Size Does Not Matter: The Outdated Practice of Using Oversized Organs for Recipients with Elevated PVR

Abstract

Elevated pulmonary vascular resistance (PVR) continues to pose challenges in heart transplantation, but does the common belief that implanting a larger organ when the PVR is high actually affect outcomes? The purpose of this study is to assess post-transplantation outcomes in recipients with increased PVR in relation to donor organ size. The United Network for Organ Sharing (UNOS) database was used to identify patients ages 0-18 years at time of listing who underwent transplantation between 2010 and 2019 and for whom cardiac catheterization and donor-recipient weight data was available. Patients were divided by listing PVR into <3, 3-6, and >6 Wood units. Donor-Recipient weight ratio was categorized as undersized (≤0.80), mid-size (0.81-1.2), and oversized (>1.2). Subgroup analysis was done with an additional supersized group (>2.0). 1491 patients met study criteria. Median age [years (IQR)] 10 (3-15) and 45% female. 4% of heart transplantation cases used undersized, 45% used mid-size, and 51% used oversized organs. More patients with PVR>6 were transplanted with an oversized organ compared to patients with PVR<3 [59% (148/252) vs 48% (430/894), p=0.003). There was no difference in survival between the organ size groups regardless of PVR; this includes patients with PVR>6 at listing who were transplanted with an oversized organ versus those transplanted with an undersized (p=0.359) or mid-sized (p=0.956) organ. In subgroup analysis, even in patients transplanted with a supersized organ, there was no survival difference noted regardless of PVR. Despite a persistent practice pattern to transplant high PVR patients with oversized organs, there remains no difference in post-transplantation survival between these patients and those transplanted with smaller organs. Therefore, transplants in patients with high PVR should not be delayed by waiting for larger organs.