Longitudinal outcomes of dialysis-dependent patients undergoing isolated coronary artery bypass grafting

Background: Dialysis-dependent patients have a higher risk of short-term morbidity and mortality following cardiac surgery. However, longitudinal survival and readmissions in this patient population after isolated coronary artery bypass grafting (CABG) are lacking in the literature.

Methods: All patients undergoing isolated CABG from 2011 to 2017 were included. Perioperative data were retrospectively extracted from a prospectively maintained cardiac surgical database with a primary focus on longitudinal mortality and readmissions.

Results: The total study population consisted of 6874 nondialysis-dependent patients and 174 patients with dialysis dependence. Patients in the dialysis-dependent group presented a higher risk of morbidity and mortality as reflected in the Society of Thoracic Surgeons-Predicted Risk of Morbidity and Mortality (STS-PROM) (8.4% ± 9.7% vs 2.3% ± 3.9%; P < 0.001). Operative (30-day) mortality was significantly higher in the dialysis group (8.6% vs 2.3%; P < 0.001). Unadjusted outcomes yielded 30-day (92% vs 98%; P < 0.001), 1-year (80% vs 94%; P < 0.001), and 5-year (38% vs 84%; P < 0.001) survival that was significantly worse for the dialysis group. Freedom from readmission at 30 days (93% vs 87%; P = 0.005), 1 year (78% vs 56%; P < 0.001), and 5 years (62% vs 39%; P < 0.001) was significantly better for the nondialysis cohort. Dialysis dependence was an independent predictor of mortality at 30 days (hazard ratio [HR], 3.86; 95% confidence interval [CI], 2.96, 5.03; P < 0.001), 1 year (HR, 3.20; 95% CI, 2.14, 2.79; P < 0.001), and 5 years (HR, 4.02; 95% CI, 3.07, 5.26; P < 0.001) despite risk adjustment.

Conclusion: Dialysis-dependent patients have significantly elevated operative risk, which translates to worse short- and long-term survival following isolated CABG. The need for dialysis alone is an independent predictor of both mortality and readmission in the midterm.