It's a frightening headline that some skeptics would argue comes long before researchers have hard evidence to show there's a danger.
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The study comes from the offices of UCSF Professor Stan Glantz, who has a growing collection of cigarette packs on his bookshelf covered with graphic images of what smoking can do to you.
"England is starting them, Canada is moving toward them," he said of government mandates to display the pictures and warnings on tobacco packaging.
Glantz says the dangers of smoking weren't always well-known, but today, they're accepted as fact.
"In the process of burning, you get a lot of cancer-causing chemicals and other bad things that you don't get with an e-cigarette," he said.
Electronic cigarettes and vaporizers have been marketed as a way to quit smoking. But Glantz says his team's latest study shows "vaping" could have serious health risks of its own.
"What we found is that daily e-cigarette user had an almost doubling in their risk of having a heart attack," Glantz said.
The study used existing data from the Centers for Disease Control. The same nationwide survey also showed those who smoke regular cigarettes had three times as many heart attacks, Glantz said. He calls the findings significant.
"The first evidence of a major clinical adverse event associated with e-cigarette use," he said.
There are some who take issue with that claim, including fellow tobacco control researcher Michael Siegel, a professor at Boston University's School of Public Health.
"We don't even know that these people used e-cigarettes before they had the heart attack," Siegel said.
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He points out that the CDC numbers are a snapshot in time, merely asking survey participants if they vape, and if they've ever had a heart attack. They don't follow subjects over a period of years to determine whether vaping was a likely cause of the cardiac event.
Siegel offered an alternative explanation for the correlation Glantz found:
"Not that e-cigarettes are causing heart attacks, but that people who have heart attacks are turning to e-cigarettes in an effort to quit smoking," he suggested.
The two professors agree that vaping is likely less harmful than smoking -- and that another study is needed to further examine its apparent impacts on heart health.
Glantz points out other research has started with this same sort of numerical snapshot, known as a "cross-sectional" study, before progressing to the much more expensive, multi-year "longitudinal" studies.
"The first evidence linking smoking with lung cancer were cross-sectional studies," he said.
He said other researchers at UCSF are also looking into the biological effects of vaping, which are not as well-understood as those of smoking.
"It's not the same toxic chemicals as a cigarette, there's probably less of them than a cigarette. But there's still enough there to be doing a lot of damage," he said.
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