The Acute Effects of Cigarette Smoking on the Heterogeneity of Ventricular Repolarization in Healthy Subjects

Abstract

Background and Objectives:Although cigarette smoking is a known risk factor of sudden cardiac death, little is known about the effects of smoking on the heart. QT interval and QT dispersion prolongation have been associated with a lowered ventricular fibrillation threshold and the occurrence of sudden cardiac death. The aim of this study was to clarify the acute effects of cigarette smoking on the QT interval and dispersion. Subjects and Methods:The study population consist of 30 young male cigarette smokers, (with a mean age, and body mass index of 26±2 years;and 22.3±2.1 kg/m) respectively. Standard 12-lead surface electrocardiograms were recorded, at immediately before, during, and 5 minutes after, smoking 3 cigarettes. The RR interval, maximum and minimum QT intervals, QT dispersion (QT maximum-QT minimum), and the ratecorrected QT dispersion were all evaluated. Results:The RR interval was significantly reduced after 1 cigarette smoking (885±200 vs. 730±110 ms, p<0.01). The maximal QTBc interval was significantly longer after smoking 1 cigarette (415±21 vs. 442±21 ms, p<0.01), but the minimum QTBc interval showed no significant changes (369±23 vs. 376±22 ms, p=0.11). The QTBc dispersion (40±14 vs. 52±12 ms, p<0.01) and QTFc dispersion (42±14 vs. 58±14 ms, p<0.01) were significantly increased after smoking. Conclusion:In young males, smoking acutely increases the maximum QT interval and QT dispersion. These changes may explain the higher risk of sudden cardiac death. (Korean Circulation J 2003;33(1):58-62)