title: Six-minute walk distance as parameter of functional outcome after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension.
abstract: OBJECTIVE
  In chronic thromboembolic pulmonary hypertension, objective data to assess the functional outcome after pulmonary endarterectomy are lacking. We studied the 6-minute walk distance in relation to the clinical and hemodynamic severity of disease, and assessed the effect of pulmonary endarterectomy on the 6-minute walk distance.
  
  
  METHODS
  A total of 50 consecutive patients with chronic thromboembolic pulmonary hypertension were studied. Subsequently, pulmonary endarterectomy was performed in 42 patients, 35 of whom underwent a 6-minute walk distance 1 year after surgery.
  
  
  RESULTS
  The mean +/- standard error of the mean 6-minute walk distance was 391 +/- 19 m. The 6-minute walk distance decreased in proportion to New York Heart Association functional class and correlated (all P < .0001) with mean pulmonary artery pressure (r = -0.62), cardiac output (r = 0.76), total pulmonary resistance (r = -0.75), mixed venous oxygen saturation (r = 0.77), and brain natriuretic peptide (r = -0.65). One year after pulmonary endarterectomy, the 6-minute walk distance increased from 417 +/- 19 m to 517 +/- 16 m (P < .0001). The change from baseline in 6-minute walk distance correlated with the changes after 1 year in New York Heart Association functional class (P < .01) and brain natriuretic peptide (r = 0.57, P < .002), and with the observed hemodynamic changes directly after pulmonary endarterectomy (change in mean pulmonary artery pressure: r = 0.52; change in cardiac output: r = 0.70; change in total pulmonary resistance r = 0.70; all P < .001). In patients with residual pulmonary hypertension after pulmonary endarterectomy, the 6-minute walk distance was significantly lower than in hemodynamically normalized patients. However, the absolute increase in the 6-minute walk distance was higher in patients with residual pulmonary hypertension (137 +/- 26 m and 82 +/- 20 m, respectively; P = .03).
  
  
  CONCLUSIONS
  The 6-minute walk distance was demonstrated to reflect the clinical and hemodynamic severity of disease in patients with chronic thromboembolic pulmonary hypertension. One year after pulmonary endarterectomy, the 6-minute walk distance had increased significantly, and the change in the 6-minute walk distance correlated with the observed clinical and hemodynamic improvement.
authors.affiliation: Department of Pulmonology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Herre J
authors.initials: HJ
authors.lastname: Reesink
authors.forename: Mart N
authors.initials: MN
authors.lastname: van der Plas
authors.forename: Niesje E
authors.initials: NE
authors.lastname: Verhey
authors.forename: Reindert P
authors.initials: RP
authors.lastname: van Steenwijk
authors.forename: Jaap J
authors.initials: JJ
authors.lastname: Kloek
authors.forename: Paul
authors.initials: P
authors.lastname: Bresser
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D015331:Cohort Studies; D004691:Endarterectomy / Q000379:methods* / Q000401:mortality; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis / Q000401:mortality / Q000601:surgery*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood; D011183:Postoperative Complications / Q000175:diagnosis; D011446:Prospective Studies; D011652:Pulmonary Circulation / Q000502:physiology; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D015996:Survival Rate; D013923:Thromboembolism / Q000175:diagnosis / Q000401:mortality / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D014654:Vascular Patency / Q000502:physiology; D016138:Walking
chemical_list: D020097:Natriuretic Peptide, Brain