Patients who continue smoking after ACS have a 35% increased risk of reinfarction or death compared with those who quit. Many patients attempt to stop smoking after an acute coronary syndrome (ACS), but relapse rates approach 66%. A variety of smoking cessation aids have been shown to be effective for the general population. However, physicians are reluctant to use a nicotine-based therapy because of its hemodynamic effects. Bupropion is the only non-nicotine replacement therapy shown to improve abstinence rates in healthy young smokers by approximately 50%. Although bupropion has successfully been used to reduce smoking rates in healthy young populations, its efficacy and safety in the setting of patients recovering from an ACS is unknown.

The ZESCA Trial will directly compare the efficacy and safety of bupropion versus placebo as a means of reducing smoking rates in patients following an ACS. The ZESCA Trial will be a multi-center effort, coordinated from the Jewish General Hospital/McGill University (Montreal, Quebec). A total of 1500 patients will be randomized following an ACS but before hospital discharge via an Internet web site. Prior to the start of the treatment, patients in both treatment arms will receive a standard physician-administered counseling session regarding smoking cessation. Patients will begin treatment in-hospital and will be monitored in-hospital for ≥ 2 days prior to discharge. Half the patients will receive bupropion for 9 weeks and the other half will receive placebo pills for 9 weeks. Patients receiving bupropion will take 150 mg once per day for 3 days and then 150 mg twice per day for the remainder of 9 weeks. Prior to discharge, the patients will receive an information sheet listing the possible side effects of bupropion. They will be advised to consult the treating physician should they experience any listed side effects. While in-hospital, patients will have quit smoking and they will be instructed to not restart smoking when discharged. Phone calls to the patients will be made by the study nurses at weeks 1 and 2 of the 9-week treatment period. In addition, the patients will have clinic visits at weeks 4 and 9 as well as months 6 and 12. Smoking abstinence will be assessed at 4 weeks, 9 weeks, 6 months, and 12 months after randomization. Smoking abstinence will be defined as the complete abstinence in the week prior to the clinic visits and levels of exhaled carbon monoxide ≤ 10 ppm. Side effects of bupropion in patients following ACS as well as clinical events following initiation of treatment will be measured at weeks 1-8 (by telephone calls), and weeks 4 and 9 as well as months 6 and 12 (by clinic visits). Withdrawal symptoms will also be assessed by the nurses during their weekly calls.

Trials previously conducted with bupropion involved young healthy smokers. The ZESCA trial will be the first to examine the utility of bupropion in a group of patients with an ACS. These patients, if they continue to smoke, are at exceptionally high risk for recurrent cardiac events. If bupropion is effective in this population, it will have a major impact on secondary prevention of recurrent clinical events in patients who suffer an ACS.