title: Mechanism of improvement in exercise capacity after the maze procedure combined with mitral valve surgery.
abstract: OBJECTIVE
  To clarify the mechanism of improvement in exercise capacity after the maze procedure.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Tertiary referral centre.
  
  
  METHODS
  26 patients (mean (SD) age 57 (9) years) with atrial fibrillation (AF) and mitral valve disease were studied with echocardiography and cardiopulmonary exercise testing before and after the maze procedure combined with mitral valve surgery. Of these, eight had persistent AF and 18 had restored sinus rhythm (SR) by the surgery. Six patients (mean (SD) age 59 (12) years) with AF undergoing mitral valve surgery without the maze procedure who had cardiopulmonary exercise testing before and after the surgery formed the control group.
  
  
  METHODS
  Echocardiographic parameters of atrial function were measured from transmitral flow recordings. Peak oxygen uptake (VO2) and the slope of the relation between VO2 and workload (ratio of DeltaVO2 to Delta work) were determined as indices of exercise capacity.
  
  
  RESULTS
  The degree of improvements in peak VO2 and the ratio of DeltaVO2 to Delta work after the mitral valve surgery was comparable between the maze and control group. It was also comparable between patients with and those without successfully restored SR after the maze procedure. The degree of the increase in peak VO2 correlated with the change in left atrial diameter (r = -0.40, p = 0.047) but atrial contraction did not correlate with the increase.
  
  
  CONCLUSIONS
  Improvement in exercise capacity may not be caused by restored SR and atrial contraction but may at least partly relate to the reduction of left atrial size and improvement of haemodynamic variables by the surgery.
authors.affiliation: Division of Cardiology, National Cardiovascular Centre, Osaka, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Yuda
authors.forename: S
authors.initials: S
authors.lastname: Nakatani
authors.forename: Y
authors.initials: Y
authors.lastname: Kosakai
authors.forename: T
authors.initials: T
authors.lastname: Satoh
authors.forename: Y
authors.initials: Y
authors.lastname: Goto
authors.forename: M
authors.initials: M
authors.lastname: Yamagishi
authors.forename: K
authors.initials: K
authors.lastname: Bando
authors.forename: S
authors.initials: S
authors.lastname: Kitamura
authors.forename: K
authors.initials: K
authors.lastname: Miyatake
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000601:surgery*; D016275:Atrial Function; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000503:physiopathology / Q000601:surgery*; D008946:Mitral Valve Stenosis / Q000503:physiopathology / Q000601:surgery*; D010101:Oxygen Consumption; D011182:Postoperative Care; D012189:Retrospective Studies; D016896:Treatment Outcome