Out-of-Sequence Donor Heart Allocation: A United Network for Organ Sharing Registry Analysis

Area of Science:

• Organ transplantation
• Transplant allocation systems
• Cardiovascular surgery

Background:

• Out-of-sequence (OOS) allocation offers donor organs outside standard matching for hard-to-match or time-sensitive cases.
• Rising OOS rates are noted in abdominal transplants, but data on heart transplantation practices are limited.

Purpose of the Study:

• To assess temporal trends and practice patterns of OOS allocation in adult heart transplantation.
• To evaluate donor and recipient characteristics and post-transplant survival outcomes for OOS heart allografts.

Main Methods:

• Utilized United Network for Organ Sharing (UNOS) data for adult heart transplant recipients and donors (January 2015-March 2024).
• Classified donations as in-sequence or OOS using the Potential Transplant Recipient file.
• Analyzed temporal trends, practice variations, donor/recipient factors, and survival outcomes.

Main Results:

• 25,608 heart transplants included; 509 (2%) were OOS.
• OOS allocation doubled from 1.4% to 3.1% over the study period.
• OOS use varied significantly by Organ Procurement Organizations (OPOs) and transplant centers; recipients were often older females with type O blood.

Conclusions:

• OOS heart allocation is increasing and shows geographic and OPO-specific variations.
• OOS allocation may improve organ recovery and access for difficult-to-match candidates.
• Standardization of OOS practices is crucial for ensuring equitable access to heart transplantation.