APIXABAN App Study

Participants must meet all of the following criteria: Adults aged 19 years or older with a diagnosis of atrial fibrillation (AF) Presence of at least one of the following cardiovascular or metabolic comorbidities: A. Heart failure B. Hypertension C. Coronary artery disease D. Peripheral arterial disease E. Diabetes mellitus F. Stroke G. Other cardiac diseases requiring treatment Currently taking or planning to initiate oral anticoagulation therapy with apixaban Able to use a smartphone with an Android operating system Voluntarily provided written informed consent to participate in the clinical trial after being adequately informed of its purpose, procedures, and potential risks 2\. Exclusion Criteria Participants will be excluded if any of the following conditions apply: Creatinine clearance (CCr) \< 15 mL/min Presence of moderate to severe mitral stenosis History of mitral valve repair or replacement Clinically significant history of alcohol or substance abuse Deemed by the investigator to be legally or psychologically unsuitable for participation in the clinical trial Participation in another clinical trial involving investigational drugs within 4 weeks prior to screening Declines or is unwilling to provide informed consent for participation in this study