Title : A decade of DCD heart transplantation utilising normothermic machine perfusion in Australia
Abstract:
The use of donation after circulatory death (DCD) donors for heart transplantation represents a relatively new entry into efforts made to help expand the donor pool. The use of Normothermic Machine Perfusion (NMP) through the Transmedics Organ Care System Heart (OCS Heart) allows for DCD hearts to be assessed for viability prior to transplantation. Our unit was the first to use NMP following procurement of a DCD heart by a direct procurement protocol (DPP) in 2014. In this abstract we describe our experience with DCD heart transplantation over the last decade.
All DCD heart transplants that have occurred in our institution since 2014 have been included in this study. Donors met inclusion criteria if they were <55yrs of age with a normal transthoracic echocardiogram and no significant prior cardiac history. Antemortem heparin was given to the donor at the discretion of the donor hospital and local policy. We use the Sydney DPP which has been previously described (Joshi et al. Transplantation. 2022).
Once the donor heart is procured, and mounted onto the OCS heart, it is reperfused in a Langendorff fashion and assessed for viability. The donor heart is deemed viable if during the period of NMP point of care sampling reveals a down-trending and extracting (venous lactate < arterial lactate) lactate profile. The right ventricle is also visually assessed for contractility. If the donor heart is deemed viable (typically following 90-120mins of NMP) transplantation can then proceed. February 2020 represents the last major change to our retrieval protocol and serves as a cut-off point when comparing eras of DCD heart transplantation (referred to as pre and post-Feb 2020).
Since 2014, of the 148 DCD donors that have progressed to circulatory arrest with subsequent mounting of the donor heart on the OCS, 116 were ultimately transplanted (78% overall transplant rate). There has been a significant increase in the transplantation rates of DCD donor hearts following reperfusion on the OCS post Feb-2020 when compared to pre-Feb 2020 (85% vs 68% respectively, p=0.04). Overall, 32/148 hearts were declined, 17 of which were declined due to poor recovery on the OCS. There is no significant difference in short or long term survival between recipients of DCD and BD heart transplants in our institution during this time period (5yr survival: 81% vs 78%; 10yr survival: 69% vs 64% respectively, p=0.6). There was no significant difference in the incidence of ISHLT (International Society of Heart and Lung Transplantation) grade severe primary graft dysfunction (sPGD) over the last decade when comparing recipients of DCD vs BD donors (14% vs 18% respectively, p=0.2). In comparing eras of DCD heart transplantation, there was a significantly reduced incidence of sPGD in DCD heart transplants performed post-Feb 2020 compared to pre-Feb 2020 (24% vs 6% respectively, p=0.007). An asystolic warm ischaemic time of >15mins remains significantly associated with an increased risk of sPGD in DCD heart transplantation (p=0.0048). Over the last 10yrs, DCD heart transplantation has accounted for 30% of all
heart transplant activity.
