Policy changes fail to improve pediatric heart transplant survival

Researchers from Stanford Medicine have found changes to waitlist rules have not improved survival odds among babies and children receiving a heart transplant (HT), publishing their findings in the Journal of the American College of Cardiology.¹

According to investigators, the sickest patients are not prioritized in the current method used in US hospitals to waitlist children for HT. Therefore, the reduction in mortality among this population has been linked to improved medical care rather than to waitlist rules.

“Wait-list mortality, which is the chance that a child will die while awaiting transplant, is higher in pediatric heart transplant than for virtually any other organ or age group,” said Christopher Almond, MD, professor of pediatrics at Stanford and senior study author.

Assessing waitlist mortality

The study was conducted to evaluate trends in pediatric HT waitlist mortality.² Participants included US pediatric patients younger than 18 years listed for isolated HT between January 20, 1999, and June 30, 2023. Data about these patients were obtained from the Scientific Registry of Transplant Recipients, a database on solid organ transplants in the United States.

Patients with in utero listing, miscoded listing status, missing anthropometric data, missing creatinine at listing, missing dialysis status at listing, transferring centers, or multilisting were excluded. Investigators hypothesized that the 2016 United Network for Organ Sharing (UNOS) revisions to its 3-tier pediatric heart allocation criteria would be linked to reduced waitlist mortality.

Allocation eras were defined based on when the UNOS revisions were implemented. On January 20, 1999, children were placed in UNOS status 1A or 1B groups. On July 12, 2006, broader regional sharing of donor hearts was implemented.

Finally, children with cardiomyopathy on high-dose inotropes were deprioritized from 1A to 1B on March 22, 2016. These periods were defined as era 1, era 2, and era 3, respectively.

Primary outcomes and participant mortality

Cases of children with lower risk of waitlist mortality being rank-ordered to receive a donor before those at an increased risk were defined as allocational inefficiencies. Types of allocational inefficiencies included those between 2 children from different UNOS status levels and those between 2 children from the same listing status.

The time from the initial listing for HT to the time of waitlist removal because of transplant, death or deterioration, or recovery was defined as the time on waitlist. The primary end point was death or permanent delisting because of clinical deterioration.

There were 12,408 children included in the analysis, 16% of whom died or were removed from the waitlist because of death or clinical deterioration. Rates of death or removal were 21% in era 1, 17% in era 2, and 13% in era 3. This indicated an overall decline in waitlist mortality of 38% during the study period.

Heart transplant and waitlist duration changes

A heart transplant was reported in 70% of the study population. Era 1, 2, and 3 rates of heart transplant were 67%, 72%, and 70%, respectively. Eight percent of patients improved and did not need a heart transplant, and 4% remained alive and on the waitlist as of June 30, 2023.

Investigators noted a decline in the average waitlist duration, from 190 days in era 1 to 180 in era 2 and 152 in era 3. Declines in mortality rates were reported across patient characteristics, including the following:

• 10 percentage points (PP) for non-White patients
• 13 PP for blood group O patients
• 12 PP for congenital heart disease patients
• 8 PP for dilated cardiomyopathy

No changes in mortality were reported for patients with hypertrophic cardiomyopathy or restrictive cardiomyopathy, nor for retransplant candidates. The disadvantage among blood group O candidates was no longer relevant in era 3.

Implications

Overall, this data indicated a downward trend rather than a sharp change related to any policy changes. In a logistic regression risk prediction model, the odds of mortality were reduced by 3% in era 3 patients vs era 1 patients, at 18% vs 21%, respectively. Therefore, investigators concluded the UNOS revisions did not impact mortality.

“Waitlist mortality should no longer be the sole driver of allocation—incorporating posttransplant outcomes into the allocation system will be another crucial step toward optimizing organ allocation,” wrote investigators.

References

1. Ongoing problems with kids’ heart transplant waitlists found in Stanford Medicine-led studies. Stanford Medicine. March 4, 2026. Accessed March 10, 2026. https://www.eurekalert.org/news-releases/1118781
2. Power A, Sweat KR, Roth A, et al. Contemporary pediatric heart transplant waitlist mortality. Journal of the American College of Cardiology. 2026;84(7). doi:10.1016/j.jacc.2026.01.052