Is the practice of using oversized organs for recipients with elevated pulmonary vascular resistance justified?

The purpose of this study was to assess post-transplantation outcomes in recipients with increased pulmonary vascular resistance (PVR) in relation to donor size.

The United Network for Organ Sharing database was used to identify patients ages 0 to 18 years at time of listing who underwent transplantation from 2010 to 2019 and for whom cardiac catheterization and donor-recipient weight ratio data were available. Patients were divided according to listing PVR into <3, 3 to 6, and >6 Wood units. Donor-recipient weight ratio was categorized as undersized (≤0.80), midsize (0.81-1.2), and oversized (>1.2). Subgroup analysis was done with an additional supersized group (>2.0).

Fourteen hundred ninety-one patients met study criteria. Median age was 10 (interquartile range, 3-15) years and 45% were female. Four percent of heart transplantation cases used undersized, 45% used midsize, and 51% used oversized organs. More patients with PVR >6 were received an oversized organ transplant compared with patients with PVR <3; 59% (148/252) versus 48% (430/894); P = .003. There was no difference in survival among organ size groups regardless of PVR; this includes patients with PVR >6 at listing who received an oversized organ transplant versus an undersized (P = .359) or midsized (P = .956) organ. In subgroup analysis, even in patients who received a supersized organ transplant, there was no survival difference noted regardless of PVR.

Despite a persistent practice pattern to transplant oversized organs in high-PVR patients, there remains no difference in post-transplantation survival among these patients and those who received smaller organ transplants. Therefore, transplants in patients with high PVR should not be delayed by waiting for larger donors.