Developing an Anti-Xa-Based Anticoagulation Protocol for Patients with Percutaneous Ventricular Assist Devices

Abstract

Because of the complexities associated with anticoagulation in temporary percutaneous ventricular assist device (pVAD) recipients, a lack of standardization exists in their management. This retrospective analysis evaluates current anticoagulation practices at a single center with the aim of identifying an optimal anticoagulation strategy and protocol. Patients were divided into two cohorts based on pVAD implanted (CentriMag (Thoratec; Pleasanton, CA) / TandemHeart (CardiacAssist; Pittsburgh, PA) or Impella (Abiomed, Danvers, MA)), with each group individually analyzed for bleeding and thrombotic complications. Patients in the CentriMag/TandemHeart cohort were subdivided based on the anticoagulation monitoring strategy (activated partial thromboplastin time (aPTT) or antifactor Xa unfractionated heparin (anti-Xa) values). In the CentriMag/TandemHeart cohort, there were five patients with anticoagulation titrated based on anti-Xa values; one patient developed a device thrombosis and a major bleed, whereas another patient experienced major bleeding. Eight patients received an Impella pVAD. Seven total major bleeds in three patients and no thrombotic events were detected. Based on distinct differences between the devices, anti-Xa values, and outcomes, two protocols were created to guide anticoagulation adjustments. However, anticoagulation in patients who require pVAD support is complex with constantly evolving anticoagulation goals. The ideal level of anticoagulation should be individually determined using several coagulation laboratory parameters in concert with hemodynamic changes in the patient's clinical status, the device, and the device cannulation.

Hemostatic complications associated with ventricular assist devices

“…However, this test can be affected by warfarin, high factor VIII due to underlying inflammation, and hemolysis. Recent studies have shown that the APTT underestimates heparin requirements for VAD patients when compared to heparin levels measured by anti‐Xa activity . One of the factors responsible for this discrepancy is residual warfarin effect.…”

“…Recent studies have shown that the APTT underestimates heparin requirements for VAD patients when compared to heparin levels measured by anti-Xa activity. 90 One of the factors responsible for this discrepancy is residual warfarin effect. It has been shown that for every 1.0unit rise in INR >1, the APTT increases by 16 seconds, which can lead to falsely high APTTs.…”

Pharmacologic Considerations in the Management of Patients Receiving Left Ventricular Percutaneous Mechanical Circulatory Support

“…Thus anti‐Xa concentrations were proposed as an alternative method for monitoring anticoagulation because better correlations with heparin activity are often observed . The reported reference range for anti‐Xa is 0.3–0.7 units/ml, but alternative goal ranges were previously described during pVAD use (0.15–0.30 units/ml for Impella and 0.2–0.4 units/ml for TandemHeart) …”

“…A retrospective review described the outcomes of an anti-factor Xa (anti-Xa)-based anticoagulation strategy in CentriMag (Thoratec, Pleasanton, CA)/TandemHeart and Impella cohorts. 30 In contrast with the preceding studies, which used only aPTT guidance, this study evaluated anticoagulation practices with both aPTT and anti-Xa concentrations. At the time of the study, the anti-Xa goal range was 0.2-0.4 units/ml, which correlated to an aPTT range of 55-75 seconds.…”

“…40,42,43 The reported reference range for anti-Xa is 0.3-0.7 units/ml, but alternative goal ranges were previously described during pVAD use (0.15-0.30 units/ml for Impella and 0.2-0.4 units/ml for Tan-demHeart). 30,44 Regardless of the institution-specific monitoring strategy, anticoagulation parameters should be monitored frequently to mitigate risks of thrombosis and bleeding. Subtherapeutic or supratherapeutic values should prompt adjustment of systemic anticoagulation and/or heparinized purge solution concentrations.…”