Abstract 2357: Permanent Para-Hisian Pacing Prevents Detrimental Effects of Apical Right Ventricular Pacing on Cardiac Function: An Acute Three-Dimensional and Tissue Doppler Echocardiographic Evaluation in Chronic Atrial Fibrillation After Atrioventricular Node Ablation
Background: recent studies suggest that right ventricular apical pacing (RVA) may impair cardiac contraction by promoting cardiac dyssynchrony and compromising hemodynamic function.
Aim of the study: to assess acute functional benefit of para-Hisian pacing in preventing detrimental effect of RVA pacing in patients with chronic AF who underwent AV node ablation.
Methods: 17 patients (mean age 75 ± 5 years, mean EF 48 ± 12) with complete AV block after ablation, implanted with a dual chamber pacemaker connected to a screw-in lead positioned in close proximity to the His-bundle and to a conventional RV apical back-up lead, were tested 24 hours after PM implantation. Conventional and TDI echo data were first collected during para-hisian pacing and 15 minutes after RVA pacing. LV volumes were computed in 3D modalities; in 13 patients mechanical dyssynchrony was examined by circumferential and longitudinal strain using speckle-tracking 2D strain analysis from 2D parasternal short axis and apical views and indexed assessing temporal uniformity of strain (TUS). A time plot of strain at each of 18 segments was generated.
Results: para-hisian pacing allowed a significant improvement in MR and TR (mitral jet area 3.8 ± 2.8 vs 6.1 ± 4.2 cm2, p< 0.001; tricuspid jet area 2.6 ± 2.1 vs 5.7 ± 3.6 cm2 ; p= 0.002). Interventricular electromechanical delay (20 ± 21 vs 42 ± 20 msec ; p= 0.002) and aortic pre-ejection interval (123 ± 25 vs 155 ± 25 msec: p= 0.002) improved as well. LV volumes and EF failed to demonstrate any significant difference. Direct comparison between reduction in MR and reversal of RV pre-activation induced by parahisian pacing showed also a significant correlation (r= 0.56; p < 0.05). A similar, but not significant, trend was noted for TR (r = 0.39; p=NS). TUS index, which reflected the 0-order (synchronous) relative to 1-order (dyssynchronous) power, didn’t show significant difference.
Conclusions: para-hisian pacing prevents functional worsening due to RVA pacing, reducing AV regurgitation and interventricular delay. This superiority does not seem to translate in a better intraventricular synchrony as analysed by longitudinal and circumferential strain.