12/20/2017 12:58 EST | Updated 12/21/2017 11:42 EST

Stop-smoking drug Champix ups risk of cardiovascular events for some people: study

TORONTO — With the new year approaching, some smokers may be resolving to butt out for good and are looking for a tobacco-cessation aid to help raise their chances of success.

One of those quit-smoking aids is the prescription drug Champix, known generically as varenicline, which research has shown can triple the odds of a person kicking the habit.

But a large Canadian study published Wednesday shows this commonly prescribed medication carries an increased risk of heart attack and other adverse cardiovascular events.

The study by researchers at the Institute for Clinical Evaluative Sciences (ICES) in Toronto found that people taking Champix had a 34 per cent higher risk for a number of cardiovascular events, compared to periods when they weren't on the drug.

Champix is an oral pill that works by blocking the effects of nicotine by binding to receptors in the brain that release the feel-good chemical dopamine. The medication can help reduce cravings and withdrawal symptoms, while diminishing the enjoyment of smoking. It typically is prescribed for 12 weeks.

To conduct the study, researchers analyzed medical records for more than 57,000 Ontarians who began using Champix between September 2011 and February 2014. During that period, 4,185 patients experienced one or more cardiovascular events requiring an emergency department visit or hospitalization.

Researchers then compared the incidence of such events — such as a heart attack, stroke, cardiac rhythm disorder or unstable angina — while patients were taking the medication and for a year before and one year after when they weren't on the drug.

The 12-week period on Champix was considered the "risk" interval, while the year-long periods before and after were defined as the "control" interval.

"We find that people are having more events in the risk interval compared to the control interval," said Dr. Andrea Gershon, a respirologist at Sunnybrook Health Sciences Centre and an ICES scientist who led the study.  

The research, published online in the American Journal of Respiratory and Critical Care Medicine, found that four cardiovascular events per 1,000 patients taking Champix could be linked to the medication.

However, Gershon said the findings should not be used to suggest people should not take Champix.  

"Smoking is a high-risk activity and quitting smoking greatly reduces a person's chances of developing heart disease and cancer and has many, many other benefits," she said.

"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."