The effect of warm ischemic intervals on primary graft dysfunction in normothermic regional perfusion for donation after circulatory death heart transplant.

Objectives: To clarify the association between warm ischemic time during donation after circulatory death (DCD) and severe primary graft dysfunction (PGD) after heart transplant.

Methods: DCD heart transplants using normothermic regional perfusion, excluding congenital etiology or multiorgan transplant, at a single institution from January 2020 to December 2024 were reviewed. Donation withdrawal ischemic time (DWIT), functional warm ischemic time, defined by oxygen saturation <80% (FWIT O), systolic blood pressure <80 mm Hg or <50 mm Hg, and asystolic warm ischemic time were examined. Propensity matching created balanced cohorts to associate warm ischemia and outcomes. Outcomes included incidence of severe PGD, lengths of stay, and mortality.

Results: The final study cohort had 135 patients, of whom 10 of 135 (7.4%) had severe PGD. When stratified by severe PGD, donor and recipient demographics were similar. DWIT (median 25.0 minutes vs 35.5 minutes, P = .031) and FWIT O (median 22.0 vs 33.0 minutes, P = .025) were lower in those without severe PGD. Logistic regression identified FWIT O as a better predictor compared with DWIT. Receiver operating characteristic curve analysis identified a FWIT threshold of 23 minutes (area under the curve, 0.714). After matching, rates of severe PGD were significantly greater in the FWIT O >23 minutes group (8/59 [13.6%] vs 1/59 [1.7%], P = .032). However, the FWIT O >23 minutes group had similar lengths of stay and mortality.

Conclusions: In DCD normothermic regional perfusion heart transplant, >23 minutes of FWIT O is associated with increased rates of severe PGD. However, increased FWIT O was not associated with other outcomes, including mortality. Rejection of allografts on the basis of prolonged warm ischemia may lead to unnecessary discard of viable hearts.