Impact of Initial Heparin Rates on Reaching Goal Anti-Xa and Activated Partial Thromboplastin Time Within 48 Hours of Initiation in Patients With Mechanical Circulatory Support

<b>Background:</b> Patients receiving mechanical circulatory support (MCS) devices should receive anticoagulation to avoid clotting of the circuit and to lower risk of acute thrombosis. Patients at our institution are initiated on UFH at 12 units/kg/h; however, patients weighing > 83 kg are weight-capped (WC) at an initial rate of 1000 units/h, which equates to < 12 units/kg/h. <b>Objective:</b> The objective of this study was to compare time to goal anticoagulation in patients receiving MCS who were WC compared to those who were not. <b>Methods:</b> A retrospective cohort study was completed of patients who received UFH during admission for an MCS device and monitored by activated partial thromboplastin time (aPTT) or anti-Xa levels. The primary outcome was the percentage of patients between groups who achieved goal anti-Xa or aPTT within 48 h of UFH initiation. <b>Results:</b> A total of 56 patients were included, with 27 not weight-capped (NWC) and 29 WC. There was no significant difference between groups in percentage of patients who achieved goal anti-Xa or aPTT within 48 h (88.9% NWC vs 89.7% WC, <i>P</i> = 0.93). There was no significant difference in time to goal between groups. The NWC group had more bleeding events (4 vs 0, <i>P</i> = 0.031), with no difference in thrombosis. <b>Conclusion:</b> There was no difference in the percentage of patients reaching goal aPTT or anti-Xa within 48 h when UFH was WC. However, future studies should compare differences in time to goal anticoagulation between different UFH intensity protocols.