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NEW YORK (Reuters Health) - Heart attack survivors who stop using snus, a Swedish smokeless tobacco, were half as likely to die in the next two years as those who didn’t, according to a new study.
The survival difference was comparable to that seen when smokers quit after a heart attack, suggesting that nicotine alone may harm the heart more than is recognized, researchers say.
“The new and most surprising finding of this study was that snus users who have a myocardial infarction (heart attack) might benefit equally from discontinuation as smokers. Therefore, if you have established coronary heart disease, my recommendation would be to give up all tobacco use,” said Gabriel Arefalk, who led the study.
He told Reuters Health the benefits of quitting smoking after a heart attack have been known for decades but there is very little evidence when it comes to the health effects of smokeless tobacco.
Understanding the impact of smokeless tobacco is important for physicians who advise patients on how they can lower their chances of a second heart attack when they are discharged from the hospital after the first one, added Arefalk, a cardiologist at Uppsala University Hospital in Sweden.
Snus is manufactured in Sweden and slightly different from snuff, although nicotine levels are similar. A user holds the moist tobacco under the top lip, but unlike chewing tobacco, it doesn’t need to be spit out.
Snus contains less of the cancer-causing chemicals called nitrosamines that are in cigarettes, which the researchers say makes it less harmful. Users also avoid inhaling tar and carbon monoxide, among other substances in tobacco smoke.
Even though using snus is not considered as detrimental to health as smoking cigarettes, that doesn’t mean it isn’t harmful, said Lucy Popova, from the Center for Tobacco Control Research and Education at the University of California, San Francisco.
Using smokeless tobacco has been associated with increased risk of oral cancer, esophageal cancer, heart attack and stroke, oral disease and reproductive problems, said Popova, who was not involved in the new study.
Arefalk’s team analyzed medical records for 9,500 people under age 75 who survived a heart attack between 2005 and 2009. About 2,500 were snus users and 7,000 were cigarette smokers.
Two months after their heart attacks, 675 snus users had quit and 1,799 continued to use snus. Two years later, researchers found there had been 14 deaths among those who had quit and 69 among those who were still using snus.
Looking at the number of deaths per 1,000 patients per year, the researchers calculated a mortality rate of 9.7 for those who had quit using snus after their heart attacks, and 18.7 for those who continued using it.
Among the smokers and those who had quit, there were similar differences, with a death rate of 13.5 per 1,000 patients per year among quitters and 28.4 among those who continued to smoke.
“We didn't expect to see such a strong association among the snus quitters,” Arefalk said.
His team notes in their report that the people who quit snus were also more likely to participate in cardiac rehabilitation and overall were more physically active, which might have contributed to their lower risk of death. But even after the researchers accounted for age and lifestyle differences, the people who quit snus were 40 percent less likely to die than those who kept using it.
They also point to animal experiments showing that the heart muscles of rats exposed to nicotine did not heal as well as those of unexposed rats, and speculate that nicotine might have similar effects on human hearts.
Because evidence about the health effects of smokeless tobacco is lacking, there has been less priority placed on advising users to quit, Arefalk said.
In the U.S, 1.7 billion cans of snuff are consumed and the market is growing every year, he and his colleagues note in the journal Circulation.
Popova told Reuters Health that even though snus originated in Sweden, “major cigarette companies in the U.S have been promoting snus with cigarette names like Marlboro snus or Camel snus since 2006.”
The addictive substance in both cigarettes and smokeless tobacco is the same – nicotine, Popova said, so quitting is essentially the same. It’s not easy and may take many attempts, but there is help out there, such as “Smokeless Tobacco: A Guide for Quitting” (1.usa.gov/1i4vktN) from the National Institutes of Health.
“In discussing probable reasons for greater mortality among continued snus users, the authors pointed out that nicotine might be directly responsible for a variety of negative cardiovascular developments, ultimately leading to premature death,” Popova added.
“This is a very important point because it relates to another tobacco product – electronic cigarettes. In e-cigarette advertisements, nicotine has often been trivialized and even in the public health arena it has been argued that ultimately, it’s not the nicotine that kills. This study shows that it actually might be the nicotine,” she said.
SOURCE: bit.ly/1qb1kPD Circulation, online June 23, 2014.