Effect of Smoking Status on Mortality and Morbidity Following Coronary Artery Bypass Surgery

Functional capacity in smoking patients after coronary artery bypass grafting surgery: a quasi-experimental study

Coronary artery bypass grafting surgery (CABG) is an important approach to treating coronary heart disease. However, patients undergoing open heart surgery are at risk of postoperative complications. Cigarette smoking is one of the preoperative risk factors that may increase postoperative complications. Studies show that early mobilization intervention may reduce these complications and improve functional capacity, but the impact of smoking on early outcomes after CABG has been controversial for the past two decades. This quasi-experimental study explored the effects of early mobilization on functional capacity among patients with different smoking histories undergoing CABG. The study involved 51 participants who underwent CABG surgery, divided into three groups: current smokers, former smokers, and non-smokers (n=17 each). A day before surgery, all groups underwent a six-minute walking test (6MWT). Every participant received the same intervention after surgery, including deep breathing exercises, an upper limb range of motion assessment, an incentive spirometer, and walking with and without assistance. Five days postoperatively, all outcomes - including the 6MWT, length of stay (LOS) in the ICU, and postoperative pulmonary complications - were assessed, and the 6MWT was repeated. There was a reduced functional capacity after CABG in ex-smokers (215.8±102 m) and current smokers (272.7±97m) compared to non-smokers (298.5±97.1m) in terms of 6MWT (p<0.05). Current smokers were more likely to have atelectasis after CABG than ex-smokers (76.5% vs. 52.9%), with non-smokers being the least likely to have atelectasis among the three groups (29.4%, p<0.05). Additionally, current smokers required longer ventilator support post-CABG (11.9±7.3 hours) compared to ex-smokers (8.3±4.3 hours) and non-smokers (7±2.5 hours, p<0.01). Smoking status significantly impacts functional capacity reduction after CABG, with current smokers being more susceptible to prolonged ventilator use and atelectasis.

Ten-year all-cause mortality according to smoking status in patients with severe coronary artery disease undergoing surgical or percutaneous revascularization

AIMS

To evaluate the impact of various smoking status on 10-year all-cause mortality and to examine a relative treatment benefit of coronary artery bypass grafting (CABG) vs. percutaneous coronary intervention (PCI) according to smoking habits.

METHODS AND RESULTS

The SYNTAX Extended Survival study evaluated vital status up to 10 years in 1800 patients with de novo three-vessel disease and/or left main coronary artery disease randomized to CABG or PCI in the SYNTAX trial. In the present analysis, patients were divided into three groups (current, former, or never smokers), and the primary endpoint of 10-year all-cause mortality was assessed according to smoking status. Smoking status was available in 1793 (99.6%) patients at the time of randomization, of whom 363 were current smokers, 798 were former smokers, and 632 were never smokers. The crude rates of 10-year all-cause mortality were 29.7% in current smokers, 25.3% in former smokers, and 25.9% in never smokers (Log-rank P = 0.343). After adjustment for imbalances in baseline characteristics, current smokers had a significantly higher risk of 10-year all-cause mortality than never smokers [adjusted hazard ratio (aHR): 2.29; 95% confidence interval (CI): 1.60-3.27; P < 0.001], whereas former smokers did not. PCI was associated with a higher risk of all-cause mortality than CABG among current smokers (HR: 1.60; 95% CI: 1.09-2.35; P = 0.017), but it failed to show a significant interaction between revascularization strategies and smoking status (Pinteraction = 0.910).

CONCLUSION

Current smokers had a higher adjusted risk of 10-year all-cause mortality, whereas former smokers did not. The treatment effect of CABG vs. PCI did not differ significantly according to smoking status.

CLINICAL TRIAL REGISTRATION

SYNTAX: ClinicalTrials.gov reference: NCT00114972; SYNTAX Extended Survival. ClinicalTrials.gov reference: NCT03417050.

Effect of Opium Addiction on Postoperative Arrhythmia Among Patients Undergoing CABG operation on Cardiopulmonary Bypass

OBJECTIVES

Postoperative arrhythmia is an important complication of coronary artery bypass grafting (CABG) surgeries among patients. It seems that opioid usage is implicated in the pathogenesis of this condition due to its impacts on different organ systems, such as the autonomic nervous system. The present study was performed to investigate the effect of opium use on postoperative arrhythmia in patients undergoing CABG surgery.

METHODS

Study participants were selected via convenience sampling from patients undergoing CABG surgery in a referral hospital. Study variables, including use of inotropic drugs, vital signs monitoring parameters and postoperative arrhythmia were observed and recorded at baseline and at follow-up time after surgery.

RESULTS

Sixty-five (14.8%) patients had postoperative arrhythmia, and 104 participants were addicted. Prevalence of postoperative arrhythmia was the same among addict and non-addict patients. According to the regression analysis model, only serum level of epinephrine in operating room, heart rate and central venous pressure at baseline and 48 hours after operation are known as independent predictors of postoperative arrhythmia among study population.

CONCLUSION

This study showed that although opium addiction increased postoperative arrhythmia among patients undergoing CABG surgery, this difference was not significant, and this association is probably mediated by other study variables.

Spirometric values and chest pain intensity three days post-operative coronary artery bypass graft surgery

Aim

Coronary artery bypass graft surgery (CABG) is proved to have ventilatory complications and reduction in spirometric values. This study aimed to examine the hypothesis that reduction of post-operative chest pain intensity would be associated with improvement in the spirometric values for patient underwent CABG.

Materials and method

26 cardiac patients recruited for this study. Their convenience to the study inclusion criteria decided their eligibility. Through 3 days after elective CABG their spirometric values were measured along with their perception to chest pain intensity using 0–10 numeric rating scale. Collected data were recorded and analyzed statistically.

Results

Chest pain intensity showed progressive significant (P = 0.0001) reduction through the 3 days post-operative. On the other hand spirometric values also showed progressive improvement through the 3 days post-operative. This improvement was significant for all measured spirometric values except for the ratio of forced expiratory volume in the 1st second to the forced vital capacity (P = 0.134). There was no significant relationship between the chest pain intensity and spirometric values. This was applied to all measured spirometric values and to the 3 days postoperative.

Conclusion

The current study findings rejected the examined hypothesis that reduction of post-operative chest pain intensity would be associated with improvement in the spirometric values for patient underwent coronary artery bypass graft surgery. There was no significant relationship between the chest pain intensity and any of the spirometric values at any of the 3 post-operative days.

Long-term survival of non-smokers undergoing coronary artery bypass surgery

OBJECTIVES

We sought to investigate long-term survival of non-smokers undergoing coronary artery bypass surgery (CABG).

METHODS

A prospective database of consecutive patients was retrospectively analysed and cross correlated with the UK strategic tracking service to evaluate survival after primary CABG. Univariate, multivariate and a propensity analyses were performed.

RESULTS

We analysed 13 337 primary CABG procedures. Median follow-up was 7 years. Kaplan-Meier survival curves demonstrate that non-smokers have a significantly improved long-term survival compared with ex- and current smokers, P < 0.0001. Cox regression analysis identified smoking status, age, diabetes, ejection fraction (EF), body mass index, cerebrovascular disease, dialysis, left internal mammary artery (LIMA) non-usage, postoperative creatinine kinase muscle-brain isoenzyme (CKMB), radial artery usage, preoperative rhythm, forced vital capacity (FVC) and logistic EuroSCORE as significant risk factors determining long-term survival. Propensity matching resulted in 3575 non-smokers being matched 1:1, with ex-smokers. After matching, univariate analysis demonstrated the significantly worse long-term survival of ex-smokers compared with non-smokers, P < 0.0001. Cox regression analysis identified smoking status, age, postoperative CKMB, cerebrovascular disease, dialysis, diabetes, EF, FVC, LIMA non-usage, radial artery used, sinus rhythm and logistic EuroSCORE as significant risk factors determining long-term survival. Survival by smoking status plotted at the mean of the covariates, prepropensity matching, demonstrated that non-smokers had a significantly better long-term survival than ex-smokers, P < 0.0001; however, after propensity matching, non-smokers under 65 years of age had a significantly worse long-term survival compared with ex-smokers, P < 0.0001.

CONCLUSIONS

Non-smokers under the age of 65 years of age have significantly worse long-term survival compared with ex-smokers after risk factor adjustment. We speculate that this is because ex-smokers have had the causative factor, smoking, removed, but non-smokers have not.

Mediation of smoking-associated postoperative mortality by perioperative complications in veterans undergoing elective surgery: data from Veterans Affairs Surgical Quality Improvement Program (VASQIP)--a cohort study

OBJECTIVE

To assess the mediation of smoking-associated postoperative mortality by postoperative complications.

DESIGN

Observational cohort study.

SETTING

Using data from the Veterans Affairs (VA) Surgical Quality Improvement Programme, a quality assurance programme for major surgical procedures in the VA healthcare system, we assessed the association of current smoking at the time of the surgery with 6-month and 1-year mortality.

PRIMARY AND SECONDARY OUTCOME MEASURES

Using mediation analyses, we calculated the relative contribution of each smoking-associated complication to smoking-associated postoperative mortality, both unadjusted and adjusted for age, race/ethnicity, work relative value unit of the operation, surgeon specialty, American Society of Anesthesiologists class and year of surgery. Smoking-associated complications included surgical site infection (SSI), cardiovascular complications (myocardial infarction, cardiac arrest and/or stroke) and pulmonary complications (pneumonia, failure to wean and/or reintubation).

RESULTS

There were 186 632 never smokers and 135 741 current smokers. The association of smoking and mortality was mediated by smoking-related complications with varying effects. In unadjusted analyses, the proportions of mediation of smoking to 6-month mortality explained by the complications were as follows: SSIs 22%, cardiovascular complications 12% and pulmonary complications 89%. In adjusted analyses, the per cents mediated by each complication were as follows: SSIs 2%, cardiovascular complications 4% and pulmonary complications 22%. In adjusted analyses for 1-year mortality, respective per cents mediated were 2%, 3% and 16%.

CONCLUSIONS

Pulmonary complications, followed by cardiovascular complications and SSIs were mediators of smoking-associated 6-month and 1-year mortality. Interventions targeting smoking cessation and prevention and early treatment of pulmonary complications has the likelihood of reducing postoperative mortality after elective surgery.

Reactive oxygen species mediate functional differences in human radial and internal thoracic arteries from smokers

OBJECTIVE

Smoking not only increases the risk that coronary heart disease will develop but also morbidity and mortality in patients with known coronary atherosclerosis and after coronary artery bypass grafting. Excessive generation of reactive oxygen species (ROS) has been implicated as the final common pathway for the development of endothelial dysfunction in various cardiovascular risk factors. This study assessed the influence of smoking on two different human arteries routinely used as coronary artery bypass graft conduits.

METHODS

Isometric tension was recorded on discarded segments of human left internal thoracic artery (ITA) and the radial artery (RA) from smokers and nonsmokers.

RESULTS

The contractile response to endothelin-1 was significantly stronger in arteries from smokers than in those from nonsmokers. By contrast, endothelium-dependent relaxant responses to acetylcholine were attenuated in RA rings but enhanced in ITA rings from smokers. In additional experiments, 5-(&6)-chloromethyl-2'-7'-dichlorodihydro-fluorescein diacetate (DCDHF) was used to photochemically detect ROS by confocal imaging of intact ITA and RA. Enhanced production of ROS was induced by exposure of tissues to 28 degrees C. While during exposure to 28 degrees C, basal fluorescence emission was unchanged in ITA rings, it increased significantly in RA rings, indicating enhanced formation of ROS in this peripheral artery.

CONCLUSIONS

Data suggest that smoking induces endothelial dysfunction by increasing vascular ROS production. Different levels of endogenous antioxidant enzyme activities and the degree of atherosclerotic changes might modulate physiologic and pharmacologic vasoreactivity and be responsible for decreased graft patency of RA compared with ITA conduits, especially in active smokers.

Acrolein generation stimulates hypercontraction in isolated human blood vessels

Increased risk of vasospasm, a spontaneous hyperconstriction, is associated with atherosclerosis, cigarette smoking, and hypertension-all conditions involving oxidative stress, lipid peroxidation, and inflammation. To test the role of the lipid peroxidation- and inflammation-derived aldehyde, acrolein, in human vasospasm, we developed an ex vivo model using human coronary artery bypass graft (CABG) blood vessels and a demonstrated acrolein precursor, allylamine. Allylamine induces hypercontraction in isolated rat coronary artery in a semicarbazide-sensitive amine oxidase activity (SSAO) dependent manner. Isolated human CABG blood vessels (internal mammary artery, radial artery, saphenous vein) were used to determine: (1) vessel responses and sensitivity to acrolein, allylamine, and H(2)O(2) exposure (1 microM-1 mM), (2) SSAO dependence of allylamine-induced effects using SSAO inhibitors (semicarbazide, 1 mM; MDL 72274-E, active isomer; MDL 72274-Z, inactive isomer; 100 microM), (3) the vasoactive effects of two other SSAO amine substrates, benzylamine and methylamine, and (4) the contribution of extracellular Ca(2+) to hypercontraction. Acrolein or allylamine but not H(2)O(2), benzylamine, or methylamine stimulated spontaneous and pharmacologically intractable hypercontraction in CABG blood vessels that was similar to clinical vasospasm. Allylamine-induced hypercontraction and blood vessel SSAO activity were abolished by pretreatment with semicarbazide or MDL 72274-E but not by MDL 72274-Z. Allylamine-induced hypercontraction also was significantly attenuated in Ca(2+)-free buffer. In isolated aorta of spontaneously hypertensive rat, allylamine-induced an SSAO-dependent contraction and enhanced norepinephrine sensitivity but not in Sprague-Dawley rat aorta. We conclude that acrolein generation in the blood vessel wall increases human susceptibility to vasospasm, an event that is enhanced in hypertension.

Strategies to implement tobacco control policy and advocacy initiatives

Critical care nursing organizations and individual critical care nurses can have an important impact on tobacco-related health policies. This article reviews the importance of critical care nursing involvement in policy efforts to achieve tobacco control goals, barriers to such involvement, and strategies to implement successful tobacco control policy initiatives. The involvement of the Association of Critical-Care Nurses and other nursing organizations in the Nursing Leadership in Tobacco Control Task Force is described.