title: Relation between variability of ventricular response intervals and exercise capacity in patients with non-valvular atrial fibrillation.
abstract: BACKGROUND
  Reduced variability of the ventricular response interval (VRI) has been reported to predict adverse prognosis in patients with atrial fibrillation (AF). To examine whether it could be related also to the quality of the daily life of patients with AF, the relationships between VRI variability and exercise tolerance, one of the markers for quality of life, were determined in patients with persistent AF.
  
  
  RESULTS
  Thirty-one patients with idiopathic AF were included in the present study. Holter monitoring results and symptom-limited treadmill exercise testing were correlated in these patients without medications for the rate control of AF. The VRI variability, both the SD of the mean R-R interval (SDNN) and the SD of the 5-min mean R-R interval (SDANN), showed significant positive correlation with the exercise capacity (r=0.583, p=0.0004, and r=0.543, p=0.0013, respectively), whereas age, left ventricular ejection fraction and body mass index did not have any significant relationships. Multiple regression analysis revealed that increased SDNN was the only independent predictor of good exercise capacity during the treadmill exercise testing.
  
  
  CONCLUSIONS
  Increased VRI variability, independently of other clinical variables, can predict good exercise capacity in patients with idiopathic AF, thus being a new sensitive maker for quality of life in AF.
authors.affiliation: The Cardiovascular Institute, Tokyo, Japan. matsu@cvi.or.jp
authors.forename: Miwa
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamashita
authors.forename: Etsuko
authors.initials: E
authors.lastname: Fukuda
authors.forename: Kouichi
authors.initials: K
authors.lastname: Sagara
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Iinuma
authors.forename: Long-Tai
authors.initials: LT
authors.lastname: Fu
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology*; D004417:Dyspnea / Q000209:etiology; D015716:Electrocardiography, Ambulatory; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011788:Quality of Life; D012680:Sensitivity and Specificity; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology