Left ventricular dyssynchrony predicts response and prognosis after cardiac resynchronization therapy

Figures

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  Figure 1. Left: Anatomical model of the four-chamber human heart with a detailed ventricular conduction system. The LBB comprises three fascicles – anterior (red), septal (yellow), and posterior (pink) – and the RBB (blue), all originating from the penetrating His-bundle (a). Bundle branch block conditions are shown in panel (b) The electric field generated by the pacing lead from the extracellular potential (c). Right: The corresponding 12-lead ECG derived from the model under normal sinus rhythm (NSR).

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  Figure 2. Metrics used to assess ventricular synchrony: (A) ECG-derived markers from the 12-lead ECG, (B) left ventricular endocardial and biventricular epicardial activation maps, and (C) activation velocity profiles of the left and right ventricles.

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  Figure 3. Pacing modalities investigated under LBBB (left: (C–E)) and RBBB (right: (F–H)). Strategies applicable to both bundle branch block conditions are shown in the top row (A, B), with LBBB-specific and RBBB-specific pacing configurations presented in the corresponding left and right panels.

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  Figure 4. Simulated 12-lead ECGs for selected pacing modalities under LBBB (left panel: (A–F)) and RBBB (right panel: (G–L)) conditions, with key ECG markers highlighted for each configuration. Red dots next to the ECG markers indicate values exceeding the scoring scheme thresholds. The corresponding star-based rating scheme is detailed in Appendix Table A.1.

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  Figure 5. Activation sequence maps of the LV endocardium (a–g) and biventricular epicardium (A–G) during NSR, LBBB, and selected pacing modalities applied under LBBB conditions. The corresponding star-based rating scheme is detailed in Appendix Table A.2.

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  Figure 6. Activation sequence maps of the LV endocardium (a–g) and biventricular epicardium (A–G) during NSR, RBBB, and selected pacing modalities applied under RBBB conditions. The corresponding star-based rating scheme is detailed in Appendix Table A.2.

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  Figure 7. Analysis of activation velocity in the RV and LV during NSR, bundle branch block, and the corresponding pacing modalities (top row). The deviation between RV and LV activation velocities, referred to as discrepancies, is shown in the middle row. The RMSE of these discrepancies is presented in the bottom row. The left panel corresponds to the LBBB condition, and the right panel to the RBBB condition. Temporal dyssynchrony, illustrated in the top panel, was quantified by calculating the interval difference between the peak velocities. The corresponding star-based rating scheme is detailed in Appendix Table A.3.

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  Figure 8. Full 3D ventricular activation patterns for all simulated conditions. Panel (A) shows NSR, LBBB, and the pacing strategies applied under LBBB; Panel (B) shows NSR, RBBB, and the pacing strategies applied under RBBB. For each condition, activation is shown on the anterior and posterior ventricular surfaces.