IJCS | Volume 32, Nº2, March/April 2019

99 1. Reybrouck T. Clinical usefulness and limitations of the 6-minute walk test in patients with cardiovascular or pulmonary disease. Chest. 2003;123(2):325-7. 2. McGavin CR, Gupta SP, McHardy GJ. Twelve-minute walking test for assessing disability in chronic bronchitis. Br Med J. 1976;1(6013):822-3. 3. Butland RJ, Pang J, Gross ER, Woodcock AA, Geddes DM. Two-, six-, and 12-minute walking tests in respiratory disease. Br Med J (Clin Res Ed). 1982;284(6329):1607-8. 4. Bittner V, Weiner DH, Yusuf S, Rogers WJ, McIntyre KM, Bangdiwala SI, et al. Prediction of mortality and morbidity with a 6-minute walk test in patients with left ventricular dysfunction. SOLVD Investigators. JAMA.1993;270(14):1702-7. 5. ATS Committee on Proficiency Standards for Clinical Pulmonary Function Laboratories. ATS statement: guidelines for the six-minute walk test. Am J Respir Crit Care Med. 2002;166(1):111-7. 6. Rostagno C, Olivo G, Comeglio M, Boddi V, Banchelli M, Galanti G, et al. Prognostic value of 6-minute walk corridor test in patients with mild to moderate heart failure: comparison with other methods of functional evaluation. Eur J Heart Fail. 2003;5(3):247-52. 7. Kervio G, Ville NS, Leclercq C, Daubert JC, Carre F. Cardiorespiratory adaptations during the six-minute walk test in chronic heart failure patients. Eur J Cardiovasc Prev Rehabil. 2004;11(2):171-7. 8. Teixeira JAC, Messias LR, Dias KP, Costa WLB, Cascon RM, Miranda SMR, et al. Estudo por analisador de gases do teste de caminhada de seis minutos na insuficiência cardíaca com fração de ejeção normal. Int J Cardiovasc Sci. 2018;31(2):143-51. 9. Oliveira MF, Zanussi G, Sprovieri B, Lobo DM, Mastrocolla LE, Umeda II, et al. Alternatives to aerobic exercise prescription in patients with chronic heart failure. Arq Bras Cardiol. 2016;106(2):97-104. 10. Morais ER , Rassi S. Determinants of the distance covered during a six- minute walk test in patients with chronic heart failure. Int J Cardiovasc Sci. 2019;32(2)134-142. References José Antônio CaldasTeixeira Simplicity and complexity of the six-minute walk test Int J Cardiovasc Sci. 2019;32(2)98-99 Editorial There is a real possibility of more severe patients perform the 6MWT near or above the first threshold, which is reinforced by its correlation with the VO 2 of the anaerobic threshold and of the VE/VCO 2 slope, as demonstrated in studies using gas analyzers during the 6MWT. 7 The authors have found mean relative peak VO 2 ≥ 85% of CPET in HF patients, similar to a Brazilian study. 8 Based on these findings, the 6MWT has been suggested to be used for prescription of the training intensity in this population. 9 Despite its high sensitivity, the 6MWT can be influenced by several factors, includingmotivational and learning factors. However, with adequate standardization of the method, the test can be highly reproducible. Possible sources of variability caused by the procedure itself should be controlled, following guidelines and quality-control programs. 5 Many factors have been reported to influence the 6MWT results, including age, sex, height (which influences the step length), body mass (obesity), muscle mass, balance, reduced strength and musculoskeletal changes. All these are potentially determinants of the distance covered. 5 Morais e Rassi, 10 evaluating determinants of the 6MWT in HF patients, showed important data in a Brazilian population. The authors correlated the distance covered in the 6MWT with clinical and socioeconomical parameters, comorbidity index, quality of life index, physical activity, depression and anxiety, respiratory functional tests, respiratory muscle strength, and handgrip strength. The authors also reported that age, female sex, vital capacity and dyspnea index for the ADL as the main negative predictors for performance of the ADL. Although a large percentage of patients had chagasic cardiomyopathy (43%), their findings corroborate previous studies on patients with HF caused by other conditions. For example, the American Thoracic Society guidelines 5 reported that these factors, in addition to the severity of underlying disease, musculoskeletal problems and cognitive impairment can reduce the distance covered in the 6MWT. The 6MWT is here to stay. Its potential use in functional assessment, in therapeutic interventions and in prognostic estimation should be further explored in HF patients. This is an open-access article distributed under the terms of the Creative Commons Attribution License