Prevalence of ECG-detected and previously unrecognized atrial fibrillation among older adults attending a family health center: a single-center cross-sectional screening study

Atrial fibrillation (AF) is an important and often unrecognized cause of ischemic stroke in older adults. The primary objective of this study was to determine the prevalence of AF detected by a single 12-lead ECG among adults aged ≥ 65 years attending primary care. Secondary objectives were the proportion previously unrecognized, thromboembolic risk and anticoagulant use, and associated characteristics. This single-center cross-sectional study enrolled consecutive consenting adults aged ≥ 65 years attending a family health center in Istanbul, Türkiye (May 2021–May 2022). Of 359 assessed, 2 with pacemakers were excluded, leaving 357. AF on the screening 12-lead ECG was diagnosed by the investigator and confirmed by a cardiologist; AF was classified as previously known when a prior diagnosis was reported and as previously unrecognized otherwise. The study-period anticoagulation threshold was defined as CHA₂DS₂-VASc ≥ 2 in men and ≥ 3 in women. Prevalences are reported with Wilson 95% confidence intervals (CIs); associations were examined with chi-square or exact tests and exploratory Firth penalized logistic regression. AF was detected on the screening ECG in 42 participants (11.8%; 95% CI 8.8–15.5), with similar prevalence by sex. Prevalence differed across age groups ( P =.034), with the highest estimate among participants aged ≥ 80 years (26.3%; 95% CI 15.0–42.0). Twenty-two of the 42 ECG-detected AF cases were previously unrecognized (52.4%; 6.2% of all screened participants, 95% CI 4.1–9.2). In an exploratory adjusted model, heart failure (aOR 5.71; 95% CI 1.81–18.00) and chronic lung disease (aOR 2.53; 95% CI 1.24–5.19) were associated with ECG-detected AF, whereas the age estimate was attenuated after adjustment (aOR 1.69 per decade; 95% CI 0.98–2.90). The mean CHA₂DS₂-VASc score was 3.64 ± 1.53, and 37 participants with AF (88.1%) met the study-period anticoagulation threshold. Twenty were not receiving anticoagulation at screening, including 18 with previously unrecognized AF; this group represented 5.6% of all screened participants (95% CI 3.7–8.5). A single screening ECG identified previously unrecognized AF, including individuals who would meet a guideline-based threshold for consideration of anticoagulation after clinical evaluation. These findings describe the potential yield of opportunistic AF detection in this primary-care setting but do not establish population-level screening effectiveness or clinical benefit.