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E-cigarette use negatively affects lipids, myocardial blood flow
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PHILADELPHIA — Electronic cigarette use appears to have detrimental effects on lipid levels and myocardial blood flow compared with nonuse, according to two studies presented at the American Heart Association Scientific Sessions.
Lipid and glucose levels
Sana Majid, MD, postdoctoral fellow in vascular biology at Boston University School of Medicine, and colleagues conducted the CITU study to determine whether e-cigarette use affected lipid and glucose levels compared with no cigarette use.
“We know that traditional cigarette use tends to change glucose and cholesterol levels in an unfavorable direction, which may be a reason for the higher rates of heart disease in traditional cigarette smokers. We were interested in finding out whether electronic cigarettes are healthier for the heart or not,” Majid told Healio. “Measuring the association with glucose and lipid levels is one way to answer this question.”
The study included 94 nonsmokers, 45 e-cigarette smokers, 285 tobacco cigarette smokers and 52 dual cigarette users. All participants were aged 21 to 45 years, free from CVD and on no medications.
After adjustment for age, race and sex, sole e-cigarette use was associated with elevated total cholesterol and LDL compared with nonusers (P < .05 for all), and dual use was associated with lower HDL compared with nonusers (P < .05).
“Our findings suggest that even when people use e-cigarettes there may continue to be abnormal lipid levels. We need more studies to help us understand what happens over time when people switch from traditional cigarettes to e-cigarettes. Our study is part of a growing set of literature that suggests that e-cigarette use may not be heart healthy,” Majid said in an interview. “Many people, especially kids and teenagers, have the belief that e-cigarettes are harmless. We want everyone to know that there are many chemicals in e-cigarettes that may alter heart health. Our study is an early view suggesting that there may be a relation between e-cigarette use and an unhealthy cardiometabolic state.”
Myocardial blood flow
For the myocardial blood flow study, researchers analyzed 19 participants (mean age, 28 years) who were chronic users of e-cigarettes or tobacco cigarettes.
“We were highly motivated to do this research for two reasons,” Florian Rader, MD, medical director of the Human Physiology Laboratory and assistant director of the Non-Invasive Laboratory at the Smidt Heart Institute at Cedars-Sinai, told Healio. “First, we have always been interested in how smoking conventional tobacco cigarette changes the cardiovascular system and especially coronary microvascular physiology — which can be the earliest, even if hard to detect, sign of adverse effect. Second, having seen the incredibly fast uptake of e-cigarette use in our own local communities as well as across the country, we felt strongly compelled to find out how the effects of e-cigarettes compared to what we had seen for conventional cigarettes.”
After overnight abstinence, all participants underwent myocardial contrast echocardiography to measure the increase in myocardial blood flow after acute exposure to a tobacco cigarette or an e-cigarette. Participants were measured at rest and after performing a handgrip exercise to simulate physiological stress.
According to the researchers, in tobacco cigarette users, myocardial blood flow increased after smoke inhalation but sharply decreased with physiological stress, whereas in e-cigarette users, myocardial blood flow decreased at rest and with physiological stress.
“We believe the most important take-home message is that e-cigarettes are not completely safe,” Rader said in an interview. “They are certainly not safe for the lung, and our study results would suggest they are likely not safe for the heart.” – by Erik Swain
References:
Majid S, et al. Presentation Mo3196. Markers of Cardiovascular Health.
Rashid M, et al. Presentation Sa3199. Smoking, Alcohol Use and Other Behavioral Risk Factors for CVD. Both presented at: American Heart Association Scientific Sessions; Nov. 16-18, 2019; Philadelphia.
Disclosures: Majid reports no relevant financial disclosures. Rader reports he is a consultant for ReCor Medical.
Perspective
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Emily Lau, MD
Traditional cigarette use has been associated with impaired coronary microvascular endothelial function, but little is known about the effects of e-cigarette use on coronary microvascular function. The authors found that myocardial blood flow, a measure of coronary microvascular function, is decreased both at rest and after physiologic stress in chronic e-cigarette users while it is only decreased after stress in traditional cigarette users. Albeit a small study, these findings offer insights into the CV safety profile of e-cigarettes, which up until recently have been marketed as a safer alternative to traditional cigarettes.
These findings tell us that we still do not understand the long-term health effects of e-cigarettes. They may be just as harmful, if not more harmful, than traditional e-cigarettes. As physicians, we should impress upon our patients who are smoking that e-cigarettes are not a safer alternative and that we should focus primarily on proven smoking cessation therapies.
This is a very small study, only 19 patients total, so any conclusions we can draw from this study are limited. First, the effect of e-cigarettes on coronary microvascular function should be explored on a larger scale. Second, better characterization of the contents of the aerosolized material in e-cigarettes will be important for better understanding the safety profile of e-cigarettes.
This work is extremely important. We are starting to learn the detrimental lung effects of chronic e-cigarette use and we still know very little about the CV effects.
Perspective
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Islam Elgendy, MB, BCh
CVD remains the No. 1 cause of death in the U.S., and is implicated in about one-third of smoking-related deaths. E-cigarettes were introduced as an alternative with less carcinogens, but their effect on CVD have not been widely studied. The study by Majid and colleagues shows that e-cigarettes are associated with changes in the blood levels of cholesterol similar to those who use traditional cigarettes. These alternations are risk factors for future CVD.
Patients and primary care physicians think that e-cigarettes could provide a “safe” alternative to traditional cigarettes. However, the findings of this study suggest otherwise, and that e-cigarette use is associated with an unfavorable lipid profile, which is a risk factor for future CVD. A recent study has also shown that the e-liquids from e-cigarettes affect the endothelial cells (Lee WH, et al. J Am Coll Cardiol. 2019;doi:10.1016/j.jacc.2019.03.476). This damage is also a risk factor for CVD. In fact, another study showed that e-cigarettes are associated with increased risk for MI (Bhatta DN, et al. J Am Heart Assoc. 2019;doi:10.1161/JAHA.119.012317). The results of these studies suggest that e-cigarettes should not be promoted as a safe or less risky alternative to traditional cigarettes.
Unfortunately, the use of e-cigarettes is very popular, especially among the youth, on the assumption that they are safe. One study showed that almost one-fourth of high school students and one-tenth of middle school students reported self-use of e-cigarettes (Cullen KA, et al. JAMA. 2019;doi:10.1001/jama.2019.18387). Our efforts should be directed towards counseling the youth about the potential hazards of e-cigarettes and educating them that e-cigarettes are associated with CVD risk.
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