Analysis: Smoking Cessation Therapy Increases Cardiovascular Risks

Andrea S. Gershon, MD

A Canadian government-funded study found that a drug commonly prescribed to help people quit smoking could be putting patients at risk for cardiovascular events.

Varenicline, the smoking cessation therapy branded as Chantix in the US, increases patients’ risk of an emergency department visit or hospitalization for a cardiovascular (CV) event by 34%, according to a 5-year medical record analysis of 56,581 varenicline patients.

Among patients prescribed the therapy who had no previous experience with a CV event, the increased rate was just 12%. Overall, there was a rate of 3.95 CV events linked to varenicline for every 1,000 patients.

The patients’ medical records were those entered between September 2011 and February 2015 in the Ontario, CA, area. In that time span, 4,185 patients experienced at least 1 CV event that resulted in an ER visit or hospitalization. Another 4,720 patients experienced at least 1 neuropsychiatric event in that time, as well.

CV events, as defined by the researchers, include:

• Heart attacks
• Strokes
• Arrhythmias
• Unstable angina
• Peripheral vascular disease
• Others

Neuropsychiatric events included depression, anxiety, psychosis, hallucinations, insomnia, and self-harm.

Because varenicline is often administered every 12 weeks, the weeks of treatment were considered the risk interval, and were compared to the weeks before treatment initiation and after treatment should have ended.

Determining the cause and effect of the therapy on CV and neuropsychiatric risk is not possible from the study’s results due to it only being observational in nature. The study similarly lacks information on patients’ smoking habits, supplemental medication for smoking cessation, and whether nicotine withdrawal account for some of the neuropsychiatric events.

Researchers hoped to study varenicline’s effects on a wider population than previous studies, lead author Andrea S. Gershon, MD, associate professor of medicine, University of Toronto, said.

“Previous studies regarding the safety of varenicline have been conflicting and most examined people with relatively similar characteristics and backgrounds in highly controlled settings,” Gershon said in a statement. “We wanted to study varenicline among all kinds of people in the real world.”

Its results concur with a safety warning issued by the US Food and Drug Administration (FDA) Safety Communication in June 2011, which stated that varenicline may be associated with a small, increased risk of particular CV events in patients already with CV disease.

In a review of a randomized clinical trial featuring 700 smokers with CV disease treated with either varenicline or placebo, the FDA found that CV events were infrequent — though events such as heart attacks were more common in the treatment patient group than in the placebo patient group.

The 52-week study period reported that — in patients aged 35 to 70 that had a CV disease diagnosed within 2 months of the screening visit — 7 varenicline patients (2%) had been diagnosed with nonfatal heart attacks, 8 (2.3%) needed coronary revascularization, and 8 (2.3%) were hospitalized for angina pectoris.

“Healthcare professionals should be aware that smoking is an independent and major risk factor for cardiovascular disease, and smoking cessation is of particular importance in this patient population,” the FDA advised. “The known benefits of Chantix should be weighed against its potential risks when deciding to use the drug in smokers with cardiovascular disease.”

However, both studies advocated for the therapy’s ability to treat smoking cessation. Researchers from the Canada-based analysis noted that varenicline can triple the odds of a patient quitting smoking.

““Our findings should not be used to suggest people not take varenicline,” Gershon 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.”

The study: "Cardiovascular and Neuropsychiatric Events Following Varenicline Use for Smoking Cessation."