Echocardiographic Assessment of Left Bundle Branch–Related Strain Dyssynchrony: A Comparison With Tagged MRI

Abstract

Recent studies have shown the efficacy of myocardial strain estimated using speckle tracking echocardiography (STE) in predicting response to cardiac resynchronisation therapy. This study focuses on circumferential strain patterns, comparing STE-acquired strains to tagged-magnetic resonance imaging (MRI-T). Second, the effect of regularisation was examined. Two-dimensional parasternal ultrasound (US) and MRI-T data were acquired in the left ventricular short-axis view of canines before (n = 8) and after (n = 9) left bunch branch block (LBBB) induction. US-based strain analysis was performed on Digital Imaging and Communications in Medicine data at the mid-level using three overall methods ("Commercial software," "Basic block-matching," "regularised block-matching"). Moreover, three regularisation approaches were implemented and compared. MRI-T analysis was performed using SinMod. Normalised regional circumferential strain curves, based on standard six or septal/lateral segments, were analysed and cross-correlated with MRI-T data. Systolic strain (SS) and septal rebound stretch (SRS) were calculated and compared. Overall agreement of normalised circumferential strain was good between all methods on a global and regional level. All STE methods showed a bias (4% strain) toward higher SS estimates. Pre-LBBB, septal and lateral segment correlation was excellent between the Basic (mean r = 0.96) and regularised (mean r = 0.97) methods and MRI-T. The Commercial method showed a significant discrepancy between the two walls (septal r = 0.94, lateral r = 0.68). Correlation with MRI-T reduced between pre-and post-LBBB (Commercial r = 0.79, Basic r = 0.82, mean regularised r = 0.86). Septal strain patterns and SRS varied with the STE software and type of regularisation, with all STE methods estimating nonzero SRS values pre-LBBB. Absolute values showed moderate agreement, with a bias for higher strain from STE. SRS varied with the type of software and extra regularisation applied. Open efforts are needed to understand the underlying causes of differences between STE methods before standardisation can be achieved. This is particularly important given the apparent clinical value of strain-based parameters such as SRS.

A Rapid Electromechanical Model To Predict Reverse Remodeling Following Cardiac Resynchronization Therapy

“…Second, the degree of mechanical dyssynchrony and maximum strain during baseline (Fig. 3) in our model is higher than reported in experimental studies (Prinzen et al 1995;Vernooy et al 2005;Aalen et al 2019;Fixsen et al 2019;Vernooy et al 2007). This could be related to how we represented coupling between electrical and mechanical activation in the active contraction model.…”

“…Left bundle branch block (LBBB), in which there is abnormal conduction on the left ventricular septum, (Bilchick et al 2007;Shamim et al 1999) leads to mechanical dyssynchrony characterized by delayed contraction and increased stretching of the LV free wall relative to the interventricular septum. (Prinzen et al 1995;Vernooy et al 2005;Aalen et al 2019;Fixsen et al 2019). As a consequence, LV pump function is impaired, and chronic LV dilation and asymmetric wall thickening occur (Baldasseroni et al 2002;Vernooy et al 2005;Prinzen et al 1995).…”

Strain-based discoordination imaging during exercise in heart failure with reduced ejection fraction: Feasibility and reproducibility

“…The lack of simultaneous blood pressure measurements throughout the exercise protocol may hamper clinical understanding of our results. Finally, the strain analysis software used in this study was not standard commercially available software, however it has previously been compared to such software on clinical data where it was found to produce similar results [ 31 ].…”

Clinical and Experimental Evidence for a Strain-Based Classification of Left Bundle Branch Block-Induced Cardiac Remodeling

“…The original LBBB classification only included longitudinal strain pattern analysis, whereas circumferential strain was used to study LBBB mechanics in sheep (due to the inherent inability in this species to display apical echo windows). Although circumferential strain pattern analysis is feasible and fits with the current classification, 12,[27][28][29] studies comparing longitudinal and circumferential strain patterns are lacking. In our animal model, rapid pacing allowed us to assess LV remodeling effects within weeks.…”