Alternative Preservation Strategies of Donation After Circulatory Death Hearts: Effect of Cold Ischemia Time Before Normothermic Machine Perfusion

BACKGROUND: Donation after circulatory death (DCD) offers a promising strategy to expand the donor pool by 20% to 30%. However, DCD heart grafts experience warm ischemia injury, making effective graft viability assessment before transplantation prudent. Current methods for assessing DCD hearts are impacted by either ethical concerns and regional limitations (thoracoabdominal normothermic regional perfusion) or the need for significant resources, expertise, and equipment, with limitations in functional assessment (direct procurement and reperfusion, via the Organ Care System by TransMedics). This study explores an alternative preservation approach using controlled hypothermia followed by normothermic machine perfusion for graft evaluation. METHODS: DCD grafts were procured from porcine donors after 19 minutes of functional warm ischemia. Hearts were preserved using controlled hypothermic static storage at 4 °C to 8 °C for up to 7 hours, followed by reanimation with normothermic machine perfusion. Graft viability was evaluated using a novel ex vivo cardiac loading method. Outcomes were compared with DCD grafts reperfused immediately after procurement. RESULTS: No significant functional, biochemical, or proteomic differences were observed between DCD cardiac grafts preserved via controlled hypothermia for up to 7 hours and those reperfused immediately after procurement. CONCLUSIONS: Controlled hypothermia may be a viable alternative to current DCD preservation methods, eliminating ethical concerns of thoracoabdominal normothermic regional perfusion and reducing logistical complexity and costs associated with direct procurement and reperfusion. These findings provide a foundation for a potential shift in DCD heart preservation practices, offering a more effective and cost-efficient approach to expand the donor pool and improve transplantation outcomes.