Smoking status and antithrombin therapy in patients with non-ST-segment elevation acute coronary syndrome

Background: Smoking remains a major public health issue. We investigated the incidence of smoking and outcomes in high-risk patients with acute coronary syndromes. Differences in treatment effect of antithrombin therapies were also investigated. Methods: Using data from SYNERGY, patients were categorized by their self-reported smoking status. They were followed at 30 days and 6 months for death, nonfatal myocardial infarction (MI), revascularization procedures, stroke, and need for rehospitalization, and at 1 year for occurrences of death. Results: Overall, 9,971 patients were evaluated, of whom 2,404 (24%) were current smokers, 3,491 (35%) were former smokers, and 4076 (41%) had never smoked. Current smokers were younger (median age 61 years, interquartile range [IQR] 52-67) than former smokers (median age 69 years, IQR 63-75) and never smokers (median age 70 years, IQR 64-77) and had fewer additional coronary artery disease risk factors (hypertension, diabetes, hypercholesterolemia). The 30-day death/MI rate was similar for former versus never smokers (15% vs 13.6%, P = .079) and for current versus never smokers (14% vs 13.6%, P = .585). Adjusted odds ratios for 30-day death/MI in patients receiving enoxaparin compared with those receiving unfractionated heparin were 1.065 (95% CI 0.883-1.283, P = .51) in never smokers, 1.034 (95% CI 0.853-1.254, P = .733) in former smokers, and 0.742 (95% CI 0.582-0.948, P = .017) in current smokers. A significant interaction for treatment and smoking status was found at 30 days (P = .0215), but not at 6 months (P = .1381) or 1 year (P = .1054). One-year unadjusted mortality rates were higher for former versus never smokers (9.1% vs 6.7%, P = .0002) but were similar for current versus never smokers (6.5% vs 6.7%, P = .7226). On follow-up at 30 days, 62.3% (n =1397) of current smokers reported not smoking. Conclusions: Smokers with non-ST-segment elevation acute coronary syndrome are generally younger and have fewer cardiac risk factors. A significant interaction of smoking and enoxaparin was seen at 30 days, but not sustained at 6 months and 1 year. More than 60% of smokers quit within 30 days of their cardiac event. There was little difference in outcomes from 30 days to 1 year for these smokers who quit versus those who did not.