title: Relationship between silent atrial fibrillation and the maximum heart rate in the 24-hour Holter: cross-sectional study.
abstract: OBJECTIVE
  Occurrences of asymptomatic atrial fibrillation (AF) are common. It is important to identify AF because it increases morbidity and mortality. 24-hour Holter has been used to detect paroxysmal AF (PAF). The objective of this study was to investigate the relationship between occurrence of PAF in 24-hour Holter and the symptoms of the population studied.
  
  
  METHODS
  Cross-sectional study conducted at a cardiology hospital.
  
  
  METHODS
  11,321 consecutive 24-hour Holter tests performed at a referral service were analyzed. Patients with pacemakers or with AF throughout the recording were excluded.
  
  
  RESULTS
  There were 75 tests (0.67%) with PAF. The mean age was 67 ± 13 years and 45% were female. The heart rate (HR) over the 24 hours was a minimum of 45 ± 8 bpm, mean of 74 ± 17 bpm and maximum of 151 ± 32 bpm. Among the tests showing PAF, only 26% had symptoms. The only factor tested that showed a correlation with symptomatic AF was maximum HR (165 ± 34 versus 147 ± 30 bpm) (P = 0.03). Use of beta blockers had a protective effect against occurrence of PAF symptoms (odds ratio: 0.24, P = 0.031).
  
  
  CONCLUSIONS
  PAF is a rare event in 24-hour Holter. The maximum HR during the 24 hours was the only factor correlated with symptomatic AF, and use of beta blockers had a protective effect against AF symptom occurrence.
authors.affiliation: Instituto de Cardiologia, Fundação Universitária de Cardiologia, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Marcelo Lapa
authors.initials: ML
authors.lastname: Kruse
authors.affiliation: Instituto de Cardiologia, Fundação Universitária de Cardiologia, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: José Cláudio Lupi
authors.initials: JC
authors.lastname: Kruse
authors.affiliation: Instituto de Cardiologia, Fundação Universitária de Cardiologia, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Tiago Luiz Luz
authors.initials: TL
authors.lastname: Leiria
authors.affiliation: Instituto de Cardiologia, Fundação Universitária de Cardiologia, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Leonardo Martins
authors.initials: LM
authors.lastname: Pires
authors.affiliation: Instituto de Cardiologia, Fundação Universitária de Cardiologia, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Caroline Saltz
authors.initials: CS
authors.lastname: Gensas
authors.affiliation: Instituto de Cardiologia, Fundação Universitária de Cardiologia, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Daniel Garcia
authors.initials: DG
authors.lastname: Gomes
authors.affiliation: Instituto de Cardiologia, Fundação Universitária de Cardiologia, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Douglas
authors.initials: D
authors.lastname: Boris
authors.affiliation: Instituto de Cardiologia, Fundação Universitária de Cardiologia, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Augusto
authors.initials: A
authors.lastname: Mantovani
authors.affiliation: Instituto de Cardiologia, Fundação Universitária de Cardiologia, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Gustavo Glotz de
authors.initials: GG
authors.lastname: Lima
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000368:Aged; D058070:Asymptomatic Diseases; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D001938:Brazil; D003430:Cross-Sectional Studies; D015716:Electrocardiography, Ambulatory / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D000319:Adrenergic beta-Antagonists