ABC | Volume 114, Nº4, April 2020

Original Article Schmidt et al. Physical fitness and quality of life in HFpEF Arq Bras Cardiol. 2020; 114(4):701-707 Physical Fitness Dynamic balance and mobility. It was assessed with the 8-foot up and go (8FUG) test. 18 The patient starts the evaluation in the sitting position. After a signal, the patient must stand up, walk 8 feet (2.44m), make a turn around a cone, and return back to the initial position as fast as possible. 18 The patients tried to perform the test twice. Time (in seconds) to complete each trial was measured with a stopwatch and the result considered was the shorter time. 19 Upper body strength. Grip strength (kg) was isometrically measured using a Lafayette Instrument Hand dynamometer ( Model 78010, 78011, Indiana, USA ). Both arms were measured 3 times while patients were seated, with shoulder adducted and neutrally rotated, the elbow flexed at 90°, and the forearm and wrist in a neutral position. The average between attempts was used as final score for each arm. 19 Cardiorespiratory fitness with pulmonary gas exchange assessment. It was assessed by the 6-minute walk test (6MWT) in a 25-m-long unobstructed corridor. Participants were instructed to walk the maximal distance in 6 minutes time. Resting stops were allowed when patients felt it to be necessary. The 6MWT was performed wearing a portable gas analyzer (K4b2, Cosmed, Rome, Italy) and a heart rate monitor (Polar Electro Oy, Kempele, Finland). Oxygen uptake (VO2; mL·min-1·kg-1) and heart rate (HR; bpm) were measured directly and continuously. Respiratory and HR measurements were collected in a breath-by-breath and beat-to-beat basis, respectively, and then, data were averaged over 5-s intervals. Data was calculated as the average of measures taken during the test total duration (6 minutes). Health-related quality of life Health-related QoL was measured through an interview using the Minnesota Living With Heart Failure Questionnaire (MLWHFQ). The MLHFQ encompasses 21 questions, whose purpose is to determine how disease affects the physical, psychological and socioeconomic conditions of the patients during the previous month. 20 The questions include symptoms and signs relevant to disease, levels of physical activity, work, social interaction, sexual activity, and emotions. The MLHFQ total score range from 0 to 105 (no impairment to maximum impairment). Two other scores can be determined: the physical dimension (8 items, 0–40), and the emotional dimension (5 items, 0–25). A higher MLHFQ score means a worse QoL. Answers options ranges from 0 (none) to 5 (very much), where 0 represents no limitation and 105 represents maximal limitation. Statistical analyses Data normality was verified by Shapiro-Wilk test. Non- normally distributed variables were transformed into a natural logarithm (weight, fat mass, free fat mass, 8FUG, MLHFQ total score, MLHFQ physical and MLHFQ emotional) for subsequent analysis and then transformed back to the original scale for the purpose of clarity. Data are expressed as mean ± standard deviation. Categorical data are reported as absolute values and percentages. Pearson’s correlation was used to analyze the association between physical fitness components (dynamic balance and mobility, upper body strength, CRF and BMI) aiming to verify collinearity between variables (r>0.75). Partial correlation (adjusted for age, gender and NYHA class) was used to assess the association between physical fitness components and QoL dimensions. A multivariate linear regression analysis, with stepwise selection of variables, was performed to determine the association between QoL dimensions and age, gender, NYHA functional class and physical fitness components, which were identified as potential independent predictors of QoL. The statistical analysis was performed using the IBM SPSS 24 software (SPSS, USA), and the statistical significance was set at p<0.05. Results Patients’ characteristics The demographic and clinical characteristics of patients are shown in Table 1. The patients’ mean age was 76±6 years old, ranging from 59 to 85 years, and 71% (n=17) were females. Hypertension was the most prevalent comorbidity (n=22, 92%), followed by dyslipidemia (n=17, 71%) and obesity (n=14, 58%). Regarding the NYHA functional class, 79% (n=19) of all patients were classified as class II. The average BNP level was 288.9±191.5 pg·mL-1. Regarding cardiac function, the mean ejection fraction was 60±6%, 23% (n=6) of patients had E/e` >15, while 90% (n=22) had LAVI >34 mL·m 2 . All patients had left ventricular hypertrophy. Quality of life The score of total MLHFQ scale was 26±24, whereas the physical and emotional MLHFQ subscales’ scores were 12±13, and 5±7, respectively. Physical fitness Overall, the 6MWT distance, 8FUG and handgrip results were 312±90 meters, 10.9±3.6 seconds, and 18.6±7.1kg, respectively. The mean VO 2 during the test was 11.2± 2.3 mL·min-1·kg-1. A bivariate correlation between physical fitness components showed that the 8FUG test was inversely correlated with handgrip (r=-0.47; p=0.01) and 6MWT distance (r=-0.81; p>0.001) (Table 2). Association between physical fitness and quality of life A partial correlation between QoL dimensions and physical fitness components are shown in Table 3. A better MLHFQ total score was directly correlated with 8FUG (r=0.563; p=0.008) and inversely correlated with 6MWT (r=-0.539; p=0.012) test results. Regarding MLHFQ physical, it was directly correlated with 8FUG (r=0.529; p=0.014) and inversely correlated with 6MWT (r=-0.478 p=0.028). Finally, MLHFQ emotional was directly correlated with 8FUG (r=0.597; p=0.004). Table 4 shows the multivariate regression analysis for QoL dimensions. All models were adjusted for age, gender and NHYA functional class as potential confounders. For MLHFQ total score, the 8FUG was the only physical fitness parameter that remained an independent predictor ( β =0.651; p=0.001). Similarly, for MLHFQ physical dimension, the 703