Simultaneous Heart-Kidney Transplant Brings Higher Risk of Kidney Failure and Death

“Since the first successful kidney transplant in the U.S. in 1954, the field of transplantation has evolved at a rapid pace, and the increased need for heart, lung, liver, and kidney transplant have only magnified the challenges to ensure equitable distribution of the limited number of organs from deceased donors,” says Kenji Okumura, M.D., assistant professor of surgery, the lead author on the study. “Furthermore, an increase in kidney dysfunction among heart transplant candidates has led to an increased need for SHKT and KAH.”

Using the United Network for Organ Sharing (UNOS) Standard Transplant Analysis and Research file, the researchers conducted a nationwide cohort analysis. In total, 1,220 pairs of kidney-alone and SHKT recipients and 441 pairs of kidney-alone and KAH recipients from 2014 to 2022 were identified.

“While our results validated some early observations being noted at various single transplant centers across the country, we were surprised at the significant and quantifiable differences in the kidney transplant outcomes and the risk factors associated with kidney loss in SHKT recipients,” says Dr. Okumura.  “On average, patients who received both a heart and kidney transplant simultaneously lost the equivalent of 57 kidney-years of function for every 100 transplants compared to those who received only a kidney transplant—a difference that was large enough to be statistically significant.”

Conversely, KAH transplant recipients had graft survival comparable to those who received a kidney transplant alone, with a loss of 17 kidney-years of function for every 100 transplants.

These results are markedly different from a period just a few years earlier than the study period, when SHKT recipients had a comparable outcome to kidney-alone transplants. This change is attributed to the combination of more recent SHKT candidates being older with more medical comorbidities, and a change in UNOS’ heart allocation policy in 2018, which prioritizes transplanting acutely ill patients with the highest waitlist mortality. A safety-net policy for KAH, implemented in 2023, to give priority to heart, lung, and heart-lung transplant recipients listed for kidney transplant within a year of their thoracic transplant, may help mitigate the significant risk of kidney transplant failure among SHKT recipients.

“Since the availability of deceased donor kidneys remains limited, it is important for the transplant community to be able to prioritize the needs of all transplant candidates, responsibly use this limited resource, and maintain equitable access to organ allocation, including for kidney-alone transplant candidates for whom kidney transplantation offers a promising long-term survival and improved quality of life with a comparatively lower postoperative risk,” says Dr. Okumura.

“With the current protection of the new safety-net policy, our results can help guide transplant centers to refine candidate selection between simultaneous transplant and KAH, with the hope of improving overall transplant outcomes and saving more lives.”