Smoking and risk for morbidity and mortality in patients who undergoes coronary artery bypass grafting

Abstract Background The association between smoking and prognosis after coronary artery bypass grafting (CABG) is sparsley studied. The few previous studies investigating this association show conflicting results. Purpose The purpose was to explore the association between smoking and long-term risk for morbidity and mortality in patients undergoing CABG. Methods Data from the SWEDEHEART registry were used to identify all patients who underwent isolated CABG in Sweden from 1992 to 2020 and smoking status at time for surgery. Three other mandatory national registries were used to collect data for comorbidities, social factors, and death (Swedish National Inpatient Register, Longitudinal Integration Database for Health Insurance and Labor Market Studies and, Swedish Cause of Death Register). Cox regression models adjusted for age and sex, comorbidities and social factors were used to assess the risk for all cause death, stroke, myocardial infarction. Mean follow-up time was 5.2 years (range 0-10). Results In total, 27,434 patients aged 18 years were identified (18.2% women). The study population was divided into; never smoker (n=8593), former smoker (n=14666) and current smoker (n=4175). The proportion of previous ST Elevation Myocardial Infarction (STEMI), heart failure, previous stroke, peripheral vascular disease, chronic respiratory disease, depression, low education was higher in current smokers than in non-smokers. Compared to never smokers, current smokers had a higher risk for all-cause death (adjusted Hazard ratio (aHR) 1.36 (95% Confidence interval (CI) (1.22-1.52)) and stroke (aHR 1.39 (1.18-1.64)) but not for myocardial infarction (aHR 1.03 (0.87-1.21). Former smoker had higher risk for all cause death (aHR1.17 (1.08-1.28)) compared to never smokers but no increased risk for myocardial infarction 0.91 (0.81-1.03) and stroke (aHR 1.11 (0.98-1.25). Conclusion There is a strong association between smoking at the time for surgery and long-term risk for worse prognosis after CABG. The results emphasize the importance of encouraging and motivate CABG patients to smoking cessation.