ABC | Volume 110, Nº4, April 2018

Brief Communication De Santi et al Aerobic training and LV contractility post-MI Arq Bras Cardiol. 2018; 110(4):383-387 consent form; randomized into three groups: moderate training (MTG), interval training (ITG) and control (CG). The inclusion criteria established were: anterior wall MI with exclusive involvement of anterior descending artery proximal third and asymptomatic ventricular dysfunction with left ventricular ejection fraction < 50%. Patients who progressed with heart failure, sustained ventricular tachycardia, chronic obstructive pulmonary disease, chronic renal failure and orthopedic or neurological limitations for physical exercise were excluded. The study was conducted in accordance with the Helsinki declaration. The research ethics committee of our Institution (n° 11612/2008) approved the consent form and study protocol. Cardiopulmonary exercise test An exercise test was performed with uptake of gases expired by the CPX/D analyzer MedGraphics (Saint Paul, USA). BreezeEX software was used for the acquisition, processing and storage of cardiorespiratory variables. A modified Balke protocol was applied on treadmill, with speed 1.5 mph in the first minute, 2.5mph in the 2nd minute and fixed in 3.0 mph from the third minute, followed by increasing increments of the slope of 2% every minute until the effort is interrupted, due to physical exhaustion. Continuous cardiac monitoring was performed by the 13-lead modified Mason-Likar shunt system, and blood pressure was measured manually every minute during the exercise and recovery period. Cardiac magnetic resonance Tests were performed on the Magneton Vision, Siemens, 1.5T (Erhlangen, Germany), with 25 mT circular polarization gradient coils. The sequence used was the fast gradient echo with steady state acquisition (TRUE_FISP) with parameters adjusted to optimize the signal-to-noise ratio. Flip angle = 10°, cut thickness = 8mm; interval between cuts = 0 mm; 13 phases of the cardiac cycle in a single cut, each expiratory apnea, always synchronized to ECG, becoming a cardiac cycle film with optimal temporal and spatial resolution. The images were obtained along the vertical axis (4 chambers) and the short axis to cover the entire extension of the left ventricle. Evaluation of myocardial deformation and ventricular rotation The evaluation of myocardial deformation and ventricular rotation was performed by the Multimodality Tissue Tracking computer program (MTT, version 6.6.0, Toshiba, Japan) through the analysis of cardiac magnetic resonance images generated with pulse sequences Steady State Free Precession (SSFP)). Prescription of physical training Patients randomized to the training groups were subjected to three supervised weekly sessions of aerobic exercise on a treadmill, for a period of 12 weeks. Training sessions were constituted by the following phases: warm-up, with 5 minutes duration; conditioning, with load adjustments (speed and incline) to maintain the heart rate (HR) within the training zone for 30 minutes; and the descent with a duration of 5 minutes. The intensity of the TFA, defined by training HR interval, was established from a percentage of peak HR reached in the cardiopulmonary exercise test. The HR of training for the randomized patients for the MTG was calculated in the following way: the minimum HR was established as representative of 60% of the peak HR, while the maximum HR of training was the representative of 70% of the Peak HR reached in the cardiopulmonary exercise test. Patients randomized to ITG performed TFA applying a model called 4x4, consisting of 4 periods of 4 minutes duration with training HR between 85 to 95% of the peak HR reached in the cardiopulmonary exercise test, interspersed with periods of active recovery time of 3 minutes duration with training HR between 60 to 70% of the peak HR reached in the cardiopulmonary exercise test. Statistic analysis Data are expressed as mean ± standard deviation. A value of p < 0.05 was considered statistically significant. The analysis of the distribution of the data was verified with the Kolmogorov-Smirnov test. The reason for the use of nonparametric tests was that the distributions of the analyzed variables did not present Gaussian distribution. The Kruskal-Wallis test with the Dunn post-test was used for intergroup comparison. The Wilcoxon rank- sum test was used for intragroup comparison. The statistical analysis was carried out with the SPSS 10.0 program (SPSS Inc., Chicago Illinois, USA). Results The comparative analysis between the groups did not present statistically significant differences for variables initial evaluation of exercise cardiopulmonary test. In contrast to the CG, the trained groups presented, after the 12-week period of TFA, increase with statistical significance of peak VO 2 , peak ventilation-minute (VM) and peak pulse oxygen (PO 2 ) (p < 0.05) (Table 1). The comparative analysis between the groups did not present statistically significant differences for variables initial evaluation of cardiac magnetic resonance, myocardial deformation and ventricular rotation. In contrast to the trained groups, the CG presented, after the 12-week period of clinical follow-up, a statistically significant increase in radial strain (STRAD) (p < 0.05) (Table 2). Discussion We conducted a pilot study in order to evaluate the influence of TFA, prescribed in two different intensities, on the physical capacity and mechanical contraction of the left ventricle in the context of post-MI. The main finding of this study was the documentation of a different behavior from the STRAD in the CG in comparison with the trained groups. This result is important insofar as it 384