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 that developed new-onset renal failure requiring dialysis following cardiac surgery at our institution from 2011-2022 were included. Renal recovery, time to renal recovery, and mortality at one year were merged with patients STS ACSD file. Kaplan-Meier analysis was used to predict time to renal recovery, censoring 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 one year was 45% (n= 141). Of those surviving at one 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 (HR 0.98, 0.514-0.94, p<.026) and increasing total PRBC (HR 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. CONCLUSION:Over two-thirds of renal failure patients who survived the peri-operative 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.