What are the outcomes associated with the use of a ventricular assist device as a bridge to heart transplantation in pediatric patients?
A multicenter prospective trial of a ventricular assist device designed specifically for children was performed. All patients were 16 years of age or younger. The study group was divided into two cohorts based on body surface area (BSA). Cohort 1 included patients with BSA <0.7 m2
, whereas cohort 2 included patients with BSA 0.7-1.5 m2
. All patients had two-ventricular circulation and were listed for cardiac transplantation. Survival of patients receiving assist devices was compared with survival in propensity-score-matched historical controls undergoing extracorporeal membrane oxygenation (ECMO). The primary endpoint for patients undergoing mechanical circulatory support was time to death or weaning from the device with an unacceptable neurologic outcome, whereas the primary endpoint for patients on ECMO was time to death.
A total of 48 patients were enrolled, with 24 in each cohort. For patients in cohort 1, the median survival time had not been reached at 174 days, whereas in the matched ECMO group, the median survival was 13 days (p = 0.001). For patients in cohort 2, the median survival was 144 days, as compared with 10 days in the matched ECMO group (p < 0.001). Successful outcome (alive and remaining on support, having undergone transplantation, or weaned from support with acceptable neurologic outcome) at 30 days occurred in 96% of patients in cohort 1, as compared with 75% of the ECMO-matched group (p = 0.048). Ninety-six percent of patients in cohort 2 had successful outcomes, as compared with 67% of patients in the ECMO-matched group (p = 0.007). In terms of outcomes at the end of circulatory support, successful outcomes occurred in 88% in cohort 1 of the assist device, as compared with 75% in the ECMO-matched group (p = 0.059). For cohort 2 of the assist device group, successful outcomes occurred in 92% of patients, as compared with 67% in the ECMO-matched group (p = 0.021). Serious adverse events included bleeding complications in 46%, infection in 56%, and stroke in 29% of all patients receiving assist devices.
Survival rates with assist devices were higher than historical ECMO controls. Serious adverse events, including infection, stroke, and bleeding, were common and occurred in a majority of study participants.
This study is the first to prospectively assess outcomes of pediatric patients with ventricular assist devices in a good-sized patient population. The lack of randomization and use of historical ECMO controls somewhat limits the ability to make comparisons between the two groups, although this was mitigated by propensity matching of the ECMO controls. The study is important in that it is a well-designed multicenter study, which could not be successfully performed at a single center. It also provides important descriptional data to understand outcomes of pediatric patients undergoing mechanical circulatory support with assist devices. Although the survival data are encouraging, serious complications including bleeding, infection, and stroke remain extremely common. Continued device development and study will be required to optimize outcomes for children with assist devices in the future.
Timothy B. Cotts, M.D., F.A.C.C. (Disclosure)
Cardiovascular Surgery, Congenital Heart Disease, Cardiac Rhythm Management