Heat-not-burn tobacco products: an emerging threat to cardiovascular health.

Cigarette smoking is at all-time lows globally, but the use of electronic cigarettes has increased profoundly. Recent reports of electronic cigarette or vaping use-associated lung injury may lead individuals to explore novel methods of nicotine consumption, such as heat-not-burn devices. IQOS from Philip Morris, a heat-not-burn device, became available for purchase in the United States in October 2019. Philip Morris claims that 8.8 million people have abandoned traditional cigarettes in favor of IQOS; however, evidence suggests that it may act as a gateway or complement to cigarette smoking, rather than a replacement. Surveys indicate that 96% of Korean IQOS users also smoke cigarettes, and 45% of Italian users of IQOS had never smoked cigarettes. In the United States, Canada, and England, susceptibility of youth to trying IQOS was slightly lower than electronic cigarettes, but higher than cigarette smoking. Heat-not-burn products produce mainstream and second-hand emissions of harmful chemicals, including nicotine, particulate matter, benzene, acrolein, and tobacco-specific nitrosamines. The levels of these emissions, despite being less than those of traditional cigarettes, are potentially harmful to cardiovascular health. A study of current smokers showed similar acute effects of heat-not-burn tobacco products and traditional cigarettes on heart rate, blood pressure, and arterial stiffness. Rats exposed to IQOS had similar vascular endothelial function impairment to those exposed to cigarettes. Heat-not-burn aerosol exposure of cultured macrophages elicited increased oxidative stress, although less than that induced by cigarette smoke. Further studies are needed to better understand the cardiovascular effects of heat-not-burn tobacco products.