Impact of Controlled Hypothermic Preservation on Outcomes Following Heart Transplantation

Background Severe primary graft dysfunction (PGD) is a major cause of early mortality after heart transplant. but the impact of donor organ preservation conditions on severity of PGD and survival have not been well characterized. Methods Data from US adult heart-transplant recipients in the GUARDIAN-Heart registry (NCT04141605) were analyzed to quantify PGD severity (stratified by ISHLT definition), mortality, and associated risk factors. The independent contributions of organ-preservation method (traditional ice storage versus controlled hypothermic preservation) and ischemic time were analyzed using propensity matching and logistic regression. Results Among 1,061 US adult heart transplants performed between October 2015 and December 2022, controlled hypothermic preservation was associated with a significant reduction in the incidence of severe PGD compared to ice (6.6% (37/559) versus 10.4% (47/452), p=0.039). Following propensity matching, severe PGD was reduced by 50% (6.0% (17/281) versus 12.1% (34/281) respectively; p=0.018). The Kaplan-Meier terminal probability of 1-year mortality was 4.2% for recipients without PGD, 7.2% for mild or moderate PGD, and 32.1%, for severe PGD (p<0.001). The probability of severe PGD increased for both cohorts with longer ischemic time, but donor hearts stored on ice were more likely to develop severe PGD at all ischemic times compared to controlled hypothermic preservation. Conclusions Severe PGD is the deadliest complication of heart transplantation and is associated with a 7.8-fold increase in probability of 1-year mortality. Controlled hypothermic preservation significantly attenuates the risk of severe PGD and is a simple yet highly effective tool for mitigating post-transplant morbidity.