(TIME) — E-cigarettes may be more harmful to a smoker’s heart than traditional tobacco cigarettes, according to a new study.
A small trial found that after exercise, blood flow increased in the hearts of tobacco smokers, but not in the hearts of e-cig smokers.
The Cedars-Sinai team compared the hearts of 10 non-smokers to the hearts of 10 tobacco smokers and 10 e-cigarette smokers. All the people in the study were younger than 40, and all were otherwise healthy. In response to a mild bout of exercise, measures of blood flow increased in the hearts of the non-smokers. Among the tobacco smokers, this increase was blunted. But among the e-cigarette smokers, there was no increase at all. “This suggests e-cigarettes cause an abnormality that impedes blood flow regulation in the heart,” says Dr. Florian Rader, coauthor of the study and a heart specialist at Cedars-Sinai’s Smidt Heart Institute.
While many people rightly associate cigarettes with lung cancer, smoking-related heart disease actually kills more Americans each year. A 2014 report from the Office of the Surgeon General concluded that smoking causes approximately one in four cardiovascular disease deaths in the U.S., which works outto roughly 210,000 deaths each year. Lung cancer, meanwhile, kills approximately140,000 Americans annually. If e-cigarettes turn out to be worse for a smoker’s heart than tobacco cigarettes, the health implications are enormous.