Prognostic implications of the updated ISHLT definition for severe graft dysfunction: An analysis from the International PGD Consortium and UNOS Databases.

The proposed 2024 ISHLT consensus definition for severe graft dysfunction after heart transplant (HT) expands the 2014 criteria by including de novo intra-aortic balloon pump (IABP) support as diagnostic for severe dysfunction. We evaluated the prognostic implications of this reclassification using data from the International Consortium on PGD (herein 'Consortium') and United Network for Organ Sharing (UNOS) registries. Heart Transplant (HT) recipients were categorized into the following groups (1) meeting 2014 severe PGD criteria, (2) reclassified as severe early graft dysfunction (EGD) by the 2024 criteria based on a newly placed IABP within 24 h of HT, or (3) not meeting severe PGD criteria. KM survival curves and log-rank tests were used to compare unadjusted survival. A multivariable Cox regression model was used to determine the association of group status on 1 year mortality. A total of 7239 HT recipients with relevant data were included in this analysis: 4087 in the Consortium and 3152 from UNOS. In the Consortium cohort, 361 (8.8%), 116 (2.8%), and 3610 (88.3%) patients comprised Groups 1, 2 and 3, respectively. Group 1 had more pre-transplant temporary and durable mechanical circulatory support, along with longer ischemic times. At 1 year post-HT, mortality in patients with de novo IABP (12.1% in Consortium, 9.6% in UNOS) was significantly lower than in patients with 2014 severe PGD (36.3% in Consortium, 27.2% in UNOS), and more closely resembled those without severe PGD (7.4% in Consortium, 5.6% in UNOS) [Log-rank p < 0.001 in both groups]. After adjustment for potential confounders, both reclassified patients with a de novo IABP [Group 2: HR 0.30 (0.17-0.51)] and patients without severe PGD [Group 3: HR 0.17 (0.14-0.22)] had significantly reduced risk of 1 year mortality compared to those with 2014 severe PGD (P<0.001) in the Consortium. These findings were replicated in the UNOS population. In this analysis of two contemporary, multicentre databases, patients who received an isolated de novo IABP within the first 24 h postoperatively had significantly better survival than those who were dependent on extra-corporeal membrane oxygenation (ECMO) or ventricular assist devices after HT. Combining these disparate patient groups in the new severe PGD definition may obscure prognostic differences and diminish recognition of the most severe PGD phenotype.