Background: Warfarin remains the most commonly used oral anticoagulant (OAC) in Thailand for stroke prevention among patients with non-valvular atrial fibrillation (NVAF). The aim of this study was to investigate the relationship between time in therapeutic range (TTR) after warfarin initiation and clinical outcomes of NVAF. Methods: TTR was calculated by the Rosendaal method from international normalized ratio (INR) data acquired from a nationwide NVAF registry in Thailand. Patients were followed-up every six months. The association between TTR and clinical outcomes was analyzed. Results: There was a total of 2233 patients from 27 hospitals. The average age was 68.4 ± 10.6 years. The average TTR was 53.56 ± 26.37%. Rates of ischemic stroke/TIA, major bleeding, ICH, and death were 1.33, 2.48, 0.76, and 3.3 per 100 person-years, respectively. When patients with a TTR < 65% were compared with those with TTR ≥ 65%, the adjusted hazard ratios (aHR) for the increased risks of ischemic stroke/TIA, major bleeding, ICH, and death were 3.07, 1.90, 2.34, and 2.11, respectively. Conclusion: Poor TTR control is associated with adverse clinical outcomes in patients with NVAF who were on warfarin. Efforts to ensure good TTR (≥65%) after initiation of warfarin are mandatory to minimize the risk of adverse clinical outcomes.
1 December 2017 in International Journal of Cardiology
Anticoagulation therapy is a standard treatment for stroke prevention in patients with non-valvular atrial fibrillation (NVAF) that have risk factors for stroke. However, anticoagulant increases the risk of bleeding, especially in Asians. We aimed to investigate the risk profiles and pattern of antithrombotic use in patients with NVAF in Thailand, and to study the reasons for not using warfarin in this patient population. A nationwide multicenter registry of patients with NVAF was created that included data from 24 hospitals located across Thailand. Demographic data, atrial fibrillation-related data, comorbid conditions, use of antithrombotic drugs, and reasons for not using warfarin were collected. Data were recorded in a case record form and then transferred into a web-based system. A total of 3218 patients were included. Average age was 67.3 ± 11.3 years, and 58.2% were male. Average CHADS2, CHA2DS2-VASc, and HAS-BLED score was 1.8 ± 1.3, 3.0 ± 1.7, and 1.5 ± 1.0, respectively. Antiplatelet was used in 26.5% of patients, whereas anticoagulant was used in 75.3%. The main reasons for not using warfarin in those with CHA2DS2-VASc ≥2 included already taking antiplatelet (26.6%), patient preference (23.1%), and using non-vitamin K antagonist oral anticoagulants (NOACs) (22.7%). Anticoagulant was used in 32.3% of CHA2DS2-VASc 0, 56.8% of CHA2DS2-VASc 1, and 81.6% of CHA2DS2-VASc ≥2. The use of NOACs increased from 1.9% in 2014 to 25.6% in 2017. Anticoagulation therapy was prescribed in 75.3% of patients with NVAF. Among those receiving anticoagulant, 90.9% used warfarin and 9.1% used NOACs. The use of NOACs increased over time.