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Randomized Controlled Trial
. 2025 Jan;11(1):110-119.
doi: 10.1016/j.jacep.2024.08.010. Epub 2024 Sep 1.

Atrial Fibrillation Burden on a 14-Day ECG Monitor: Findings From the GUARD-AF Trial Screening Arm

Daniel E Singer  1 , Steven J Atlas  2 , Alan S Go  3 , Steven A Lubitz  4 , David D McManus  5 , Rowena J Dolor  6 , Ranee Chatterjee  6 , Michael B Rothberg  7 , David R Rushlow  8 , Lori A Crosson  9 , Ronald S Aronson  10 , Donna Mills  10 , Michael Patlakh  10 , Dianne Gallup  11 , Emily C O'Brien  11 , Renato D Lopes  11
Affiliations
Free article
Randomized Controlled Trial

Atrial Fibrillation Burden on a 14-Day ECG Monitor: Findings From the GUARD-AF Trial Screening Arm

Daniel E Singer et al. JACC Clin Electrophysiol. 2025 Jan.
Free article

Abstract

Background: The "burden" of atrial fibrillation (AF) detected by screening likely influences stroke risk, but the distribution of burden is not well described.

Objectives: This study aims to determine the frequency of AF and the distribution of AF burden found when screening individuals ≥70 years of age with a 14-day electrocardiograph monitor.

Methods: This is a cohort study of the screening arm of a randomized AF screening trial among those ≥70 years of age without a prior AF diagnosis (between 2019 and 2021). Screening was performed with a 14-day continuous electrocardiogram patch monitor.

Results: Analyzable patches were returned by 5,684 (95%) of screening arm participants; the median age was 75 years (Q1-Q3: 72-78 years), 57% were female, and the median CHA2DS2-VASc score was 3 (Q1-Q3: 2-4). AF was detected in 252 participants (4.4%); 29 (0.5%) patients had continuous AF and 223 (3.9%) had paroxysmal AF. Among those with paroxysmal AF, the average indices of AF burden were of low magnitude with right-skewed distributions. The median percent time in AF was 0.46% (Q1-Q3: 0.02%-2.48%), or 75 (Q1-Q3: 3-454) minutes, and the median longest episode was 38 (Q1-Q3: 2-245) minutes. The upper quartile threshold of 2.48% time in AF corresponded to 7.6 hours. Age >80 years was associated with screen-detected AF in our multivariable model (OR: 1.46; 95% CI: 1.06-2.02).

Conclusions: Most AF detected in these older patients was very low burden. However, one-quarter of those with AF had multiple hours of AF, raising concern about stroke risk. These findings have implications for targeting populations for AF screening trials and for responding to heart rhythm alerts from mobile devices (GUARD-AF [A Study to Determine if Identification of Undiagnosed Atrial Fibrillation in People at least 70 Years of Age Reduces the Risk of Stroke]; NCT04126486).

Keywords: atrial fibrillation burden; screening; subclinical atrial fibrillation.

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Conflict of interest statement

Funding Support and Author Disclosures The GUARD-AF trial was funded by Bristol Myers Squibb (Princeton, New Jersey, USA) and Pfizer (New York, New York, USA). The authors are solely responsible for the drafting and editing of the paper and its final contents. Dr Singer has received research support from Bristol Myers Squibb; has received consulting fees from Bristol Myers Squibb, Fitbit, Medtronic, and Pfizer; and has been supported, in part, by the Eliot B. and Edith C. Shoolman Fund of Massachusetts General Hospital. Dr Atlas has received sponsored research support from Bristol Myers Squibb/Pfizer and the American Heart Association (18SFRN34250007); and he has received consulting fees from Bristol Myers Squibb, Pfizer, and Fitbit. Dr Go has received research support through his institution from Bristol Myers Squibb/Pfizer, Johnson & Johnson, and iRhythm Technologies. Dr Lubitz has received support from National Institutes of Health (NIH) grants R01HL139731 and R01HL157635, and the American Heart Association (18SFRN34250007); has received sponsored research support from Bristol Myers Squibb, Pfizer, Boehringer Ingelheim, Fitbit, Medtronic, Premier, and IBM; has received consulting fees from Bristol Myers Squibb, Pfizer, Blackstone Life Sciences, and Invitae; and is an employee of Novartis as of July 18, 2022. Dr McManus has received sponsored research support from Bristol Myers Squibb, Pfizer, Flexcon, and Boehringer Ingelheim; has received consulting fees from Bristol Myers Squibb, Pfizer, Fitbit, Heart Rhythm Society, and Flexcon; and has received payment to serve on Data Safety Boards for NAMSA and Avania. Dr Rothberg has received consulting fees from Blue Cross/Blue Shield Association. Dr Crosson has formerly been employed at iRhythm Technologies. Dr Aronson, Ms Mills, and Mr Patlakh are employees of Bristol Myers Squibb. Dr Lopes has received grants or contracts from Amgen, Bristol-Myers Squibb, GlaxoSmithKline, Medtronic, Pfizer, and Sanofi-Aventis; has received funding for educational activities or lectures from Pfizer, Bristol-Myers Squibb, Novo Nordisk, and AstraZeneca; and has received consulting fees from Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Novo Nordisk, and AstraZeneca. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.

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