Novel echocardiographic tools for predicting a good response to cardiac resynchronization therapy: a narrative review

Figures

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  Figure 1. Typical LBBB contraction pattern visualized using 2D-STE in the apical four-chamber (upper panels) and apical long-axis/three-chamber (lower panels) views (for better clarity of the image, the curves for the apical segments were removed). Early peak strain of the septum is followed by continued stretching during the remainder of systole. Similar patterns are observed in 3AC. 2D-STE, two-dimensional speckle-tracking echocardiography; 3AC, apical long-axis (three-chamber) view; 4AC, apical four-chamber view; LBBB, left bundle branch block.

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  Figure 2. Left ventricular mechanical dispersion in a patient with typical LBBB measured by speckle-tracking echocardiography. The bull's-eye (polar) plot illustrates the timing of peak longitudinal strain in each LV segment. In this patient with LBBB, the early activation of the septal segments (blue areas, shorter time to peak strain) contrasts with the markedly delayed contraction of the lateral wall (yellow zones, longer time to peak strain). This electromechanical dyssynchrony leads to increased mechanical dispersion, quantified as the standard deviation of time-to-peak strain across all segments (PSD = 175.8 ms). The global longitudinal strain (GLS) is reduced (−6.3%), consistent with impaired systolic function and asynchronous contraction typical for LBBB. GLS, global longitudinal strain; LBBB, left bundle branch block; LV, left ventricle; PSD, peak-strain dispersion (standard deviation of the time to peak longitudinal strain across all LV segments).

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  Figure 3. Torsional mechanics evaluated by 2D STE in normal condition (above) and in a patient with dilated cardiomyopathy and LBBB (below). In the normal heart (upper panels), LV twist increases smoothly and progressively during systole to a single, well-defined positive peak around aortic valve closure (AVC), and the twist-rate curve shows an orderly systolic peak followed by a coordinated diastolic untwisting (recoil). In the patient with dilated cardiomyopathy and LBBB (lower panels), peak systolic twist is markedly reduced and temporally delayed, and both the twist and twist-rate curves become irregular and multiphasic with loss of the coordinated systolic peak, reflecting impaired and dyssynchronous rotational mechanics. 2D STE, two-dimensional speckle-tracking echocardiography; AVC, aortic valve closure; LBBB, left bundle branch block; LV, left ventricle.

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  Figure 4. Global and regional myocardial work (MW) abnormalities in left bundle branch block (LBBB). The first panel presents global myocardial work parameters, including global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE), together with the corresponding non-invasive pressure–strain loop and the average constructive vs. wasted work distribution. These values reflect overall mechanical performance of the left ventricle. The subsequent four panels illustrate regional myocardial work patterns characteristic of LBBB. In each regional assessment, the pressure–strain loop demonstrates typical mechanical dyssynchrony, with early paradoxical shortening of the septum and delayed, dominant contraction of the lateral wall. The bull's-eye maps show a consistent pattern of reduced constructive work and low work efficiency in the septal and anteroseptal segments, accompanied by compensatory increases in constructive work within the lateral and posterior walls. Bar graphs further highlight these regional disparities, with markedly elevated wasted work in septal regions and predominance of constructive work…