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Effect of ischemic time on pediatric heart transplantation outcomes: is it the same for all allografts?
Alia Dani1, Quyen Vu1, Karthik Thangappan1
1Department of Cardiothoracic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
Insights
Pediatric heart transplant recipients with donor hearts having LVEF ≥ 65% can tolerate ischemia time up to 6 hours. This finding may help reduce waiting times and improve donor heart availability.
Area of Science:
- Cardiology
- Transplantation Medicine
- Pediatric Surgery
Background:
- Pediatric heart transplantation (PHT) outcomes are influenced by ischemia time (IT).
- Previous studies suggest an optimal IT threshold of up to 4 hours, irrespective of donor factors.
- The impact of donor left ventricular ejection fraction (LVEF) on IT tolerance in PHT is not fully understood.
Purpose of the Study:
- To investigate the relationship between ischemia time (IT) and donor left ventricular ejection fraction (LVEF).
- To evaluate the combined impact of IT and LVEF on pediatric heart transplantation (PHT) outcomes.
Main Methods:
- Retrospective cohort study of pediatric heart transplant recipients (<18 years) from UNOS (2000-2020).
- Survival analysis using Kaplan-Meier curves for donor hearts with varying IT (<4, 4-6, >6 hours).
- Cox regression analysis adjusted for donor and recipient variables.
Main Results:
- Overall, IT > 6 hours was linked to worse survival compared to IT < 4 hours, regardless of LVEF.
- For allografts with LVEF < 65%, IT of 4-6 hours was associated with worse survival than IT < 4 hours.
- For allografts with LVEF ≥ 65%, IT of 4-6 hours showed similar survival to IT < 4 hours and improved survival compared to IT > 6 hours.
Conclusions:
- The 4-hour IT threshold is not universally applicable in pediatric heart transplantation.
- Donor hearts with LVEF ≥ 65% can tolerate IT up to 6 hours without negatively impacting survival.
- Accepting these donor hearts could reduce waiting times and address donor organ scarcity.
Background:
Studies have shown that the optimal ischemia time (IT) threshold in pediatric heart transplantation (PHT) is up to 4 h, independent of other donor organ factors. The purpose of this study was to examine the relationship between IT and donor left ventricular ejection fraction (LVEF) and study their impact on PHT outcomes.
Methods:
This is a retrospective cohort study of PHT (<18 years) identified in UNOS between January 2000 and March 2020. Post-transplantation survival analysis of patients receiving donor hearts with IT<4, 4-6, and >6 h was performed using Kaplan-Meier curves. Cohort was divided according to donor LVEF median value, and survival was analyzed. Cox regression was performed.
Results:
Median LVEF was 65% in the study cohort (6669 PHT). Overall, IT>6 h was associated with worse survival compared to <4 h regardless of donor LVEF. For allografts with LVEF < 65%, IT = 4-6 h was associated with worse survival compared with IT < 4 h (p = .006) but had similar survival compared with IT > 6 h (p = .315). For allografts with LVEF ≥ 65%, IT = 4-6 h had similar survival compared with <4 h (p = .175) but improved survival compared with >6 h (p = .003). After adjusting for donor and recipient variables, Cox regression showed that IT = 4-6 h was not associated with increased mortality for LVEF ≥ 65%.
Conclusions:
The IT threshold of 4 h does not apply to all allografts. Recipients of hearts with LVEF≥65% can tolerate an IT up to 6 h without any detriment to survival. Routine acceptance of these donor hearts could mitigate longer waiting times and poor donor availability for many candidates.
