| Summary: | Introduction: Atrial fibrillation (AF) is the most common cardiac arrhythmia, with a prevalence of 2% in a general Western population, rising to 22% in patients with heart failure (HF). AF can occur in paroxysms or be present continuously. HF with AF is associated with an increased risk of stroke. Strokes due to AF that occur in HF patients are more severe than those that occur in patients without HF. Oral anticoagulation therapy (OAT) reduces the risk of stroke in patients with AF, although with an increased risk of major bleeding. While the relationship between persistent AF and stroke events in HF patients is well described, there is less clarity about the stroke risk from paroxysmal forms of AF. Paroxysmal AF is commonly described with reference to an ‘AF burden’, but how large a burden of paroxysmal AF warrants therapy with OAT is not known. Remote monitoring of Cardiac Implantable Electronic Devices (CIEDs) can provide a continuous assessment of cardiac rhythm. This offers a new method of describing the burden of paroxysmal AF that occurs in patients with HF. Methods: Remote monitoring data downloads from patients with CIEDs and HF were collected from patients at 2 UK hospitals. 169 patients were analysed in the first centre. Both AF episode data and clinical data were collected. The data from this centre was used to determine the feasibility of the technique, and the burden of AF was described. AF episodes were then collated into ‘AF days’ and the incidence of significant AF days was described with reference to 5 previously used definitions of a significant AF day in previously published work. 327 patients were analysed from a second UK centre with data collected in order to validate the incidence of AF observed in the first centre. Results: In patients from Centre 1, 3,426 episode of AF were detected during remote follow-up in 115 patients over 446 patient years. Paroxysmal AF was detected in 63% of patients who were presumed to have sinus rhythm at the time of implant. The median total AF burden in this group was small (187 seconds; 16 seconds – 7.2 days), but 32% of patients with pAF had a total burden of greater than 1 day. The burden of AF was described in several ways, and exploratory 12 analyses of AF burden was also carried out. The burden of AF was compared to that in the 5 previously published studies of remotely detected AF. One definition (‘≥ 30 seconds of AF in a 24 hour period’) was found to be met by all patients who then also met other definitions, and patients appeared to fulfil this definition of a clinically significant burden of AF sooner. In centre 2, 7,148 episodes of AF occurred in 236 patients over a follow period of 805 patient years. The burden of AF appeared broadly similar to that observed in the first centre, and the comparison with the previously published data was also similar. Conclusions: AF occurs frequently in patients with HF in whom dual chamber CIEDs have been implanted. Many patients spend only a short amount of time in AF, and the clinical significance of this is unclear. A definition of ‘at least 30 seconds in a 24 hour period’ was met by all patients who met other published definitions of a significant burden of AF and was met sooner than the other definitions of significance. Further work is needed to determine if this burden of AF could predict longer burdens and to correlate pAF burden with stroke risk.
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