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Published on: February 2, 2021
Off-pump coronary artery bypass surgery and acute kidney injury: a meta-analysis of randomized and observational
Sagar U Nigwekar1, Praveen Kandula, John K Hix
1Department of Internal Medicine, Rochester General Hospital and University of Rochester School of Medicine and Dentistry, Rochester, NY 14621, USA. sagarnigs@hotmail.com
Insights
Off-pump coronary artery bypass grafting (CABG) significantly reduces acute kidney injury (AKI) and the need for renal replacement therapy (RRT) compared to conventional CABG. However, inconsistent AKI definitions limit current evidence.
Area of Science:
- Nephrology
- Cardiovascular Surgery
- Critical Care Medicine
Background:
- Acute kidney injury (AKI) is a significant complication following coronary artery bypass grafting (CABG), associated with increased morbidity and mortality.
- The potential benefit of off-pump CABG (OPCAB) in mitigating post-operative renal injury remains a subject of debate.
Purpose of the Study:
- To systematically review and meta-analyze existing evidence comparing renal outcomes between OPCAB and conventional CABG (CAB).
- To assess the impact of OPCAB on the incidence of overall AKI and AKI requiring renal replacement therapy (RRT).
Main Methods:
- A systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies were conducted.
- Studies published before May 2008 were identified through comprehensive database searches (MEDLINE, EMBASE, Cochrane Renal Library, Google Scholar).
- Included studies compared OPCAB with CAB in adult patients, excluding those on long-term RRT.
Main Results:
- The meta-analysis of 22 studies (27,806 patients) revealed a significant reduction in overall AKI (OR, 0.57; 95% CI, 0.43-0.76) and AKI requiring RRT (OR, 0.55; 95% CI, 0.43-0.71) with OPCAB versus CAB.
- In RCTs, OPCAB significantly reduced overall AKI (OR, 0.27; 95% CI, 0.13-0.54), but a significant difference in AKI requiring RRT was not observed (OR, 0.31; 95% CI, 0.06-1.59).
- Observational studies demonstrated significant reductions in both overall AKI (OR, 0.61; 95% CI, 0.45-0.81) and AKI requiring RRT (OR, 0.54; 95% CI, 0.40-0.73) with OPCAB. Sensitivity analysis of high-quality studies confirmed reduced AKI.
Conclusions:
- The OPCAB technique appears to reduce the incidence of AKI after CABG.
- Heterogeneity in AKI definitions across studies and underpowered RCTs limit definitive conclusions, particularly for AKI requiring RRT.
- Future research should standardize AKI definitions and focus on high-risk patient populations to further elucidate the benefits of OPCAB.
Background:
Acute kidney injury (AKI) after coronary artery bypass grafting (CABG) is associated with significant morbidity and mortality. Controversy exists regarding whether an off-pump technique can reduce post-CABG renal injury.
Study Design:
Systematic review and meta-analysis.
Setting & Population:
Adult patients undergoing CABG.
Selection Criteria For Studies:
MEDLINE, EMBASE, Cochrane Renal Library, and Google Scholar were searched in May 2008 for randomized controlled trials (RCTs) and observational studies comparing off-pump CABG (OPCAB) with conventional CABG (CAB) for renal outcomes. Studies involving patients on long-term renal replacement therapy (RRT) were excluded.
Intervention:
OPCAB.
Outcomes:
Primary outcomes were overall AKI and AKI requiring RRT.
Results:
22 studies (6 RCTs and 16 observational studies) comprising 27,806 patients met the inclusion criteria. The pooled effect from both study cohorts showed a significant reduction in overall AKI (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.43 to 0.76; P for effect < 0.001; I(2) = 67%; P for heterogeneity < 0.001) and AKI requiring RRT (OR, 0.55; 95% CI, 0.43 to 0.71; P for effect < 0.001; I(2) = 0%; P for heterogeneity = 0.5) in the OPCAB group compared with the CAB group. In RCTs, overall AKI was significantly reduced in the OPCAB group (OR, 0.27; 95% CI, 0.13 to 0.54); however, no statistically significant difference was noted in AKI requiring RRT (OR, 0.31; 95% CI, 0.06 to 1.59). In the observational cohort, both overall AKI (OR, 0.61; 95% CI, 0.45 to 0.81) and AKI requiring RRT (OR, 0.54; 95% CI, 0.40 to 0.73) were significantly less in the OPCAB group. RCTs were noted to be underpowered and biased toward recruiting low-risk patients. Sensitivity analysis restricted to good-quality studies showed a significant reduction in AKI.
Limitations:
Lack of uniform AKI definition in the included studies, heterogeneity for overall AKI outcome.
Conclusions:
Analysis of the current evidence suggests a reduction in AKI using the OPCAB technique; however, studies lack consistency in defining AKI. Available RCTs are underpowered to detect a difference in AKI requiring RRT; evidence from observational studies suggests a reduction in RRT requirement. Future studies should apply a standard definition of AKI and target a high-risk population.
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