Daily use of e-cigarette doubles risk of heart attack

The research also found that dual use of e-cigarettes and conventional cigarettes was more dangerous than using either product alone. and it raises the heart attack risk five-fold when compared to people who don't use either product.

"Most adults who use e-cigarettes continue to smoke cigarettes," said senior author Stanton Glantz, Ph.D., a UCSF professor of medicine and director of the UCSF Center for Tobacco Control Research and Education.

"While people may think they are reducing their health risks, we found that the heart attack risk of e-cigarettes adds to the risk of smoking cigarettes," Glantz said. "Using both products at the same time is worse than using either one separately. Someone who continues to smoke daily while using e-cigarettes daily increases the odds of a heart attack by a factor of five."

"The risk of heart attack starts to drop immediately after you stop smoking," said Glantz. "Our results suggest the same is true when they stop using e-cigarettes."

The new analysis involved 69,452 people in a cross-sectional study in which in-person interviewers asked participants whether they had ever used e-cigarettes and/or cigarettes and whether they had ever been told by a doctor or other health professional that they had a heart attack.

The study found that among the 9,352 current and former e-cigarette users, 333 (3.6 per cent) had experienced a heart attack at some point, with the highest percentage (6.1 per cent) among those who used e-cigarettes daily. More than a quarter of the 2,259 people who currently used e-cigarettes were former smokers of conventional cigarettes and about 66 percent of current e-cigarette users were also current cigarette smokers.

The researchers found that the total odds of having a heart attack were about the same for those who continued to smoke cigarettes daily as those who switched to daily e-cigarette use. For those who used both products daily, the odds of having had a heart attack were 4.6 times that of people who had never used either product.

The authors also said that while there was a "lasting effect" associated with being a former smoker, there was not a significant increase in myocardial infarction risk for former or (sometimes) e-cigarette users. They proposed that the risks of e-cigarette use may dissipate rapidly when someone stops using them, that some people briefly experiment with e-cigarettes and stop using them before any lasting damage is done, or that e-cigarettes have not been available long enough to cause permanent damage to the cardiovascular system.