Characterization of pulmonary arterial hypertension patients walking more than 450 m in 6 min at diagnosis.
BACKGROUND
At diagnosis of pulmonary arterial hypertension (PAH), some patients are considered to have a "near-normal" 6-min walk distance (6MWD) (ie, > 450 m). Because they are generally excluded from randomized controlled trials, little is known about these patients.


METHODS
We analyzed the baseline characteristics and treatment responses of 49 consecutive patients with a 6MWD > 450 m at the time of newly diagnosed PAH. Data from this cohort were then compared with data from hemodynamically matched patients with a 6MWD < or = 450 m.


RESULTS
Patients with a 6MWD > 450 m were either in World Health Organization (WHO) functional class (FC) II (n = 23) or III (n = 26) at baseline. Compared with patients in FC II, those in FC III had more severe hemodynamic impairment (ie, a lower cardiac index and higher pulmonary vascular pressures and resistance) but similar 6MWD. At first evaluation after initiation of PAH-specific treatment (3-6 months), FC improved (FC I-II: n = 38; FC III: n = 11, P < .005) and cardiac index increased. However, 6MWD remained unchanged. Compared with matched patients with a 6MWD < or = 450 m (n = 98), individuals with a 6MWD > 450 m were approximately 9 years younger (P = .0006) and had a lower BMI (P = .0009).


CONCLUSIONS
Anthropometric characteristics such as younger age and lower BMI may explain higher 6MWD in some PAH patients. In the cohort of patients with a 6MWD > 450 m, hemodynamic indices and WHO FC were more sensitive than 6MWD in detecting changes secondary to PAH-specific treatments.
Degano
Bruno
B
Service de Pneumologie, Hôpital Antoine-Béclère, 157 rue de la Porte de Trivaux, 92141 Clamart, France. degano.b@gmail.com
Sitbon
Olivier
O
Savale
Laurent
L
Garcia
Gilles
G
O'Callaghan
Dermot S
DS
Jaïs
Xavier
X
Humbert
Marc
M
Simonneau
Gérald
G
D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D000959:Antihypertensive Agents / Q000627:therapeutic use; D015992:Body Mass Index; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy / Q000503:physiopathology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012042:Registries; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012307:Risk Factors; D016138:Walking / Q000502:physiology*
D000959:Antihypertensive Agents