BACKGROUND
Smoking is a major risk factor for cardiovascular disease and smoking cessation reduces excess risk. E-cigarettes are popular for smoking cessation but there is little evidence on their cardiovascular health effect. Our objective was to compare the medium- and longer-term cardiovascular effects in smokers attempting to quit smoking using e-cigarettes with or without nicotine or prescription nicotine replacement therapy (NRT).

METHODS
This was a single-center, pragmatic three-arm randomized (1:1:1) controlled trial, which recruited adult smokers (≥ 10 cigarettes/day), who were willing to attempt to stop smoking with support (n = 248). Participants were randomized to receive behavioral support with either (a) e-cigarettes with 18 mg/ml nicotine, (b) e-cigarettes without nicotine, and (c) NRT. Flow-mediated dilation (%FMD) and peak cutaneous vascular conductance (CVCmax) responses to acetylcholine (ACh) and sodium nitroprusside (SNP), mean arterial pressure (MAP), and other outcomes were recorded at baseline, 3, and 6 months after stopping smoking. Data were analyzed using generalized estimating equations (GEE).

RESULTS
At 3- and 6-month follow-up, %FMD showed an improvement over baseline in all three groups (e.g., p < 0.0001 at 6 months). Similarly, ACh, SNP, and MAP improved significantly over baseline in all groups both at 3 and 6 months (e.g., ACh: p = 0.004, at 6 months).

CONCLUSIONS
Smokers attempting to quit experienced positive cardiovascular impact after both a 3- and 6-month period. None of the groups (i.e., nicotine-containing and nicotine-free e-cigarettes or NRT) offered superior cardiovascular benefits to the others.

TRIAL REGISTRATION
ClinicalTrials.gov NCT03061253 . Registered on 17 February 2017.