Elsevier

Heart Rhythm

Volume 14, Issue 7, July 2017, Pages 955-961
Heart Rhythm

Clinical
Atrial Fibrillation
Predicting Determinants of Atrial Fibrillation or Flutter for Therapy Elucidation in Patients at Risk for Thromboembolic Events (PREDATE AF) Study

https://doi.org/10.1016/j.hrthm.2017.04.026Get rights and content

Background

Atrial fibrillation (AF) is the most common clinically significant cardiac rhythm disorder. There is considerable interest in screening for AF, as it is a leading cause of stroke, and oral anticoagulants (OACs) have been shown to significantly reduce the risk of stroke in patients with AF. Improved screening for AF with subsequent treatment may help improve long-term outcomes, but the optimal patient population and screening intensity are unknown.

Objectives

In this study, we prospectively evaluated the use of the CHA2DS2-VASc score for the prediction of new-onset AF using insertable cardiac monitors (ICMs) and examined whether this screening led to the initiation of OAC therapy.

Methods

We enrolled 245 subjects with no history of AF and CHA2DS2-VASc score ≥2 to be screened for AF with an ICM. The ICMs were programmed to record AF episodes ≥6 minutes in duration. Subjects were followed for 18 months with monthly remote interrogations and all events adjudicated by cardiologists. In subjects diagnosed with AF, medical records were reviewed to determine subsequent care.

Results

During a mean follow-up of 451 ± 185 days, the incidence of AF was 22.4% (95% confidence interval 17.2%–27.7%) with a mean time to detection of 141.3 ± 139.5 days. Among subjects newly diagnosed with AF, 76.4% were prescribed anticoagulation with either a novel OAC (n = 38) or warfarin (n = 4).

Conclusion

In this large prospective cohort of subjects with CHA2DS2-VASc scores ≥2, 22.4% were newly diagnosed with AF and the majority of these subjects were given OACs, suggesting a potential role of ICMs in AF screening.

Introduction

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Atrial fibrillation (AF) is the most common clinically significant cardiac rhythm disorder. It has been estimated to affect 33.5 million persons worldwide, with a lifetime risk of ∼1 in 4 for both men and women 40 years and older.1, 2 AF has also been associated with increased mortality and multiple morbidities including increased risk of stroke, physical disability, heart failure, myocardial infarction, kidney disease, and dementia.1

There is considerable interest in screening for AF, as it is a leading cause of stroke,3, 4, 5 and oral anticoagulants (OACs) have been shown to significantly reduce the risk of stroke in patients with AF.6, 7, 8, 9 Current guidelines recommend screening for AF with opportunistic pulse taking or an electrocardiographic (ECG) rhythm strip in patients older than 65 years. For those with a prior transient ischemic attack (TIA) or ischemic stroke, prolonged ECG monitoring is recommended.10, 11 Unfortunately, in spite of opportunistic screening, there remains a large burden of undiagnosed AF with recent screening trials showing that one-fourth to one-third of AF remains undiagnosed in elderly populations.12, 13

Improved screening for AF with subsequent treatment may help improve long-term outcomes, but the optimal patient population and screening intensity are unknown. Multiple models have been developed for the prediction of incident AF,14, 15 but these remain impractical for clinical screening. Given that many of the risk factors predictive of thromboembolic complications in AF are also predictive for the development of AF,14, 15, 16, 17 both the CHADS2 and CHA2DS2-VASc scoring systems have been retrospectively validated for the prediction of new-onset AF.18, 19 In this study, we prospectively evaluated the use of the CHA2DS2-VASc score for the prediction of new-onset AF using insertable cardiac monitors (ICMs) and examined whether this screening led to the initiation of OAC therapy.

Section snippets

Study design

The Predicting Determinants of Atrial Fibrillation or Flutter for Therapy Elucidation in Patients at Risk for Thromboembolic Events (PREDATE AF) study was an investigator-initiated, prospective, single-center trial of asymptomatic subjects with CHA2DS2-VASc score ≥2 and no history of AF or atrial flutter (AFL) who underwent insertion of an ICM for screening for AF or AFL. The trial was approved by the local institutional review board and registered with the US National Institutes of Health

Study population

During the study period, a total of 249 subjects were enrolled. Subjects were implanted with an ICM within 30 days of enrollment (mean 10.8 ± 9.0 days). Of the 249 subjects enrolled, 245 (98.3%) were included in the study (3 withdrew from the trial and 1 was explanted to allow radiation therapy for lung cancer). Of the 245 subjects included in this trial, 3 (1.2%) died during the study from noncardiac causes and their data were included through their last monthly transmission. In addition, 5

Discussion

AF is the most common clinically significant cardiac arrhythmia and is associated with multiple morbidities and increased mortality.1 Given that OACs have been shown to significantly reduce the risk of stroke in patients with AF,6, 7, 8, 9 there is considerable interest in screening for AF but the optimal patient population and screening intensity are unknown.4, 5 In the PREDATE AF trial, we prospectively evaluated the use of an ICM for AF screening in a population with CHA2DS2-VASc score ≥2.

Conclusion

In this large prospective cohort of asymptomatic subjects with CHA2DS2-VASc score ≥2 who underwent screening for AF with an ICM, 22.4% were newly diagnosed during 18 months of follow-up. Excluding a trial in patients who had cryptogenic stroke,4 this is the first reported large prospective trial examining screening for AF with an ICM. Our data reveal a much higher incidence of AF than has been previously appreciated. In addition, the discovery of AF affected management, with the majority of

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      It is difficult to directly compare these findings, since there are significant differences between the studies. The incidence of subclinical AF likely depends not only on the characteristics of the population analyzed, but also on the sensitivity and specificity of the devices used in each study and the diagnostic criteria applied, which differ among the studies (for example, the criterion of 30 s of irregular rhythm is used in the CRISTAL-AF and EMBRACE studies [13,14], 5 min in ASSERT II [9] and 6 min in REVEAL-AF, PREDATE AF and LOOP [10,15,16]). Three recent papers assessed the incidence of subclinical AF through continuous monitoring with an ICM in a selected high-risk population.

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    This project was supported by Keesler Medical Center and did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

    Dr Kindsvater received speaker honoraria in 2015 from Medtronic Vascular, Inc unrelated to this study. The content is solely the responsibility of the authors and does not necessarily represent the views of the United States Air Force, the Department of Defense, or the United States Government.

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