Opportunistic and systematic screening for atrial fibrillation in adults aged ≥ 65 years in primary care: a systematic review of randomized and cluster randomized trials.

To evaluate whether opportunistic atrial fibrillation (AF) screening in adults aged ≥ 65 years improves AF detection and clinical outcomes compared with usual care, and to compare opportunistic and systematic screening strategies in terms of AF detection and clinical outcomes. A systematic review was conducted in accordance with PRISMA 2020 guidelines. Randomized and cluster-randomized controlled trials evaluating opportunistic or systematic AF screening in adults aged ≥ 65 years were included. Electronic databases (MEDLINE, Embase, and CENTRAL) were searched from inception to December 2024. Studies with sufficiently comparable outcome data were included in a structured descriptive quantitative synthesis of AF detection rates. Because of substantial clinical and methodological heterogeneity among the included studies, a pooled meta-analysis was not performed. Instead, study-level outcomes were summarized descriptively. Studies with heterogeneous designs or outcome reporting were synthesized narratively. Outcomes of interest included AF detection, initiation of oral anticoagulation, stroke incidence, and all-cause mortality. Risk of bias was assessed using the Cochrane Risk of Bias 2.0 tool. Study selection and data extraction were performed independently by two reviewers. Nine randomized or cluster-randomized trials were included. Both opportunistic and systematic screening approaches were associated with increased detection of previously undiagnosed AF compared with usual care. Opportunistic screening increased AF detection in several trials; however, direct comparisons with systematic approaches should be interpreted cautiously because of heterogeneity in monitoring intensity, follow-up duration, and population characteristics. Studies employing prolonged or continuous monitoring generally yielded higher AF detection rates; however, direct comparisons with opportunistic screening should be interpreted cautiously because of differences in monitoring intensity, follow-up duration, and population characteristics. Anticoagulation initiation varied across studies. Across studies, no consistent reduction in stroke incidence or all-cause mortality was observed. Most trials were judged to have some concerns regarding risk of bias, primarily related to pragmatic trial designs. Because AF diagnosis was confirmed using objective electrocardiographic criteria, the risk of outcome measurement bias was generally low. AF screening increases detection of previously undiagnosed AF in older adults. Opportunistic screening may be more readily integrated into routine healthcare encounters than organized systematic screening programs; however, implementation outcomes and cost-effectiveness were not consistently evaluated across the included trials. Current randomized evidence does not demonstrate consistent improvement in clinical outcomes such as stroke reduction or mortality, highlighting the need for further high-quality randomized trials evaluating integrated screening and post-detection care pathways.