Six-minute walk distance as parameter of functional outcome after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension.
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.
Reesink
Herre J
HJ
Department of Pulmonology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
van der Plas
Mart N
MN
Verhey
Niesje E
NE
van Steenwijk
Reindert P
RP
Kloek
Jaap J
JJ
Bresser
Paul
P
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
D020097:Natriuretic Peptide, Brain