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Combined heart–kidney transplantation (HKT) has been the source of significant discord between transplant cardiologists and nephrologists in recent years. Renal dysfunction (serum creatinine [Cr] of 2 mg/dL) is a major risk factor for morbidity and mortality after heart transplantation (HT) [1]. The risk associated with HT in patients with end-stage renal disease (ESRD) is prohibitive and HT alone is considered ill-advised. Combined HKT has been successfully performed since 1978 for patients with end-stage cardiac and renal failure. Patients with HKT have excellent intermediate and long-term survival, similar to patients with acceptable kidney function and HT alone [2]. In addition, transplantation of multiple organs from a single donor is associated with less acute and chronic rejection and less cardiac allograft vasculopathy than HT alone [3].

In this issue of the journal, Schaefer et al [4] examine the survival benefits of HKT in patients with end-stage heart disease (ESHD) and concomitant renal insufficiency (RI). The authors conclude that all dialysis-dependent patients with ESHD should be listed for HKT; those with nondialysis-dependent RI (NDDRI) should be considered for transplantation, with early listing and strong consideration to list for HKT if clinically thought to have “irreversible disease.”

The first conclusion is easily agreed upon. However, the idea of considering HKT in patients with ESHD and NDDRI is intriguing and requires further exploration. Among those with NDDRI, progressing to ESRD before or after transplantation may be less of a concern than imminent death. Unfortunately, the current study does not provide definitive answers as to the irreversibility of RI. By using propensity score, the nondialysis-dependent groups are “matched” at a Cr clearance (CrCL) close to 50 mL/min. In fact, over half of the patients matched had a CrCl > 50 mL/min, a level that by itself does not constitute an indication for kidney transplantation, and would not dissuade most transplant programs from proceeding with HT alone. Also, there is no single test that defines “irreversible kidney injury” in patients with ESHD. Knowledge of preexisting chronic kidney disease; cause, duration and degree of acute RI; number of prior acute RI episodes; kidney congestion or low perfusion; small kidney size; abnormal urinary sediment and kidney biopsy findings may each be useful in trying to assess irreversibility of RI.

It is routine to utilize left ventricular assist device (LVAD) as a way to evaluate reversibility of end-organ damage in patients with ESHD. Placement of an LVAD in patients with ESHD invariably improves renal function with more than half of patients with CrCl <45 mL/min achieving a CrCl ≥60 mL/min 30 days after implant [5]. The lack of analyses of patient outcomes who have received an LVAD also creates a major weakness in the current analysis. Most, if not all, patients in the current study would have benefited from placement of an LVAD during the waiting period, minimizing the need for HKT. Therefore, the authors' recommendations to give higher priority status exemption to patients who need multiple organs need to be approached with caution.

A cardiologist might see the work of Schaefer et al [4] as “vindication” of a liberal approach to combined HKT. A nephrologist, on the other hand, might interpret the limitations of the current study as exemplary of the difficulties in reaching a consensus regarding the role of HKT. However, we agree that the overwhelming demand for transplantable kidneys creates an ethical imperative to perform HKT transplants only when the risk of ESRD with HT is high, despite pretransplant optimization of cardio-renal function. At the present time, the authors are absolutely correct in their assertion that a multidisciplinary effort is necessary in evaluating and delivering optimal therapy to ESHD patients with RI. Before uniform criteria for HKT versus HT alone can emerge, much more granular information will need to be gathered. In the absence of such criteria, resolving the discord among transplant colleagues will remain dependent on affability and shared concern for the patient.

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The authors of this manuscript have no conflicts of interest to disclose as described by the American Journal of Transplantation.

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