Subclinical atrial fibrillation in patients with implanted antiarrhythmic devices

Abstract

Advances in the technology of implantable antiarrhythmic devices, including pacemakers, implantable cardioverter-defibrillators, and cardiac resynchronization therapy systems, have markedly increased the detection of brief, asymptomatic, or minimally symptomatic atrial tachyarrhythmias. However, the relationship between such rhythm disturbances and the risk of thromboembolic events or the development and progression of atrial cardiomyopathy remains uncertain.
This narrative review summarizes current evidence on the prevalence of atrial high-rate episodes (AHRE) and subclinical atrial fibrillation (SCAF) and their association with stroke risk. A comprehensive literature search was conducted in PubMed and Medline. Observational studies addressing AHRE detection algorithms in terms of atrial rate thresholds and episode duration were reviewed, along with randomized clinical trials assessing the efficacy of oral anticoagulation in this population.
Available data indicate that AHRE are identified in 10–30 % of patients with implanted devices and no prior history of atrial fibrillation. Their presence is associated with a modestly increased risk of stroke (0.8 %–1.0 % per year) compared with patients without AHRE. Oral anticoagulants may reduce stroke incidence in patients with AHRE, but this benefit is counterbalanced by an increased risk of major bleeding, reaching up to 2 % per year. Findings from the NOAH-AFNET 6 and ARTESiA randomized trials did not conclusively demonstrate a net clinical benefit of direct oral anticoagulants in this setting, largely due to study design limitations, choice of anticoagulant, and relatively short follow-up periods.