Effect of 6-min Walk Test on pro-BNP Levels in Patients with Pulmonary Arterial Hypertension
- 185 Downloads
Plasma pro-BNP (brain natriuretic peptide) levels are often elevated in response to right ventricular (RV) volume and pressure overload, parameters potentially affected by exercise. Plasma pro-BNP levels change in association with long-term changes in pulmonary hemodynamics, thereby serving as a potential biomarker in pulmonary arterial hypertension (PAH). The 6-min Walk Test (6MWT) and pro-BNP level are often checked in a single office visit. There is no universal standard for measuring Pro-BNP levels relative to the timing of the 6MWT. Based on the studies in normal subjects indicating that pro-BNP levels changes after exercise, we hypothesized that the pro-BNP might rise after the 6MWT in PAH patients, potentially impacting clinical decisions.
Patients at our center with WHO Group 1 PAH on active therapy at a stable dose for 30 days or more were enrolled. After resting the patient for 30 min, blood was drawn for baseline pro-BNP and a 6MWT was performed. Pro-BNP levels were drawn immediately after the 6MWT and 1 and 2 h later. Pro-BNP was measured using a commercially available ELISA kit. The levels before exercise and after exercise were compared using student’s paired t tests.
There were 17 females and 3 male subjects. The mean age was 53 ± 11 years. Seven patients had systemic lupus erythematosus-related PAH, six had idiopathic PAH, three had scleroderma, three had portopulmonary hypertension, and one had HIV-related PAH. The mean PA pressure was 50 ± 15 mmHg with a mean pulmonary vascular resistance of 10 ± 4 Wood units. The majority of the patients were on multimodality PAH therapy, including parenteral prostacyclins. Mean 6MWT distance was 377 ± 140 m. In 14/20 patients, the pro-BNP level increased immediately after the 6MWT; in 12/20 patients, the pro-BNP level was elevated at 1 h post exercise. In the majority of the patients, the pro-BNP fell to baseline 2 h post 6MWT.
There appears to be a trend of pro-BNP level increasing immediately after exercise and continuing to be elevated at 1 h. Pro-BNP levels then return to baseline at 2 h post 6MWT.
KeywordsPulmonary hypertension Pro-BNP Six-min walk test
VP: Study design, conducted the study, data collection, manuscript preparation. RA: Study design, manuscript preparation. BJ: Running the samples, manuscript preparation. WH: Running the samples, manuscript preparation. HJF: Study design, patient identification, manuscript preparation.
This study was funded by Division of pulmonary and critical care medicine, University of North Carolina at Chapel Hill.
Compliance with Ethical Standards
Conflict of interest
The authors report no real or potential conflict of interest.
- 12.Tsutamoto T, Wada A, Maeda K et al (1997) Attenuation of compensation of endogenous cardiac natriuretic peptide system in chronic heart failure: prognostic role of plasma brain natriuretic peptide concentration in patients with chronic symptomatic left ventricular dysfunction. Circulation 96(2):509–516CrossRefPubMedGoogle Scholar
- 13.Omland T, Aakvaag A, Bonarjee VV et al (1996) Plasma brain natriuretic peptide as an indicator of left ventricular systolic function and long-term survival after acute myocardial infarction. Comparison with plasma atrial natriuretic peptide and N-terminal proatrial natriuretic peptide. Circulation 93(11):1963–1969CrossRefPubMedGoogle Scholar
- 20.McLaughlin VV, Archer SL, Badesch DB et al (2009) ACCF/AHA 2009 expert consensus document on pulmonary hypertension a report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents and the American Heart Association developed in collaboration with the American College of Chest Physicians; American Thoracic Society, Inc.; and the Pulmonary Hypertension Association. J Am Coll Cardiol 53(17):1573–1619CrossRefPubMedGoogle Scholar