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Published on: March 27, 2018
Long-term mortality after isolated coronary artery bypass grafting and risk factors for mortality
Therese K T Chua1, Fei Gao2,3, Shaw Yang Chia4
1Lee Kong Chian School of Medicine, Nanyang Technological University, 11 Mandalay Road, Singapore, 308232, Singapore. tchua010@e.ntu.edu.sg.
Insights
Coronary artery bypass grafting (CABG) mortality is predicted by poorer renal function (eGFR). Other key factors include logistic EuroSCORE, age, diabetes, and BMI, with chronic kidney disease stage 3B and above posing the highest risk.
Area of Science:
- Cardiovascular Surgery
- Nephrology
- Public Health
Background:
- Coronary artery bypass grafting (CABG) patients often have multiple comorbidities impacting surgical risk.
- Comprehensive assessment of these conditions is crucial for determining patient outcomes.
Purpose of the Study:
- To evaluate short-term and long-term mortality rates following isolated CABG.
- To identify significant risk factors associated with post-CABG mortality.
Main Methods:
- Analysis of a complete dataset of isolated CABG patients from January 2008 to December 2017.
- Application of univariate and multivariate Cox regression and Classification and Regression Tree (CART) analysis.
Main Results:
- Overall mortality was 25.7%; in-hospital mortality was 1.62%.
- Key predictors of mortality included lower estimated glomerular filtration rate (eGFR), older age, lower BMI, hypertension, diabetes, COPD, pre-operative renal failure, heart failure, and lower ejection fraction.
- CART analysis identified pre-operative eGFR < 46.9 as the strongest predictor, followed by logistic EuroSCORE ≥ 2.4.
Conclusions:
- Reduced renal function (lower eGFR) is the primary predictor of post-CABG mortality.
- Logistic EuroSCORE, age, diabetes, and BMI significantly impact mortality risk.
- Patients with chronic kidney disease stage 3B or higher face the highest mortality risk, emphasizing the need for renal function preservation.
Background:
Patients requiring coronary artery bypass grafting (CABG) have multiple co-morbidities which need to be considered in totality when determining surgical risks. The objective of this study is to evaluate short-term and long-term mortality rates of CABG surgery, as well as to identify the most significant risk factors for mortality after isolated CABG.
Methods:
All patients with complete dataset who underwent isolated CABG between January 2008 and December 2017 were included. Univariate and multivariate Cox regression was performed to determine the risk factors for all-cause mortality. Classification and regression tree analysis was performed to identify the relative importance of these risk factors.
Results:
3,573 patients were included in the study. Overall mortality rate was 25.7%. In-hospital mortality rate was 1.62% overall. 30-day, 1-year, 5-year, 10-year and 14.5-year mortality rates were 1.46%, 2.94%, 9.89%, 22.79% and 36.30% respectively. Factors associated with death after adjustment for other risk factors were older age, lower body mass index (BMI), hypertension, diabetes mellitus, chronic obstructive pulmonary disease, pre-operative renal failure on dialysis, higher last pre-operative creatinine level, lower estimated glomerular filtration rate (eGFR), heart failure, lower left ventricular ejection fraction and New York Heart Association class II, III and IV. Additionally, female gender and logistic EuroSCORE were associated with death on univariate Cox analysis, but not associated with death after adjustment with multivariate Cox analysis. Using CART analysis, the strongest predictor of mortality was pre-operative eGFR < 46.9, followed by logistic EuroSCORE ≥ 2.4.
Conclusion:
Poorer renal function, quantified by a lower eGFR, is the best predictor of post-CABG mortality. Amongst other risk factors, logistic EuroSCORE, age, diabetes and BMI had a relatively greater impact on mortality. Patients with chronic kidney disease stage 3B and above are at highest risk for mortality. We hope these findings heighten awareness to optimise current medical therapy in preserving renal function upon diagnosis of any atherosclerotic disease and risk factors contributing to coronary artery disease.
