Impact of delayed kidney graft function on long-term outcomes in simultaneous heart-kidney transplantation

The incidence of simultaneous heart-kidney transplantation is increasing in the current era of transplantation. Whether delayed graft function of the kidney (requiring use of dialysis within the first week post-transplant) influences long-term patient survival remains underexplored.

This retrospective cohort study analyzed 1737 recipients of simultaneous heart-kidney transplants from the United Network for Organ Sharing database between October 2018 and October 2024. Patients were divided into groups based on the presence or absence of delayed kidney graft function. The primary outcome measure included patient survival at two years, and the principal secondary outcome was kidney allograft survival.

Delayed graft function (DGF) occurred in 31.1% (n=540) of patients and was more common among those who were receiving extracorporeal membrane oxygenation at the time of transplantation. (10.6% vs. 4.3%, p<0.001) and a greater history of prior dialysis (65.4% vs. 37.0%, p<0.001). Patients in the DGF group had a lower two-year survival rate (72.0% vs. 89.7%, p<0.001), with infection (7.2% vs. 2.8%, p<0.001) and organ failure (kidney, liver, or multiple, 5.9% vs. 1.1%, p<0.001) being the primary causes of death. The adjusted multivariate Cox hazards model revealed that DGF increased patient mortality risk (adjusted hazard ratio:3.29, 95%CI: 2.51-4.33; p<0.001). Similarly, DGF was associated with kidney graft loss (adjusted hazard ratio:3.84; 95% CI: 3.01-4.90; p<0.001).

Among those undergoing simultaneous heart-kidney transplantation, DGF of the renal allograft is associated with an increase in late kidney graft failure and reduced long-term patient survival.