Left Ventricular Activation Time Research Articles

Difference of ventricular synchrony between LBBP, LBFP and LVSP: A speckle tracking echocardiographic study.

Left bundle branch area pacing (LBBAP) has emerged as a physiological and stable form of pacing. We aim to compare the mechanical ventricular synchrony of LBBP, LBFP, and LVSP. Proximal Left bundle branch pacing (LBBP), left bundle fascicular pacing (LBFP) and left ventricular septal pacing (LVSP) were identified in patients with bradycardia who successfully underwent LBBAP. Patients with left ventricular ejection fraction (LVEF) < 50% or QRS duration (QRSd) ≥ 120ms were excluded. By using electrocardiograms, the left ventricular activation time (LVAT) and QRS duration (QRSd) were measured to examine electrophysiological synchrony. As indications of mechanical synchrony, global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), and peak strain dispersion (PSD) were evaluated by using 2-dimensional speckle tracking echocardiography (2D-STE). In 56 patients, data were collected during LBBP (n = 18), LBFP (n = 16), and LVSP (n = 22). LVSP resulted in a longer LVAT (91.3 ± 14.9ms) than LBBP (77.1 ± 10.8ms, P < 0.05) and LBFP (72.1 ± 9.6ms, P < 0.05), but all three groups had similar QRSd. There were no differences in GLS, GCS, GRS, or PSD between LBBP, LBFP, and LVSP. In patients with normal cardiac function and narrow QRS, though LBBAP with LBB capture resulted in better electrophysiological synchrony than without, the mechanical synchrony of the three groups was comparable.

Predictors of implantation failure in left bundle branch area pacing using a lumenless lead in patients with bradycardia.

Left bundle branch area pacing (LBBAP) is a novel conduction system pacing technique. In this multicenter study, we aimed to evaluate the procedural success, safety, and preoperative predictors of procedural failure of LBBAP. LBBAP was attempted in 285 patients with pacemaker indications for bradyarrhythmia, which were mainly atrioventricular block (AVB) (68.1%) and sick sinus syndrome (26.7%). Procedural success and electrophysiological and echocardiographic parameters were evaluated. LBBAP was successful in 247 (86.7%) patients. Left bundle branch (LBB) capture was confirmed in 54.7% of the population. The primary reasons for procedural failure were the inability of the pacemaker lead to penetrate deep into the septum (76.3%) and failure to achieve shortening of stimulus to left ventricular (LV) activation time in lead V6 (18.4%). Thickened interventricular septum (odds ratio [OR], 2.48; 95% confidence interval [CI], 1.15-5.35), severe tricuspid regurgitation (OR, 8.84; 95% CI, 1.22-64.06), and intraventricular conduction delay (OR, 8.16; 95% CI, 2.32-28.75) were preoperative predictors of procedural failure. The capture threshold and ventricular amplitude remained stable, and no major complications occurred throughout the 2-year follow-up. In patients with ventricular pacing burden >40%, the LV ejection fraction remained high regardless of LBB capture. Successful LBBAP was affected by abnormal cardiac anatomy and intraventricular conduction. LBBAP is feasible and safe as a primary strategy for patients with AVB, depending on ventricular pacing.

Time-related factors predicting a positive response to cardiac resynchronisation therapy in patients with heart failure

This study aimed to identify time parameters predicting favourable CRT response. A total of 38 patients with ischemic cardiomyopathy, qualified for CRT implantation, were enrolled in the study. A 15% reduction in indexed end-systolic volume after 6 months was a criterion for a positive response to CRT. We evaluated QRS duration, measured from a standard ECG before and after CRT implantation and obtained from mapping with NOGA XP system (AEMM); and the delay, measured with the implanted device algorithm (DCD) and its change after 6 months (ΔDCD); and selected delay parameters between the left and right ventricles based on AEMM data. A total of 24 patients presented with a positive response to CRT versus 9 non-responders. After CRT implantation, we observed differences between responders and non-responders group in the reduction of QRS duration (31 ms vs. 16 ms), duration of paced QRS (123 ms vs. 142 ms), and the change of ΔDCDMaximum (4.9 ms vs. 0.44 ms) and ΔDCDMean (7.7 ms vs. 0.9 ms). The difference in selected parameters obtained during AEMM in both groups was related to interventricular delay (40.3 ms vs. 18.6 ms). Concerning local activation time and left ventricular activation time, we analysed the delays in individual left ventricular segments. Predominant activation delay of the posterior wall middle segment was associated with a better response to CRT. Some AEMM parameters, paced QRS time of less than 120 ms and reduction of QRS duration greater than 20 ms predict the response to CRT. ΔDCD is associated with favourable electrical and structural remodelling.Clinical trial registration: SUM No. KNW/0022/KB1/17/15.

Conduction system pacing guided by 3d-electroanatomic mapping system preserves systolic function in paediatric patients

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Paediatric transvenous permanent pacing from alternative ventricular sites including conduction system pacing may prevent ventricular dyssynchrony and systolic dysfunction. These procedures may be difficult and require higher fluoroscopic exposures. The use of three-dimensional-electroanatomic mapping system (3D-EAM) may guide lead implantation toward these alternative sites and reduce fluoroscopic exposure. Purpose of this study is the outcome of 3D-EAM-guided alternative sites pacing in paediatric patients. Methods Retrospective analysis of children and young patients with congenital or acquired complete atrioventricular block (CAVB) with or without other congenital heart disease (CHD) who underwent 3D-EAM-guided transvenous pacing in alternative sites of the subpulmonary ventricle, to perform non-selective His bundle pacing (NSHBP), pacing of ventricular septum close to conduction system (VS-CSP) or outflow tract (OT). 3D-pacing map guided stylet-directed screw-in lead implantation toward septal sites with narrower paced QRS. Procedure and follow-up data were recorded. Parameters of ECG (QRS duration, left ventricular activation time, LVAT), echocardiogram (3D ejection fraction, EF, global longitudinal strain, GLS, of the systemic ventricle) and lead (threshold, sensing) were registered and compared at baseline (pre-implantation) and during follow-up (1-3-year). Data are reported as median (25th-75th centiles). P&amp;lt;0.05 was significant. Results 64 patients (47 females) with CAVB, of whom 11 with CHD, underwent 3D EAM-guided pacing (31 VVIR, 33 DDD) at age 12 (8-15) years, weight 44 (27-57) kg. Prior pacing (RV apex, RV and LV free wall, also biventricular) was present in 27 patients. Pacing sites were: 10 NSHBP, 5 RVOT, 49 VS-CSP (Figure 1). Procedure time was 175 (146-200) min, fluoroscopy exposure was: 3.0 (1.2-5.0) mGy and 90 (33-146) microGy/m2. Echographic parameters at baseline and follow-up are reported in Table 1. Baseline QRS duration 85 (80-130) ms, increased after implantation, 115 (100-120) ms (P=0.002), with LVAT 80 (70-81) ms (Figure 1). In patients with prior pacing, QRS shortened post-implantation: QRS 130 (120-160) vs. 120 (110-125)ms (P=0.004). Lead parameters were good post-implantation and at 3-year follow-up: threshold 0.5 (0.4-0.7) vs. 0.9 (0.7-1.2)V/0.5 ms; R-wave sensing 9 (6-12) vs. 7 (4-9)mV. Four NSHBP patients showed lead dislodgement requiring lead repositioning. Conclusions 3D-EAM-guided alternative site pacing was accomplished with low fluoroscopic exposure. Paced QRS duration was significantly broader than in junctional rhythm but it was significantly narrower than prior epi/conventional site endo pacing. This pacing approach preserved ventricular systolic function in paediatric patients with CAVB at mid-term follow-up.

Comparison of myocardial depolarization spreading after resynchronization with left bundle branch area pacing versus biventricular pacing

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Left bundle branch area pacing (LBBAP) is an emerging new method of cardiac resynchronization therapy (CRT) in patients with left bundle branch block (LBBB). Studies comparing LBBAP with standard biventricular pacing (BiV) have shown similar post-operative shortening of QRS duration and left ventricular activation times. Calculation of equivalent dipole (ED) trajectories from 12-lead high-resolution ECG (hrECG) provides additional insight into myocardial depolarization and may be used for further assessment of left ventricular activation. Purpose The aim of this study was to determine myocardial depolarization patterns with assessment of ED trajectories in patients undergoing CRT with LBBAP or BiV and to compare them to myocardial depolarization patterns of healthy controls. Methods Twenty-five heart failure patients in sinus rhythm and LBBB with indication for CRT were randomized in LBBAP or BiV pacing group. Five-minute supine 12-lead hrECG recordings before and one month after implantation were assessed. LBBAP group was compared to BiV group and both groups were compared to the control of healthy subjects with normal surface ECG. The QRS duration was measured manually by two independent electrophysiologists and averaged. ED trajectories were constructed with the use of inverse algorithm method. The length of ED trajectory was defined as a line between the start and the end of the ED trajectory and its orientation with azimuth and elevation angles. (Figure 1). Results Eleven patients received LBBAP and 14 BiV. There were no differences in baseline characteristics (72% male, 64% non-ischemic cardiomyopathy) between groups. The average baseline QRS duration was 174±20 ms in LBBAP and 180±17 ms in BiV group (p=0.42). QRS duration decreased to 134±14 ms after LBBAP (p&amp;lt;0.01) and 137±11 ms after BiV pacing (p&amp;lt;0.01) and was comparable in both groups (p=0.59). There was also no difference in absolute (p=0.72) or relative (p=0.72) QRS shortening. The absolute and relative ED shortening did not differ (p=0.43 and p=0.38, respectively). At follow-up, analysis of ED trajectories showed a significant difference in elevation angle in both groups (p&amp;lt;0.01). The elevation angle in LBBAP group (6±30°) was significantly different from the angle in BiV group (-44±33°) (p &amp;lt; 0.01), pointing more toward apex of the heart (Figure 2). Furthermore, elevation angle in LBBAP was more similar (absolute difference 49°) to healthy subjects than the elevation angle in BiV group (absolute difference 103°) (p&amp;lt;0.01). There was no intergroup difference in azimuth angle (p=0.07). Conclusion Compared to BiV pacing, resynchronization with LBBAP produces significantly different ED trajectory orientation, which was more comparable to orientation in healthy controls. While both resynchronization methods result in similar QRS narrowing, LBBAP may provide more physiological depolarization of the left ventricle in comparison to BiV.

Impact of left ventricular scar burden on response to two different modalities of conduction system CRT

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Introduction Cardiac resynchronisation therapy (CRT) in the form of His bundle CRT and left bundle area CRT can be more effective than the gold standard, biventricular pacing (BVP). In BVP scar burden is known to predict response whether this is true for these novel modalities is not known. Purpose The purpose of this study was to determine whether left ventricular scar burden assessed using cardiac MRI can be used to predict the electrical and acute haemodynamic response to two novel CRT modalities. Methods Patients with standard CRT indications were recruited. They underwent a pre-procedure cardiac MRI, with late gadolinium enhancement (LGE) to quantify scar. His bundle CRT (His CRT) and left bundle area CRT (LBA CRT) were attempted. The electrical response was measured using high precision non-invasive mapping ECGi (CardioInsight, Medtronic). The haemodynamic response was measured with a high precision protocol. We investigated the impact of scar and baseline electrical characteristic on ECGi and haemodynamic response. Results 26 patients were recruited (85% male, mean age 69 ± 10, with ischaemic cardiomyopathy in 35%). LGE was observed in 96% of cases and the mean (range 1-39%). We found a significant correlation between scar extent and the electrical response with both modalities. There was a significant correlation between a lower scar burden and better electrical response. For His CRT the reduction in left ventricular activation time was better with lower scar burden (R= 0.77, p &amp;lt; 0.01, Picture 1), for LBA CRT for reduction in left ventricular activation was also better with lower scar burden (R = 0.53, p = 0.05, Picture 2). With His CRT there was also a significant correlation between lower scar extent and better acute haemodynamic response ( R = 0.6, p = 0.002) but this was not observed with LBA CRT (R = 0.07, p = 0.77). Conclusion Left ventricular myocardial scar can be used to predict the electrical response to two different conduction system CRT modalities.

Stepwise application of ECG and electrogram based criteria to ensure left bundle branch pacing

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): MPL received the Catalan Society of Cardiology Research Grant in 2019 and 2020 (Catalonia, Spain); the Josep Font Grant (2019-2022) from Hospital Clínic Barcelona (Catalonia, Spain). Background Left bundle branch pacing (LBBP) has emerged as an alternative to biventricular pacing. However, lack of a systematic stepwise application of the left bundle branch (LBB) capture criteria complicates implantation. Objective To define a stepwise application of LBBP capture criteria that will simplify implantation and ensure LBB capture. Methods A cohort of 24 patients from the LEVEL-AT trial who received LBBP and had electrocardiographic imaging (ECGI) at 45 days post-implant were included. The usefulness of ECG and electrogram based criteria to predict accurate LBB capture were analyzed. A two-step approach was developed to ensure LBB capture. The gold standard used to confirm LBB capture was the change in ventricular activation pattern and shortening in left ventricular activation time, assessed by ECGI. Results Twenty-two (91.6%) patients showed LBBP capture on ECGI. All patients fulfilled pre-screwing requisites: lead in septal position in left-oblique projection and W paced morphology in V1. In the first step, presence of either right bundle branch conduction delay pattern (qR or rSR in V1) or left bundle branch capture Plus (QRS ≤120ms) resulted in 95% sensitivity and 100% specificity to predict LBB capture, with an accuracy of 95.8%. In the second step, the presence of selective capture (100% specificity, only 41% sensitivity) or a spike-R&amp;lt;80ms (100% specificity, sensitivity 46%) ensured 100% accuracy to predict LBBP capture. Conclusions Stepwise application of ECG and electrogram criteria ensured an accurate assessment of left conduction system capture.

Left bundle branch area pacing versus biventricular pacing for cardiac resynchronisation therapy

Abstract Funding Acknowledgements Type of funding sources: None. Background Conventional right ventricular pacing induces dyssynchrony and 20% of patients may need upgrade for resynchronisation therapy (CRT). Currently, left bundle branch area pacing (LBBAP) is growing as an alternative for conventional pacing, preserving left ventricular function. Purpose We aimed to describe procedural characteristics of a group of consecutive patients submitted to LBBAP, and to compare the final QRS duration to a group of consecutive idiopathic LBB patients submitted to conventional CRT. Methods Single-centre cohort including consecutive patients submitted to LBBAP or CRT since November 2021. Feasibility, procedure and fluoroscopy times, final QRS duration during pacing immediately after implantation, and periprocedural complications were assessed. Successful implantation of LBBA pacing was defined as a left ventricular activation time (LVAT) &amp;lt; 90ms plus right bundle branch block pattern in V1. Results A total of 91 patients (mean age 75±11 years, 70.3% male, and 43 [47.3%] with LBBAP) were included. Total procedure (63min [50-76] vs. 91min [71-131], p&amp;lt;0.001) and fluoroscopy times (4.1min [2.4-6.4] vs. 13.4min [8.3-23.1], p&amp;lt;0.001) were significantly lower in the LBBAP vs. CRT group, respectively. In the LBBA pacing group, median LVAT was 86ms (IQR 81-94) and no cases of electrode dislocation or perforation at discharge were reported. Final QRS duration was 112ms (IQR 105-125) vs 127ms (IQR 115-143) in the LBBAP vs CRT groups respectively (p&amp;lt;0.001). Conclusion When compared to a group of idiopathic LBB block patients submitted to CRT, LBBAP was faster, required less fluoroscopy time and was associated with final narrower QRS. Further studies are necessary to understand its role in patients with LV dysfunction and indication for resynchronisation therapy.

PO-02-013 EFFICACY OF LEFT BUNDLE BRANCH PACING IN PATIENTS WITH DIFFERENT LEFT BUNDLE BRANCH BLOCK MORPHOLOGIES

Left bundle branch pacing (LBBP) is a novel technique to deliver cardiac resynchronization therapy (CRT) by correcting intrinsic LBBB to achieve electrical and mechanical resynchrony. Whether the efficacy of LBBP is different across different LBBB morphologies has not been reported. To explore the efficacy of LBBP in patients with different LBBB morphologies. Consecutive patients who received LBBP due to either heart failure (HF) with LBBB or atrioventricular block accompanied with a LBBB pattern escape rhythm were recruited. The changes of QRS duration (ΔQRSd) and left ventricular activation time (ΔLVAT) were compared before and after LBBP. Relationships of ΔQRSd and ΔLVAT with cardiac function in HF patients were also explored. HF patients were followed up for at least 6 months. Electrical resynchrony and cardiac function were compared based on 4 major LBBB morphological criteria. Comparison 1: LBBB meeting Strauss criteria vs not; Comparison 2: presence of q wave in lead I and aVL vs not; Comparison 3: presence of QS vs rS morphology of QRS in lead V1; and Comparison 4: presence of S wave in lead V6 vs not. A total of 82 patients were enrolled from January 2018 to August 2022. In Comparison 1, 59 patients had LBBB meeting Strauss criteria vs 23 not meeting criteria. Patients with LBBB meeting Strauss criteria had greater reduction in QRSd (56.95±24.10ms vs 36.83±32.16ms, P<0.05) and LVAT (56.47±14.90ms vs 41.52±17.13ms, P<0.001). Forty-two HF patients met the Strauss criteria had greater LVEF improvement (19.92±6.89% vs 12.41±13.10%, P<0.05) compared to those not meeting the criteria. Comparison 4 included 61 patients without S wave in lead V6 and these patients exhibited better electrical synchrony after LBBP (ΔQRSd: -55.18±24.79ms vs -40.05±33.67ms, P<0.05; ΔLVAT: -55.74±14.70ms vs -41.67±18.55ms, P<0.05) than patients with S wave in V6. Among them, 51 patients without S wave in V6 had HF and showed greater LVEF improvements than those with S wave in V6 (ΔLVEF: 18.65±10.13% vs 6.61±7.78%, P<0.05). Correlation analyses showed significant associations between both ΔQRSd (R=0.55, P <0.001) and ΔLVAT (R=0.39, P <0.01) with LVEF improvement. In multivariate analysis, ΔQRSd>53 ms is an independent predictor of cardiac super response (LVEF improvement>15%). LBBB pattern meeting the Strauss criteria and absence of S wave in lead V6 can predict better electrical resynchrony and LVEF improvement by LBBP.

PO-03-012 STEPWISE APPLICATION OF ECG AND ELECTROGRAM BASED CRITERIA TO ENSURE ELECTRICAL RESYNCHRONIZATION WITH LEFT BUNDLE BRANCH PACING

Left bundle branch pacing (LBBP) has emerged as an alternative to biventricular pacing. However, a systematic stepwise approach to ensure electrical resynchronization is lacking. To define a stepwise application of LBBP criteria that will simplify implantation and guarantee electrical resynchronization. A cohort of 24 patients from the LEVEL-AT trial (NCT04054895) who received LBBP and had electrocardiographic imaging (ECGI) (CardioinsightTM Medtronic, USA) at 45 days post-implant were included. The usefulness of ECG and electrogram based criteria to predict accurate electrical resynchronization with LBBP were analyzed. A two-step approach was developed. The gold standard used to confirm resynchronization was the change in ventricular activation pattern and shortening in left ventricular activation time, assessed by ECGI. Twenty-two (91.6%) patients showed electrical resynchronization on ECGI. All patients fulfilled pre-screwing requisites: lead in septal position in left-oblique projection and W paced morphology in V1. In the first step, presence of either right bundle branch conduction delay pattern (qR or rSR in V1) or left bundle branch capture Plus (QRS ≤120ms) resulted in 95% sensitivity and 100% specificity to predict LBBP resynchronization, with an accuracy of 95.8%. In the second step, the presence of selective capture (100% specificity, only 41% sensitivity) or a spike-R<80ms (100% specificity, sensitivity 46%) ensured 100% accuracy to predict resynchronization by LBBP. Stepwise application of ECG and electrogram criteria ensured accurate assessment of electrical resynchronization with left bundle branch pacing.

PO-03-023 OUTCOMES OF LEFT BUNDLE BRANCH AREA PACING AND ATRIOVENTRICULAR NODE ABLATION IN PATIENTS WITH GROUP III PULMONARY HYPERTENSION AND ATRIAL FIBRILLATION IN REDUCING RECURRENT HOSPITALIZATION

Data on the feasibility of left bundle branch area pacing (LBBAP) and atrioventricular node (AVN) ablation in patients with pulmonary hypertension (PH) are limited. This study investigated the characteristics and outcomes of LBBAP and AVN ablation in patients with PH. This is a retrospective study of patients with PH and AF who underwent LBBAP and AVN ablation at the Cleveland Clinic between January 1, 2019 and August 1, 2022. Pre-procedural, post-procedural, and follow-up patient data were obtained. A total of 11 patients (mean age 74±10 years old, 100% female) with PH and AF who underwent concomitant LBBAP and AVN ablation were included. The etiology of PH was Group III PH in all patients (55% had COPD and 91% had restrictive lung disease), with the average pulmonary arterial systolic pressure (PASP) of 42 mmHg by echocardiogram, FEV1 of 61.9±17.4% predicted, and FVC of 59.9±7.8% predicted. Baseline ejection fraction was 57±10%, QRS duration was 96±20 ms. Concomitant LBBAP and AVN ablation was successful in all patients. Final implant characteristics included: QRS duration was 124±8 ms, left ventricular activation time was 73.7±5.4 ms; threshold 0.6±0.2 mV @ 0.4 ms and was 0.7±0.2 mV @ 0.4 ms on follow-up; impedance was 618±119 ohms and was 545±145 ohms on follow-up. Prior to the LBBAP and AVN ablation procedure, the average number of AF or heart failure (HF) hospitalizations 24 months prior to the procedure was 4.9±5.3, 64% of patients were on antiarrhythmic drugs, and 100% were on either beta-blockers or calcium channel blockers. During a mean follow-up of 21.9±15.3 months after the LBBAP and AVN ablation procedure, the average AF or HF hospitalization was 0.4±0.9, and all patients were no longer on any antiarrhythmic drugs, beta-blockers, or calcium channel blockers. There were no cases of lead dislodgement. In patients with elevated PA systolic pressure, successful LBBAP and AVN ablation with good two-year outcomes are achievable.Tabled 1Pre LBBAP and AVN ablation*Post LBBAP and AVN ablation**P-valueAF or HF hospitalizations4.9 ± 5.30.4 ± 0.9P<0.01On antiarrhythmic drugs7 (63.6%)0 (0%)P<0.01On rate control drugs11 (100%)0 (0%)NALead dislodgement-0 (0%)NALead capture threshold, mV-0.7 ± 0.2NAValues are mean ± SD or n (%) *24 months prior to LBBAP and AVN ablation **Average follow-up of 22±15 months after LBBAP and AVN ablation Open table in a new tab

PO-03-009 3830 LEAD TIP POSITION ON COMPUTED TOMOGRAPHY AND ELECTROPHYSIOLOGIC OUTCOMES IN LEFT BUNDLE BRANCH AREA PACING

Prior studies have evaluated the impact of lead tip distance from the LV blood pool on pacing parameters during left bundle branch area pacing (LBBAP). Few studies to date have evaluated lead tip angulation within the interventricular septum (IVS) in relation to pacing morphology on surface 12-lead ECG. To establish the observed lead tip trajectories within the interventricular septum encountered during LBBAP. Patients who underwent LBBAP implantation between 02/2019-07/2022 were retrospectively analyzed. Patients who underwent computed tomography (CT) of the chest or thorax post-implantation for any indication were included for analysis. Lead distance from the mitral annulus, lead tip distance from LV blood pool (DEBP), lead tip angle of incidence (AOI), and post-implantation electrocardiographic and pacing parameters were analyzed (Figure 1a). 38 pts were identified, out of whom 37 pts had CT images available for analysis. In the 20 pts with contrast enhanced imaging, DEBP was 2.1±1.8mm. Average observed AOI was 10.9±20.6 degrees in the axial plane (long axis; Figure 1b) and 12.4±22.2 degrees in the saggital plane (short axis; Figure 1c). Lead impedance at time of implant did not correlate strongly with axial or sagittal angle of incidence (R2=0.01 and 0.03 respectively) or with distance from LV endocardial blood pool (R2=0.04). The most commonly encountered lead insertion locations included the mid-septal (22, 59.5%), basal septal (4, 10.8%), and mid antero-septal (3, 8.1%) positions (Figure 1d). Average lead tip distance from the AV annulus was 36.6±8.2mm. Mean paced QRSd for the basal, mid, and apical cohorts were 122.5±8.1ms, 118.5±10.7ms, and 120±15.9ms, respectively. Left ventricular activation time in lead V6 numerically decreased for more apical positions, with basal, mid and apical values of 84.4±11.9ms, 73.9±10.6ms, and 69.5±6.0ms, respectively. Lead threshold, impedance, and sensed R waves were stable at time of 2 year follow-up. No analyzed patients underwent lead revision. Multiple lead tip orientations are observed in relation to the IVS during successful LBBAP. More apical lead tip positioning may result in numerically lower LVAT values, despite similar overall QRS duration.

PO-01-182 CONDUCTION SYSTEM PACING REMAINS EFFECTIVE IN PATIENTS WITH NON-CONDUCTIVE SEPTAL SCAR BUT SURVIVING PURKINJE

Conduction system pacing (CSP), delivered through His bundle (HBP) or left bundle pacing (LBP), is a novel effective treatment for patients with proximal left bundle branch block (LBBB). The presence of septal scar is known to affect response to CSP, but the effect of scar conduction properties on response to CSP has never been investigated. To quantify the effect of scarred myocardium and Purkinje conduction velocity (CV) on response to CSP using computational modelling. We computed ventricular activation on 24 four-chamber heart geometries generated from heart failure patients, inclusive of septal scar and His-Purkinje networks with proximal LBBB. We simulated LBBB baseline, selective HBP and selective LBP with optimized atrioventricular delay (AVD) with the following myocardium and Purkinje conduction properties within the scar: A) non-conductive myocardium and Purkinje; B) slow conductive myocardium and Purkinje (10% CV compared to healthy tissue); C) non-conductive myocardium and slow conductive Purkinje. Response was quantified with 90% biventricular (BIVAT90) and 95% left ventricular (LV) activation times. HBP and LBP were ineffective in the presence of non-conductive septal myocardium and Purkinje (LVAT95: baseline 130.9±11.2ms vs HBP 129.4±13.9ms vs LBP: 130.2±11.6, P=0.9, Fig A,D). CSP reduced BIVAT90 and LVAT95 compared to baseline when the myocardium and the Purkinje within the scar were slow but conductive (BIVAT90: baseline 120.7±9.5ms, HBP: 98.1±11.2ms, LBP: 82.9±9.4ms, P<0.01 vs baseline, Fig B,D). CSP remained effective when the scarred myocardium was non-conductive and the Purkinje was slow but conductive (BIVAT90: baseline 115.7±11.2ms, HBP: 84.4±7.6ms, LBP: 64.3±8.6ms, P<0.01 vs baseline, Fig C,D). The presence of septal scar does not necessarily make CSP ineffective. CSP remains effective in patients with LBBB and septal scar if the Purkinje within the scar is still conductive.

Left bundle branch area pacing: How to prevent a coronary venous fistula.

Left bundle branch area pacing: How to prevent a coronary venous fistula.

Approach to Left Bundle Branch Pacing.

Cardiac pacing refers to the implantation tool serving as a treatment modality for various indications, the most common of which is symptomatic bradyarrhythmia. Left bundle branch pacing has been noted in the literature to be safer than biventricular pacing or His-bundle pacing in patients with left bundle branch block (LBBB) and heart failure, thereby becoming the focus of further research on cardiac pacing. A review of the literature was conducted using a combination of keywords, including "Left Bundle Branch Block," "Procedural techniques," "Left Bundle Capture," and "Complications." The following factors have been investigated as key criteria for direct capture: paced QRS morphology, peak left ventricular activation time, left bundle potential, nonselective and selective left bundle capture, and programmed deep septal stimulation protocol. In addition, complications of LBBP, inclusive of septal perforation, thromboembolism, right bundle branch injury, septal artery injury, lead dislodgement, lead fracture, and lead extraction, have also been elaborated on. Despite clinical implications based on clinical research comparing the use of LBBP with other forms such as right ventricular apex pacing, His-bundle pacing, biventricular pacing, and left ventricular septal pacing, a paucity in the literature on long-term effects and efficacy has been noted. LBBP can thus be considered to have a promising future in patients requiring cardiac pacing, assuming that additional research on clinical outcomes and the limitation of significant complications such as thromboembolism can be established.

Comparison of Depolarization and Repolarization Parameters in Left vs. Right Ventricular Septal Pacing-An Intraprocedural Electrocardiographic Study.

Compared with conventional right ventricular septal pacing (RVSP), several studies have shown a net clinical benefit of left bundle branch area pacing (LBBAP) in terms of ejection fraction preservation and reduced hospitalizations for heart failure. The purpose of this study was to compare acute depolarization and repolarization electrocardiographic parameters between LBBAP and RVSP in the same patients during the LBBAP implant procedure. We prospectively included 74 consecutive patients subjected to LBBAP from 1 January to 31 December 2021 at our institution in the study. After the lead was placed deep into the ventricular septum, unipolar pacing was performed and 12-lead ECGs were recorded from the distal (LBBAP) and proximal (RVSP) electrodes. QRS duration (QRSd), left ventricular activation time (LVAT), right ventricular activation time (RVAT), QT and JT intervals, QT dispersion (QTd), T-wave peak-to-end interval (Tpe), and Tpe/QT were measured for both instances. The final LBBAP threshold was a 0.7 ± 0.31 V at 0.4 ms duration with a sensing threshold of 10.7 ± 4.1 mV. RVSP produced a significantly larger QRS complex than the baseline QRS (194.88 ± 17.29 ms vs. 141.89 ± 35.41 ms, p < 0.001), while LBBAP did not significantly change the mean QRSd (148.10 ± 11.52 ms vs. 141.89 ± 35.41 ms, p = 0.135). LVAT (67.63 ± 8.79 ms vs. 95.89 ± 12.02 ms, p < 0.001) and RVAT (80.54 ± 10.94 ms vs. 98.99 ± 13.80 ms, p < 0.001) were significantly shorter with LBBAP than with RVSP. Moreover, all the repolarization parameters studied were significantly shorter in LBBAP than in RVSP (QT-425.95 ± 47.54 vs. 487.30 ± 52.32; JT-281.85 ± 53.66 vs. 297.69 ± 59.02; QTd-41.62 ± 20.07 vs. 58.38 ± 24.44; Tpe-67.03 ± 11.19 vs. 80.27 ± 10.72; and Tpe/QT-0.158 ± 0.028 vs. 0.165 ± 0.021, p < 0.05 for all), irrespective of the baseline QRS morphology. LBBAP was associated with significantly better acute depolarization and repolarization electrocardiographic parameters compared with RVSP.

The effectiveness and feasibility of using multi-lead ECG monitoring combined with a programmed intracavitary ECG to complete left bundle branch area pacing.

Left bundle branch area pacing (LBBaP) as an alternative method for delivering physiological pacing, is difficult for many primary hospitals that lack the electrophysiological multichannel recorder to carry out. We hope to find a simple and feasible method that combines the multi-lead surface electrocardiogram (ECG) monitoring and the intracavity ECG of the pacing programmer to achieve LBBaP. A total of 50 patients with bradycardia indications who attempted permanent pacemaker implantation were included in this study. We referred to multi-lead surface ECG monitoring and pacing system analyzer (PSA), combined with the nine-zone pacing method of the LBBaP, to complete LBBaP. We assessed multiple parameters to verify whether the LBBaP was successfully achieved and used univariable analysis of variance for repeated measures to judge the feasibility and effectiveness of LBBaP without the electrophysiological multichannel recorder. LBBaP was successfully archived without the electrophysiological multichannel recorder in 44 of 50 patients (88%). In the study, paced QRS duration and the stimulus to peak left ventricular activation time (Sti-LVAT) were 117.04±10.34ms and 71.10±7.91ms and had no significant changes in the 3-month follow-up. The unipolar pacing threshold and R-wave amplitudes were 0.85±0.32V and 10.36±5.24mV at baseline respectively, which also showed stability during the 1-month and 3-month follow-up. During the 3-month follow-up, no lead-related complication was recorded. It is effective and feasible to achieve LBBaP combining the multi-lead ECG monitoring and the intracavitary ECG of PSA without the electrophysiological multichannel recorder, which could be an alternative to perform LBBaP.

Left Bundle Branch Pacing for Bradycardia in Non-obstructive Hypertrophic Cardiomyopathy Patients: Feasibility, Safety, and Effect.

Left bundle branch pacing (LBBP) is as an innovative physiological pacing approach. The research on LBBP in non-obstructive hypertrophic cardiomyopathy (NOHCM) patients is scarce. This study aimed to assess the feasibility, safety, and effect of LBBP in bradycardia NOHCM patients with permanent pacemaker (PPM) implantation indication. Thirteen consecutive patients with NOHCM who received LBBP were retrospectively enrolled as a hypertrophic cardiomyopathy (HCM) group. Following 1:3 matching, 39 patients without HCM were randomly matched as a control group. Echocardiographic index and pacing parameters were collected. The successful LBBP was achieved in 96.2% of all cases (50/52), and the success rate of the HCM group was 92.3% (12/13). In the HCM group, the paced QRS duration (from the pacing stimulus to QRS end) was 145.6±20.8 ms. The stimulus to left ventricular activation time (s-LVAT) was 87.4±15.2 ms. In the control group, the paced QRS duration was 139.4±17.2 ms, and the s-LVAT was 79.9±14.1 ms. During the implantation, R-wave sensing and the pacing threshold of the HCM group were significantly higher than the control group (20.2±10.5 vs 12.5±5.9 mV, P < 0.05; 0.8±0.3 vs 0.6±0.2V/0.4 ms, P < 0.05). In addition, the fluoroscopic duration and procedural duration were longer in the HCM group (14.8±8.3 vs 10.3±6.6min, P = 0.07; 131.8±50.5 vs 101.4±41.6 min, P < 0.05). The lead insertion depth was 15±2 mm in the HCM group, and no procedure-related complications occurred. During the 12-month follow-up, pacing parameters remained stable and were of no significance in the two groups. The cardiac function did not deteriorate, and the left ventricular outflow tract gradient (LVOTG) did not increase in the follow-up. LBBP might be feasible and safe for NOHCM patients with conventional bradycardia pacing indication, and there is no deterioration in cardiac function and LVOTG of patients with NOHCM.

A novel approach for developing left bundle branch pacing and left bundle branch block in a canine model.

Left bundle branch pacing (LBBP) has shown the benefits in the treatment of dyssynchronous heart failure (HF). The purpose of this study was to develop a novel approach for LBBP and left bundle branch block (LBBB) in a canine model. A "triangle-center" method by tricuspid valve annulus angiography for LBBP implantation was performed in 6 canines. A catheter was then applied for retrograde His potential recording and left bundle branch (LBB) ablation simultaneously. The conduction system was stained to verify the "triangle-center" method for LBBP and assess the locations of the LBB ablation site in relation to the left septal fascicle (LSF). The mean LBB potential to ventricular interval and stimulus-peak left ventricular activation time were 11.8 ± 1.2 and 35.7 ± 3.1 ms, respectively. The average intrinsic QRS duration was 44.7 ± 4.7 ms. LBB ablation significantly prolonged the QRS duration (106.3 ± 8.3 ms, p < .001) while LBBP significantly shortened the LBBB-QRS duration to 62.5 ± 5.3 ms (p < .001). After 6 weeks of follow-up, both paced QRS duration (63.0 ± 5.4 ms; p = .203) and LBBB-QRS duration (107.3 ± 7.4 ms; p = .144) were unchanged when comparing to the acute phase, respectively. Anatomical analysis of 6 canine hearts showed that the LBBP lead-tip was all placed in LSF area. The new approach for LBBP and LBBB canine model was stable and feasible to simulate the clinical dyssynchrony and resynchronization. It provided a useful tool to investigate the basic mechanisms of underlying physiological pacing benefits.

Reversal of pacing-induced cardiomyopathy after left bundle branch area pacing: a case report

BackgroundConventional right ventricular apex (RVa) pacing increases the risk of pacing-induced cardiomyopathy (PICM), especially in elderly patients with a higher ventricular pacing burden. Left bundle branch area pacing (LBBAP) has been suggested as an alternative to conventional RVa pacing. However, there is a lack of evidence that LBBAP may reverse PICM. We report a case of a reversal of PICM after LBBAP.Case presentationAn 81-year-old woman with a history of complete atrioventricular block and baseline QRS duration of 142 ms received permanent pacemaker implantation with dual pacing. The ventricular lead was placed at the apical direction and paced QRS duration was 146 ms. After 8 months, the patient visited with acute heart failure. The patient’s ventricular pacing burden was > 99%, and echocardiography found severe depression of left ventricular ejection fraction (LVEF, 30%), left ventricular dyssynchrony, and global hypokinesia. Despite 3 months of optimal medical management of heart failure, there was minimal improvement in LVEF (35%) and ventricular dyssynchrony persisted. The patient's presentation was consistent with PICM. LBBAP was performed with a stylet-driven lead and a delivery sheath (Biotronik Selectra 3D, Biotronik, Berlin, Germany). The lead was placed at the area of the left bundle branch trunk and non-selective LBBAP was achieved with a left ventricular activation time of 71 ms, paced QRS duration of 110 ms, and bipolar stimulation to QRS end of 136 ms. After a month, echocardiography found improved LVEF (53%) and N-terminal Pro-B-Type natriuretic peptide was decreased from 1011 to 645 pg/mL. The patient was relieved from dyspnea.ConclusionsWe report a case that PICM was resolved after LBBAP. LBBAP could be a rescue therapy for PICM induced by conventional RVa pacing.