This was a prospective, multicenter, observational cohort study. Patients with atrial fibrillation were consecutively recruited from the Cardiovascular Research Platform. After providing written informed consent, research assistants scheduled and assigned the patients to the participating centers of the BEAT-AF TE project according to their individual circumstances. Each center conducted follow-up management in accordance with the investigator's handbook, with a follow-up duration of 24 months. The patients were managed according to local clinical practice, and no study-related interventions were administered in this study; only follow-up data were recorded. This real-world data analysis aimed to investigate, based on the primary exposure variable (atrial fibrillation burden), primary outcome variables (ischemic stroke, systemic embolism, etc.), and secondary outcome variables (transient ischemic attack, hospitalization for heart failure, major bleeding events, all-cause mortality, etc.), whether there is a risk inflection point between atrial fibrillation burden and stroke, whether there is a reasonable threshold for the benefit of anticoagulation therapy, and whether there is a time-dependent risk of atrial fibrillation burden prior to stroke/thromboembolic events.

Inclusion Criteria:

• (1) age ≥ 18 years; (2) confirmed diagnosis of atrial fibrillation (paroxysmal, persistent, or permanent); (3) ownership of a smartphone and a smartwatch, with the ability to perform basic operations; (4) provision of electronic informed consent.

Exclusion Criteria:

• (1) presence of clear indications for anticoagulation therapy (e.g., mechanical heart valve, recent venous thromboembolism); (2) life expectancy < 1 year; (3) severe cognitive impairment or psychiatric disorder; (4) known allergy to materials used in wearable devices; (5) concurrent participation in another clinical trial that may interfere with the outcomes of this study; (6) presence of an implanted pacemaker, implantable cardioverter-defibrillator, or cardiac resynchronization therapy device; (7) pregnancy, lactation, or planned pregnancy during the study period.

This was a prospective, multicenter, observational cohort study of adult patients with a confirmed diagnosis of atrial fibrillation. Patients meeting the inclusion and exclusion criteria were planned to be consecutively recruited through the Cardiovascular Research Platform, with an expected total sample size of 10,000 patients and an estimated screening pool of approximately 670,000 patients. The patients were enrolled from 55 research centers across the country, covering multiple geographic regions. All enrolled patients will undergo a 24-month follow-up period, with follow-up visits scheduled at 3, 6, 12, and 24 months after enrollment. No additional interventions were applied in this study; patient management was based on local clinical practice. The primary exposure variable was the five-dimensional atrial fibrillation burden indicator, and the primary outcome was the first occurrence of ischemic stroke or systemic embolism within 12 months.