High-Intensity interval training improves global longitudinal strain in patients with metabolic syndrome and high risk of heart failure

Abstract Background Metabolic syndrome (MS) has been associated with the development of myocardial dysfunction which can lead to heart failure (HF). It is possible to detect early signs of myocardial dysfunction by assessing the global longitudinal strain (GLS) in a transthoracic echocardiography. A reduced GLS is considered as a predictor of HF development. Preventive strategies are recommended in patients with MS to avoid the progression to HF. Although exercise improves cardiovascular and metabolic health in MS patients, it is unknown whether exercise can affect the evolution of GLS in a group of patients with MS who are under medical treatment. Purpose To assess the prevalence of myocardial dysfunction (i.e., reduced GLS) in a heterogeneous group of patients with MS who are under medical treatment, and to test in these patients if 16 weeks of high-intensity interval training (HIIT) can improve the GLS. Methods Seventy-seven volunteers with MS and without signs or symptoms of HF were randomized in one of two 16-week intervention: i). HIIT in stationary bikes 3 sessions/week, 50 minutes/session + medical treatment (HIIT group), or ii). medical treatment (CONTROL). Maximal oxygen consumption (VO2max), and GLS together with rutinary echocardiographic parameters were assessed before and after intervention. The effect of HIIT compared to CONTROL was analyzed by a split-plot ANOVA to compare the effects of time (pre vs. post) and group (HIIT vs. CONTROL), and the interaction between the two factors. Results Before intervention 48.9% of participants from the HIIT group, and 46.7% from the CON group had a reduced GLS (i.e., >17% for men and >18% for women). However, none of them had a reduced left ventricular ejection fraction (LVEF), signs of diastolic dysfunction or an abnormal VO2max (less than 80% of predicted VO2max). After the 16-week intervention, only individuals from the HIIT group improved their VO2max (time*group P<0.001). LVEF did not improve in any of the experimental groups (time P=0.278) HIIT group improved their GLS by 0.51%, whereas CONTROL group improved it by 0.05% without reaching statistical significance (time*group P=0.186). However, a subgroup analysis of GLS conducted among the participants from the HIIT group discriminated by their pre-intervention values (GLS normal or reduced), showed that individuals with reduced GLS improved significantly by 1,41% (P=0.001) whereas those with a normal GLS improved by 0.14% without reaching statistical significance (P=0.736, time*group P=0.009). Conclusions Myocardial dysfunction assessed by GLS is present in MS even in the absence of symptoms, diastolic dysfunction, or reductions in the LVEF. HIIT can reduce the risk of HF development by improving GLS in patients with MS and early signs of myocardial dysfunction.A. Overall changes in GLSB. Subgroup analysis of GLS pre vs. post