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