The COOL-AF Phase 2 Registry: COhort of Antithrombotic Use and Clinical Outcomes in Atrial Fibrillation Patients.

Background: Atrial fibrillation (AF) is a common condition leading to an increased risk of death and complications such as stroke. Even though direct oral anticoagulants (DOACs) can reduce the risk of ICH, the rate of DOAC use remains low in many Asian countries because of cost concerns. Objectives: The purpose of this protocol paper of the COOL-AF (COhort of antithrOmbotic use and cLinical outcomes in patients with Atrial Fibrillation) Phase 2 registry is to determine the rate of clinical outcome, changes in antithrombotic patterns, and their impact on clinical outcomes, and to develop a prediction model for clinical outcomes. Methods: The COOL-AF Phase 2 study is a prospective observational multicenter study of patients with known or newly diagnosed nonvalvular AF in Thailand. The aim is to achieve a sample size of 3,667 patients from 33 centers. Patients will be followed up every 6 months for up to 3 years. Data collection on and doses of oral anticoagulants (warfarin, dabigatran, rivaroxaban, apixaban, and edoxaban) and antiplatelets are collected. The study outcomes include death, ischemic stroke/systemic embolism, major bleeding, myocardial infarction, heart failure, and quality of life. All events will be adjudicated. Results: Enrollment started in June 2024. The results of the COOL-AF phase 2 registry will be reported when enrollment is complete and one year of follow-up data is available. Conclusions: The COOL-AF Phase 2 trial will provide valuable information about the real-world practice of AF management and outcomes in Asia, which should be able to improve AF outcomes in the future. (COhort of antithrOmbotic Use and cLinical Outcomes in Patients With Atrial Fibrillation [COOL-AF] Phase 2; NCT06396299).