Effect of habitual cigarette smoking on the index of cardiac electrophysiological balance in apparently healthy individuals

Background and aim: Chronic cigarette smoking has been suggested to portend risk for cardiac arrhythmia generation. Index of cardiac electrophysiological balance (iCEB) is a relatively newECG parameter indicating balance between ventricular depolarization and repolarization, thereby providing more insight concerning ventricular arrhythmogenesis (VA) than other classical ECG parameters such as QT and corrected QT (QTc) intervals. The present study aimed to assess the status of iCEB in healthy habitual smokers.Methods: This retrospective study included a total of 80 apparently healthy subjects (45% female, mean age 39.4 +/- 8.1 years) with smoking habit and 82 healthy non-smoking subjects (40% female, mean age 37.0 +/- 8.6 years) were included between January-September 2019. Demographic, clinical and ECG characteristics were obtained frommedical records. iCEB and corrected iCEB values were calculated by dividing respective QT and QTc intervals by QRS duration.Results: Mean PR, QRS and QT intervals were similar between the groups, whereas mean heart rate and QTc interval were greater in the smoker group compared with the non-smokers [(82.0 +/- 8.9 bpm vs 77.8 +/- 12.4 bpm, respectively, p= 0.016) and (427.05 +/- 22.6 msec vs 399.9 +/- 12.8 msec, respectively, p < 0.001)]. Subject with smoking habit had greater iCEBc than the controls (5.10 +/- 0.49 vs 4.68 +/- 0.39, respectively, p < 0.001). However, there was no significant difference in regard of iCEB between the groups (4.37 +/- 0.46 vs 4.32 +/- 0.42, respectively, p = 0.456).Conclusion: iCEBc increases significantly in healthy smokers compared with non-smokers. This may suggest an increased predisposition to Torsades de Pointes-mediated VA in healthy smokers, or in chronic smokers with inherent QT-prolonging genetic variations or those on QT-prolonging drug therapy. (c) 2020 Elsevier Inc. All rights reserved