Renal recovery in cardiac surgery patients requiring postoperative renal-replacement therapy.

Objective: Renal failure after cardiac surgery is associated with increased morbidity and mortality. There is a lack of data examining the rate of renal recovery after patients have started dialysis following cardiac surgery. We aimed to determine the frequency of and time to renal recovery of patients requiring dialysis after cardiac surgery.

Methods: All patients who developed new-onset renal failure requiring dialysis following cardiac surgery at our institution from 2011 to 2022 were included. Renal recovery, time to renal recovery, and mortality at 1 year were merged with patients' Society of Thoracic Surgeons Adult Cardiac Surgery Database files. Kaplan-Meier analysis was used to predict time to renal recovery; we censored patients who died or were lost to follow up. Cox regression was used for risk-adjustment.

Results: A total of 312 patients were included in the final analysis. Mortality during index hospital admission was 33% (n = 105), and mortality at 1 year was 45% (n = 141). Of those surviving at 1 year, 69% (n = 118) remained renally recovered. Median renal recovery time was 56 (37-74) days. Accounting for mortality as a competing risk, 51% of patients were predicted to achieve renal recovery. Increasing age (hazard ratio, 0.98; 0.514-0.94, P < .026) and increasing total packed red blood cells (hazard ratio, 0.0958; 0.937-0.987, P < .001) received were found to be significant negative predictors of renal recovery in the Fine-Gray model for subhazard distribution.

Conclusions: More than two-thirds of patients with renal failure who survived the perioperative period had renal recovery within 1 year after surgery. Recovery was driven primarily by postoperative complications rather than comorbidities and intraoperative factors, suggesting renal failure in the postoperative cardiac surgery patient surviving to discharge is unlikely to be permanent.