Optimizing electrical efficacy of leadless cardiac resynchronization therapy and leadless left ventricular septal pacing: Insights on left and right ventricular activation from electrocardiographic imaging

Figures

• 

  Figure 1. Improvement from baseline (underlying rhythm or RVP for those with CHB) in each activation metric when the optimal pacing modality is chosen (orange bars) compared to when empirical BiV pacing is chosen (blue bars). BiV = biventricular; BIVAT-90 = time for 90% biventricular activation; BiVDI = biventricular dyssynchrony index; LVAT95 = time for 95% left ventricular activation; LVDI = left ventricular dyssynchrony index; RVAT90 = time for 90% right ventricular activation.

• 

  Figure 2. Mean improvement in each activation metric with BiV pacing and at the optimal pacing modality (OPM) compared to baseline (underlying rhythm or RVP for those with CHB)—septal implant subgroup. ∗P < .05. BiV = biventricular; BIVAT-90 = time for 90% biventricular activation; BiVDI = biventricular dyssynchrony index; LVAT95 = time for 95% left ventricular activation; LVDI = left ventricular dyssynchrony index; RVAT90 = time for 90% right ventricular activation.

• 

  Figure 3. Mean improvement in activation metric with BiV, LV only, and LV only with optimized AV delay compared to baseline (underlying rhythm or RVP for those with CHB)—septal implant subgroup. ∗P < .05. AV, atrioventricular; BiV = biventricular; BIVAT-90 = time for 90% biventricular activation; BiVDI = biventricular dyssynchrony index; LV, left ventricular; LVAT95 = time for 95% left ventricular activation; LVDI = left ventricular dyssynchrony index; RVAT90 = time for 90% right ventricular activation.

• 

  Figure 4. Activation maps for patient 2 (septal implant) at each pacing modality. Top row: Activation time maps. The red and blue areas indicate early and late activation. Bottom row: Unipolar electrograms for 1 LV and 1 RV location are indicated in pink on the activation maps above. The dots on the electrograms indicate the annotated activation times. BiV = biventricular; BIVAT-90 = time for 90% biventricular activation; BiVDI = biventricular dyssynchrony index; LV, left ventricular; LVAT95 = time for 95% left ventricular activation; LVDI = left ventricular dyssynchrony index; RVAT90 = time for 90% right ventricular activation.

• 

  Figure 5. Activation maps (top row) and unipolar electrograms for 1 LV and 1 RV location (bottom row) for patient 8 (lateral LV implant) at each pacing modality. BiV = biventricular; BIVAT-90 = time for 90% biventricular activation; BiVDI = biventricular dyssynchrony index; LV, left ventricular; LVAT95 = time for 95% left ventricular activation; LVDI = left ventricular dyssynchrony index; RV, right ventricular; RVAT90 = time for 90% right ventricular activation.

• 

  Figure 6. Improvement in BiVAT-90 at varying AV delays (AVDs) using synchronous LV-only pacing compared to baseline, with example ECGi-derived lead V1 equivalent electrograms (right panels). BiVAT-90 improvement using BiV pacing is demonstrated with the dashed line. A: Patient 2—septal implant. B: Patient 8—lateral implant. AV, atrioventricular; BiV = biventricular; BIVAT-90 = time for 90% biventricular activation; BiVDI = biventricular dyssynchrony index; ECGi, electrocardiographic imaging; LV, left ventricular; LVAT95 = time for 95% left ventricular activation; LVDI = left ventricular dyssynchrony index; RVAT90 = time for 90% right ventricular activation.