Pfizer Inc announced the results of a study that found that 47 per cent of smokers with a history of cardiovascular disease who took Chantix/Champix (varenicline) were able to quit smoking and remain abstinent during the last four weeks of treatment (weeks 9-12) compared with just 13.9 per cent of those given placebo. These findings were presented today at the American College of Cardiology 58th Annual Scientific Session in Orlando, Fla.

"These data are consistent with the findings from the pivotal varenicline trials, which showed that varenicline was more effective than placebo among smokers who were generally healthy," said Dr Nancy A. Rigotti, professor of medicine at Harvard Medical School, director of the Tobacco Research and Treatment Center at Massachusetts General Hospital, and lead study investigator. "This study demonstrates that varenicline is effective in helping smokers with cardiovascular disease quit smoking. The safety profile of varenicline in this study also resembles that of the pivotal studies. The results are encouraging because the participants were at greater risk for death given their advanced ages, durations of smoking and histories of cardiovascular disease."

Cigarette smoking is a well-established risk for cardiovascular disease. In the United States, approximately 130,000 adults die each year from smoking-related cardiovascular disease. This figure is approximately one-third of all smoking-related deaths among adults age 35 and older. Studies have shown that quitting smoking reduces the risk of death by 36 percent for smokers who have coronary heart disease, a type of cardiovascular disease.

"Patients are always encouraged to quit smoking after experiencing a cardiac event, such as a heart attack or stroke, but many eventually start smoking again, putting themselves at serious risk for a second event," said Dr Robert A. Kloner, director of research at the Heart Institute of Good Samaritan Hospital and professor of medicine at the Keck School of Medicine at the University of Southern California in Los Angeles. "It's important that every smoker, and particularly those with heart disease, work with a health care professional to develop a quit plan."

The multicenter, double-blind, placebo-controlled trial included 714 adult patients (ages 35-75 years) who had smoked an average of 10 or more cigarettes daily in the year before enrollment. All patients wanted to quit smoking but had not tried to in the past three months, and had stable, documented cardiovascular disease that had been diagnosed more than two months prior. Eligible cardiovascular disease diagnoses included history of heart attack, a certain type of heart surgery, chest pain, peripheral arterial vascular disease, and stroke or transient ischemic attack.

Patients were randomized to twelve weeks of treatment with either varenicline (n=355) or placebo (n=359) and were followed to week 52 in a blinded post-treatment phase. All patients received smoking cessation counseling throughout the study. The primary study endpoint was continuous abstinence rate during the last four weeks of treatment (weeks 9-12). The key secondary endpoint was continuous abstinence rate from the last four weeks of treatment through the post-treatment phase (weeks 9-52).

At the end of 52 weeks, 19.2 per cent of patients who were randomized to take varenicline during the treatment phase remained abstinent, compared with 7.2 percent of patients randomized to take placebo.

Varenicline was generally well-tolerated. In the varenicline group, 7.4 per cent of patients experienced cardiovascular events vs. 6.6 per cent in the placebo group (difference 0.8, 95 percent CI: -3.0 to 4.6). Serious adverse events occurred in 6.5 per cent patients treated with varenicline compared with 6.0 per cent of those given placebo. None of the serious adverse events involved depression, suicidality, or abnormal behaviour.

This trial was funded by Pfizer Inc and was conducted in 15 countries.