The survival benefit of simultaneous heart-kidney transplantation extends beyond dialysis-dependent patients

Background This study evaluated the effect of simultaneous heart-kidney transplantation (SHK) on survival stratified by preoperative renal function. Methods Patients undergoing SHK or heart transplant alone (HTA) between 1992 and 2012 were identified in the United Network for Organ Sharing database. Patients were primarily stratified by the need for dialysis before transplantation. Nondialysis patients were further stratified by preoperative glomerular filtration rate (GFR) and likelihood of postoperative development of renal failure requiring new-onset dialysis (high risk defined as ≥75th percentile according to a previously derived and validated risk score). The primary outcome was 5-year survival, evaluated by Kaplan-Meier and multivariable logistic regression analyses. Results Included were 665 (2%) SHK and 38,488 (98%) HTA patients. SHK improved 5-year survival in dialysis-dependent patients (69% vs 54%, p < 0.001), with no survival difference in patients with a preoperative GFR ≥60 mL/min/1.73 m² (84% SHK vs 77% HTA, p = 0.34). In patients with a preoperative GFR of less than 60 mL/min/1.73 m², being high risk for postoperative new-onset dialysis discriminated those patients who would benefit from SHK (5-year survival low risk: 82% SHK vs 76% HTA, p = 0.27; 5-year survival high risk: 86% SHK vs 67% HTA, p < 0.001). Risk-adjusted analysis confirmed these findings. SHK comprised only 2.6% of heart transplants in patients with a preoperative GFR of less than 60 mL/min/1.73 m² who were at high risk for postoperative renal failure. Conclusions SHK improves long-term survival not only in dialysis-dependent patients but also in patients with reduced preoperative GFR who are at high risk for postoperative new-onset dialysis. Expansion of SHK into this subset warrants further study, especially considering its low current utilization.