Quality of vitamin K antagonist oral anticoagulation in 322 patients with atrial fibrillation - real-life data from a survey in Eastern Switzerland

AIM OF THE STUDY: To better appreciate the role of the non-vitamin K oral anticoagulants (NOACs) for patients with non-valvular atrial fibrillation in Switzerland we aimed to assess the quality of vitamin K antagonist (VKA) anticoagulation in daily practice. METHODS: In a cross-sectional study, clinically stable patients on VKA treatment for non-valvular atrial fibrillation for at least 6 months, documentation of international normalised ratio (INR) values for at least 3 months and with at least two INR values were included. The percentage of INR values within the therapeutic range of 2.0 to 3.0 and the time in therapeutic range (TTR; Rosendaal method) and predictors for these measures of VKA anticoagulation quality were assessed. RESULTS: We studied 332 patients (62% male, mean age 74 +/- 9 years) with median (interquartile range) CHA(2)DS(2)Vasc and HAS-BLED scores of 4 (3-5) and 3 (2-4) points. The median number of INR values per patient was 8 (5-14), and the average interval between INR measurements was 20 (13-27) days. The percentage of INR values between 2.0 and 3.0 was 67% (50-83%). The median TTR was 69% (51-89%), and TTR >= 65% was found in 202 (61%) patients. Independent predictors of >= 80% INR values between 2.0 and 3.0 included a longer interval between INR measurements and the non-use of spironolactone. The non-use of amiodarone and spironolactone and a longer interval between INR measurements were the only independent predictors of a TTR >= 65%. CONCLUSIONS: The quality of VKA anticoagulation in Switzerland is highly variable. Importantly, only 60% of patients achieve a TTR >= 65%, which is currently considered to be the minimal acceptable TTR required for VKA therapy. There are few clinical predictors of a good VKA anticoagulation quality. These data may represent a novel basis for decision making regarding the choice of anticoagulation for atrial fibrillation in Switzerland.