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

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.