ISSN: 1885-5857 Impact factor 2023 7.2
Vol. 69. Num. 6.
Pages 630 (June 2016)

Letter to the editor
The Limitations of the 6-Minute Walk Test as a Measurement Tool in Chronic Heart Failure Patients. Response

Limitaciones de la prueba de marcha de 6 minutos como instrumento de medida en pacientes con insuficiencia cardiaca crónica. Respuesta

Cristina EnjuanesabPedro Moliner-BorjaabOona MeroñobJosep Comín-Coletabc
Rev Esp Cardiol. 2016;69:62910.1016/j.rec.2016.01.024
Harsha V. Ganga, Jennifer Jantz

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To the Editor,

We thank Ganga and Jantz for their interest in our article.1 Assessment of functional capacity in heart failure is complex; available tools are the 6-minute walk test (6MWT), functional class, and cardiopulmonary exercise testing with gas exchange measurements, but each of them evaluates a specific aspect of functional status and their interpretations are complementary.

Any limitations of the interpretation of the 6MWT related to comorbidities are likewise applicable to tests involving oxygen consumption.

A number of the clinical trials carried out to study heart failure have used the 6MWT as the primary endpoint for evaluating the effectiveness of a given treatment and the beneficial effects on the symptoms.2 Likewise, in the study of pulmonary hypertension, comparable to heart failure because of its impact on quality of life, the 6MWT is the only test approved for the assessment of functional class and is the primary endpoint in the assessment of exercise capacity.3

The evaluation of functional capacity using the New York Heart Association (NYHA) functional classification is a subjective assessment from the perspective of the physician that does not correlate perfectly with other patient-centered outcomes, such as quality of life1 and the 6MWT.4 Like other authors,5 we did not include the NYHA class in the model because of the risk of its collinearity with the dependent variable, that is, the 6MWT distance.

Efforts to investigate evaluation methods that provide more information on functional aspects are undoubtedly necessary.

REFERENCES
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C. Enjuanes, J. Bruguera, M. Grau, M. Cladellas, G. Gonzalez, O. Meroño, et al.
Estado del hierro en la insuficiencia cardiaca crónica: impacto en síntomas, clase funcional y capacidad de ejercicio submáxima.
Rev Esp Cardiol., (2016), 69 pp. 247-255
[2]
L.G. Olsson, K. Swedberg, A.L. Clark, K.K. Witte, J.G. Cleland.
Six minute corridor walk test as an outcome measure for the assessment of treatment in randomized, blinded intervention trials of chronic heart failure: a systematic review.
Eur Heart J., (2005), 26 pp. 778-793
[3]
M. Hoeper, R. Oudiz, A. Peacock, V.F. Tapson, S.G. Haworth, A.E. Frost, et al.
End points and clinical trial designs in pulmonary arterial hypertension.
J Am Coll Cardiol., (2004), 43 pp. S48-S55
[4]
J. Yap, F.Y. Lim, F. Gao, L.L. Teo, C.S. Lam, K.K. Yeo.
Correlation of the New York Heart Association classification and the 6-minute walk distance: a systematic review.
Clin Cardiol., (2015), 38 pp. 621-628
[5]
E.A. Jankowska, P. Rozentry, A. Witkowska, J. Nowak, O. Hartmann, B. Ponikowska, et al.
Iron deficiency predicts impaired exercise capacity in patients with systolic chronic heart failure.
J Card Fail., (2011), 17 pp. 899-906
Copyright © 2016. Sociedad Española de Cardiología
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