A large nationwide study has found no increase in the risk of cardiovascular events with the use of varenicline compared with bupropion.

The authors conducted a historical cohort study, comparing 17,926 new users of varenicline with the same number of new users of bupropion, between 2007 and 2010. The investigators set out to answer the question ‘are those who use varenicline to help them stop smoking more at risk of a cardiovascular event than those who use bupropion?’ Bupropion was chosen as a comparator because it has no known cardiovascular risk, and in Denmark, the setting for the study, is only prescribed in smoking cessation.

After correcting for known potential confounders data were analysed to estimate the relative hazard ratios (HR) for cardiovascular events, including primary outcomes of acute coronary syndrome, ischaemic stroke and cardiovascular death, six months after the start of treatment.

There were 57 major cardiovascular events among varenicline users (6.9 cases per 1,000 person-years) and 60 among bupropion users (7.1 cases per 1,000 person-years). The HR for any major event was 0.96 (95% CI:0.67-1.39).

Varenicline was not found to be associated with an increased risk of acute coronary syndrome HR 1.2 (95% CI:0.75-1.91); ischaemic stroke HR 0.77 (95% CI:0.40-1.48); or cardiovascular death HR 0.51 (95% CI: 0.13-2.02).

The phrase ‘first do no harm’ has been known to doctors for many centuries, and some have been concerned that recent studies have suggested that use of varenicline to aid smoking cessation may increase the risk of cardiovascular events.

The authors of this large, nationwide study were able to conclude that there is no increased risk of serious cardiovascular events in those using varenicline compared with those who use bupropion.

Dr Jez Thompson

• Svanstrom H, Pasternak B, Hviid A et al. Use of varenicline for smoking cessation and risk of serious cardiovascular events: nationwide cohort study. BMJ 2012;345:e7176