The Moderating Effect of Physical Activity Between IQOS Smoking and Ventricular Repolarization Parameters in Lebanese University Students.

Background: Cigarette smoking is a major modifiable risk factor for cardiovascular morbidity and sudden cardiac death, in part through abnormalities in ventricular repolarization. However, little data are available on other tobacco products and alternative tobacco use delivery devices, such as heated tobacco products, as well as the modifying impact of physical activity, on repolarization among young adults. Objective: To assess the association between dependence on cigarettes, waterpipe and heated tobacco products and indices of ventricular repolarization among a sample of Lebanese university students and to examine the moderating effect of physical activity on such an association. Methods: Eighty-one Lebanese university students participated in this observational cross-sectional study (mean age 21.3 ± 1.7 years). Tobacco, waterpipe and heated tobacco product dependence were assessed with the Fagerström Test for Nicotine Dependence (FTND), the Lebanese Waterpipe Dependence Scale (LWDS), and the Heated Tobacco Products Addiction Questionnaire (HeaTPAQ) respectively. Physical activity were also evaluated using the physical activity index (PAI). Standard resting 12-lead electrocardiograms were recorded, and Tp-e interval, Tp-e/QT and Tp-e/QTc ratios were measured. Bivariate correlations and multivariable linear regression models, as well as moderation analyses were performed. Results: Dependence on cigarettes, waterpipe and heated tobacco products were significantly associated with higher Tp-e interval values and higher Tp-e/QT and Tp-e/QTc ratios. Male sex was associated with higher repolarization indices, while female participants had lower values. Physical activity significantly moderated the association between dependence on heated tobacco products and repolarization indices in moderation analyses. Higher dependence on heated tobacco products was associated with higher Tp-e based indices at low levels of physical activity. This association was no longer significant at moderate and high levels of physical activity. No significant differences were found in QT or QTc intervals. Conclusion: Dependence on cigarettes, waterpipe and heated tobacco products is associated with higher ventricular repolarization heterogeneity in young adults, even in the absence of conventional QT abnormalities. Physical activity may attenuate the negative association between dependence on heated tobacco products and repolarization indices. Such findings may indicate the early presence of subclinical electrophysiologic risk and suggest that Tp-e based indices should be further assessed and used in future studies, while also highlighting the role of both nicotine dependence and lifestyle behaviors in young populations.