Daily usage of conventional and electronic cigarettes together can increase your chances of heart attack by five times, a new study has warned.
The findings showed that the use of both cigarettes in a day - which was the most common pattern observed among e-cigarette users - appeared to be more dangerous than using either product alone.
The research team also found that the use of electronic cigarettes everyday can nearly double the odds of a heart attack.
"Most adults who use e-cigarettes continue to smoke cigarettes. While they 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," said senior author Stanton Glantz, Professor at University of California, San Francisco (UCSF).
E-cigarettes deliver aerosol of nicotine and other flavours by heating a liquid, and are promoted as a safer alternative to conventional cigarettes, which generate the nicotine aerosol by burning tobacco.
The study found that while e-cigarettes deliver lower level of carcinogens than conventional cigarettes, they deliver both ultrafine particles (about 1/50 the size of human hair) and other toxins that have been linked to cardiovascular and non-cancer lung disease risks.
For the study, the team involved 69,452 people. The participants were asked if 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.
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.
In the study, a quarter of the 2,259 people who currently used e-cigarettes were former smokers of conventional cigarettes and about 66 per cent of current e-cigarette users were also current cigarette smokers.
However, the research also reported some good news if smokers quit.
"The risk of heart attack starts to drop immediately after you stop smoking. Our results suggest the same is true when they stop using e-cigarettes," Glantz mentioned.