Risk Factors for Thromboembolic Events in Pediatric Patients with Ventricular Assist Devices

Background: Pediatric patients on ventricular assist device (VAD) support are at risk of thromboembolic (TE) complications which include pump thrombosis, ischemic stroke, and transient ischemic attack. Methods: We conducted a retrospective chart review of pediatric patients implanted with Paracorporeal Pulsatile (PP) or Paracorporeal Continuous (PC) VADs between 2005-2022, at the Stollery Children’s Hospital (Edmonton, AB). Patients that transitioned from PC to PP were classified in a combination group. Patient and device related factors, including initial anti-coagulation strategies were collected. Kaplan Meier (KM) survival analysis was performed to determine freedom from TE event based on initial anti-coagulation strategy and VAD type. Univariate and multivariate Cox proportional hazard analysis was conducted to look for factors associated with TE events. Results: Of the 95 patients included, median age was 0.92 years (IQR 0.27, 5.37), median weight at implant was 8.4 kg (IQR 4.4, 18.0). Almost two-thirds (63%) had non congenital disease, with 47% supported on PC devices, 25% on PP devices, and 28% with a combination of devices. Initial anti-coagulation was with either Heparin (61.5%) or Bivalirudin (38.5%). Unadjusted freedom from a TE event was significantly higher in those who received Bivalirudin as their initial anti-coagulation strategy (p=0.022, Figure 1). KM analysis based on device type found that PC VADs predicted shorter freedom from TE events (p=0.012). In multivariate analysis, initial anticoagulation strategy (HR 0.359, 95% CI 0.165–0.785, p=0.01) for Bivalirudin was protective against events, while device type (HR 10.9, 95% CI 2.68–44.2, p<0.001), specifically PC devices, was found to be a predictor of TE events. Conclusions: This study suggests that device type, particularly PC, and heparin as an initial anti-coagulation strategy are risk factors TE events. Further work is needed to understand the interaction between device type and initial anti-coagulation strategy.