IJCS | Volume 31, Nº2, March / April 2018

DOI: 10.5935/2359-4802.20180001 143 International Journal of Cardiovascular Sciences. 2018;31(2)143-151 ORIGINAL ARTICLE Mailing Address: José Antônio Caldas Teixeira • Rua Presidente João Pessoa, 248. Postal Code: 24220-331, Icaraí, Niterói, RJ – Brazil. E-mail: jacaldas_@hotmail.com , jacaldas@uninet.com.br Study with a Portable Gas Analyzer of the 6-Minute Walk Test in Heart Failure with Normal Ejection Fraction José Antônio Caldas Teixeira, 1 Leandro Rocha Messias, 1 Kátia Pedreira Dias, 1 Washington Luiz Batista da Costa, 1 Roberto Macedo Cascon, 2 Sandra Marina Ribeiro de Miranda, 1 Pedro Soares Teixeira, 3 Juliana Grael Jorge, 4 Antonio Claudio Lucas da Nobrega, 1 Denizar V. Araujo 5 Universidade Federal Fluminense (UFF), 1 Clínica Fit Center, 2 Complexo Hospitalar de Niterói, 3 Serviço de Arritmia da Rede Dor, 4 Universidade do Estado do Rio de Janeiro, 5 Rio de Janeiro, RJ – Brazil Manuscript received February 06, 2017, revised manuscript June 01, 2017, accepted July 31, 2017 Abstract Background: Few studies have used portable gas analyzers during the 6-minute walk test (6MWT) in patients with heart failure and normal ejection fraction (HFNEF). Objectives: To analyze the kinetics of hemodynamic, ventilatory, and metabolic variables in patients with HFNEF during the T6m using a portable gas analyzer. Methods: Prospective, analytical study with an intentional, non-probabilistic, convenience sample. In total, 24 patients with HFNEF and past hospital admissions due to a clinical diagnosis of heart failure (HF) were included using the 2007 criteria established by the European Society of Cardiology. Three assessments were performed: 6MWT familiarization, 6MWT with the portable gas analyzer, and cardiopulmonary exercise test (CPET). Results: The heart rates (HRs) and the peak VO 2 at the end of the 6MWT corresponded to 85.7% and 86.45% of the values obtained during the CPET. The final HRs after the T6m were equivalent to those obtained at the CPET anaerobic threshold (AT), with relative VO 2 values at the end of the 6MWT above the VO 2 of the CPET AT. There was no difference between the maximum respiratory quotient (RQ) values in these two tests, whichwere both above 1.0. The VE/VO 2 slope descended initially and then ascended significantly after the fifthminute of the test, estimating the identification of the AT. Conclusions: In patients with HFNEF, the 6MWT represents an almost maximum effort, and is performed above the CPET AT and 85% above the maximum HR and the CPET peak VO 2 , with a maximum RQ similar to that in the CPET. (Int J Cardiovasc Sci. 2018;31(2)143-151) Keywords: Heart Failure; Blood Gas Analysis; Stroke Volume; Exercise; Walk Test. Introduction Heart failure (HF) evokes the image of a dilated heart with reduced systolic function and ejection fraction (HF with reduced ejection fraction, HFREF). However, the study by Burkhoff et al. 1 has shown that a large proportion of patients with HF symptoms has an ejection fraction within the normal range, and are then classified as having HF with normal ejection fraction (HFNEF). 2,3 The limited tolerance to physical effort in HF is often the first and main clinical characteristic of the disease. 4 In the identification of this exercise intolerance, the 6-minute walk test (6MWT) has been used as an instrument to evaluate the progression after different interventions. 5 Only a fewstudies have been conducted using portable gas analyzers to describe and analyze the behavior of variables in the 6MWT and possible characteristics or markers that may help guide the therapy and improve the prognosis in HF, 6-10 particularly in patients with HFNEF.