Eficácia e segurança do treinamento intervalado de alta intensidade em pacientes com insuficiência cardíaca

Abstract

Cardiac Rehabilitation (CR) improves the physiological response to exercise, increases functional capacity (FC), daily life activities and quality of life in patients with heart failure (HF). Continuous moderate intensity training (IMT) is the type of exercise most used for this population with positive results described in the literature. Currently, high intensity interval training (TIAI) has been used; However, considering that the effects on CF and safety for patients with HF are still controversial, the present study aimed to investigate this issue. Two studies were developed for this purpose. The first study is a pilot of a randomized blind-trial, two-arm, randomized trial: TIAI versus TCMI. Patients with heart failure (NYHA I, II and III) who were referred to CR were randomized to IMTT (intensity between 50 and 80% of Heart Rate Reserve (HRR) for 30 minutes continuously) or to TIAI (also for 30 minutes of interval training : 30 seconds in 80% to 90% of the FCR followed by 30 seconds of rest). Both groups trained three times a week for 60 minutes per day (considering warm-up and cool down). The Incremental Shuttle Walk Test (ISWT), the Duke Activity Status Index (DASI) and the Minnesota Living with Heart Failure Questionnaire (MLHFQ) questionnaire were applied before and after three months of CR. Descriptive analysis was performed for the studied variables (functional capacity, physical activity and quality of life). The sample calculation for the pilot indicated the need for 5 patients in each group. 10 patients were included so far, and 6 (5 men) who completed the protocol had a mean age of 69.17 ± 7.3 years and LVEF of 37% ± 6.9%. Both groups showed improvement in the analyzed aspects, even without statistical value. Adherence had an average of 87.5% for both groups. In general all patients involved in the study had positive responses in the studied variables and no adverse events during the training were identified. Although preliminary, the findings indicate good acceptance. The second major study, a systematic review, included randomized clinical trials (RCTs) of the MEDLINE, EMBASE, CINAHL and Web of Science databases that compared TIAI and TCMI in HF patients. The outcomes evaluated were oxygen consumption, echocardiographic parameters and quality of life. Two authors independently selected the studies, assessed trial quality, and extracted data. RevMan® software was used for data analysis based on the fixed-effect model in cases where there was substantial heterogeneity (I2 value less than 50%), for the other cases a random-effects model was used. Continuous variables were expressed as mean differences (DM) with 95% confidence intervals (CI). Subgroup analysis was performed in relation to the frequency, duration and intensity of training. Five RCTs involving 165 participants were included. All studies evaluated peak oxygen consumption (peak VO2) and four assessed oxygen consumption at the first ventilatory threshold (VT1). There was a significant difference for VO2 in VT1 in favor of TIAI protocols with more than 30 minutes of aerobic exercise (mean 1.25, 95% CI [0.48, 2.01], p = 0.001) and for training protocols (Mean 1.50, 95% CI [0.60, 2.40], p = 0.001). No statistically significant difference was found in the subgroups for peak VO2 (Mean 1.71, 95% CI [-0.61, 4.03], p = 0.15). Three studies evaluated the echocardiogram results (Mean 1.88, 95% CI [2.98, 6.75], p = 0.45 and Mean 0.35, 95% CI [1.91, 2.61], p = 0.76) for E / A ratio (filling time) and E / E '(filling pressure) and LVEF (left ventricular ejection fraction), respectively. Only two studies evaluated the quality of life (mean 7.39, 95% CI [17.89, 3.11], p = 0.17 for SF36 and mean 4.20, 95% CI [6.76, 15.17] , P = 0.45) for MLHFQ, with no difference between groups. Most studies showed I2 less than 50%. In general, the review indicated that compared to the IMT, TIAI has positive effects, with improvement in submaximal functional capacity, although not superior for echocardiogram parameters and quality of life. In addition, the TIAI performed for more than 30 minutes and that used long interval protocols exceeded the TCMI in relation to the increase of VO2 in VT1. The number of studies was the main limitation of this study.