Introduction: Several nicotine delivery devices are discussed as a harm reduction strategy for smoking, thereunder e-cigarettes and heated tobacco products, which are also intensively promoted by tobacco companies We investigated the acute effects of heated tobacco products (IQOS) compared head-to-head to e-Cigarettes (eDIPSE) with and without nicotine and combustible cigarettes on small airway and vascular function.

Methods: This single-center four-arm cross-overstudy included 20 healthy occasional smokers (25-5±0.7 years). The participants had to consume each device after an abstinence of 48 hours of smoking. We measured vascular function (Mobil-O-Graph?) every 5 minutes and resistance of the small airways (tremoFloÒ c-100) 5, 15, 30 and 60 minutes after inhalation.

Results: All 4 devices significantly increased the small airway resistance (R5-20 - p<0.05) after inhalation, whereby the significant increase in the e-cigarette without nicotine could only be measured later than in the other devices. All 4 products significantly increased parameters of peripheral and central hemodynamic and arterial stiffness (AIx@75 - p<0.05).

Conclusion: Heated tobacco products and e-Cigarettes induce vascular and small airway dysfunction, which indicates an increased cardiovascular risk and airway damage with no harm reduction compared to combustible cigarettes.