Delayed Graft Function After Simultaneous Heart-Kidney Transplantation Across Heart Allocation Eras: Predictors and Impact on Kidney Graft Survival in a National Cohort.

BACKGROUND: Delayed graft function (DGF) is common after simultaneous heart-kidney (SHK) transplantation, yet its predictors and long-term consequences in contemporary practice remain incompletely defined. We evaluated the incidence, determinants, and impact of DGF on kidney graft outcomes in a national SHK cohort. METHODS: Using the Scientific Registry of Transplant Recipients, between 2014-2025, we identified adult SHK recipients. After exclusions, 1637 recipients were analyzed. Baseline characteristics were compared by DGF status. Multivariable logistic regression identified DGF predictors. Cox proportional hazards models assessed DGF association with death-censored and overall kidney graft survival. RESULTS: DGF occurred in 29.1% of recipients (n = 477). Independent predictors of higher DGF odds included higher recipient BMI, pre-transplant dialysis, longer cold ischemia time, and higher refitted KDRI (all p < 0.01). In the adjusted models for long-term kidney graft outcomes, DGF was associated with higher death-censored graft loss (HR 2.02, 95% CI 1.11-3.65; p = 0.021) and overall graft loss (HR 2.04, 95% CI 1.47-2.82; p < 0.001). DGF rates and graft outcomes did not differ by heart allocation era (p = 0.179), and DGF was not associated with higher kidney (p = 0.133) or heart rejection (p = 0.848) at 1 year. CONCLUSION: DGF is frequent after SHK transplantation and identifies a high-risk subgroup with substantially inferior long-term kidney graft survival, independent of rejection and allocation era. Given the frequency of DGF and its adverse outcomes, future studies are needed to evaluate kidney-after-heart safety-net utilization and post-heart-transplant renal recovery to optimize outcomes and promote judicious kidney allocation in SHK candidates at high risk for DGF.