SPC365

Left Bundle Branch Pacing and Mechanical Desynchrony: A Real-World Perspective

Session: SESSÃO DE COMUNICAÇÕES ORAIS 05 – AVANÇOS NA GESTÃO DO RITMO CARDÍACO: UM OLHAR SOBRE AS INOVAÇÕES E OS RESULTADOS DO PACING
Speaker: Margarida De Castro

Congress: CPC 2025
Topic: C. Arrhythmias and Device Therapy
Theme: 09. Device Therapy
Subtheme: 09.1 Antibradycardia Pacing
Session Type: Comunicações Orais
FP Number: ---
Authors: MARGARIDA DE CASTRO; Luísa Pinheiro; Mariana Tinoco; Emídio Mata; Lucy Calvo; Cláudia Mendes; Assunção Alves; Sílvia Ribeiro; Olga Azevedo; Victor Sanfins; João Português; António Lourenço

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><u>Introduction:</u> Left Bundle Branch (LBB) Area Pacing (LBBAP) is a pacing technique designed to mitigate the adverse effects of right ventricular pacing. It is believed to preserve inter- and intraventricular synchrony and reduce QRS duration (QRSd).</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><u>Aim:</u> To evaluate the performance and success rate of LBBAP in a real-world population. To compare the results of LBBAP under unipolar and bipolar&nbsp;configuration. To assess the effect of LBBAP on mechanical dyssynchrony (MD) in the subset of patients (pts) with intraventricular conduction disturbances (IVCD).</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><u>Methods:</u> Retrospective study of pts&nbsp;undergoing LBBAP (intention-to-treat) for bradycardia indication. Performance, success rate and complications&nbsp;are described. </span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">In pts&nbsp;with baseline QRS &gt;110ms, QRSd&nbsp;after LBBAP was measured and compared under unipolar and bipolar configuration.</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">In the subset of pts with IVCD, echocardiographic (echo)&nbsp;evaluation of MD<span style="font-size:8.0pt">&nbsp;</span>was performed offline by 2&nbsp;independent observers in 3&nbsp;scenarios: baseline rhythm and under unipolar and bipolar configuration.</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">MD was defined using septal flash (SF)&nbsp;and interventricular mechanical delay (IVMD)&gt;40ms.</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><u>Results:</u> Of the 68 pts enrolled, LBBAP was successfully performed in 86,8% (n=59). Median left ventricular activation time (LVAT) was 72.05&plusmn;1.65ms. One septal lead displacement and 2&nbsp;cases of loss of LBB capture criteria occurred during a mean follow-up (FU) of 11.85&plusmn;0.86 months. </span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Ventricular threshold showed stability over time. Ventricular lead impedance decreased significantly (<em>p</em>&lt;.001) while R wave amplitude increased (<em>p</em>&lt;.001). </span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Pts&nbsp;with a baseline QRS&gt;110ms (n=31) exhibited a significant reduction in QRSd&nbsp;(134&plusmn;28 <em>vs </em>120&plusmn;4; <em>p</em>=.002), particularly those with LBB block (LBBB). No significant difference was observed between bipolar and unipolar&nbsp;(<em>p=</em>1.000). </span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">A subset of 14 pts&nbsp;with IVCD (3 with right bundle branch block (RBBB) and 11 with LBBB) underwent echo&nbsp;analysis of MD. At baseline, QRSd was 155.50ms (IQR 24.25) and left ventricular ejection fraction (LVEF) was 56.7%&plusmn;2.19.</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">With LBBAP, LVEF remained&nbsp;stable. Regarding interventricular desynchrony, a significant reduction in IVMD was shown&nbsp;(<em>p</em>=.003) with both polarities (42&plusmn;52ms <em>vs</em> 18&plusmn;31ms in unipolar; <em>vs</em> 10&plusmn;15ms in bipolar)&nbsp;with a greater number of pts losing MD criteria&nbsp;with bipolar configuration (<em>p</em>=.004). SF resolved significantly with LBBAP (<em>p</em>=0.030) on both polarities, especially under unipolar<span style="font-size:8.0pt">&nbsp;</span>(<em>p</em>=0.028).</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><u>Conclusion:</u> LBBAP demonstrated high success rates and reduced QRSd, with minimal complications. Polarity configuration&nbsp;showed no significant impact on MD.&nbsp;Given that the unipolar configuration leads to greater battery drain, the polarity must be defined case by case in order to guarantee greater optimization of MD. MD improved in pts with IVCD, so LBBAP may be preferable to minimize the risk of LV dysfunction mediated by dyssynchrony<span style="font-size:8.0pt">&nbsp;</span>in these pts.&nbsp;More research with larger samples is needed for robust conclusions.</span></span></p>