Allocation changes in heart transplantation: What has really changed?

Regional variation in donation after circulatory death heart allograft utilization

Objective

Randomized data support transplantation of hearts from donors after circulatory death. This may lead to a sizeable increase in the donor pool. Regional variations in donors after circulatory death heart use were examined to help elucidate barriers to donor pool expansion.

Methods

The United Network for Organ Sharing deceased donor dataset was queried for adult (age ≥ 18 years) donors after circulatory death donors of at least 1 organ between January 2020 and December 2023. Donors were stratified by the extent their respective cardiac allografts progressed through the donation process. United Network for Organ Sharing region-level use rates and annual trends were assessed.

Results

Of 17,239 adult donors after circulatory death donors who donated at least 1 organ for transplant during the study period, 1196 (9.4%) were heart donors. Regional donors after circulatory death heart donor pursuit rates ranged from 97% to 100%, consent attainment rates from 94% to 99%, and heart recovery rates from 5% to 10%. The transplantation rate of recovered organs ranged from 90% to 97%. Multivariable logistic regression demonstrated United Network for Organ Sharing region to be independently associated with donors after circulatory death heart use after controlling for baseline differences in donor risk.

Conclusions

Transplantation of donors after circulatory death heart allografts has increased in the United States since 2020, but the overall number of hearts procured and transplanted from donors after circulatory death donors remains low. The operational barriers to transplantation of donors after circulatory death hearts require further investigation. Further, significant regional variation exists regarding rates of progression of donors after circulatory death hearts through the donation process. Sharing of successful practices among Organ Procurement Organizations and transplant centers will facilitate maximal use of this new donor pool.

Heart Transplantation

Heart transplantation (HTx) remains the last therapeutic resort for patients with advanced heart failure. The present work is a clinically focused review discussing current issues in heart transplantation. Several factors have been associated with the outcome of HTx, such as ABO and HLA compatibility, graft size, ischemic time, age, infections, and the cause of death, as well as imaging and laboratory tests. In 2018, UNOS changed the organ allocation policy for HTx. The aim of this change was to prioritize patients with a more severe clinical condition resulting in a reduction in mortality of people on the waiting list. Advanced heart failure and resistant angina are among the main indications of HTx, whereas active infection, peripheral vascular disease, malignancies, and increased body mass index (BMI) are important contraindications. The main complications of HTx include graft rejection, graft angiopathy, primary graft failure, infection, neoplasms, and retransplantation. Recent advances in the field of HTx include the first two porcine-to-human xenotransplantations, the inclusion of hepatitis C donors, donation after circulatory death, novel monitoring for acute cellular rejection and antibody-mediated rejection, and advances in donor heart preservation and transportation. Lastly, novel immunosuppression therapies such as daratumumab, belatacept, IL 6 directed therapy, and IgG endopeptidase have shown promising results.

Center-Level Variation in Transplant Rates Following the Heart Allocation Policy Change

IMPORTANCE

Wide state-level variability in waiting list outcomes have been noted for patients listed for heart transplant in the US, but little is known regarding center-level transplant rates since the heart allocation policy change.

OBJECTIVE

To evaluate center-level transplant rates following the recent allocation policy change for heart transplant.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from the United Network for Organ Sharing database from October 18, 2015, to March 1, 2020, for a nationwide analysis of transplant centers in the US. Transplant candidates were stratified into 2 time cohorts, with era 1 denoting the 3-year period before the policy change (October 18, 2018), and era 2 representing the 500-day period after the policy change but before the beginning of the COVID-19 pandemic. Data were analyzed from May to June 2021.

EXPOSURE

The heart allocation policy change enacted on October 18, 2018.

MAIN OUTCOMES AND MEASURES

Competing risk regression for waiting list outcomes was performed to calculate adjusted era 1 and era 2 center-level transplant rates. Rates were compared across regions and states, as well as within organ procurement organizations. Pearson correlation coefficient was used to assess center-level factors associated with era 2 transplant rates.

RESULTS

Of 15 940 transplant candidates included for analysis, 5063 (median [IQR] age, 56 [45-63] years; 1385 women [27.4%]) comprised the era 2 cohort. The proportion of patients with temporary mechanical circulatory support increased between era 1 and era 2 (extracorporeal membrane oxygenation, 2.00% vs 3.42%; percutaneous ventricular assist device, 0.66% vs 1.86%; intra-aortic balloon pump, 5.21% vs 13.10%). The adjusted mean center-level likelihood of transplant increased after the rule change (from 48.1% in era 1 to 78.0% in era 2). Significant variation in transplant rates was observed across regions and states even among centers with shared organ procurement organizations. The largest absolute difference in transplant rates was 27.1% for 2 centers belonging to the same organ procurement organization. Centers with higher transplant volumes in era 2 and with a greater proportion of candidates with intra-aortic balloon pump were observed to have higher transplant rates.

CONCLUSIONS AND RELEVANCE

Despite sharing organ supply and having a small geographical distance, these findings suggest that intercenter disparities in the likelihood of transplant have persisted following the heart allocation policy change. Further work is necessary to ensure equitable allocation of organs in heart transplant.

Trends, risk factors, and outcomes of post-operative stroke after heart transplantation: an analysis of the UNOS database

BACKGROUND

Post-operative stroke increases morbidity and mortality after cardiac surgery. Data on characteristics and outcomes of stroke after heart transplantation (HTx) are limited.

METHODS AND RESULTS

We conducted a retrospective analysis of the United Network for Organ Sharing (UNOS) database from 2009 to 2020 to identify adults who developed stroke after orthotropic HTx. Heart transplant recipients were divided according to the presence or absence of post-operative stroke. The primary endpoint was all-cause mortality. A total of 25 015 HT recipients were analysed, including 719 (2.9%) patients who suffered a post-operative stroke. The stroke rates increased from 2.1% in 2009 to 3.7% in 2019, and the risk of stroke was higher after the implantation of the new allocation system [odds ratio 1.29, 95% confidence intervals (CI) 1.06-1.56, P = 0.01]. HTx recipients with post-operative stroke were older (P = 0.008), with higher rates of prior cerebrovascular accident (CVA) (P = 0.004), prior cardiac surgery (P < 0.001), longer waitlist time (P = 0.04), higher rates of extracorporeal membrane oxygenation (ECMO) support (P < 0.001), left ventricular assist devices (LVADs) (P < 0.001), mechanical ventilation (P = 0.003), and longer ischaemic time (P < 0.001). After multivariable adjustment for recipient and donor characteristics, age, prior cardiac surgery, CVA, support with LVAD, ECMO, ischaemic time, and mechanical ventilation at the time of HTx were independent predictors of post-operative stroke. Stroke was associated with increased risk of 30 day and all-cause mortality (hazard ratio 1.49, 95% CI 1.12-1.99, P = 0.007).

CONCLUSIONS

Post-operative stroke after HTx is infrequent but associated with higher mortality. Redo sternotomy, LVAD, and ECMO support at HTx are among the risk factors identified.