title: Cardiopulmonary exercise testing determination of functional capacity in mitral regurgitation: physiologic and outcome implications.
abstract: OBJECTIVE
  This study was designed to evaluate prevalence, determinants, and clinical outcome implications of reduced functional capacity (FC) in patients with organic mitral regurgitation (MR).
  
  
  BACKGROUND
  Evaluation of FC by exercise testing is rarely performed in MR because little is known about the clinical determinants and outcome implications of FC.
  
  
  METHODS
  Cardiopulmonary exercise testing (CPET) was prospectively performed in 134 asymptomatic patients with organic MR to assess FC (peak oxygen consumption [VO2]) simultaneously to Doppler-echocardiographic quantitation of MR (effective regurgitant orifice [ERO]) and left ventricular (LV) systolic and diastolic function.
  
  
  RESULTS
  Peak VO2 was 26 +/- 6 ml/kg/min (96 +/- 16% of age-predicted), but varied widely (57% to 145% of predicted) and was markedly reduced (< or =84% of predicted) in 19% of patients. Although ERO of MR was univariately associated with reduced FC (26 vs. 9% with ERO > or =40 vs. <40 mm2), independent determinants of reduced FC were LV diastolic function (higher E/E' ratio, p = 0.006), atrial fibrillation (p = 0.01), and lower forward stroke volume (p = 0.03). Clinical events (death, heart failure, new atrial fibrillation) and clinical events or surgery were more frequent with than without reduced FC (3 years, 36 +/- 14% vs. 13 +/- 4%, p = 0.02; and 66 +/- 11% vs. 29 +/- 5%, p = 0.001, respectively), even adjusting (risk ratios 1.80 and 1.54 respectively, both p < or = 0.03) for age and ERO.
  
  
  CONCLUSIONS
  In asymptomatic organic MR, FC quantitatively assessed by CPET is unexpectedly markedly reduced in one out of every four to five patients. Reduced FC is independently determined by consequences rather than severity of MR and predicts increased subsequent clinical events. Therefore, CPET frequently reveals functional limitations not detected clinically and is an important tool in managing patients with organic MR.
authors.affiliation: Division of Cardiovascular Diseases and Internal Medicine, Mayo College of Medicine, Rochester, Minnesota, USA.
authors.forename: David
authors.initials: D
authors.lastname: Messika-Zeitoun
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Johnson
authors.forename: Vuyisile
authors.initials: V
authors.lastname: Nkomo
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Avierinos
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Allison
authors.forename: Christopher
authors.initials: C
authors.lastname: Scott
authors.forename: A Jamil
authors.initials: AJ
authors.lastname: Tajik
authors.forename: Maurice
authors.initials: M
authors.lastname: Enriquez-Sarano
mesh_terms: D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000503:physiopathology*; D011379:Prognosis; D011446:Prospective Studies