Does the mortality risk of Coronary Artery Bypass Grafting (CABG) increase in patients with Chronic Kidney Disease (CKD)?

Does Mortality Risk of CABG Increase in CKD?

Yes, chronic kidney disease significantly increases both perioperative and long-term mortality risk after CABG, with operative mortality rising from 2.2% in patients without CKD to 4.8% in stage 3 CKD and 7.1% in stage 4-5 CKD. 1

Magnitude of Mortality Risk

Cardiovascular morbidity and mortality rates are markedly increased in patients with CKD compared to age-matched controls without CKD. 2 The mortality rate for patients on hemodialysis is 20% per year, with approximately 50% of deaths due to cardiovascular causes. 2

Perioperative Mortality

• Stage 3 CKD (eGFR 30-59 mL/min/1.73 m²): Operative mortality of 4.8% compared to 2.2% in patients without significant CKD (P<0.001) 1
• Stage 4-5 CKD (eGFR <30 mL/min/1.73 m²): Operative mortality of 7.1% 1
• Early postoperative period (first 3 months): CABG carries a higher adjusted hazard ratio of death (1.25; 95% CI 1.12-1.40; P<0.001) compared to PCI 3

Long-Term Mortality

Despite higher perioperative risk, patients with CKD who survive CABG hospitalization have favorable long-term outcomes. 1 The analysis of the Duke cardiac revascularization database found a graded relationship between renal insufficiency and increased mortality compared to patients with normal renal function. 2

• Stage 3 CKD: Hazard ratio 1.64 (95% CI 1.30-2.07) for long-term death compared to no CKD 1
• Stage 4-5 CKD: Hazard ratio 2.77 (95% CI 1.00-7.68) for long-term death 1
• However, among hospital survivors: Annual mortality rates are relatively low—0.006 deaths/year for stage 3 CKD and 0.009/year for stage 4-5 CKD 1
• From 6 months onward: CABG shows lower adjusted hazard ratio of death (0.61; 95% CI 0.55-0.69) compared to PCI 3

Perioperative Complications Associated with Increased Mortality

The incidence of periprocedural complications is increased in patients with CKD compared to those without renal dysfunction. 2

Specific Complications

• Post-operative blood transfusion: Strongly associated with CKD and linked to in-hospital death 1
• Acute kidney injury: Strongly associated with in-hospital death in CKD patients 1
• Myocardial injury and cardiac arrest: More frequent in CKD patients 1
• Surgical complications: Increased frequencies of mediastinitis, stroke, and prolonged mechanical ventilation in patients with ESRD compared to those without ESRD 2
• New dialysis requirement: At 30 days, 3.4% of CABG patients with CKD require de novo dialysis 4

CABG vs Medical Therapy in CKD

Despite increased perioperative risk, CABG demonstrates survival benefit over medical management in patients with severe CKD and multivessel CAD. Among patients with estimated creatinine clearance <15 mL/min/1.73 m² or on dialysis, CABG was associated with a survival benefit compared to medical management (adjusted HR 0.45; 95% CI 0.27-0.74). 2, 5

CABG vs PCI in CKD

CABG is associated with greater long-term survival benefit than PCI among patients with severe renal dysfunction, despite higher perioperative risk. 2

Comparative Outcomes

• ESRD patients: CABG associated with 61% relative mortality reduction compared to PCI (RR 0.39; 95% CI 0.22-0.67) after adjustment for severity of CAD, left ventricular dysfunction, and other comorbid conditions 2, 5
• Stage 3b-5 CKD (eGFR <45 mL/min/m²): At 3 years, PCI associated with significantly higher risk of mortality (50.4% vs 32.9%; adjusted HR 1.77,95% CI 1.13-2.77) compared to CABG 4
• Three-vessel CAD with non-HD CKD: CABG patients tended to have lower long-term mortality rate than PCI patients (HR 0.61,95% CI 0.36-1.03; p=0.06) 6

Trade-offs

CABG carries higher short-term risk of requiring permanent hemodialysis but provides better long-term survival. 6 The adjusted hazard ratio of ESRD after CABG was higher during the first 3 months (1.59; 95% CI 1.27-2.01; P<0.001), but was not statistically significant from 3 months onward. 3

Predictors of Operative Mortality in CKD Patients

A CKD-specific scoring system identifies high-risk patients with 96.4% specificity for in-hospital death: 1

• Urgent or emergent surgery: OR 2.30
• Prior cardiac surgery: OR 3.06
• Concurrent valve surgery: OR 2.06
• Preoperative shock: OR 6.18
• Prior stroke: OR 1.98

Clinical Implications

The fear of postoperative dialysis rates after CABG appears overemphasized since less than 5% of patients needed dialysis in the early postoperative period. 4 Among patients with non-HD CKD undergoing either CABG or PCI, only 2.4% were hemodialysis dependent after revascularization. 6

Revascularization (CABG or PCI) might be reasonable to improve survival in patients with chronic kidney disease (creatinine clearance <60 mL/min), with CABG associated with a greater benefit than PCI among patients with more advanced renal dysfunction (Class IIb, Level of Evidence B). 2

Common Pitfalls

• Deferring revascularization to avoid precipitating ESRD: Death is more frequent than ESRD among CKD patients undergoing coronary revascularization, and long-term risks of death or combined death and ESRD are lower after CABG than PCI 3
• Underestimating bleeding risk: Platelet dysfunction persists in uremia despite normal platelet counts 7
• Assuming poor long-term outcomes: Patients with stage 3-5 CKD who survive hospitalization have favorable long-term outcomes with low annual mortality rates 1