title: Atrial fibrillation in cardiac resynchronization recipients with and without prior arrhythmic history. How much of arrhythmia is too much?
abstract: BACKGROUND
  The aim of the study was to assess long-term incidence of atrial fibrillation (AF) in cardiac resynchronization (CRT) recipients with and without prior arrhythmic history, factors predisposing to arrhythmia, as well as to evaluate the prognostic power of cumulative arrhythmia burden, duration of the longest episode and the number of episodes.
  
  
  METHODS
  Device-collected data on AF episodes during 24 months in 96 participants of a randomized CRT-trial were analyzed (15% in NYHA class IV, sinus rhythm, median left ventricular ejection fraction 24% and QRS 169 ms). Blindly adjudicated major adverse cardiac events (MACE) and any-cause death were censoring variables.
  
  
  RESULTS
  Two-year incidence of AF was 70%, including 66% of patients without previous AF history. No baseline characteristics distinguished those who developed new onset AF. Percent of time spent in AF, but not number of episodes predicted mortality (adjusted hazard ratio [HR] 1.05 ± 95% confidence interval CI 1.01-1.10) and MACE incidence (HR 1.03 ± 1.01-1.07; p = 0.03). Duration of the longest episode also predicted mortality (HR 1.06 ± 1.01-1.12; both p = 0.03). Prognostic impact of AF load was marked only in patients with slower ventricular response (< 98/min), but was independent from CHADS2 scores, pacing burden, or prior atrioventricular nodal ablation.
  
  
  CONCLUSIONS
  Seven out of 10 CRT-patients had AF within 2 years, including two-thirds of subjects without arrhythmic history. No baseline features distinguished those who developed new onset AF. Arrhythmia burden and duration of the longest episode, but not number of episodes influenced outcomes in CRT-patients, irrespectively from pacing burden or prior atrioventricular node ablation.
authors.forename: Radosław
authors.initials: R
authors.lastname: Lenarczyk
authors.affiliation: Department of Cardiology, Congenital Heart Diseases and Electr otherapy, Silesian Medical University, Silesian Center for Heart Diseases Zabrze. ewajczyk@op.pl.
authors.forename: Ewa
authors.initials: E
authors.lastname: Jędrzejczyk-Patej
authors.forename: Mariola
authors.initials: M
authors.lastname: Szulik
authors.forename: Michał
authors.initials: M
authors.lastname: Mazurek
authors.forename: Tomasz
authors.initials: T
authors.lastname: Podolecki
authors.forename: Jacek
authors.initials: J
authors.lastname: Kowalczyk
authors.forename: Oskar
authors.initials: O
authors.lastname: Kowalski
authors.forename: Beata
authors.initials: B
authors.lastname: Średniawa
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Kalarus
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects* / Q000401:mortality; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011044:Poland / Q000453:epidemiology; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome