Modern development in the treatment of congenital heart disease has led to the survival of the majority of children with congenital heart defects well into adulthood. As a consequence, in the current era the number of adults with congenital heart diseases (ACHD) surpasses that of children. This has translated into an increasing number of ACHD patients who develop heart failure. Heart transplantation is a life-saving treatment in this population, but ACHD patients seem to suffer more from the shortage of donor hearts then their non-congenital (NCHD) counterparts with longer waitlist times, lower probability of priority listing, and ultimately, lower likelihood of transplantation. This is partially due to “anticipation” of an optimal donor organ with a goal to increase post-transplant survival in mostly younger group of patients.
Recent study by Huntley et al. questioned the rationale behind “cherry-picking” donors with desirable characteristics to improve post-transplant outcomes in ACHD population, hypothesizing that it leads to lengthening of the waitlist times and worsening outcomes instead.
The study used data from Scientific Registry of Transplant Recipients (SRTR), a comprehensive database on all heart transplant candidates, recipients and donors in the United States (USA). The study included patients older than 18 years and study period from 2000 to 2016. Patients were divided into ACHD and NCHD group and subdivided into candidate or recipient subgroup. Primary outcome for candidates was waitlist time at transplant, death, or delisting, while primary outcome for recipient subgroup was post-transplant survival with censoring at the time of death or re-transplant.
During the study period, 903 out of 1649 ACHD patients underwent heart transplantation, compared to 35 274 out of 54 330 NCHD patients. Less ACHD patients were 1A listed, the highest urgency status in the USA (45%, compared to 52% of NCHD patients). Donors to ACHD patients were found to have higher ejection fraction, were younger, shorter, weighted less and were more likely to be women. ACHD heart transplant recipients had worse 30-day survival than NCHD group, but better survival beyond the 4-year period; the survival in the intermediate period was not significantly different between the two groups. Multivariable analysis of donor characteristics to ACHD recipients found no discernible donor characteristic linked to early or intermediate survival. Increasing donor age was associated with late mortality, and increasing ejection fraction was associated with late survival. Concerning the waiting list times, diagnosis of ACHD increased waiting list time by 69.5 days in the whole group, and 76.4 days for status 1A subset. Among the status 1A subset donor characteristics associated with longer waitlist times were waiting for an Epstein-Barr negative donor (increasing the waiting list by 313±148 days), cytomegalovirus (CMV) negative donor (122±43 days) and a donor without an alcohol use disorder (199±66 days). Furthermore, increased donor body weight, male donors and, possibly, increased donor height were associated with longer waitlist times.
Paradoxical findings of higher short-term mortality and better long-term survival in ACHD heart transplant recipients were elaborated in this study by describing three distinct postoperative periods with different survival trends. Furthermore, it attempted to elucidate which donor characteristics influence post-transplant outcomes in this group. Receiving a graft from a high-risk donor was linked to late mortality, which is challenging to explain because the risk of infections is most pronounced in the early post-transplant period when the immunosuppression is highest. Authors try to interpret this anomaly by development of late vasculopathy or malignancy after receiving a graft from an infectious donor. The study found that waiting for a donor with certain desirable characteristics such as CMV negative status and greater height and weight was associated with longer waitlist times. This is somewhat controversial and authors argue that this selection could be avoided. For example, a heart from a CMV positive donor can be transplanted to CMV negative recipient without significant complications if post-transplant treatment is adjusted. Empirical oversizing to reduce the impact of high pulmonary vascular resistance has not been shown to improve survival.
Results suggest that there is no need for separate criteria for ACHD patients in contrast to NCHD patients in terms of donor characteristics, since waiting for specific characteristics only prolonged the waitlist time in ACHD and was not associated with survival benefit. This study, as authors correctly note, includes inherent selection bias, as many donor characteristics are recognized risk factors and are well ingrained in the donor selection criteria. An obvious limitation of the study is that the ACHD patient cohort, due to grouping of individual diagnoses under an umbrella term in the SRTR registry, included a heterogenous set of specific anatomical and hemodynamical relations, which makes application of the data in an individual patient difficult.
In conclusion, the results of the study suggest that liberalization of donor criteria, rather than “cherry picking”, may improve outcomes in ACHD patients with end-stage heart failure.
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