Varenicline is effective in helping patients with acute coronary syndrome (ACS) abstain from smoking, yet more than half of patients who received this therapy regressed to smoking by 1 year, according to study findings published in the Canadian Medical Association Journal.
In the Evaluation of Varenicline in Smoking Cessation for Patients Post-Acute Coronary Syndrome (EVITA; ClinicalTrials.gov Identifier: NCT00794573) trial, a total of 302 participants with ACS across North America were randomly assigned (1:1) to a 12-week regimen of either varenicline (n=151) or placebo (n=151). Participants also received low-intensity counselling for smoking cessation and relapse prevention during the 52-week study period. The primary outcome was smoking cessation at 24 weeks of treatment. A 7-day recall as well as biochemical validation with exhaled carbon monoxide were used to assess smoking abstinence.
A greater proportion of participants randomly assigned to varenicline maintained smoking abstinence at 1 week compared with those who received placebo (39.9% vs 29.1%; difference, 10.7%; 95% CI, 0.01%-21.44%; number needed to treat=10). Similarly, more patients receiving treatment reported higher continuous abstinence, defined as smoking abstinence within the past week at all follow-up periods (31.1% vs 21.2%; difference, 9.9%; 95% CI, –0.01% to 19.8%).
In addition, more participants in the varenicline arm reported reductions in daily cigarette smoking of ≥50% (57.8% vs 49.7%; difference, 8.1%; 95% CI, –3.1% to 19.4%). The rates of serious adverse events (24.5% vs 21.9%; risk difference, 2.7%; 95% CI, –7.3% to 12.6%) and major adverse cardiovascular events (8.6% vs 9.3%; risk difference, –0.7%; 95% CI, –7.8% to 6.5%) were similar among the treatment and placebo groups (8.6% vs 9.3%; risk difference, –0.7%; 95% CI, –7.8% to 6.5%). By 1 year, approximately 60% of smokers who were randomly assigned to varenicline had returned to smoking.
The investigators enrolled only patients with ACS who had a motivation to quit smoking, and this motivation may have affected the observed abstinence rates. In addition, a greater proportion of patients receiving treatment vs placebo had another smoker living in their home, which may have influenced relapse rates.
“If varenicline were used routinely after ACS, for every 10 smokers who received treatment, there would be 1 less smoker a year later,” concluded the investigators.
Windle SB, Dehghani P, Roy N, et al; for the EVITA Investigators. Smoking abstinence 1 year after acute coronary syndrome: follow-up from a randomized controlled trial of varenicline in patients admitted to hospital. CMAJ. 2018;190(12):E347-E354.