Cardiovascular magnetic resonance features of mechanical dyssynchrony in patients with left bundle branch block

Abstract

Patients with left bundle branch block (LBBB) can exhibit mechanical dyssynchrony which may contribute to heart failure; such patients may benefit from cardiac resynchronization treatment (CRT). While cardiac magnetic resonance imaging (CMR) has become a common part of heart failure work-up, CMR features of mechanical dyssynchrony in patients with LBBB have not been well characterized. This study aims to investigate the potential of CMR to characterize mechanical features of LBBB. CMR examinations from 43 patients with LBBB on their electrocardiogram, but without significant focal structural abnormalities, and from 43 age- and gender-matched normal controls were retrospectively reviewed. The following mechanical features of LBBB were evaluated: septal flash (SF), apical rocking (AR), delayed aortic valve opening measured relative to both end-diastole (AVO) and pulmonic valve opening (AVO), delayed left-ventricular (LV) free-wall contraction, and curvatures of the septum and LV free-wall. Septal displacement curves were also generated, using feature-tracking techniques. The echocardiographic findings of LBBB were also reviewed in those subjects for whom they were available. LBBB was significantly associated with the presence of SF and AR; within the LBBB group, 79 % had SF and 65 % had AR. Delayed AVO, AVO, and delayed LV free-wall contraction were significantly associated with LBBB. AVO and AVO positively correlated with QRS duration and negatively correlated with ejection fraction. Hearts with electrocardiographic evidence of LBBB showed lower septal-to-LV free-wall curvature ratios at end-diastole compared to normal controls. CMR can be used to identify and evaluate mechanical dyssynchrony in patients with LBBB. None of the normal controls showed the mechanical features associated with LBBB. Moreover, not all patients with LBBB showed the same degree of mechanical dyssynchrony, which could have implications for CRT.

Strain imaging to predict response to cardiac resynchronization therapy: a systematic comparison of strain parameters using multiple imaging techniques

“…Inhomogeneity of contraction during LBBB reduces left ventricular (LV) pump function efficiency, 4 and CRT subsequently improves LV pump function by restoring mechanical efficiency of the heart. Cardiovascular magnetic resonance (CMR) imaging offers assessment of myocardial strains using feature tracking (CMR-FT) software on standard cine images, [10][11][12] or by the implementation of myocardial taglines (CMR-TAG). [7][8][9] Most of these parameters were introduced using a single-imaging modality, but at present, multiple imaging modalities are available.…”

“…[7][8][9] Most of these parameters were introduced using a single-imaging modality, but at present, multiple imaging modalities are available. Cardiovascular magnetic resonance (CMR) imaging offers assessment of myocardial strains using feature tracking (CMR-FT) software on standard cine images, [10][11][12] or by the implementation of myocardial taglines (CMR-TAG). 8,[13][14][15] Although CMR-TAG is often used as reference technique in scientific research, availability is limited in clinical practice.…”

Cardiac Resynchronization Therapy Optimization: A Comprehensive Approach

“…Tissue tracking by using cine cardiac magnetic resonance (cine-CMR) has shown promising results, with recent studies reporting comparable results for radial dyssynchrony between cine-CMR and STE [26]; CMR can also be used to identify and evaluate mechanical dyssynchrony in patients with LBBB [27]. However, CMR has technical limitations in HF patients with LBBB, and further evaluation is needed before it can be clinically implemented [27].…”

“…However, CMR has technical limitations in HF patients with LBBB, and further evaluation is needed before it can be clinically implemented [27]. Other limitations are high costs and limited availability.…”

Cardiovascular imaging 2016 in the International Journal of Cardiovascular Imaging

“…Reval et al [20] studied patients with left bundle branch block for mechanical features of dyssynchrony and found to more frequently have septal flash, apical rocking, and delayed aortic opening relative to end-diastole and pulmonic valve opening. The delayed aortic valve opening was found to be positively correlated with QRS duration and negatively correlated with ejection fraction.…”