Incremental yield of ECG screening repeated annually over 4 years in an adult Japanese population without prior atrial fibrillation: a retrospective cohort study

Objectives: International guidelines recommend opportunistic screening for atrial fibrillation (AF); however, there is no current data to inform how often to repeat screening. We aimed to investigate the incremental annual yield and stroke risk of new AF cases in individuals screened annually over 4 years.

Design: A retrospective cohort study.

Setting: Hokuriku Health Service Association, Toyama prefecture, Japan.

Participants: Employees and their families receiving annual health examinations from Hokuriku Health Service Association.

Intervention: Each subject received an annual health examination (including 12-lead ECG) from 2014 to 2017. Only subjects with baseline ECGs in 2012 and/or 2013 were included.

Main outcome measures: Rates (cases/100 person-years) of new AF identified each year for 4 consecutive years of screening (stratified according to gender and age groups). Calculated stroke risk of new AF cases using modified CHA₂DS₂-VASc scores (without heart failure data) (CHA₂DS₂VASc = C: congestive heart failure [1 point]; H: hypertension [1 point]; A2: age 65-74 years [1 point] or age ≥75 years [2 points]; D: diabetes mellitus [1 point]; S: prior stroke or transient ischemic attack [2 points]; VA: vascular disease [1 point]; and Sc: sex category [female] [1 point]) RESULTS: In 2014, 88 218 subjects had an ECG (46.8±12.5 years; 64% men): identifying 346 (0.39%) known AF and 69 (0.08%) new AF. The incidence rate of new AF increased with age from 0.01% (<50 years) to 0.98% (≥75 years) and was higher in men (0.1%) than women (0.05%). Repeated annual screening over 4 years identified a consistent new AF yield 0.06%-0.10% per year (0.33%-0.55% ≥65 years). Forty-two per cent of all new AF cases, and 76% of cases aged ≥65 years, had a class-1 oral anticoagulation (OAC) recommendation (modified CHA₂DS₂-VASc score ≥2 men, ≥3 women).

Conclusions: Repeated annual ECG screening of the same population provides a consistent yield of new AF each year. The majority of new AF (≥65 years) are eligible for anticoagulation for stroke prevention. Although AF prevalence and incidence are lower in Japan than Western countries, 2318 new cases would be identified in Toyama prefecture each year with annual screening, of whom ~927 would have a high stroke risk with a recommendation for OAC therapy.