Research has indicated that chronic combustible cigarette users are at an increased risk of developing coronary artery disease and heart attacks due to disturbances in blood flow. For a study published in Circulation, Florian Rader, MD, MSc, and colleagues analyzed the regulation of blood flow in e-cigarette and combustible cigarette users to determine if e-cigarette use is safer—as marketed by the makers of these products—or if users have similar disturbances in blood flow regulation as combustible cigarette users and are at a similar risk for coronary artery disease and heart attack.

Participants were healthy (aged 28±4) individuals who self-reported chronic e-cigarette or combustible cigarette use. After abstaining overnight, participants were allowed a single use (15 puffs in 7 minutes) of a common e-cigarette (3.7V battery, 18 mg nicotine) or one combustible cigarette (filtered, ≈0.8 mg of nicotine). Immediately after exposure, participants underwent myocardial contrast echocardiography to measure acute increases in myocardial blood flow (MBF). The test was then repeated during post-handgrip cuff ischemia, meant to cause sympathetically mediated increases in myocardial work and oxygen demand and, thus, shear stress, nitric oxide production, and coronary endothelial-dependent vasodilation.

The test results indicate that combustible cigarette users’ MBF increased slightly after smoke inhalation—matching cigarette-induced increases in myocardial oxygen demand— and decreased markedly with physiologic stress—despite greater myocardial demand for oxygen. Comparatively, e-cigarette users’ MBF decreased both at rest and during handgrip stress, suggesting that e-cigarette users experience chronically abnormal coronary vascular function, even in the absence of stress, according to Dr. Rader and colleagues.

“Our results are a cautionary note that should alert e-cigarette smokers to re-think their habits,” explains Dr. Rader. “Further research in larger studies is warranted to confirm our results and determine the exact mechanism of how these coronary blood flow abnormalities are developing in e-cigarette smokers. Such research will inform the public and hopefully put an end to the ongoing vaping epidemic in the US and beyond.”