Heart and Kidney: When Do We Perform Combined Transplants?

Historically, candidacy for simultaneous heart-kidney (SHK) transplantation, or transplantation of both the heart and kidney from the same deceased donor into the same candidate, has only been considered for patients who have end-stage heart failure as the primary disease process. In this setting, kidney diseases, which may or may not be a result of heart failure, are frequently milder than that which would prompt consideration for kidney transplantation in a non-heart transplant candidate. This has been the approach undertaken by the newly considered eligibility criteria for SHK under deliberation at the Organ Procurement & Transplantation Network (OPTN) (1). These eligibility criteria have largely followed the same framework as established for simultaneous liver-kidney transplantation in 2017 on the grounds of transparency and consistency (2). In specific terms, sustained acute kidney injury lasting 6 weeks or longer or chronic kidney disease (defined as estimated glomerular filtration rate [eGFR] ≤60 mL/min for 6 months and eGFR ≤30 mL/min at the time of listing) is sufficient to qualify the heart transplant candidate for SHK transplantation. Additional priority is granted for heart transplant recipients who develop kidney failure and meet usual kidney transplant eligibility within 1 year after heart transplant (the “safety net” provision).

Eligibility is only half of the equation. We have recently pointed out how the current allocation, or how patients who meet eligibility criteria for an organ or organ combination are prioritized for said organ or organ combination, is systemically biased against candidates for kidney transplant alone who suffer real harm from the delay in transplant (3, 4). SHK further decreases access to kidneys in that it preferentially draws high-quality kidneys (5) but yields poorer kidney graft outcomes, owing to the disease acuity of SHK candidates (6). Currently, allocation priority for SHK is determined by the patient's severity of heart disease: Any time the patient is offered a heart, the kidney will be offered, regardless of the severity of the kidney disease, the urgency of the next-sequence kidney transplant candidate (who may be highly sensitized, a child, a prior kidney transplant donor, or a dialysis patient running out of access), or the likelihood that the kidney even survives the SHK transplant. Wait time or urgency for kidney transplant does not factor into allocation priority for SHK at all. A candidate on dialysis for many years and running out of access, who has stable heart disease that puts him or her into a lower allocation tier for the heart, will not be granted additional priority. The current allocation system is ethically unjustifiable and disadvantages all patients with kidney diseases, except the minority who happen to have high-acuity failure of non-kidney organs (6).

The establishment of eligibility criteria for SHK at the OPTN level is, therefore, only a start to the conversation. As OPTN works out how to incorporate combined organ transplants into the allocation system, we need sustained efforts from the nephrology and kidney diseases community to engage with the OPTN to advocate for the needs of all patients with kidney diseases who may benefit from a kidney transplant.

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