Relation between mild renal dysfunction and outcomes after coronary artery bypass grafting

Area of Science:

• Cardiology
• Nephrology
• Surgical Risk Assessment

Background:

• Current coronary artery bypass grafting (CABG) risk stratification models lack specific weighting for mild renal impairment.
• Mild renal impairment, defined as serum creatinine 130-199 µmol/L (1.47-2.25 mg/dL), may significantly impact patient outcomes post-CABG.

Purpose of the Study:

• To investigate the impact of preoperative mild renal dysfunction on in-hospital mortality, morbidity, and midterm survival in patients undergoing isolated CABG.
• To determine if mild renal impairment is an independent predictor of adverse outcomes after CABG.

Main Methods:

• A review of prospectively collected data from 4403 consecutive patients undergoing first-time isolated CABG between 1997 and 2004.
• Patients were categorized based on preoperative serum creatinine levels: mild renal dysfunction (130-199 µmol/L) and normal renal function (<130 µmol/L).
• Multivariate analysis was performed to adjust for known risk factors and identify independent predictors of mortality.

Main Results:

• Patients with mild renal dysfunction (n=458) exhibited higher operative mortality (6.1% vs. 2.1%, P<0.001) compared to those with normal renal function (n=3945).
• Mild renal impairment was associated with increased rates of new dialysis/hemofiltration (5.2% vs. 0.8%, P<0.001) and postoperative stroke (5.0% vs. 2.2%, P<0.01).
• Mild renal dysfunction (OR, 1.91; P=0.007) and estimated glomerular filtration rate <60 mL/min/1.73 m² (OR, 1.98; P=0.015) were independent predictors of in-hospital mortality. Three-year survival was significantly lower in the mild renal dysfunction group (81% vs. 93%, P<0.001).

Conclusions:

• Preoperative mild renal dysfunction is a significant independent predictor of adverse outcomes in patients undergoing CABG.
• Mild renal impairment is associated with increased in-hospital mortality, morbidity (dialysis, stroke), and reduced midterm survival after CABG.
• Current risk stratification algorithms for CABG should be updated to include preoperative mild renal impairment as a critical factor.