Pondering Higher-Risk Pediatric Heart Donors: Can We Use More?

A comprehensive, multifaceted strategy to increase pediatric donor heart utilization

BACKGROUND

In 2016, we initiated a quality improvement endeavor to increase pediatric heart offer acceptance. This study assessed the effect of these interventions at our center.

METHODS

We evaluted pre- and postimplementation cohorts (January 1, 2008-December 31, 2016 vs January 1, 2017-July 1, 2023) comparing donor heart utilization. Six interventions were iterated over time to increase offer acceptance ("extended criteria"): ABO-incompatible transplant, ex vivo perfusion for distanced donors, 3-dimensional total cardiac volume (TCV) assessment, acceptance of hepatitis-C or Severe Acute Respiratory Syndrome Coronavirus 2 infected donors, and institutional culture change favoring consideration of donors previously considered unacceptable. Outcomes studied included annual HT volume, median waitlist duration, sequence number at acceptance, and post-transplant clinical outcomes.

RESULTS

During the study period, annual transplant volume increased from 16/year to 25/year pre- and postimplementation. Three hundred thirteen of 389 (80%) listed patients were transplanted. Waitlist duration shortened postimplementation (p = 0.01), as did the percentage of accepted heart offers utilizing at least 1 extended criterion (p < 0.001). Institutional culture change and TCV assessment had the largest impact on donor heart utilization (p = 0.04 and p < 0.001). There was no difference in post-HT intubation or intensive care unit days (p = 0.05-0.9), though post-transplant hospitalization duration (p < 0.001) increased. Post-transplant survival was unaffected by the use of extended criteria hearts (p = 0.3).

CONCLUSIONS

We report a successful longitudinal, multifaceted effort to increase organ offer utilization, with institutional culture change and TCV assessments most impactful. The use of extended criteria hearts was not associated with inferior survival.

Elective and non-elective endomyocardial biopsy in heart transplant patients and procedural outcomes: An IMPACT registry analysis

BACKGROUND

Endomyocardial biopsies are standard of care for transplant surveillance, however the procedural risks are not well established, especially in children. The purpose of the study was therefore to assess procedural risks and outcomes associated with elective (surveillance) biopsies and non-elective (clinically indicated) biopsies.

METHODS

We used the NCDR IMPACT registry database for this retrospective analysis. Patients undergoing an endomyocardial biopsy were identified using the procedural code, with a diagnosis of heart transplantation required. Data regarding indication, hemodynamics, adverse events and outcomes was gathered and analyzed.

RESULTS

A total of 32 547 endomyocardial biopsies were performed between 2012-2020; 31 298 (96.5%) elective and 1133 (3.5%) were non-elective biopsies. Non-elective biopsy was more commonly performed in infants and in those above 18 years of age, in female and in Black race patients and in those with non-private insurance (all p < .05) and showed hemodynamic derangements. Overall rate of complications was low. Combined major adverse events were more common in non-elective patients, with sicker patient profile, use of general anesthesia and femoral access with overall decline in these events over time.

CONCLUSIONS

This large-scale analysis shows safety of surveillance biopsies and that non-elective biopsies carry a small but significant risk of major adverse event. Patient profile impacts the safety of the procedure. These data may serve as important comparison point for newer non-invasive tests and for bench marking, especially in children.

Partial heart transplantation can ameliorate donor organ utilization

BACKGROUND

The treatment of babies with unrepairable heart valve dysfunction remains an unsolved problem because there are no growing heart valve implants. However, orthotopic heart transplants are known to grow with recipients.

AIM

Partial heart transplantation is a new approach to delivering growing heart valve implants, which involves transplantation of the part of the heart containing the valves only. In this review, we discuss the benefits of this procedure in children with unrepairable valve dysfunction.

CONCLUSION

Partial heart transplantation can be performed using donor hearts with poor ventricular function and slow progression to donation after cardiac death. This should ameliorate donor heart utilization and avoid both primary orthotopic heart transplantation in children with unrepairable heart valve dysfunction and progression of these children to end-stage heart failure.

External validation and comparison of risk score models in pediatric heart transplants

BACKGROUND

Pediatric heart transplant (PHT) patients have the highest waitlist mortality of solid organ transplants, yet more than 40% of viable hearts are unutilized. A tool for risk prediction could impact these outcomes. This study aimed to compare and validate the PHT risk score models (RSMs) in the literature.

METHODS

The literature was reviewed to identify RSMs published. The United Network for Organ Sharing (UNOS) registry was used to validate the published models identified in a pediatric cohort (<18 years) transplanted between 2017 and 2019 and compared against the Scientific Registry of Transplant Recipients (SRTR) 2021 model. Primary outcome was post-transplant 1-year mortality. Odds ratios were obtained to evaluate the association between risk score groups and 1-year mortality. Area under the curve (AUC) was used to compare the RSM scores on their goodness-of-fit, using Delong's test.

RESULTS

Six recipient and one donor RSMs published between 2008 and 2021 were included in the analysis. The validation cohort included 1,003 PHT. Low-risk groups had a significantly better survival than high-risk groups as predicted by Choudhry (OR = 4.59, 95% CI [2.36-8.93]) and Fraser III (3.17 [1.43-7.05]) models. Choudhry's and SRTR models achieved the best overall performance (AUC = 0.69 and 0.68, respectively). When adjusted for CHD and ventricular assist device support, all models reported better predictability [AUC > 0.6]. Choudhry (AUC = 0.69) and SRTR (AUC = 0.71) remained the best predicting RSMs even after adjustment.

CONCLUSION

Although the RSMs by SRTR and Choudhry provided the best prediction for 1-year mortality, none demonstrated a strong (AUC ≥ 0.8) concordance statistic. All published studies lacked advanced analytical approaches and were derived from an inherently limited dataset.

Outcomes From Three Decades of Infant and Pediatric Heart Transplantation

Infants are a unique transplant population due to a suspected immunologic advantage, in addition to differences in size and physiology. Consequently, we expect infants to have significantly different diagnoses, comorbidities, and outcomes than pediatric transplant recipients. In this study, we compare patterns and trends in pediatric and infant heart transplantation during three decades. The United Network for Organ Sharing (UNOS) database was queried for transplants occurring between January 1990 and December 2018. Patients were categorized as pediatric (1-17) or infant (0-1). Congenital heart disease (CHD) primary diagnoses have increased from 37% to 42% in pediatric patients (p = 0.001) and decreased from 80% to 61% in infants during the 1990s and 2010s (p < 0.001). Those with CHD had worse outcomes in both age groups (p < 0.001). Infants who underwent ABO-incompatible transplants had similar survival as compared to those with compatible transplants (p = 0.18). Overall, infants had better long-term survival and long-term graft survival than pediatric patients; however, they had worse short-term survival (p < 0.001). Death due to rejection or graft failure was less likely in infants (p = 0.034). However, death from infection was over twice as common (p < 0.001). In summary, pediatric and infant heart transplant recipients differ in diagnoses, comorbidities, and outcomes, necessitating different care for these populations.

Heart Transplantation of a Preterm Infant With HLHS

A 33-week gestation, 1.75-kg female infant with mitral stenosis/aortic atresia variant of hypoplastic left heart syndrome and severe ventriculo-coronary connections underwent surgical septectomy and bilateral pulmonary artery banding at five weeks of age (2.10 kg). After separation from bypass, she developed hemodynamic instability requiring venoarterial extracorporeal membrane oxygenation support. She was listed for heart transplantation and transplanted after three days of support with an oversized heart (4.7:1 donor-recipient weight ratio).