Risk Analysis and Outcomes of Postoperative Renal Failure After Aortic Valve Surgery in the United States

Background: Postoperative renal failure (RF) compromises early outcomes in cardiac surgery. In contrast, long-term survival and progression of RF after aortic valve replacement (AVR) with or without coronary artery bypass graft surgery (CABG) remain undefined. Methods: From 2008 through 2015, records of AVR with or without CABG in The Society of Thoracic Surgeons database were linked to Medicare claims data. Postoperative RF was categorized as being with new dialysis (RF-D) or without new dialysis (RF no-D). Cox proportional hazards models were used to conduct a risk analysis and evaluate outcomes in this patient group. Results: Of 164,727 patients undergoing AVR with or without CABG, 3.5% had postoperative RF, of whom 63.3% required dialysis. Operative mortality of postoperative RF was 39.2%, higher for dialysis than for no-dialysis patients (46.1% vs 26.1%, P < .0001). Both RF dialysis patients and no-dialysis patients had a higher early (less than 30-day) mortality risk (hazard ratio [HR] 11.29, P < .0001 and HR 8.03, P < .0001, respectively) compared with no postoperative RF. At a median follow-up of 2.7 years, RF-D and RF no-D remained relevant risk factors, however, with a lower magnitude of effect (HR 2.42, P < .0001, and HR 1.69, P < .0001, respectively). Preoperative glomerular filtration rate (GFR) less than 30 mL · min⁻¹ · 1.73 m⁻² had a lower early mortality risk (HR 0.48, P < .0001) but higher late mortality risk (HR 1.5, P < .0001) compared with GFR greater than 60. Predictors for long-term progression to RF-D included preoperative GFR less than 30 (HR 13, P < .0001), GFR 30 to 60 (HR 2.47, P = .006), and insulin-dependent diabetes mellitus (HR 1.96, P = .001). Conclusions: Postoperative RF after AVR with or without CABG was associated with higher early and late mortality, which further increased with a new requirement for dialysis. Once postoperative RF develops, preoperative renal dysfunction does not increase early mortality; however, it predicts late survival. Preoperative renal function is associated with progression of postoperative RF to dialysis.