Donor heart ischemic time can be extended to 8 hours using hypothermic machine perfusion in sheep.

Overall, compared to current clinical SCS, recipient outcomes following transplantation are not adversely impacted by extending HMP to 8 hours. These results have important implications for clinical transplantation where longer ischemic times may be required (e.g., complex surgical cases, transport across long distances). Additionally, HMP may allow safe preservation of 'marginal' donor hearts that are more susceptible to myocardial injury and facilitate increased utilisation of these hearts for transplantation.