Impact of preoperative renal dysfunction on long-term survival for patients undergoing aortic valve replacement

Background: The impact of the degrees of renal dysfunction (RD) after aortic valve replacement (AVR) has not been well described. The purpose of this study was to compare patients undergoing AVR with a range of renal function from normal to dialysis-dependence. Methods: A retrospective review of 2,408 patients undergoing AVR with or without coronary artery bypass graft surgery (CABG) from January 1996 to March 2009 was performed. Glomerular filtration rate (GFR) was estimated for patients using the Modification of Diet in Renal Disease formula. Multivariable logistic and Cox regression methods were used to determine the independent association of GFR with outcomes. Adjusted odds ratios were calculated for in-hospital outcomes, and Kaplan-Meier curves were created to estimate long-term survival. Results: In all, 1,512 patients (62.8%) had isolated AVR, and 896 (37.2%) underwent AVR plus CABG. Preoperative RD was common among all patients: 1,148 of 2,408 (47.7%) with mild RD (GFR 60 to 90 mL · min^-1 · 1.73 m^-2), 644 of 2,408 (26.7%) moderate RD (GFR 30 to 59 mL · min^-1 · 1.73 m ^-2), 59 of 2,408 (2.5%) severe RD (GFR 15 to 30 mL · min ^-1 · 1.73 m^-2), and 114 (4.7%) with kidney failure (GFR <15) or requiring dialysis. In-hospital mortality generally rose with RD, from 2.9% for patients with no RD to 15.8% for patients with severe RD, and 17.3% for patients requiring dialysis. Patients with severe RD or preoperative dialysis were associated with significantly poorer outcomes. Adjusted long-term survival is progressively worse across levels of RD, as was postoperative length of stay (p < 0.001). Conclusions: Preoperative RD is common among the AVR population and is associated with diminished long-term survival. The association between RD and worse outcomes after AVR surgery has significant clinical implications.