Management of antithrombotic therapy (ATT) for pediatric ventricular assist devices is challenging, and the Berlin EXCOR remains the only Food and Drug Administration (FDA)-approved option. Among those on the EXCOR, 28% have neurologic complications and major bleeding occurs in 50%. The Edmonton Protocol was developed to guide ATT, but the adverse event rate remains high, leading most centers to make modifications. The objective of this study is to characterize antithrombotic practice variation among North American pediatric ventricular assist device programs, in order to guide future research. In this descriptive cross-sectional study, a survey assessing antithrombotic (AT) practices was distributed by Berlin Heart Inc. to centers that implanted ≥1 EXCOR between January 2012 and January 2016. Practices were compared at high- versus low-volume centers. High volume was defined as ≥14 implants in this period. Seventeen of 38 centers (44.7%) participated; 4 were high volume. At half of all centers (9/17), ≤2 clinicians managed all AT decisions. Although 47.1% (8/17) followed the protocol "extremely/very closely," only 5.9% (1/17) felt it to be "very effective." Most centers (10/15; 66.7%) deviated in ≥2 protocol aspects. Over half modified either recommended antiplatelet agents (5/15) or anticoagulants (4/15). Adjunct medication use was highly variable. Most (11/17; 64.7%) deviated from protocol in either timing or type of AT lab monitoring. Despite widespread use of Thromboelastography (TEG)/Platelet Mapping (PM), concerns of inaccuracy were common. Most high-volume centers (3/4; 75%) abandoned TEG/PM as a primary tool. These practice variation analyses have identified areas in ATT that are amenable to care standardization and further research. Systematic study of optimal AT medication dosing and monitoring is needed.