Common anti-smoking drug may raise stroke, heart attack risk

Anyone thinking of giving up smoking as a New Year's resolution should think carefully about what quitting aids they should use to help achieve this — particularly if the results of a new study are anything to go by.

Research published in the American Journal of Respiratory and Critical Care Medicine suggests that a commonly prescribed drug to help those who smoke to quit, called varenicline (brand name Chantix), may raise the risk of having a cardiovascular event.

Cardiovascular events are heart problems such as heart attack, stroke, arrhythmias, or irregular heartbeats, and unstable angina, in which the heart does not receive enough blood and oxygen.

Commenting on the reasons why the researchers conducted the study, lead author Dr. Andrea S. Gershon — an associate professor of medicine at the University of Toronto in Canada, explains, "Previous studies regarding the safety of varenicline have been conflicting and most examined people with relatively similar characteristics and backgrounds in highly controlled settings."

"We wanted to study varenicline among all kinds of people in the real world."

Cardiovascular event risk increased

The team analyzed the health records of 56,851 people in Ontario, Canada, who had begun using varenicline between 2011 and 2015. Specifically, the researchers looked at the health data for a year prior to and a year following these people taking the drug for 12 weeks.

The analysis showed that, during the studied periods, 4,185 of the people experienced a problem with their hearts that required hospitalization or an emergency room (ER) visit.

There were 3.95 cardiovascular events per 1,000 varenicline users in the study that "could be attributed to the drug." From this, the authors calculated that people prescribed varenicline were 34 percent more likely to be hospitalized or visit the ER due to a heart problem while taking the drug.

However, among people taking varenicline who had not previously had a problem with their heart, there was only a 12 percent increased risk of a cardiovascular event.

Study 'should help make informed decisions'

This type of study is called an observational study and it cannot determine cause and effect. Thus, based on these results, it is not possible to say for sure whether it is varenicline that increased risk of heart problems in these patients. The study can only report that there is a link between taking varenicline and being at increased risk of having a heart problem.

The authors also say that their study was limited by not including information about whether the subjects quit smoking or whether they also took other drugs to help them give up smoking.

Previous studies have found that varenicline "triples the odds" of a person who smokes quitting. The authors behind the new study say that this health benefit needs to be considered when weighing up any potential risks associated with taking the drug.

"Our findings should not be used to suggest people not take varenicline," explains Dr. Gershon. "The findings should be used to help people make an informed decision about whether they should take varenicline based on accurate information about its risks as well as its benefits."

She adds that the results of this study suggest that doctors should monitor patients closely if they are taking varenicline, in order to catch any potential heart problems early.