Researchers in the US have warned that using e-cigarettes significantly raises the risk of heart attacks.
Concerns around the long-term health impact of vaping has been growing as their popularity increases.
The health benefits of the e-cigarettes have been said to outweigh potential harms by medical officials, and numerous tobacco smokers have made the switch to vaping.
The study, to be presented at the American College of Cardiology conference in New Orleans later this month, is one of the largest ever conducted on the impact of vaping, the Daily Mail reported.
Experts from the University of Kansas studied data from 90,000 e-cigarette users.
They found people who vaped every day were 34 per cent more likely than non-e-cigarette users to suffer a heart attack, and those who used the devices more sporadically had a 29 per cent increased risk.
"Until now, little has been known about cardiovascular events relative to e-cigarette use," said study leader Dr Mohinder Vindhyal.
"These data are a real wake-up call and should prompt more action and awareness about the dangers of e-cigarettes."
He sounded a note of warning, saying most of the e-cigarette users were ex-smokers so the heart problems could be due to their lifetime of tobacco use.
"I wouldn't want any of my patients nor my family members to vape," he said
Roughly a third of the 90,000 e-cigarette users were also smokers.
The team's initial analysis suggested e-cigarette users had a 56 per cent increased risk of heart attack than those who did not vape.
But taking into account the fact that people who were also regularly smoking tobacco had a 165 per cent increased heart attack risk, they calculated the increased isk of vaping alone dropped to about 34 per cent.
They found e-cigarette users were also 55 per cent more likely to suffer from depression or anxiety.
Despite a degree of uncertainty, Dr Vindhyal insisted the findings are concerning and more research is required into the risks of e-cigarettes.
"We found that regardless of how frequently someone uses e-cigarettes, daily or just on some days, they are still more likely to have a heart attack or coronary artery disease," he said.