title: How much atrial fibrillation causes symptoms of heart failure?
abstract: BACKGROUND
  Patients with atrial fibrillation (AF) are more symptomatic than patients with sinus rhythm. However, it is unknown what per cent of time spent in AF is associated with symptoms.
  
  
  METHODS
  We used a limited access dataset from the Atrial Fibrillation Follow-up Investigation of Rhythm Management trial. Patients had their current rhythm and New York Heart Association (NYHA) class recorded at baseline and at every follow-up visit. The ratio of number of visits when patients were in AF to the total number of visits was used as a surrogate measure of AF burden. The median number of visits was 12 per patient. We grouped patients labelled as class 0 and I by NYHA as having no symptoms and NYHA II or III as having symptoms. Furthermore, we calculated mortality and the prevalence of symptoms depending on the per cent of visits when they had AF.
  
  
  RESULTS
  Of 4060 patients enrolled in the trial, 74 had no follow-up visits and were excluded; the remaining 3986 patients were analysed. Patients who had no or little AF throughout the study (0-20%) had the lowest prevalence of symptoms. Prevalence of symptoms increased with greater per cent of time spent in AF. Specifically, symptoms became more prevalent when AF burden reached 20-40%. Mortality was similar regardless of proportion of visits when patients were in AF.
  
  
  CONCLUSIONS
  Higher AF burden is associated with higher prevalence of symptoms. The increment became significant when patients were in AF at 20-40% of visits.
authors.affiliation: University of South Florida, Tampa, FL, USA.
authors.forename: M
authors.initials: M
authors.lastname: Guglin
authors.forename: R
authors.initials: R
authors.lastname: Chen
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000150:complications* / Q000453:epidemiology / Q000401:mortality; D017281:Cost of Illness; D005260:Female; D006333:Heart Failure / Q000209:etiology* / Q000401:mortality; D006801:Humans; D008297:Male; D015995:Prevalence; D012189:Retrospective Studies; D013997:Time Factors