Short-term effects of varenicline therapy on homogeneity of heart rate, atrioventricular conduction and ventricular repolarization

BaCKgRound: The effects of varenicline, an effective drug for smoking cessation, on atrioventricular and ventricular conductance remain unknown. oBjeCTive: To evaluate the effects of varenicline on heart rate, PR interval, QT interval and QT dispersion (QTd). MeTHodS: A total of 60 smokers were prospectively enrolled in the present study. Twelve-lead electrocardiogram recordings were obtained for all subjects before and on the 15th day of drug administration. Electrocardiograms were recorded at an amplitude of 20 mm/mV and a sweep speed of 50 mm/s. ReSulTS: The mean (± SD) age of the volunteers was 38±10 years. Thirtyfour (57%) were male. Fourteen (23%) had hypertension, eight (13%) had diabetes and six (10%) had chronic obstructive pulmonary disease. The mean heart rate was 74.7±13.3 beats/min, and mean systolic and diastolic blood pressures on admission were 122.3±14.3 mmHg and 76.5±10.2 mmHg, respectively. Heart rate, and systolic and diastolic blood pressures did not change with varenicline treatment. Varenicline treatment resulted in limited prolongation in PR interval, which appropached significance (163.5±18.3 ms versus 168.2±17.9 ms; P=0.053), while RR interval (796.3±117.4 ms versus 798.3±123.7 ms; P=0.926), QT interval (384.1±17.5 ms versus 383.4±20.9 ms; P=0.852) and QTd (52.6±14.9 ms versus 52.2±14.9 ms; P=0.919) were not significantly changed. ConCluSion: Varenicline had a limited effect on atrioventricular conduction, while it had no effect on heart rate, QT interval and QTd. Further studies are needed to prove the effects of varenicline on the conduction system of the heart, especially on PR interval.