Background Cardiovascular safety is an important consideration regarding the benefits versus risks of electronic cigarette use (EC) for public health. The single-use cardiovascular effects of EC have been well studied but may not reflect effects of ad libitum use throughout the day. We aimed to compare the circadian hemodynamic effects as well as 24-hour biomarkers of oxidative stress, and platelet aggregation and inflammation, with ad libitum cigarette smoking (CS) versus EC versus no tobacco product use. Methods and Results Thirty-six healthy dual CS and EC users participated in a crossover study in a confined research setting. Circadian heart rate, blood pressure and plasma nicotine levels, 24-hour urinary catecholamines, 8-isoprostane and 11-dehydro-thromboxane B2, and plasma interleukin-6 and interleukin-8 were compared in CS, EC, and no nicotine conditions. Over 24 hours, and during daytime, heart rate and blood pressure were higher in CS and EC compared with no tobacco product conditions (P<0.01). Heart rate on average was higher with CS versus EC. Urinary catecholamines, 8-isoprostane, and 11-dehydro-thromboxane B2 were not significantly different, but plasma IL-6 and IL-8 were higher with both CS and EC compared with no tobacco product (P<0.01). Conclusions CS and EC had similar 24-hour patterns of hemodynamic effects compared with no tobacco product, with a higher average heart rate with CS versus EC, and similar effects on biomarkers of inflammation. EC may pose some cardiovascular risk, particularly to smokers with underlying cardiovascular disease, but may also provide a harm reduction opportunity for smokers willing to switch entirely to EC. Registration URL: https://www.clinicaltrials.gov; Unique Identifier: NCT02470754.
Keywords: biomarkers; electronic cigarettes; nicotine; tobacco.