Considerations for Assessment of Simultaneous Heart and Kidney Transplant Eligibility

More than 1% of US kidney transplants comprise simultaneous heart and kidney transplantation (SHKT), an increase from 0.2% in 2003. In June 2023, the United Network for Organ Sharing (UNOS) published medical eligibility criteria for SHKT candidates based on measured glomerular filtration rate (mGFR) or estimated GFR (eGFR).

According to those criteria, a heart transplant candidate is eligible for SHKT if they have chronic kidney disease (CKD; GFR <60 mL/min/1.73 m²) and are receiving regular dialysis or if they have GFR/creatine clearance (CrCl) of 30 mL/min/1.73 m² or lower. If the heart transplant candidate does not have CKD, they are eligible for SHKT if they have been receiving dialysis for six weeks or have GFR/CrCl 25 mL/min/1.73 m² or lower.

Krishna Agarwal and colleagues highlighted the wide variation among creatinine-based eGFR (eGFRcr), measured CrCl (mCrCl), and mGFR and errors in eGFRcr as demonstrated by six cases of patients ranging in age from 33 to 62 years.

As part of evaluation for SHKT eligibility, the patients’ eGFRcr, cystatin C–based eGFR (eGFRcys; per CKD Epidemiology [CKD-EPI] 2012), eGFR using both creatinine and cystatin C (eGFRcr-cys; per CKD-EPI 2021), 24-hour mCrCl, and mGFR using plasma iohexol clearance were obtained. The researchers evaluated bias (systematic error) as the mean difference between mGFR and eGFR. Positive bias revealed underestimation of mGFR, whereas negative bias revealed overestimation of mGFR.

The researchers observed large discrepancies between eGFRcr, eGFRcys, mCrCl, and mGFR among the cases, with eGFRcr overestimating mGFR (mean overestimation, 7.5 mL/min/1.73 m²). In addition, eGFRcr-cys was more like mGFR with the lowest bias (mean overestimation of mGFR, 1.3 mL/min/1.73 m²). Just 50% of SHKT recipients received dialysis, compared with 87% receiving only kidney transplants, and more than 20% had a GFR greater than 45 mL/min/1.73 m² at the time of transplant.

Because multiorgan transplant recipients have lower patient and graft survival rates, it is critical that they be carefully vetted to ensure optimal equity and effectiveness of transplantation. The authors concluded that the current UNOS eligibility criteria for SHKT does not account for errors in eGFRcr, and centers should consider guidelines for eGFRcr-cys when making decisions about such eligibility.

Source: Agarwal K, Inker L, Levey A. Challenges and opportunities in assessing kidney function in simultaneous heart-kidney transplant candidates. #WCN25-989. Presented at the World Congress of Nephrology; February 6-9, 2025; New Delhi, India.