Overview: Vitamin K antagonists (VKAs) are the most commonly used to prevent thrombotic and embolic complications associated with atrial fibrillation, mechanical valves and deep vein thrombosis. However, the narrow therapeutic window, food and drug interactions are their limitations. The efficacy and safety of these drugs depend on the International Normalized Ratio (INR). Time in Therapeutic Range (TTR) is a parameter that reflects the effectiveness of VKAs over time. Objectives: The study aimed to evaluate of time in therapeutic range with vitamin K antagonists. Subjects and research methods: Cross-sectional research included 301 patients being treated for VKAs at Dong Nai General Hospital from 12/2018 to 09/2019 and TTR was evaluated by Rosendaal methods. Results: The mean age was 61.6 ± 12.1 years, women accounted for 56.1%. Atrial fibrillation without heart valve disease accounted for 44.8%, mechanical valve accounted for 31.2%
Atrial fibrillation / moderate mitral stenosis accounted for 14%. The average dose of Acenocoumarol was 10.9 ± 4.3mg / week, the average INR test interval was 26 days Time in the therapeutic range (TTR) 40.3 ± 22.2. The INR ratio in the therapeutic threshold (FIR) was 41.6 ± 22. The mechanical valve group had a higher TTR than that of the atrial fibrillation group (42.6 ± 23.6 with 38.7 ± 20.4). Conclusion: Patients on VKAs have low TTR. In order to improve the quality of treatment, patients should be closely monitored, adequately educated for diet restrictions , and drug interactions. An anticoagulation patient club should be established. Anticoagulation clinics should be organized.