Impact of synchronous atrioventricular delay optimization on left ventricle flow force angle evaluated by echocardiographic particle image velocimetry

Purpose: To evaluate the improvement in electrical synchrony and left ventricle (LV) hemodynamics provided by combining the dynamic atrioventricular delay (AVD) of SyncAVTM CRT and the multiple LV pacing sites of MultiPoint pacing (MPP). Methods: Patients with LBBB and QRS duration (QRSd) > 140 ms implanted with a CRT-D or CRT-P device and quadripolar LV lead were enrolled in this prospective study. During a post-implant follow-up visit, QRSd was measured from 12-lead surface electrograms by experts blinded to pacing configurations. QRSd reduction relative to intrinsic rhythm was evaluated during biventricular pacing (BiV) and MPP for two AVDs: nominal (140/110 ms paced/sensed) and SyncAV (patient-optimized SyncAV offset [10–60 ms] minimizing QRSd). Echocardiography particle imaging velocimetry (Echo-PIV) analysis was performed for each configuration. The resulting hemodynamic force LV flow angle (φ) was analyzed, which ranges from 0o (predominantly base-apex forces) to 90o (predominantly transverse forces). Higher angles indicate more energy dissipation at lateral walls due to transverse flow; lower angles indicate healthier flow aligned with the longitudinal base-apex path of the pressure gradient. Results: Twelve patients (58% male, 17% ischemic, 32±7% ejection fraction, 165 ± 18 ms intrinsic QRSd) completed QRSd and Echo-PIV assessment. Relative to intrinsic rhythm, BiV and MPP with nominal AVD reduced QRSd by 10 ± 9% and 12 ± 9%, respectively. BiV+SyncAV and MPP+SyncAV further reduced QRSd by 19 ± 8%, (p < 0.05 vs. BiV with nominal AVD) and 23 ± 9% (p < 0.05 vs BiV+SyncAV), respectively. Echo-PIV showed similar sequential hemodynamic improvements. LV flow angular orientation during intrinsic activation (46 ± 3o) reduced with BiV+SyncAV (37 ± 4o, p < 0.05 vs intrinsic) and further with MPP+SyncAV (34 ± 4o, p < 0.05 vs BiV+SyncAV). Conclusion: These results suggest that SyncAV may improve electrical synchrony and influence LV flow patterns in patients suffering from heart failure compared to conventional CRT with a fixed AVD, with further improvement observed by combining with MPP.