Limitations
First, the subjectivity inherent to the echocardiogram exam can lead to quantification bias. Small variations in the acquisition at LV apical level, which do not have an anatomical marker, can result in distorted values. Image was acquired as the maximum apical SAX view achieved with still a clear visibility of the myocardial segments. Additionally, we created another criterion to ratify the correct acquisition, which was the visualization of at least a trend of a counterclockwise rotation of these segments, which would be physiologically expected. Finally, it is important to remind that the examiner was blinded to the patient’s group allocation.
Second, in this study we used the 2D-STE technique, which would have the limitation of detecting off-plane movement of the speckles, causing eventual values underestimation. Theoretically, the use of the three-dimensional methodology (3D-STE) would have the possibility to correct this limitation.
Finally, the relatively small sample size, short duration of the exercise program and the number of training sessions for patients allocated to the TRAINING group (twice a week), with the aggravation of low adherence of some patients to the program, may have decreased the power of the study to demonstrate possible intergroup differences.