Outcomes of children supported with an intracorporeal continuous-flow left ventricular assist system

Background: Since 2012, there has been growing use of the HeartWare (Medtronic, Mounds View, MN) intracorporeal continuous flow (CF) ventricular assist device (VAD) in children, despite it not being labeled for use in pediatric patients. We sought to describe the use and outcomes of children with HeartWare VADs.

Methods: We identified all patients aged < 19 years and young adults aged 19 to 30 years supported with HeartWare who were entered into the pediatric portion (Pedimacs) of the Interagency Registry for Mechanically Assisted Circulatory Support (Intermacs) and the Intermacs registries, respectively, between September 2012 and June 2017. Adverse events and outcomes were analyzed and compared.

Results: We identified 192 children and 247 young adult HeartWare patients. Baseline characteristics of children differed from young adults, with lower median weight of 51.5 kg (range, 13.1-162) vs 75.8 kg (range, 29.8-191; p ≤ 0.0001) and body surface area of 1.5 m² (range, 0.6-2.9 m²) vs 1.9 m² (range, 1.1-3.2 m²; p ≤ 0.0001) . At the time of implant, 12 children weighed < 20 kg, and 58.3% of these children had congenital heart disease compared with 11.7% in children who weighed ≥ 20 kg and 6.1% in young adults (p ≤ 0.0001). Median duration of support was 2.8 months (IQR, 1.3-6.0 months) in children and 9.7 months (IQR 4.0-19.2 months) in young adults (p ≤ 0.0001). Serious adverse events in children and young adults included infection in 27% and 44% of patients, respectively (p=0.0002), major bleeding in 23% and 23%, respectively (p = 0.9), device malfunction/pump thrombosis in 11% and 19.0%, respectively (p = 0.04), and stroke in 10% and 12%, respectively (p = 0.5). Of the children who weighed < 20 kg at time of implant, 0% had major bleeding, 16.7% had infections, and 8.3% had stroke. Overall survival was not statistically different between children and young adults, and there was no increased mortality in children who weighed < 20 kg. Rate of discharge on HeartWare was 80% in young adults vs 48% in children who weighed ≥ 20 kg and only 33% in children who weighed < 20 kg.

Conclusions: Survival in children supported with HeartWare is encouraging and comparable to young adults; however, adverse events are not uncommon in children. Ongoing evaluation of the HeartWare use in children is necessary to further decrease the rate of adverse events and understand obstacles to discharge.