Presence of Paradoxical Mid-Systolic Longitudinal Strain (Stretching) with Speckle Tracking in the Basal Inferior-to-Lateral Segments in Mitral Valve Prolapse

Background and Purpose: Abnormality in the motion of the inferior papillary muscle was found in an early study of mitral valve prolapse (MVP). We visually observed an abnormal movement not only in the inferior wall but also in the anterolateral and inferolateral basal walls in several patients with MVP. Therefore, the aim of this work was to analyze these findings using strain (Speckle Tracking—STE). Methods: A total of 60 MVP patients having a superior systolic displacement of the posterior leaflet, in whole or in part of the scallops, of at least 2 mm, and 20 normal subjects as controls were included. Longitudinal strain was calculated in the three apical views (Philips iE 33 Matrix—implemented strain software). The strain in the three abovementioned basal segments was measured at 160 ms from the beginning of systole (mid-systole), and then we averaged their values to form a “triad” of averaged values that could be subsequently compared among the groups for statistical calculations. The Global Longitudinal Strain (GLS) was also calculated for all subjects. The Mann–Whitney U-test was used for comparisons. A “p” value ≤ 0.05 was considered significant. Results: According to the strain patterns, we were able to identify two distinct groups in MVP patients: Group 1 had a “paradoxical” strain at 160 ms (=positive, that means “mechanical stretching”) in at least a single segment of the aforementioned “triad” of basal segments (n = 35), and Group 2 had not a “paradoxical” strain (n = 25) in any of the aforementioned “triad” segments at the same mid-systolic point. Statistical significance was found between Group 1 and Group 2 at 160 ms and at the peak (p < 0.0001 for both) and the same was found for GLS (p < 0.01). Group 1 vs. controls, as expected, displayed a significant difference in the strain at 160 ms (p < 0.0001) while Group 2 vs. controls did not differ significantly, even at the peak. Conclusions: According to our results, we found in our MVP population (more than half of the patients) that some MVP patients have a “paradoxical” strain (=mechanical stretching) in at least a single segment of the basal inferior-to-lateral segments (that we have named the “triad”) in mid-systole, whereas others do not. The passive continuous stretching of myocardial cells is known to lead, with time, to the replacement of cells by fibrosis (and fibrosis is a condition that is well known to be a source of arrhythmias, and even malignant). Previous Cardiac Magnetic Resonance (CMR) studies already reported the presence of fibrosis in the same basal wall segments in some MVP patients. Thus, considering our strain results, in MVP patients, but only in those with ventricular arrhythmias, it is indicated, in our opinion the strain should be analyzed, as it is an inexpensive tool. If the strain is found to be “paradoxical” even in a single segment of what we have named the “triad”, a further evaluation with CMR (even if expensive) is recommended to look for the presence of fibrosis. Strain analysis is indicated because these findings may have implications for prognosis, further evaluation of arrhythmias and the selection of appropriate therapy.