Most smokers are also vaping because they think it's a safe way to cut back on cigarettes, but they would be better off just smoking the real thing, say researchers from the University of California at San Francisco.
Not that either approach is great: people who just vape (smoking e-cigarettes) nearly double the risk of a heart attack, but those who vape and continue smoking raise the chances five-fold compared to a non-smoker, the researchers found after surveying nearly 70,000 people.
The one piece of good news is that people who quit cigarettes see their heart attack risk drop 'significantly'.
"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. Using both products at the same time is worse than using either one separately," said lead researcher Stanton Glantz.
Electronic cigarettes have been considered safer because they deliver an aerosol of nicotine by heating a liquid, but while they are producing lower levels of carcinogens, they send out ultrafine particles and other toxins that have been linked to cardiovascular disease and non-cancerous lung problems.
Glantz and his researchers surveyed 69,452 smokers and nonsmokers; of the 9,352 current and former e-cigarette users, 333, or 3.6 per cent, had suffered a heart attack, but this rose to 6.1 per cent among those who vaped every day.
The odds of having a heart attack were roughly the same whether you vaped or smoked conventional cigarettes—and were around double that of a non-smoker—but it increased 4.6 times for those who were combining vaping with cigarettes.
Former smokers and occasional and former e-cigarette users see their risk drop dramatically and quickly.