Clinical Question: Does varenicline increase the risk of serious adverse cardiovascular events?

Bottom Line: Varenicline increased the risk of adverse cardiovascular (CV) events in the participants of 14 clinical trials, despite the fact that these trials typically excluded patients with known heart disease. The authors apply the relative risk of 1.72 to a patient with known heart disease, and estimate a number needed to treat to harm of 28 for patients with heart disease who take vareniciline (95% CI, 13 - 213). This drug should be used with caution in patients with, or at high risk for, CV disease, particularly since there are alternative pharmacologic approaches for these patients. (Level of Evidence: 1b-)

Reference: Singh S, Loke YK, Spangler JG, Furberg CD. Risk of serious adverse cardiovascular events associated with varenicline: a systematic review and meta-analysis. CMAJ 2011;183(12):1359-1366.

Study Design: Meta-analysis (randomized controlled trials)

Funding Source: Government

Setting: Outpatient (any)

Synopsis: Smoking is bad for you, no doubt, so quitting is a good thing. However, previous reports have described an increased risk of adverse CV events among users of varenicline. This systematic review provides the best estimate to date of the extent of that risk. These authors identified all double-blinded, randomized controlled trials that compared varenicline with placebo for smoking cessation and reported at least one adverse CV event or death. They included 14 studies with a total of 8217 patients. Most studies were of high quality, with adequate randomization, allocation concealment, masking, follow-up, and reporting of adverse events. The studies treated patients with varenicline for between 8 and 12 weeks, and then followed up patients for a total of between 24 and 52 weeks. There was no evidence of publication bias (ie, not publishing small studies or those with negative findings). The mean age of patients was approximately 43 years, and the majority were male. The studies were consistent in their results, and the weighted odds ratio of an adverse CV event in patients randomized to receive varenicline was 1.72 (95% CI, 1.1 - 2.7).