Abstract 18357: Outcomes and Quality of Anticoagulant Control in Patients Newly Diagnosed with Non-valvular Atrial Fibrillation: Insights from the Worldwide GARFIELD Registry

Abstract

Background: Prevalence of atrial fibrillation (AF) is increasing due to an aging population. Most AF patients require long-term anticoagulant treatment to prevent stroke. Consequences of insufficient or excessive anticoagulation with vitamin K antagonists (VKAs) can be serious. Time within therapeutic INR range (TTR) evaluates the efficacy and quality of INR control. It remains unclear whether better anticoagulation control (TTR >60%) is associated with lower thrombotic and bleeding events in real-world clinical practice. Hypothesis: The incidence of thrombotic and bleeding events in anticoagulated AF patients treated with VKAs is increased when INR is not well controlled (TTR <60%).

Methods: Patients were recruited at 543 sites selected at random in accordance with nationally defined AF care settings. A total of 10,609 patients newly diagnosed with non-valvular AF and with ≥1 additional investigator-determined stroke risk factor were recruited consecutively between Dec 2009 and Oct 2011. TTR was calculated by percentage of INR recordings in target range.

Results: In 6047 patients treated with VKAs, 3952 had INR recordings available at the time of this analysis. TTR was >60% in 1660 (42.0%) of these patients. A total of 55,257 INR measurements were recorded. Event rates and monitoring frequency in relation to quality of INR control are shown in the Table. Mean length of follow-up was 15.2 (SD 6.9) months. Patients with INR not well controlled were more likely to have a stroke/TIA, a major bleed, an ICH and death than patients with INR well controlled.

Conclusions: These observational data support the findings of randomized clinical trials, by indicating that INR control is instrumental in determining adverse event rates in patients treated with VKAs, but are not consistent with the post-hoc comparisons of novel OACs with warfarin. Table: Event rates and INR recordings in relation to TTR.