Advancements in heart failure therapies have extended patient longevity, thereby raising the age at which advanced interventions, such as heart transplantation (HTx) or durable left ventricular assist device (LVAD) implantation, may become necessary. In the United States, life expectancy stands at 73.5 years for men and 79.3 years for women, which is lower than in Spain, where life expectancy is 81.8 years for men and 87 years for women.

Daniel et al. assessed HTx recipients over 60 in the UNOS dataset from 2004 to 2013, noting reduced post-transplant survival in those receiving hearts from donors around 50. Other pre-existing studies support the benefit for HTx candidates in receiving hearts from donors over 40, rather than remaining on the waitlist. Similarly, Laks et al., in 1990, pioneered an “alternative” waitlist concept, where recipients over 65 could receive hearts from donors older than 55.

This study aims to evaluate outcomes for septuagenarian HTx recipients who received hearts from donors below and above 50. Data were sourced from the UNOS database between January 2011 and December 2021, yielding 989 HTx recipients over 70, with multiorgan recipients or re-HTx cases excluded. Propensity matching yielded 167 pairs based on 14 characteristics: age, sex, race, ABO blood group, body mass index, diabetes mellitus, hemodialysis, smoking status, ischemic or non-ischemic etiology, prior cardiac surgery, total bilirubin, ECMO support, prior intra-aortic balloon pump (IABP) or LVAD use. The median follow-up was 1288 days for donors under 50 and 1447 days for those over 50.

In the <50 donor group, mean donor age was 30 years, while it was 54 in the ≥50 group. No significant differences were observed in postoperative cerebrovascular accident (CVA), hemodialysis, or pacemaker implantation. Thirty-day mortality was 4.8% in recipients of <50 donors versus 3.6% in those with ≥50 donors (p = 0.59). Survival rates and graft failure were similar across groups. Post-matching, survival at 1 and 5 years was 88.0% and 79.2% for <50 donors, compared to 87.2% and 72.3% for ≥50 donors, respectively (p = 0.41). Infection, COVID-19 (2019), and CVA were among the primary causes of death. Waitlist mortality at 30 and 90 days was 3.0% and 6.0%, respectively, with an increase in transplants (p < 0.001) and a tendency towards lower waitlist mortality or delisting (p = 0.097). The primary cause of donor death differed by age group, with traumatic brain injury and anoxia predominant in donors <50, while cerebrovascular disease was most common in donors ≥50 (p < 0.001).

The study’s main finding indicates that donor hearts aged ≥50 are safe for use, with comparable post-HTx survival among septuagenarians regardless of donor age. Improved outcomes over time reflect advancements in donor-recipient matching and understanding of the physiological versus chronological age of recipients.

COMMENTARY:

This study provides insight into the future of HTx, highlighting changes already made in the U.S. waitlist system; a 70-year-old patient with heart failure and shock requiring IABP support may now receive urgent priority on the waitlist (UNOS Status 2), whereas the previous protocol would have limited them to LVAD destination therapy.

Thus, this study offers a potential approach to an issue of particular importance in HTx: expanding the donor pool without compromising medium- and long-term outcomes. Accepting older donor hearts for older recipients expands the donor pool without affecting HTx outcomes, while also reducing waitlist time. Furthermore, it decreases the rejection rate of hearts that may be suboptimal for younger recipients but suitable for older candidates.

Comparable survival at 1 and 5 years with hearts from donors under and over 50 aligns with similar findings in Spain, where older donor organs are accepted. Additionally, non-cardiac causes, such as infections and malignancies, are primary causes of mortality among elderly HTx recipients, supporting the notion that using older donor hearts does not compromise HTx outcomes.

This study has limitations associated with retrospective analyses of national databases. Early post-HTx outcomes, such as primary graft dysfunction, mechanical circulatory support requirements, respiratory failure, or acute kidney injury not requiring dialysis, are unavailable for analysis. Additionally, national database studies are susceptible to errors in variable coding and data entry, a limitation inherent to this study type.

REFERENCE:

Ohira S, Okumura K, Hirani R, Martinez S, Ichikawa H, et al. Use of Donor Hearts ≥50 Years Old for Septuagenarians in Heart Transplantation. Ann Thorac Surg. 2023 Sep;116(3):580-586. doi: 10.1016/j.athoracsur.2023.04.032.