title: [Relationship between E/Em ratio and exercise capacity in patients with atrial fibrillation].
abstract: OBJECTIVE
  To explore the relationship between the ratio of early diastolic transmitral velocity to early diastolic mitral annular velocity (E/Em) and exercise capacity in patients with atrial fibrillation.
  
  
  METHODS
  A total of 94 consecutive patients with non-valvular atrial fibrillation and preserved left ventricular ejection fraction admitted into our department from December 2011 to June 2013 were included. Echocardiography and cardiopulmonary exercise test were performed. According to E/Em, they were divided into two groups of normal E/Em (E/Em ≤ 9) and elevated E/Em (E/Em>9). The parameters of exercise capacity, including VO2max/kg, anaerobic threshold/kg (AT/kg) and exercise time duration were compared between two groups. And the determinants of VO2max/kg were identified by multivariate regression analysis.
  
  
  RESULTS
  The number of patients was 57(60.6%) with normal E/Em and 37 (39.4%) with elevated E/Em. As compared to those with normal E/Em, the patients with elevated E/Em had lower VO₂max/kg [(26 ± 4) vs (20 ± 4) ml × min⁻¹ × kg⁻¹, P < 0.001], lower AT/kg [(25 ± 4) vs (19 ± 5) ml ×min⁻¹ × kg⁻¹, P < 0.001] and shorter exercise time duration [(7.2 ± 1.3) vs (5.8 ± 1.3) min, P < 0.001]. Multivariate regression analysis revealed that three significant variables were independently associated with VO₂max/kg: age (r = -0.412, P < 0.001), gender ((25 ± 5) and (21 ± 4) ml × min⁻¹ × kg⁻¹ for males and females separately, P < 0.001) and E/Em (r = -0.535, P < 0.001).
  
  
  CONCLUSIONS
  E/Em was independently associated with exercise capacity in patients with atrial fibrillation.
authors.affiliation: Department of Cardiology, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology & Regulatory Peptides, Ministry of Health, Beijing 100191, China.
authors.forename: Shaomin
authors.initials: S
authors.lastname: Chen
authors.forename: Rong
authors.initials: R
authors.lastname: He
authors.affiliation: Email: 13901078064@139.com.
authors.forename: Weihong
authors.initials: W
authors.lastname: Li
authors.forename: Xinheng
authors.initials: X
authors.lastname: Feng
authors.forename: Zhaoping
authors.initials: Z
authors.lastname: Li
authors.forename: Baoxia
authors.initials: B
authors.lastname: Chen
authors.forename: Shuwang
authors.initials: S
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
mesh_terms: D015308:Anaerobic Threshold; D001281:Atrial Fibrillation; D003971:Diastole; D004452:Echocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008943:Mitral Valve; D016277:Ventricular Function, Left