The modified US heart allocation system improves transplant rates and decreases status upgrade utilization for patients with hypertrophic cardiomyopathy

https://doi.org/10.1016/j.healun.2021.06.018Get rights and content

Background

On October 18, 2018, the US heart allocation policy was restructured to improve transplant waitlist outcomes. Previously, hypertrophic cardiomyopathy (HCM) patients experienced significant waitlist mortality and functional decline, often requiring status exemptions to be transplanted. This study aims to examine changes in waitlist mortality and transplant rates of HCM patients in the new system.

Methods

Retrospective analysis was performed of the United Network for Organ Sharing Transplant Database for all isolated adult single-organ first-time heart transplant patients with HCM listed between October 17, 2013 and September 4, 2020. Patients were divided by listing date into eras based on allocation system. Era 1 spanned October 17, 2013 to October 17th, 2018 and Era 2 spanned October 18th, 2018 to September 4, 2020.

Results

During the study period, 436 and 212 HCM patients were listed in Eras 1 and 2, respectively. Across eras, no differences in gender, ethnicity, BMI or functional status were noted (p>0.05). LVAD utilization remained low (Era 1: 3.7% vs Era 2: 3.3%, p = 0.297). Status upgrades decreased from 49.1% to 31.6% across eras (p = 0.001). There was no statistically significant difference in waitlist mortality across eras (p = 0.332). Transplant rates were improved in Era 2 (p = 0.005). Waitlist time among transplanted patients decreased in Era 2 from 97.1 to 63.9 days (p<0.001). There was no difference in one-year survival post-transplant (p = 0.602).

Conclusions

The new allocation system has significantly increased transplant rates, shortened waitlist times, and decreased status upgrade utilization for HCM patients. Moreover, waitlist mortality remained unchanged in the new system.

Section snippets

Study design and population

We performed a retrospective cohort study of adult (≥18 years old) patients listed for single-organ heart transplant between October 17, 2013 and September 4, 2020 using the UNOS database. Repeat heart transplants and patients without HCM were excluded. This study was approved by the University of Pennsylvania Institutional Review Board.

The study population was divided by listing date into two eras. Era 1 spanned October 17, 2013 to October 17, 2018 and Era 2 spanned October 18, 2018 to

Results

During the study period, 648 patients who were listed for heart transplant met inclusion criteria. Era 1 included 436 (67.3%) patients and Era 2 included 212 (32.7%). Of those listed in Era 1, 75 patients crossed into Era 2 while on the waitlist and had their outcomes censored at October 17, 2018. Average follow-up time in Era 1 was greater than in Era 2 (Era 1: 225.5±291.4 vs Era 2: 128.6±150.1 days, p<0.001).

Discussion

In this study, we found that the new UNOS heart allocation system has led to an increase in one-year transplant rates, a decrease in status upgrade utilization, and reduced waitlist times with no significant change in waitlist mortality. Following the implementation, post-transplant survival rates remained high for HCM patients.3 These findings coincide with the goals of the new system, contrary to predictions by experts who raised concerns in the past.8,10

While era-based confounding is

Conclusions

The new UNOS heart allocation system has produced favorable outcomes for patients with hypertrophic cardiomyopathy with significantly improved transplant rates, shortened waitlist times, and reduced need for status upgrades with unchanged waitlist mortality. These patients continued to experience excellent long-term post-transplant outcomes in the new allocation system.

Author contributions

CF, MH, and PA conceived the project. CF, with support from MH, designed the study, carried out the analysis, and drafted the manuscript. All authors aided in interpreting the results, revising manuscript drafts, and contributed to the final manuscript.

Disclosure statement

The authors have no financial disclosures or conflicts of interest.

Acknowledgments

The authors have no funding or other acknowledgements.

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