Pharmacist-Managed International Normalized Ratio Patient Self-Testing Is Associated with Increased Time in Therapeutic Range in Patients with Left Ventricular Assist Devices at an Academic Medical Center
ABSTRACT Patients with left ventricular assist devices (LVADs) are at increased risk of bleeding and thrombotic complications making warfarin therapy particularly challenging. Patient self-testing (PST) using point-of-care international normalized ratio (INR) devices has shown favorable outcomes in other populations, but the use of PST in LVAD patients has not been well described. The purpose of this study was to evaluate the effectiveness of pharmacist-managed INR PST versus usual care (UC) in patients with LVADs at a single center. We performed a retrospective cohort study of adult patients (in a 1:4 ratio PST versus UC) implanted with an LVAD (HeartMate II or HVAD) treated with warfarin from January 1, 2007, to January 31, 2013. We reviewed all INRs and bleeding/thrombotic events in LVAD patients whose anticoagulation was managed by clinical pharmacists via INR PST versus UC and calculated a percent time in therapeutic range (%TTR) by Rosendaal method. Fifty-five patients were studied. Demographic data were generally similar between the cohorts. Mean %TTR was higher in the PST cohort versus UC (44.4% vs. 30.6%, p = 0.026). There was no difference in the rate per patient-year of bleeding (0.23 vs. 0.33, p = 0.55) or thrombotic events (0.12 vs. 0.13, p = 0.88). Pharmacist-managed INR PST is associated with an increased %TTR in patients with LVADs.
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ABSTRACT: Left ventricular assist devices (LVADs) have increased the survival of patients with advanced heart failure fourfold. Despite these advances, significant bleeding and thrombotic complications occur. Hemorrhage requiring surgery has been reported in up to 30 % of adults and 50 % of children after LVAD placement. LVAD thrombosis and embolic stroke lead to significant long-term morbidity. Adults are treated with antithrombotic therapy to prevent thrombotic complications, but the amount and intensity of treatment differs between institutions. The goal international normalized ratio for warfarin therapy varies from 1.5 to 3.0. Some physicians manage adult LVAD patients without antiplatelet medication, whereas other adults are treated with aspirin as a single agent or combined with dipyridamole. In contrast, physicians typically manage children with LVADs using the Edmonton Anticoagulation and Platelet Inhibition Protocol, a detailed algorithm for anticoagulation and antiplatelet treatment modified based on thromboelastography results. LVAD implantation causes consumption of coagulation proteins, activation of fibrinolysis, and loss of high molecular weight von Willebrand protein multimers. How these changes in the coagulation system influence the risk of hemorrhage and initiation of thrombosis is unknown. Prospective, controlled studies are needed to determine the antithrombotic regimen that most effectively balances bleeding and thrombosis in LVAD patients.Journal of Thrombosis and Thrombolysis 12/2014; 39(3). DOI:10.1007/s11239-014-1162-6 · 2.04 Impact Factor