Importance: Atrial fibrillation is the most common arrhythmia and increases the risk of stroke.
Objective: To review the evidence on screening for nonvalvular atrial fibrillation with electrocardiography (ECG) and stroke prevention treatment in asymptomatic adults 65 years or older to inform the US Preventive Services Task Force.
Data sources: MEDLINE, Cochrane Library, and trial registries through May 2017; references; experts; literature surveillance through June 6, 2018.
Study selection: English-language randomized clinical trials (RCTs), prospective cohort studies evaluating detection rates of atrial fibrillation or harms of screening, and systematic reviews evaluating stroke prevention treatment. Eligible treatment studies compared warfarin, aspirin, or novel oral anticoagulants (NOACs) with placebo or no treatment. Studies were excluded that focused on persons with a history of cardiovascular disease.
Data extraction and synthesis: Dual review of abstracts, full-text articles, and study quality. When at least 3 similar studies were available, random-effects meta-analyses were conducted.
Main outcomes and measures: Detection of previously undiagnosed atrial fibrillation, mortality, stroke, stroke-related morbidity, and harms.
Results: Seventeen studies were included (n = 135 300). No studies evaluated screening compared with no screening and focused on health outcomes. Systematic screening with ECG identified more new cases of atrial fibrillation than no screening (absolute increase, from 0.6% [95% CI, 0.1%-0.9%] to 2.8% [95% CI, 0.9%-4.7%] over 12 months; 2 RCTs, n = 15 803), but a systematic approach using ECG did not detect more cases than an approach using pulse palpation (2 RCTs, n = 17 803). For potential harms, no eligible studies compared screening with no screening. Warfarin (mean, 1.5 years) was associated with a reduced risk of ischemic stroke (relative risk [RR], 0.32 [95% CI, 0.20-0.51]) and all-cause mortality (RR, 0.68 [95% CI, 0.50-0.93]) and with increased risk of bleeding (5 trials, n = 2415). Participants in treatment trials were not screen detected, and most had long-standing persistent atrial fibrillation. A network meta-analysis reported that NOACs were associated with a significantly lower risk of a composite outcome of stroke and systemic embolism (adjusted odds ratios compared with placebo or control ranged from 0.32-0.44); the risk of bleeding was increased (adjusted odds ratios, 1.4-2.2), but confidence intervals were wide and differences between groups were not statistically significant.
Conclusions and relevance: Although screening with ECG can detect previously unknown cases of atrial fibrillation, it has not been shown to detect more cases than screening focused on pulse palpation. Treatments for atrial fibrillation reduce the risk of stroke and all-cause mortality and increase the risk of bleeding, but trials have not assessed whether treatment of screen-detected asymptomatic older adults results in better health outcomes than treatment after detection by usual care or after symptoms develop.