The midterm differential effects of heat-not-burn and conventional cigarettes on coronary flow, vascular function and oxidative stress are independent of nicotine levels

Abstract

Abstract Introduction Heat-not-burn cigarette (HNBC) constitutes a non-combustible smoke product linked to reduced exposure to carbon monoxide (CO). Methods We compared the effects of HNBC to those of tobacco cigarette (TCig) on endothelial and coronary function as well as on nicotine levels, oxidative stress and platelet activation after 1 month of switching to HNBC. We examined 75 smokers. Of those, 50 were switched to HNBC and 25 continued Tcig for 1 month. At baseline and at 1 month, we assessed a) coronary flow reserve (CFR) by echocardiography b) flow-mediated dilation (FMD) c) Cotinine blood levels, a stable metabolite of nicotine d) malondialdehyde (MDA), a marker of oxidative stress and thromboxane B2 (TXB2), a marker of platelet activation e) the exhaled CO and the number of cigarettes and/or heat stick of HNBC used. Fagerstrom score, a marker of dependence from smoking habit was also calculated. Results Compared to Tcig smoking, switching to HNBC for 1-month improved CO (difference in CO between groups: 10.42 ppm; 95% CI 3.07 to 17.76, p=0.007), FMD (difference in FMD=4.3%; 95% CI: 1.23 to 7.51, p=0.009; and CFR (difference in CFR =0.98; 95% CI: 0.23 to 1.80, p=0.02). MDA and TXB2 concentration significantly decreased in subjects switching to HNBC compared to tobacco smokers (difference MDA=0.38 nmol/L; 95% CI 0.10 to 0.66, p=0.009, 45pg/mL; 95% CI 5.28 to 86.31, p=0.03). None of the aforementioned parameters changed in the control group at 1 month compared to baseline (p>0.05). Cotinine blood levels were similar between the TC cig and HNBC group both at baseline and after one month of use (p>0.05). However, cotinine blood levels at baseline and 1 month correlated with the number cigarettes used at baseline (r=0.45 p=0.04) or the number of heat sticks used at one month (r=0.50, p=0.03) respectively, Baseline Fagerstrom score was also associated with number of heat sticks used at 1 month (r=0.48, p=0.04) and cotinine levels at baseline and at 1 month (p=0.50, p=0.03 and r=0.57, p=0.01 respectively). Conclusions HNBCs exert a less detrimental effect on vascular function platelet activation and oxidative stress than tobacco smoking that is independent of nicotine levels and is linked with the parallel reduction the exhaled of CO. Funding Acknowledgement Type of funding sources: None.