Summary of Evidence of Effects of IQOS on Endothelial function
Nabavizadeh and colleagues from the University of California, San Francisco, USA have recently published a Research Paper in Tobacco Control (Nabavizadeh, 2018) claiming that “mainstream IQOS aerosol from a single HeatStick can rapidly and substantially impair endothelial function in rats comparably to smoke from a cigarette”. Findings from this article are not new and were originally published by the authors in a public comment to the FDA PMI MRTP Application on Dec 4th 2017 (FDA-2017-D-3001-0118) and at the American Heart Association Conference.
PMI appreciates independent research and the motivation to perform studies that investigate potential health impact of smoke-free products compared to cigarettes. We conduct a thorough, objective review of the methodologies used, results generated and the conclusions drawn, and compare with other relevant studies conducted by PMI and other research groups, and whether the results agree or disagree with ours we share our findings from such a review in order to increase the scientific knowledge surrounding the assessment for Tobacco Heated System (THS) commercialized as IQOS.
Our analysis of the study by Nabavizadeh et al. can be found here, and is summarized as follows:
● Endothelial dysfunction is an important prognostic factor in the development of atherosclerosis, hypertension and heart failure.
● Flow mediated dilation (FMD) is a noninvasive technique used to assess endothelial function and considered predictive of cardiovascular risk when executed following a strictly standardized protocol.
● The internationally accepted guidelines for the conduct of the FMD measurement in humans (published by the International Brachial Artery Reactivity Task Force) clearly state that the ingestion of “substances that might affect FMD such as caffeine, high-fat foods and vitamin C or use of tobacco for at least 4 to 6 hours before the study” should be avoided prior to the measurement.
● The acute change in FMD measured immediately after the ingestion of the above mentioned substances are not predictive of cardiovascular risk.
● Therefore the effects observed in the study by Nabavizadeh et al. are actually expected short-term sympathomimetic effects of nicotine that are well known and are not predictive of the development of cardiovascular disease in humans.
● Furthermore, the comparisons between THS and cigarettes in this study are inappropriate because of the methodological issues that led to nicotine exposure from THS being much higher than nicotine exposure from cigarettes.
● In summary, the conclusion stated by the authors that, based on these results, “IQOS use does not necessarily avoid the adverse cardiovascular effects of smoking cigarettes” is incorrect and misleading and the study provides no reliable scientific information about the effects of THS on the risk of cardiovascular disease.