Impact of Mechanical Circulatory Support on Pediatric Heart Transplant Candidates with Elevated Pulmonary Vascular Resistance

Abstract

With the new era of more effective medicines and increasing use of mechanical circulatory support (MCS) in children, seemingly more patients with elevated pulmonary vascular resistance (PVR) are having positive outcomes. The purpose of this study is to define the effect of MCS on pediatric patients listed for heart transplant with an elevated PVR. The United Network for Organ Sharing (UNOS) database was used to identify patients ages 0-18 at time of listing for heart transplant between 2010 and 2019 who had PVR documented. Patients were divided into MCS (LVAD, RVAD, BiVAD, and TAH) and No-MCS groups, then divided by indexed PVR (PVRi) at time of listing: <3, 3-6, and >6 Wood units. Positive waitlist outcome was defined as reaching transplant or delisted because of clinical improvement. Negative waitlist outcome was defined as death or delisted because too sick to transplant. 2081 pediatric patients were listed for heart transplant between 2010 and 2019. MCS was used in 20% overall (n=426); 57% of those with PVRi <3, 27% with PVRi 3-6, and 16% with PVRi >6. Median MCS duration was 68 days (IQR 30-142). In all three PVRi groups, MCS patients had a significantly higher incidence of positive waitlist outcome compared to No-MCS patients (Table 1). Within the No-MCS group, patients with a PVRi >6 had a higher incidence of negative waitlist outcome compared to PVRi <3 (17 vs 10%, p=0.002). This was not true in the MCS group (5 vs 6%, p=0.693). No significant differences in post-transplant survival were found between the subgroups. Patients supported with MCS had a significantly higher chance of a positive waitlist outcome than those without such support regardless of PVR status. With better waitlist survival and equivalent post-transplant survival compared to No-MCS patients, MCS patients had better overall survival from listing regardless of PVR.