Characterization of pulmonary arterial hypertension patients walking more than 450 m in 6 min at diagnosis

Chest. 2010 Jun;137(6):1297-303. doi: 10.1378/chest.09-2060. Epub 2010 Jan 29.


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.

MeSH terms

  • Adult
  • Age Factors
  • Analysis of Variance
  • Antihypertensive Agents / therapeutic use
  • Body Mass Index
  • Case-Control Studies
  • Chi-Square Distribution
  • Exercise Test*
  • Exercise Tolerance / physiology
  • Female
  • Hemodynamics / physiology
  • Humans
  • Hypertension, Pulmonary / drug therapy
  • Hypertension, Pulmonary / physiopathology*
  • Linear Models
  • Male
  • Middle Aged
  • Registries
  • Respiratory Function Tests
  • Retrospective Studies
  • Risk Factors
  • Walking / physiology*


  • Antihypertensive Agents