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Angiographic coronary diffuseness and outcomes in dialysis patients undergoing coronary artery bypass grafting
Daniel Wong1, Greg Thompson, Karen Buth
1Division of Cardiac Surgery, Dalhousie University, Halifax, Nova Scotia, Canada.
Insights
Patients with dialysis-dependent renal failure (DDRF) undergoing coronary artery bypass grafting (CABG) do not have a greater coronary artery atherosclerosis burden. Increased morbidity in DDRF patients is likely due to systemic effects of renal failure, not diffuse coronary disease.
Area of Science:
- Cardiology
- Nephrology
- Cardiac Surgery
Background:
- Pre-operative dialysis-dependent renal failure (DDRF) is linked to higher morbidity and mortality after coronary artery bypass grafting (CABG).
- The underlying reason for this increased risk, specifically whether it involves a more diffuse coronary atherosclerotic burden, remains unclear.
Purpose of the Study:
- To compare the extent of coronary atherosclerotic disease burden in patients with and without pre-existing DDRF who are undergoing CABG.
Main Methods:
- A retrospective analysis matched 35 DDRF patients undergoing isolated CABG with 70 non-dialysis-dependent (NDD) controls.
- Coronary angiograms were analyzed by a blinded adjudicator using a coronary diffuseness score.
- Pre-operative characteristics and outcomes were compared between groups.
Main Results:
- No significant difference in coronary diffuseness scores was observed between DDRF (18.2) and NDD (20.6) groups (p=0.13).
- DDRF patients experienced more frequent transfusions (77% vs. 23%) and longer hospital stays (9 vs. 7 days).
- Both groups showed low rates of peri-operative myocardial infarction, stroke, re-operation, and in-hospital mortality.
Conclusions:
- Patients with DDRF undergoing CABG do not exhibit a greater coronary artery atherosclerosis burden compared to matched controls.
- The increased morbidity and mortality in DDRF patients undergoing CABG are more likely attributable to the systemic effects of renal failure and dialysis on the cardiovascular system, rather than diffuse coronary disease.
Objective:
Pre-operative dialysis-dependent renal failure (DDRF) is a predictor of morbidity and mortality following coronary artery bypass grafting surgery (CABG). Whether this is due in part to a more diffuse coronary atherosclerotic burden in these patients is unknown. The purpose of this study was to compare coronary atherosclerotic disease burden in patients with and without pre-existing DDRF undergoing CABG.
Methods:
From a retrospective analysis of a single-centre cardiac surgical database, consecutive DDRF patients undergoing isolated CABG (n=35) were matched to 70 non-dialysis-dependent (NDD) patients without renal failure by procedure, age, sex, functional status, ejection fraction, number of diseased vessels, and diabetes. Pre-operative angiograms were analyzed by a single, blinded adjudicator using a modification of a previously published coronary diffuseness score (range: 0-45). Angiographic scores and baseline and outcome characteristics were compared using chi(2) tests, Fisher's Exact tests, and t-tests as appropriate.
Results:
No statistical differences were found among pre-operative characteristics between the two groups. The mean angiographic coronary diffuseness scores for the dialysis and non-dialysis groups were 18.2 and 20.6, respectively (p=0.13). Transfusion was more frequent (77 vs. 23%, p<0.0001) and median length of stay longer (9 vs. 7 days, p=0.02) in the DDRF group. There were no differences in the number of distal anastomoses performed in the two groups. Low rates of peri-operative myocardial infarction, stroke, re-operation, and in-hospital mortality were observed in both groups.
Conclusions:
Objective quantification revealed that patients with DDRF undergoing CABG did not have a greater coronary artery atherosclerosis disease burden than matched controls who did not have pre-operative DDRF. This may be due to pre-operative patient selection bias. The increased morbidity and mortality of CABG in patients with DDRF is more likely to be due to the multiple adverse systemic effects of renal failure and dialysis on the cardiovascular system as opposed to diffuseness of distal coronary disease.