.17 vs. 425.28 +/- 32.79; p = 0.02, Tp-e/QT: 0.18 +/- 0.02 vs. 0.19 +/- 0.03; p = 0.04, Tp-e/QTc: 0.17 +/- 0.02 vs. 0.19 +/- 0.02; p = 001) but these parameters were not changed in the NS group. Conclusions: Tp-e and QTc interval, and Tpe/QT and Tpe/QTc ratio were increased after varenicline administration in smokers.