The effects of cigarette smoking on the heterogeneity of ventricular repolarization

Background Although the circulatory effects of cigarette smoking have been studied extensively, its impact on ventricular repolarization has not been adequately evaluated. Methods The goal of our study was to determine whether cigarette smoking influences the spatial and temporal heterogeneity of ventricular repolarization in a population of young, healthy, male subjects. A digital 12-lead surface electrocardiogram was obtained from 1394 men recruited from the Hellenic Air Force and classified as smokers and nonsmokers. The maximum, minimum, and median QT intervals, QT dispersion (QT maximum - QT minimum), the rate-corrected maximum and median QT intervals, the slopes of the QT maximum/RR and QT median/RR regression equations, and the vectorcardiographic markers spatial T amplitude and spatial QRS-T angle were evaluated in the 2 groups. Results Heart rate was significantly higher (P < .001) in smokers (n = 691) compared with nonsmokers (n = 703). QT maximum, QT minimum, and QT median were significantly lower (P < .001), whereas the rate-corrected QT maximum (P = .04) and QT median (P = .06) were marginally higher in smokers than in nonsmokers. The spatial T amplitude was lower (P = .002), whereas the spatial QRS-T angle was higher (P = .01) in smokers compared with nonsmokers. Neither QT dispersion nor the slopes of the QT/RR and the spatial descriptors/RR regression equations differed between smokers and nonsmokers. Conclusions Ventricular repolarization is altered in young male cigarette smokers. The differences in the heterogeneity of ventricular repolarization between smokers and nonsmokers are mainly due to heart rate differences between the 2 study groups.