Subclinical Atrial Fibrillation and Anticoagulation: Weighing the Absolute Risks and Benefits

Abstract

Contemporary cardiac implantable electronic devices and electronic wearables (eg, smart watches) are capable of routinely detecting shorter episodes of atrial fibrillation (AF), which may previously have never surfaced to clinical attention.This entity of subclinical AF is often referred to as atrial high-rate episodes, although the latter may be more broadly inclusive of other atrial tachyarrhythmias, and marked variability exists with respect to device-specific thresholds for detection. 1The increasing prevalence and recognition of such incidental device-detected AF in the context of an ever-increasing proportion of the population using devices capable of continuous rhythm monitoring has raised the clinical quandary of how best to manage this condition.It is well recognized that a quarter of patients presenting with ischemic stroke ultimately have no final etiologic diagnosis and, in this context, such occult AF that may have escaped clinical detection has been postulated to play a role.Optimal management of patients with only device-detected AF, particularly with respect to the benefit of anticoagulation, remains uncertain.Observational studies have demonstrated a graded association between device-detected AF duration and thromboembolic risk, with people having longer durations of AF being at greater risk than those with shorter durations of AF, and with those having any devicedetected AF being at higher risk than those without. 2,3However, the absolute rates of ischemic stroke in populations with only device-detected AF have been significantly lower, approximately half on average, compared with patients who have clinically evident AF (Figure), with the latter also varying based on the presence of other thromboembolic risk factors and overall AF burden. 2-6Moreover, therapeutic anticoagulation even with contemporary direct oral anticoagulants (DOACs) is not without significant bleeding risk. 7s such, whether the absolute risk-benefit favors anticoagulation in patients with only device-detected AF who otherwise do not have clinically documented AF remains unclear.

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