Close to 70% of hearts consented for donation in the US are never transplanted. A portable perfusion technology now under FDA review could significantly reduce that.
A study of the OCS™ Heart perfusion system to resuscitate, preserve, and assess donor hearts that would not otherwise meet criteria for transplantation resulted in utilization of 81% of the original donor organs. The findings, from the Heart EXPAND study, were presented early in April 2019 at the 39th Scientific Sessions of The International Society for Heart & Lung Transplantation (ISHLT) in Orlando, Florida and published in theJournal of Heart and Lung Transplant.
Approximately 70% of hearts consented for donation in the US are never transplanted. The primary reason is prolonged ischemic time. The current standard of practice in the US limits the interval between harvesting and implantation to no more than 4 hours. Organ rejection is more likely for hearts kept on ice for longer periods before being reperfused.
“The Heart EXPAND study showed that using the OCS perfusion system is safe, effective--and can significantly expand our current donor pool of hearts for transplantation,” first author Jacob Schroder MD, Duke University Medical Center (Durham, North Carolina), said in a press release.
According to information from manufacturer TransMedics, Inc, the Organ Care System (OCS) Heart portable technology reproduces near-physiologic conditions for donor hearts once harvested, addressing current limitations of cold storage. The simulated stable environment could greatly expand the distance hearts for transplant can travel, in addition to reducing the possibility of lost viability.
Heart EXPAND was a prospective, multicenter trial conducted at 12 transplant centers in the US. The single arm study included 93 donor hearts that would not ordinarily meet standard criteria for transplant: ischemic time >4 hrs (37%); age >55 years (13%); down time up to 20 minutes (28%); left ventricular hypertrophy (LVH, 23%), ejection fraction 40-50% (23%). Thirty-three percent of these hearts met multiple inclusion criteria.
Hearts were eligible for transplant if they had final OCS™ Heart arterial lactate <5 mmol/L and stable OCS™ perfusion parameters within recommended ranges.
Use of OCS™ Heart enabled utilization of 81% of donor hearts in this study, with a mean OCS™ perfusion time of 6.35 hours.
Eighty-eight percent of transplant recipients achieved the primary effectiveness endpoint, a composite of patient survival at 30 days and no severe primary graft dysfunction (PGD) in the first 24 hours after transplant. Nearly all recipients (94.7%) survived at least 30 days after transplant, compared to a US national average of 96.3%. Incidence of severe PGD at 24 hours was 10.7%. 30-day and 6-month survival were 94.7% and 88% respectively.
“The use of OCS™ Heart System resulted in high utilization of ECD [extended criteria donor] hearts with excellent short-term post-transplant outcomes, most notably a low rate of PGD. These results provide clinical evidence supporting its use in ECD heart preservation and assessment, and may significantly increase donor utilization for transplantation,” the authors concluded.
OCS™ Heart is made by TransMedics Inc, (Andover, Massachusetts), and is currently under review by the FDA. TransMedics Inc. has also developed the OCS™ Lung System, which is already FDA approved. Both systems are already used in Europe, Australia, and Canada.
Shroder JN, D’Alessandro D, Esmailian F, et al. Successful utilization of extended criteria donor (ECD) hearts for transplantation-results of the OCS™ Heart EXPAND Trial to evaluate the effectiveness and safety of the OCS Heart System to preserve and assess ECD hearts for transplantation. J Heart Lung Transplant. 2019;38:S42.