Abstract
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 VO2 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 VO2 values at the end of the 6MWT above the VO2 of the CPET AT. There was no difference between the maximum respiratory quotient (RQ) values in these two tests, which were both above 1.0. The VE/VO2 slope descended initially and then ascended significantly after the fifth minute 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 VO2, with a maximum RQ similar to that in the CPET.
Highlights
Heart failure (HF) evokes the image of a dilated heart with reduced systolic function and ejection fraction (HF with reduced ejection fraction, HFREF)
The inclusion criteria adopted to characterize heart failure and normal ejection fraction (HFNEF) were those described by Paulus et al.,[11] in addition to the following factors: (A) complaints suggestive of heart failure (HF); (B) report of prior hospitalization due to decompensated heart disease, but at the moment of the test presenting with a functional class II to III according to the New York Heart Association (NYHA); (c) age > 18 years; (d) disease duration greater than 6 months; (e) use of medication; and (F) stable disease
Riley et al.,[6] Foray et al.,[7] Faggiano et al.,[8] and Kervio et al.[10] analyzed the kinetics of variables using a portable gas analyzer and demonstrated that the kinetics and other cardiovascular parameters are decreased in HFREF in response to the effort imposed by the 6-minute walk test (6MWT)
Summary
Heart failure (HF) evokes the image of a dilated heart with reduced systolic function and ejection fraction (HF with reduced ejection fraction, HFREF). 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 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]. Few studies have used portable gas analyzers during the 6-minute walk test (6MWT) in patients with heart failure and normal ejection fraction (HFNEF). 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 VO2, 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
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