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Published on: March 27, 2018
Significance of preoperative left ventricular ejection fraction in 5-year outcome after isolated CABG
Aida Fallahzadeh1, Ali Sheikhy1, Ali Ajam2
1Research Department, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran.
Insights
Patients with severely reduced ejection fraction (EF) face higher mortality after coronary artery bypass graft (CABG) surgery. However, cerebro-cardiovascular events (CCVEs) risk may not increase significantly after accounting for other health conditions.
Area of Science:
- Cardiology
- Cardiac Surgery
- Outcomes Research
Background:
- Pre-operative ejection fraction (EF) and comorbidities significantly influence outcomes following cardiac surgery.
- Understanding the impact of varying EF levels on mortality and adverse events is crucial for patient management.
- Comorbidity distribution across different EF groups requires detailed evaluation.
Purpose of the Study:
- To compare mortality and adverse events in patients undergoing isolated coronary artery bypass graft (CABG) surgery based on pre-operative ejection fraction (EF).
- To analyze the distribution of comorbidities within different EF categories.
- To identify predictors of mortality and cerebro-cardiovascular events (CCVEs) after CABG.
Main Methods:
- A retrospective analysis of 20,937 patients undergoing isolated CABG between 2006 and 2016.
- Patients were stratified into three groups: Normal EF (≥50%), Mild-Moderately Reduced EF (35-50%), and Severely Reduced EF (<35%).
- Multivariate Cox-regression analysis was employed to identify predictors of mortality and CCVEs, with a median follow-up of 5.61 years.
Main Results:
- The median 5-year mortality rates were 9.5% (Normal EF), 12.8% (Mild-Moderately Reduced EF), and 22.7% (Severely Reduced EF) (P<0.001).
- Diabetes mellitus was a common risk factor for mortality and CCVEs across all EF groups.
- Impaired renal function (GFR<60 ml/min) independently increased mortality risk post-CABG, irrespective of EF.
Conclusions:
- Severely reduced EF is a significant predictor of increased mortality risk following CABG.
- While trends suggest higher CCVEs in severe LV dysfunction, this did not reach statistical significance after adjusting for comorbidities.
- Pre-operative comorbidities play a critical role in modulating the risk of adverse events after CABG, particularly in patients with reduced EF.
Background:
Pre-operative ejection fraction (EF) and comorbidities affect post-op outcomes. We aimed to compare the mortality and adverse events of patients with different baseline EF and also to evaluate the distribution of comorbidities in each EF group.
Methods:
A total of 20,937 patients who underwent isolated coronary artery bypass graft (CABG) surgery from January 2006 to December 2016 was included. Patients were divided into three groups based on their pre-operative left ventricular EF as follows; (1) Normal: EF ≥ 50%; (2) Mild to moderately reduced: 50% < EF ≤ 35%; and (3) Severely reduced: EF < 35%. The backward elimination method was considered for multivariate Cox-regression analysis to locate predictors of mortality and non-fatal cerebro-cardiovascular events (CCVEs). The median follow-up time was 5.61 [3.12-8.0] years.
Results:
The mean age in the total population was 60.94 ± 9.51 years and 73.6% of the total population was male. Diabetes mellitus was the common risk factor of mortality and CCVE in all EF groups. Impaired renal function (GFR < 60 ml/min) was associated with a higher risk of mortality after CABG regardless of EF level. The median 5-year mortality rate in patients with normal EF, mild-moderately reduced EF and severely reduced EF were 9.5%, 12.8%, and 22.7% respectively (P < 0.001). Although the trend of CCVEs was higher in severe left ventricle (LV) dysfunction, it was not statistically significant (p = 0.071).
Conclusion:
Patients with severely reduced EF are at higher risk of mortality after CABG compared to those with higher EF levels; however, the rate of CCVEs may not be necessarily higher after adjustment for multiple pre-operative comorbidities.
