Despite the decline in cigarette smoking over the past 40 years, self-reported data from the National Health Interview Survey show that 19.8% (43.4 million) of US adults were still smokers in 2007.1 Attempts to quit during the previous year in the general population decreased from 47% in 1993 to 38.8% in 2007, and only 4% to 7% of smokers trying to quit each year will eventually succeed. Cardiovascular diseases are the leading cause of death in Western countries, and cigarette smoking has a clear cause-and-effect relationship with atherosclerotic disease with the risk of myocardial infarction (MI) increasing with the number of cigarettes smoked.

Similarly strong evidence indicates that smoking cessation alone can result in a 36% reduction in the crude relative risk of mortality in smokers who quit versus those who do not.5 The risk decreases rapidly: after only 1 year of cessation, quitters have a lower relative risk (RR=0.63) of death from coronary heart disease (CHD) than do nonquitters, which decreases even further (RR=0.38) after 3 years of cessation. Consequently, efforts to find effective treatments to enhance smoking cessation are of great importance.