PURPOSE: Pulmonary arterial hypertension (PAH) limits cardiorespiratory capacity, restricts the ability to engage in physical activity, and decreases longevity. This exploratory analysis examined the use of aerobic exercise training for improving function in patients with WHO Group 1 PAH.
METHODS: Sixteen patients (14 females, 2 males; age: 52 ± 12 years; BMI: 34 ± 7 kg/m2; mean ± SD) with PAH (NYHA/WHO functional classes I-III) were randomized to either 10 weeks of an education only program (EDU; n = 9) or 10 weeks of education combined with an exercise program (EXE; n = 7). The exercise program consisted of 24-30 sessions of treadmill walking at an intensity of 70 - 80% of patients’ heart rate reserve, for 30-45 minutes per session. Clinical outcome variables included pre to post changes in 6-minute walk test distance (6MWD) as well as peak O2 consumption (VO2peak) and anaerobic threshold (AT) determined by a symptom-limited cardiopulmonary treadmill exercise test.
RESULTS: A significantly greater improvement in 6MWD was observed for EXE compared to EDU (66 ± 47 m vs 14 ± 23 m, p < 0.05). While no between group difference was observed for the change in VO2peak, a significantly greater change in AT (EXE: 1.1 ± 2.1; EDU: -0.6 ± 1.8 ml/kg/min, p < 0.05) and time to volitional fatigue (EXE: 190 ± 88; EDU: 41 ± 86 s, p < 0.05) was observed for EXE than for EDU. No significant adverse events were noted in either treatment group.
CONCLUSIONS: Ten weeks of brisk treadmill walking improved 6MWD and cardiorespiratory fitness in these patients with Group 1 PAH. AT may be a more sensitive marker for exercise-induced improvements in cardiorespiratory function than VO2peak in patients with PAH.
CLINICAL IMPLICATIONS: A 40 meter improvement in 6MWD has been shown to be clinically significant in populations with PAH. Our findings of a corrected 52 meter improvement after 10-weeks of brisk walking, in a small sample, could have important implications for improving the functional capacity of patients with PAH.
DISCLOSURE: Steven Nathan: Consultant fee, speaker bureau, advisory committee, etc.: Actelion, Gilead, and United Therapeutics, Grant monies (from industry related sources): Actelion, Gilead, and United Therapeutics
The following authors have nothing to disclose: Leighton Chan, Michelle Kennedy, Joshua Woolstenhulme, Gerilynn Connors, Nargues Weir, Lisa Chin, Bart Drinkard, Randall Keyser
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