Fate of the Kidneys in Patients with Post-Operative Renal Failure After Cardiac Surgery.

Background: This study evaluates the clinical and renal-related outcomes in patients with acute renal failure (ARF) following cardiac surgery.

Methods: Index adult cardiac operations at a single institution from 2010-2018 were reviewed. Patients requiring dialysis pre-operatively were excluded. ARF was stratified as either creatinine rise (≥3-times baseline or ≥4.0 mg/dL) or post-operative dialysis. Outcomes included mortality, rates of progression to dialysis, and renal recovery. Multivariable Cox regression was used for risk-adjustment.

Results: A total of 10,037 patients, including 6,275 (62.5%) isolated coronary artery bypass grafting (CABG), 2,243 (22.3%) isolated valve, and 1,519 (15.1%) CABG plus valve cases, were included. Post-operative ARF occurred in 346 (3.5%) patients, with 230 (66.5%) requiring dialysis. Survival was significantly reduced in patients with ARF at 30-days (97.9 versus 70.8%, P <0.001), 1-year (94.9 versus 48.0%, P <0.001), and 5-years (86.2 versus 38.2%, P <0.001) with more profound reductions in those requiring dialysis, findings which persisted after risk-adjustment. Progression to subsequent dialysis in the creatinine rise group was rare (n = 1). The median time to dialysis initiation in the dialysis group was 5 days (IQR 2-12 days) with a median time of dialysis dependence of 72 days (IQR 38-1229 days). Of those patients requiring postoperative dialysis, 30.9% demonstrated renal recovery.

Conclusions: Post-operative ARF and in particular the need for dialysis are associated with substantial reductions in survival that persist during longitudinal follow-up. This occurs despite the finding that patients experiencing creatinine rise only rarely progress to dialysis, and that nearly one-third of patients requiring post-operative dialysis recover renal function.