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Individualized Antithrombotic Therapy in Heartware HVAD Recipients

Sorensen, Erik N.*; Voorhees, Hannah J.*; Dees, Lynn M.; Pham, Si M.; Kon, Zachary N.; Griffith, Bartley P.; Feller, Erika D.

doi: 10.1097/MAT.0000000000000751
Adult Circulatory Support

There are no evidence-based guidelines for antithrombotic therapy in left ventricular assist device patients. We evaluated the efficacy of a multi-agent, test-guided protocol, which remained consistent throughout our use of the Heartware HVAD. Thrombelastography and platelet function analyzer (PFA)-100 guide antiplatelet titration. Goals are normal kaolin thrombelastography maximum amplitude and prolonged PFA-100. We analyzed incidence and rates of nonprocedural bleeding, stroke, and pump thrombosis for all 81 primary Heartware left ventricular assist devices implanted since 2011. For each event, we examined whether each test was within goal range. We also compared medication burden and dosage between patients with and without events. Pump thrombosis and hemorrhagic stroke each occurred in two patients (2.5%; 0.03 events/patient-year [EPPY]), and ischemic stroke in six (7.4%; 0.10 EPPY). Nonprocedural bleeding occurred 75 times in 34 patients (42%; 1.24 EPPY), primarily gastrointestinal (28%; 0.66 EPPY). Subtherapeutic international normalized ratio (INR) was the most common at thrombotic events; supratherapeutic partial thromboplastin time, international normalized ratio (INR), and PFA-adenosine diphosphate (ADP) were common at bleeding events. Medication burden and dosage were lower in patients with events than in stable patients. Protocol-guided antithrombotic therapy resulted in low rates of pump thrombosis and hemorrhagic stroke. Ischemic stroke and gastrointestinal bleeding rates were higher than in a comparable HVAD population. Optimization of our protocol to decrease its complexity and to reduce bleeding is underway.

From the *Department of Clinical Engineering

Division of Cardiology, Department of Medicine

Division of Cardiac Surgery, Department of Surgery, University of Maryland Medical Center, Baltimore, MD

Cardiothoracic Surgery, Mayo Clinic in Florida, Jacksonville, FL.

Submitted for consideration September 2017; accepted for publication in revised form November 2017.

Disclosure: Sorensen & Kon: consultants for Medtronic; Pham: scientific advisory board for Abiomed.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML and PDF versions of this article on the journal’s Web site (

Correspondence: Erik Sorensen, Department of Clinical Engineering, University of Maryland Medical Center, 22 S. Greene St., Room PTH06, Baltimore, MD 21201. Email:

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