title: Atrial fibrillation burden estimates derived from intermittent rhythm monitoring are unreliable estimates of the true atrial fibrillation burden.
abstract: BACKGROUND
  Estimates of atrial fibrillation (AF) burden (AFB) derived from intermittent rhythm monitoring (IRM) are increasingly being used as an outcome measure after therapeutic interventions; however, their accuracy has never been validated. The aim of this study was to compare IRM-derived AFB estimates to the true AFB as measured by implantable continuous monitoring (CM) devices.
  
  
  METHODS
  Rhythm histories from 647 patients (mean AFB: 12 ± 22%; 687 patient·years) with CM devices were analyzed. IRM of various frequencies and durations were simulated and the obtained IRM-derived AF burdens were compared to the true AFB measured by CM.
  
  
  RESULTS
  The relative error of the IRM burden estimates was dependent on the IRM length (P < 0.001), frequency of IRM (P < 0.001), the true AFB (P < 0.001), and its temporal aggregation (AF density, P < 0.001). In paroxysmal AF patients, the relative error even with aggressive IRM strategies was >80% of the true AFB. The relative error decreased with higher true AF burdens, lower AF densities, and higher IRM frequency or duration (P < 0.001). However, even in patients with high AF burdens and/or low AF densities, IRM estimates of AFB significantly deviated from the true AFB (relative error >20%, P < 0.001) and resulted in a substantial measurement error.
  
  
  CONCLUSIONS
  IRM-derived AFB estimates are unreliable estimators of the true AFB. Particularly for paroxysmal AF patients, IRM-derived AFB estimates should not be used to evaluate outcomes after AF interventions.
authors.affiliation: Department of Cardiac and Thoracic Vascular Surgery, University of Luebeck, Luebeck, Germany.
authors.forename: Efstratios I
authors.initials: EI
authors.lastname: Charitos
authors.forename: Paul D
authors.initials: PD
authors.lastname: Ziegler
authors.forename: Ulrich
authors.initials: U
authors.lastname: Stierle
authors.forename: Derek R
authors.initials: DR
authors.lastname: Robinson
authors.forename: Bernhard
authors.initials: B
authors.lastname: Graf
authors.forename: Hans-Hinrich
authors.initials: HH
authors.lastname: Sievers
authors.forename: Thorsten
authors.initials: T
authors.lastname: Hanke
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation*; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008297:Male; D012680:Sensitivity and Specificity
keywords: arrhythmia; atrial fibrillation; clinical trial design; monitoring