Rate and Reasons for the Use of Oral Anticoagulants in Patients with Non-Valvular Atrial Fibrillation and a CHA₂DS₂-VASc Score of 0 in Thailand: The COOL-AF Registry

Background: A substantial number of patients with non-valvular atrial fibrillation (NVAF) and a CHA₂DS₂-VASc score of 0 (i.e., low-risk group) use oral anticoagulants (OACs). Objective: To investigate the rate and reasons for OAC use in Thai patients with NVAF and having a CHA₂DS₂-VASc score of 0. Materials and Methods: A nationwide observational multicenter registry of patients with NVAF was set up in Thailand. The patients’ demographic and clinical data were recorded on a case record form and then entered into a web-based data collection and management system. Results: One hundred seventy-six patients with NVAF and a CHA₂DS₂-VASc score of 0 were included. The average age was 53.9±8.2 years old, and all patients were male. Forty-six (26.1%) of the patients received OACs. NVAF patients receiving OACs had a longer duration of AF, more persistent and permanent AF, and mild left ventricular dysfunction. NVAF patients not receiving OACs were significantly more likely to be taking antiplatelet drugs. The reasons for using OACs in patients with a CHA₂DS₂-VASc score of 0 included thrombus in the left atrial appendage, post-AF ablation, planned cardioversion, hypertrophic cardiomyopathy, hyperthyroidism, and endomyocardial fibrosis. Physicians or patients preferred OAC use despite having a CHA₂DS₂-VASc score of 0 in 24 patients (52.2%). The use of OACs did not decrease clinical events, but it increased the bleeding risk. Conclusion: Among Thai NVAF patients with CHA₂DS₂-VASc score of 0, OAC was used in 26.1%. Some stroke risk factors were identified but were not included in the current risk scoring tool. Keywords: Oral anticoagulant, Outcomes, Non-valvular atrial fibrillation, CHA₂DS₂-VASc score, Thailand