*2.1. Study Participants*

Eligible participants were Japanese residents aged ≥40 years who had undergone 12-lead ECG at the Japanese-specific health checkups in Kanazawa City in 2013 (*n* = 47,551; Figure 1). We excluded participants with missing baseline characteristics, those who did not complete a follow-up examination at least once during a 5-year follow-up period, those with AF detected at the baseline ECG, and those without adequate follow-up (*n* = 10,028). An event was defined as a new onset of AF diagnosed by automatic analysis of ECG based on the Minnesota code (8-3) during the follow-up period. Results of all automatically coded ECGs were confirmed by experienced physicians for health checkups.

**Figure 1.** Study flow chart. Eligible participants were Japanese residents aged ≥40 years who had undergone 12-lead electrocardiogram (ECG) during a Japanese-specific health checkup in Kanazawa City in 2013 (*n* = 47,551). We excluded participants with missing baseline characteristics, those who did not complete a follow-up examination at least once during the 5-year follow-up period, those with AF detected at the baseline ECG, and those without adequate follow-up (*n* = 10,028). An event was defined as a new onset of AF diagnosed by automatic analysis of ECG based on the Minnesota code (8-3) during the follow-up period.
