<h3>Purpose</h3> Patients with continuous-flow (CF) left ventricular assist devices (LVADs) as destination therapy (DT) require anticoagulation with vitamin K antagonists (VKAs). A time in therapeutic range (TTR) of international normalized ratio above 60% is associated with fewer clinical events in atrial fibrillation patients. However, data on this association in LVAD patients are lacking. We therefore aimed to study the association between TTR and clinical events in patients with CF-LVAD as DT. <h3>Methods</h3> We performed a single center cohort study of patients implanted with a HeartWare LVAD as DT who were discharged from the hospital between 2010 and 2020. Patients were followed from day of discharge until their first event, death or end of follow-up. During follow-up, the TTR (< 60% and ≥ 60%) with periods of 1 month was calculated by means of the Roosendaal method. The outcomes were death, and thromboembolic, neurologic and hemorrhagic events that were adjudicated by two physicians according to the "2020 Updated definitions of adverse events for trials and registries of mechanical circulatory support". We calculated incidence rates (IRs) per 10 patient years with 95% confidence intervals (CIs) and stratified these by TTR. Incidence rate ratios (IRRs) with 95% CIs were calculated with TTR < 60% as reference group. <h3>Results</h3> A total of 63 patients were included with a median age of 63 years (range 29-72), under whom 50 (79%) males and 36 (57%) had ischemic heart failure. During 156 years of follow-up, 13 thromboembolic, 19 hemorrhagic, 19 neurologic events and 34 deaths occurred. IRs were slightly higher among patients with a TTR < 60% compared with ≥ 60% (any event 8.7 vs 6.0; thromboembolic 1.3 vs 0.5; hemorrhagic 2.0 vs 1.3; death 2.9 vs 1.1 resp, see Table) except for neurologic events (1.2 vs 1.9 resp). A high TTR was associated with a 62% reduction of death (IRR 0.38 95%CI 0.15-0.84). <h3>Conclusion</h3> A high TTR in patients with a CF-LVAD as DT is associated with fewer thromboembolic and hemorrhagic events and death.
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