ABC | Volume 111, Nº5, November 2018

Original Article Lima et al High-intensity interval training and heart failure Arq Bras Cardiol. 2018; 111(5):699-707 Figure 1 – Study flow diagram. Enrollment Assessed for eligibility (n = 19) Visit 1 (n = 19) Informed consent Questionnaire Anthropometric measurements Transthoracic echocardiogram Visit 2 (n = 19) Cardiopulmonary exercise test (CPET) Excluded (n = 3) • not completed CPET (n = 2) • presented limiting medical conditions (n = 1) Experimental session Visit 3 (n = 16) Analysis (n = 16) Before Immediately before 5 minutes after 30 minutes after Step 1 Step 2 Step 3 Step 4 Step 5 Assessment of blood pressure and endothelial function Meansurement of blood pressure HIIT session Exercise Assessment of blood pressure and endothelial function Measurement of blood pressure Exercise-mediated increases in shear stress have a strong and dose-dependent effect on conduit artery dilation. 33 Birk et al. 34 observed that vasodilation occurred in a greater extent immediately after highly intensive exercising compared to lowly intensive exercise sessions. 34 However, it seems that the greater the vasodilation promoted by exercise, the lower the vasodilating response observed by occlusion immediately after the exercise session in healthy individuals. Although there is no previous publication concerning subacute effect of an exercise session on endothelial function in patients with HFpEF, previous studies have evaluated patients with heart failure with reduced ejection fraction in a similar context. 35,36 Those participants responded to a single cycling exercise session with improved forearm endothelium‑dependent vasodilation (reactive hyperemia) evaluated by plethysmography up to 30 minutes after exercise. 35 Currie et al. 20 evaluated coronary artery disease patients after one single HIIT session and found an increase in the endothelial function after 60 minutes. 20 In other experiment, the same group showed that only individuals with coronary artery disease with endothelial dysfunction presented augmentation in FMD after 15 minutes of a HIIT session. 21 Interestingly, as in our experiment, in both studies the brachial artery diameter was increased. Some evidence points out that exercising performed at submaximal intensities closer to the peak of exercise promotes a greater and longer reduction in BP after exercising than when exercising less intensively. 37,38 The hypotensive effect of HIIT is already well established in the literature, but prior to this study, BP had not been evaluated in patients with HFpEF after a session of any type of exercise. In our experiment, we observed an absolute reduction of 12.7 ± 3.8 mmHg in systolic BP 30 minutes after an exercise session. On a chronic basis, this reduction may have clinical relevance, especially in the case of a syndrome whose strict control of BP pressure is crucial. Interestingly, a recent meta‑analysis has demonstrated that HIIT performed at least 3 times a week for 12 weeks resulted in a significant reduction in systolic BP in overweigh/obese individuals. 19 It is noteworthy that in this subgroup of individuals with HFpEF and reduced functional capacity, high-intensity exercising was well tolerated, once appropriate overload (speed and slope) was individually prescribed, always considering the target zones established based on maximal cardiopulmonary exercise test results of each individual. 702