title: Early detection of atrial high rate episodes predicts atrial fibrillation and thromboembolic events in patients with cardiac resynchronization therapy.
abstract: BACKGROUND
  In patients without any history of atrial fibrillation (AF), detection of subclinical atrial high rate episodes (AHRE) by implanted devices has been associated with an increased thromboembolic risk. The predictive value of AHREs in patients with cardiac resynchronization therapy (CRT) is uncertain.
  
  
  OBJECTIVE
  We aimed to investigate the prognostic value of early detected AHRE in patients with CRT.
  
  
  METHODS
  This observational study included patients who received CRT and no history of AF. Patients had standard indication for CRT treatment. They were screened for early detected AHREs longer than 6 minutes occurring before 6-month follow-up, and the longest duration of AHREs was recorded. Information on clinical AF and thromboembolic events was obtained from the Danish National Patient Registry. The Cox regression model was used to compute hazard ratios (HRs) with 95% confidence intervals (CIs).
  
  
  RESULTS
  Of 394 eligible patients, 79 patients (20%) had early AHRE detected. During a median follow-up of 4.6 years, patients with early detected AHREs had an increased risk of clinical AF (HR 2.35; 95% CI 1.47-3.74; P < .001) and thromboembolic events (HR 2.30; 95% CI 1.09-4.83; P = .028). For patients with AHREs longer than 24 hours, these associations were stronger. The risk of mortality was not higher with early detected AHREs (HR 0.97; 95% CI 0.64-1.45; P = .87). Of the 27 patients with thromboembolic events, only 10 patients (37%) had AHREs detected within a 2-month period before the thromboembolic event.
  
  
  CONCLUSIONS
  In patients without any history of AF, detection of early AHREs after CRT implantation is associated with a significantly increased risk of clinical AF and thromboembolic events, particularly AHRE longer than 24 hours.
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark. Electronic address: CTWI@clin.au.dk.
authors.forename: Christoffer Tobias
authors.initials: CT
authors.lastname: Witt
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Mads Brix
authors.initials: MB
authors.lastname: Kronborg
authors.affiliation: Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Ellen Aagaard
authors.initials: EA
authors.lastname: Nohr
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Peter Thomas
authors.initials: PT
authors.lastname: Mortensen
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Gerdes
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Jens Cosedis
authors.initials: JC
authors.lastname: Nielsen
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000209:etiology* / Q000628:therapy; D058406:Cardiac Resynchronization Therapy; D058409:Cardiac Resynchronization Therapy Devices; D015331:Cohort Studies; D017147:Defibrillators, Implantable; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D018570:Risk Assessment; D013923:Thromboembolism / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D013997:Time Factors
keywords: Atrial fibrillation; Atrial high rate episodes; Cardiac resynchronization therapy; Mortality; Thromboembolic event