Optimal and Equitable Allocation of Donor Hearts: Which Principles Are We Translating Into Practices?

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Selection of heart transplantation (HTx) candidates should take into account the need and the probability of success of transplantation. The output of a process that is focused on the careful evaluation of individuals, per international experts' recommendations,1 is by the end, the building of a group, because each patient that is deemed eligible and deserving of an HTx is added to the others on a transplant waitlist. Conversely, organ allocation criteria are defined within each country, considering ethical principles and societal values besides strictly medical considerations.2,3 The output of this process is the assignment of single hearts to single patients. Balancing the best interests of individual with a community's interests may be a difficult task when the gap between demand and supply is wide, as in the case with HTx. Local heart allocation per the “first come, first serve” rule has been progressively abandoned in favor of broader organ sharing and urgency-based prioritization to reduce inequalities and meet the patient needs (Table 1). The increasing proportion of patients undergoing HTx in critical conditions could limit posttransplant survival without reducing the waitlist mortality, ultimately worsening overall patient outcomes.4
In this issue, Cantrelle et al5 analyzed 1-year mortality in patients listed for HTx in France from 2010 to 2013, with the aim to distinguish patient-related predictors and the influence of allocation policy. Of the 2053 candidates, two thirds underwent HTx within 1 year, and a quarter died while waiting for transplantation, with half of them passing away in the first year. Independent predictors for death or delisting due to worsening conditions within 1 year were as follows: age, >55 years, New York Heart Association class IV, being hospitalized and/or on inotropes, high levels of natriuretic peptides, pulmonary hypertension, and renal and/or liver dysfunction. These parameters were consistent with those included in a multivariable score obtained by the same authors from 2010 to 2014 candidates, but not identical.6 Zero blood type and body mass index greater than 30 were associated with lower access to HTx because donors with these characteristics were used for other candidates in high-urgency status. Considering HTx as a competing event, zero blood type and obesity also emerged as risk factors for dying on the waitlist. Conversely, prioritization of candidates requiring inotropes or temporary mechanical circulatory support (MCS) resulted in similar or even lower than average 1-year waitlist mortality. Lower access to transplantation did not impact 1-year survival of candidates with long-term MCS (mostly left ventricular assist devices [LVAD]), whose proper priority level beyond 1 year was not analyzed. In the authors' opinion, prioritization rules miss the declared scope of minimizing mortality on the waitlist. Moreover, they modify natural risk of death, but do not correct all risk factors in the right proportion to favor equitable access to HTx and may contribute to creating disparities.
The article by Cantrelle et al analyzes a country-specific condition, offering important warnings and a methodological approach rather than ready-made solutions to the ongoing debate about heart allocation.2,4-9 Where do we go from there? The main questions can be summarized as follows:
Various scores have been published in the recent years to estimate the risk of death on the waitlist and/or the early probability of survival and life expectancy after transplantation, either excluding or including donor-related parameters.8,10-12 The set of variables and endpoints were chosen and analyzed per the intended scope that is to verify and improve the performance of allocation algorithms based on the urgency of need and/or evaluate the accuracy of new models based on the estimate of the net transplant benefit.
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