Eficácia do treinamento muscular inspiratório associado a um programa de reabilitação cardíaca na atividade simpática e na capacidade funcional em pacientes com insuficiência cardíaca

Abstract

Introduction: Heart failure (HF) is considered a clinical syndrome with typical signs and symptoms such as dyspnea, low exercise tolerance, fatigue and dysautonomia. It occurs due to structural and functional cardiac changes that generally cause decreased cardiac output and/or increased intracardiac pressures, resulting in systolic and/or diastolic dysfunction. Different treatment approaches are investigated to improve the therapeutic management of these patients. Among the treatment modalities, the inclusion of inspiratory muscle training (IMT) in cardiac Rehabilitation programs has been largely considered a good strategy for clinical improvement of additional findings in patients with HF. Objectives - Study 1: Evaluate the effectiveness of low-intensity IMT associated with exercise-based cardiac rehabilitation (CR) in improving maximal and submaximal functional capacity, diaphragmatic mobility and thickness, respiratory muscle strength, quality of life and patient satisfaction in individuals with Heart Failure and weakness of the respiratory muscles. Study 2: Evaluate the effectiveness of low intensity Inspiratory Muscle Training associated with a cardiac rehabilitation program in the modulation of myocardial sympathetic activity in patients with Heart failure, reduced ejection fraction and inspiratory muscle weakness. Study 3: To determine the cutoff point of Glittre ADL-Test that indicates a better functional capacity of individuals with CI and reduced ejection fraction (EF), compared to the cardiopulmonary exercise test (CPX), considered the gold standard test. Also, determine their agreement and reliability, and finally estimate the minimum detectable change. Methods - Study 1: This is a pilot study of a parallel, controlled, randomized, double-blind clinical trial, with 19 sedentary adult individuals, aged from 21 to 60 years old, of both genders, diagnosed with heart failure, systolic dysfunction, with reduced and borderline left ventricular ejection fraction and inspiratory muscle weakness. Before and after the rehabilitation program, individuals were submitted to evaluation with CPX, ADL-Glittre test, manovacuometry, pulmonary function test, diaphragmatic ultrasound, quality of life and functional capacity and satisfaction questionnaires. The program consisted of 36 sessions, divided into 12 weeks, with three weekly sessions of aerobic exercise, peripheral muscle fitness and IMT. The IMT was performed seven days a week, at the patient's home, using the POWERBreathe® device, which in the group 1 was calibrated at 30% of the maximum inspiratory pressure (MIP) and in the group 2 at 10% of the MIP. Study 2: A series of cases was performed with 11 patients divided into two groups with low intensity IMT, Group 1 (12 weeks of aerobic exercise, peripheral muscle strength and IMT - 7 days a week with 30% of maximal inspiratory pressure) and Group 2 (12 weeks of aerobic exercise, peripheral muscle strength and TMI with up to 10% of maximum inspiratory pressure). Patients diagnosed with HF of any etiology, clinically stable, aged between 21 and 65 years old, of both genders, reduced or borderline ejection fraction (<45%) and functional class II and III according to the New York Heart Association were included. Cardiac sympathetic activity was evaluated by myocardial scintigraphy with Iodine-123 metaiodobenzylguinadine (123I-mIBG) and chest images were obtained after receiving an intravenous injection of 185 MBq (5 mCi) of 123I-mIBG. Study 3: Cross-sectional study conducted with 77 adults aged from 21 to 65 years old, with heart failure and reduced ejection fraction, NYHA II-III. An analysis of Glittre ADL-Test was made and compared to CPX was performed. For comparison between the two tests, Total Time of Glittre ADL-Test and VO2peak of the CPX were used, and cutoff point used for VO2 was 16 ml/Kg/min-1 , and according to the Weber classification, results below this value mean low functional capacity and worse prognosis. Through a ROC curve, it was possible to determine the cutoff point with the best sensitivity and specificity, a test-retest reliability, an absolute reliability and a minimum detectable change. Results - Study 1: Nine individuals were allocated to group 1 and ten to group 2, in both groups an increase in functional capacity, exercise tolerance, respiratory muscle strength, diaphragmatic mechanics and quality of life was observed, with group 1 showing a slightly higher performance, but without statistical significance. Study 2: After the intervention, the average of early RC/M was 2.47 (1.94-2.72) versus 2.02 (1.60-2.36) and the late RC/M was 2.02 (1.86-2.32) versus 1.64 (1.52-2.33), groups 1 and 2, respectively. The average of washout rate was 27.82% (22.10-30.65) in the experimental group and 34.49% (26.89-38.10) in the control group. Despite being not statistically significant, results after intervention show better control of cardiac sympathetic activity, with higher RC/M and lower washout rate of 123I-mIBG in the experimental group. Study 3: The defined cutoff point was 255 seconds with a sensitivity of 75.76% (95% CI, 57.7- 88.9) and specificity of 72.09% (95% CI, 56.3-84, 7), with an area under the curve of 0.773 (95% CI 0.663-0.861 and p<0.0001). The correlation between the tests was 0.83 with an effect size (R 2 ) of 0.69 and p<0.001. The intraclass correlation coefficient between the two tests was 0.841 (95%CI: 0.454 – 0.936, p < 0.001) and Absolute Reliability (intra-subject variability) of 3.17%, the minimum detectable change (MDC95), is 23.07 seconds or 8.78%. Conclusion: Overall, results found indicate that very low amount of IMT already have the potential to provide additional benefits to the rehabilitation of patients with CI, reduced LVEF and inspiratory muscle weakness. Furthermore, Glittre ADL-Test used as a test of tolerance to submaximal exertion proved to be capable of predicting the prognosis of patients with CI, besides the fact it is easily reproducible and with good stability in repeated tests. The determined cutoff point can be used in clinical practice to identify more severe patients when there is difficulty in performing CPX. Due to the learning effect, two tests are recommended in clinical practice.