IJCS | Volume 32, Nº2, March/April 2019

135 Morais and Rassi Six-minute walk test in heart failure Int J Cardiovasc Sci. 2019;32(2)134-142 Original Article patients, aiming a better functionality and quality of life. Studies on factors associated with the 6MWT in patients withHP usingmultivariate analysis are scarce, especially in the Brazilian population, thus supporting the relevance of the present study. This study aimed to identify determinants of the 6MWT in patients with chronic HF patients with NYHA classes I-III. Methods This was a cross-sectional study with 81 patients with chronic HF seen at the HF outpatient clinic of a referral hospital in Goiania, Goias, Brazil. Sample size was calculated using the GPower ® software, using a significance level of 5%, power of 0.90, effect size of 0.59 (calculated from the determination coefficient – R 2 ) and number of predicting variables. A minimum of 79 patients with HF would be needed. Inclusion criteria were: patients of both sexes aged ≥ 18 years old, with clinical diagnosis of HF, left ventricular ejection fraction (LVEF) < 50%, NYHA functional class I-III, not receiving optimized treatment, and clinically stability for at least one month. Patients with acute myocardial infarction in the last month, unstable angina, stroke, musculoskeletal disorders, understanding impairment that wouldmake it difficult to perform the tests, neoplasms or diagnosis of pulmonary diseases, pregnant women, patients using medications or ergogenic aids were excluded from the study. Ethical aspects All participants signed the informed consent form. The study was approved by the research ethical committee of the General Hospital of the Federal University of Goias (approval number: 883 281/2014) and of the Pontifical Catholic University of Goias (approval number: 922826/2014), following the regulatory norms and standards for research involving human subjects (Brazilian National Council, resolution number 466/2012). Procedures Screening of patients was performed by analysis of medical records. Eligible patients were invited to participate in the study on the visit day at the HF outpatient clinic, or later by telephone contact. All tests were carried out by the same investigators on the same day. Questionnaires on clinical and sociodemographic data were partially completed with data obtained from medical records and complemented by interview on the visit day. The other endpoints were measured up to two weeks following the initial evaluation at a university health clinic. The distance covered during the 6MWT (6MWD) was considered the outcome variable whereas sociodemographic, clinical, physical functional and emotional data, as well as quality of life used as exposure data. The 6MWT was conducted following international standards. 4 Two tests were performed on one day, with a 30-minute interval between them, for recovery of baseline heart rate (HR). The following parameters weremeasured immediately before the test, at the end (sixth minute) of the test and during recovery (5 minutes after the test) – HR, Borg dyspnea scale, peripheral oxygen saturation (SpO 2 ), systolic arterial pressure (SAP) and diastolic arterial pressure (DAP). Measurements of HR, Borg scale and SpO 2 were also made during the test (at minutes 2 and 4). The longest distance covered and the highest Borg scale rating between the two tests were considered for analysis. The distance covered was also compared with that expected one for the Brazilian population and expressed as percentage. 5 Sociodemographic variables were age (years), sex, ethnicity (Caucasian and non-Caucasian), occupation (working or unemployed) income (Brazilian reals) (≤ 3 minimumwages and > 3minimumwages), marital status (with a companion or single), smoking (yes or no/ex), alcohol consumption (yes or no/ex). Clinical variables were: HF etiology (Chagasic or non-Chagasic), time of HF diagnosis (≤ 2 years or > 2 years), New York Heart Association (NYHA) functional class (class I = asymptomatic and classes II and III = symptomatic), LVEF, left ventricular end- systolic diameter (LVESD), left ventricular end-diastolic diameter (LVEDD), number of medications being used, and number of hospitalizations in the past year. We also measured the Charlson comorbidity index 6 which evaluates 19 clinical conditions combined (scores ranging from 0 to 6) and age (scores ranging from 0 to 4). The total score was the sum of clinical condition and age scores. Resting HR was measured after 5-10-minute rest using a pulse oximeter (Onyx Nonin ® ), and systolic and diastolic blood pressure was measured using a