The effects of cigarette smoking on the Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio

Background. Cigarette smoking increases the risk of sudden cardiac death. Smoking may predispose individuals to ventricular fibrillation and sudden cardiac death by altering ventricular repolarization and stimulating sympathetic nervous system activity. Objectives. The aim of the study was to investigate the instantaneous effects of smoking on ventricular repolarization. Material and Methods. The study included 47 healthy subjects; 24 long-term heavy smokers (10 women, mean age: 40 ± 5 years) constituted the study group, and 23 non-smokers (10 women, mean age: 42 ± 10 years) constituted the control group. ECGs were performed on all the subjects. The Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio were measured and compared between the groups. Results. There were no significant differences between smokers and nonsmokers in the basic clinical and echocardiographic variables (p > 0.05). The QT interval and QTc interval were similar in both groups. The Tp-e interval (p = 0.02) and Tpe/QT ratio (p = 0.001) were higher in the heavy smokers than in the non-smokers. The Tpe/QTc ratio (p = 0.001) was also higher in the smokers. Other ECG parameters were similar between the smokers and nonsmokers. Conclusions. The results show that chronic cigarette smoking is associated with a prolonged Tp-e interval, increased Tp-e/QT ratio and Tp-e/QTc ratio. These observations may indicate that there may be a relationship between smoking and altered ventricular repolarization. Abnormal ventricular repolarization values on an ECG may explain the increased cardiovascular event risk in long-term heavy cigarette smokers.