Remote Screening for Asymptomatic Atrial Fibrillation: The AMALFI Randomized Clinical Trial.

IMPORTANCE: Screening for atrial fibrillation (AF) might reduce stroke if it increases long-term AF detection and anticoagulation use compared with usual care. OBJECTIVE: To investigate the long-term efficacy of AF screening in older individuals at moderate to high risk of stroke using 14-day, patch-based continuous ambulatory electrocardiogram (ECG) monitoring. DESIGN, SETTING, AND PARTICIPANTS: A parallel-group, unblinded, remote randomized clinical trial recruiting from 27 UK primary care practices from May 2, 2019, to February 28, 2022. All eligible individuals 65 years or older with a CHA2DS2VASc score of 3 or higher (men) or 4 or higher (women) with no previous AF or atrial flutter were identified via automated electronic health record searches. Last follow-up was on August 29, 2024, and statistical analysis was conducted from May to July 2025. INTERVENTION: Participants were randomized to receive and return an ECG patch monitor by postal mail (intervention, n = 2520) or usual care (control, n = 2520). MAIN OUTCOMES AND MEASURES: Intention-to-treat analysis of the proportion of participants with AF recorded in primary care records within 2.5 years postrandomization. Exploratory outcomes included exposure to oral anticoagulation and stroke. RESULTS: Of the 22 044 individuals invited, 5040 (22.9%) were randomized. The participants' mean (SD) age was 78 (6) years, 47% were female, and the median (IQR) CHA2DS2VASc score was 4 (3-5). A total of 2126 participants (84.4%) wore and returned the patch. AF was detected by patch in 89 participants (4.2%), 55% of whom had an AF burden less than 10%. After 2.5 years, a postrandomization record of AF was present in 172 individuals (6.8%) in the intervention group vs 136 (5.4%) in the control group (ratio of proportions, 1.26 [95% CI, 1.02-1.57]; P = .03), with consistent results in prespecified subgroups. Mean exposure to oral anticoagulation by 2.5 years was 1.63 months (95% CI, 1.50-1.76) in the intervention group and 1.14 months (95% CI, 1.01-1.26) in the control group (difference, 0.50 months [95% CI, 0.24-0.75]; P < .001). Stroke occurred in 69 participants (2.7%) in the intervention group and 64 (2.5%) in the control group (rate ratio, 1.08 [95% CI, 0.76-1.53]). CONCLUSIONS AND RELEVANCE: In this remote randomized clinical trial, mail-based AF screening with an ECG patch in older patients at moderate to high risk of stroke led to a modest long-term increase in AF diagnosis at 2.5 years. TRIAL REGISTRATION: ISRCTN Identifier: 15544176.