Left Ventricular Activation Research Articles

Initial experience of left bundle branch area pacing using stylet-driven pacing leads: A multicenter study.

Left bundle branch area pacing (LBBAP) has been performed exclusively using lumen-less pacing leads (LLL) with fixed helix design. This registry study explores the safety and feasibility of LBBAP using stylet-driven leads (SDL) with extendable helix design in a multicenter patient population. This study prospectively enrolled consecutive patients who underwent LBBAP for bradycardia pacing or heart failure indications at eight Belgian hospitals. LBBAP was attempted using SDL (Solia S60; Biotronik) delivered through dedicated delivery sheath (Selectra3D). Implant success, complications, procedural, and pacing characteristics were recorded at implant and follow-up. The study enrolled 353 patients (mean age 76 ± 39 years, 43% female). The mean number of implants per center was 25 (range: 5-162). Overall, LBBAP with SDL was successful in 334/353 (94%), varying from 93% to 100% among centers. Pacing response was labeled as left bundle branch pacing in 73%, whereas 27% were labeled as myocardial capture. Mean paced QRS duration and stimulus to left ventricular activation time measured 126 ± 21 ms and 74 ± 17. SDL-LBBAP resulted in low pacing thresholds (0.6 ± 0.4 V at 0.4 ms), which remained stable at 12 months follow-up (0.7 ± 0.3, p = .291). Lead revisions for SDL-LBBAP occurred in 5 (1.4%) patients occurred during a mean follow up of 9 ± 5 months. Five (1.4%) septal coronary artery fistulas and 8 (2%) septal perforations occurred, none of them causing persistent ventricular septal defects. The use of SDL to achieve LBBAP is safe and feasible, characterized by high implant success in low and high volume centers, low complication rates, and stable low pacing thresholds.

Electrocardiographic analysis of left bundle branch area pacing induced right ventricular activation delay

Abstract Funding Acknowledgements Type of funding sources: None. Background Left bundle branch area pacing (LBBAP) aims to capture the area of left bundle branch, resulting in fast activation of the left ventricle (LV) but delayed right ventricular (RV) activation. During intrinsic cardiac conduction, delayed RV activation results on the electrocardiogram (ECG) in a right bundle branch block (RBBB) pattern and is generally considered benign. As such, LBBAP-induced delayed RV activation is thought not to be harmful. However, to what extent left and right ventricular activation times during LBBAP resembles that of healthy individuals with acquired RBBB is currently not known. Methods Individuals with incomplete RBBB (iRBBB), complete RBBB (cRBBB) and LBBAP were included. Standard twelve lead electrocardiograms (ECG) were stored and analysed digitally using the MUSE ECG database. QRS duration was measured as global QRS duration. Left and right ventricular activation times were estimated by R-wave peak time in lead V6 (V6RWPT) and R’ peak time in lead V1 (V1RWPT), respectively. Delayed RV activation was further characterized by duration and area of R’ wave in lead V1. Results Paced QRS duration during LBBAP (n=86) measured 129±15ms whereas QRS duration of iRBBB (n=422) and cRBBB (n=223) individuals measured 103±8ms and 142±17ms respectively (p<0.001). V6RWPT during LBBAP (47±15ms) was significantly longer than V6RWPT in iRBBB (40±5ms) and cRBBB (39±7ms) (p<0.001). With LBBAP, V1RWPT (83±15ms) became delayed compared to iRBBB (74±9ms, p< 0.001), but remained shorter in comparison to cRBBB (98±17ms, p<0.001). Patients with LBBAP were further characterized by V1 R’ duration and R’ area which were shorter and smaller compared to cRBBB but similar to iRBBB individuals. Conclusion LBBAP-induced delayed RV activation resembles electrocardiographically more closely to the delayed RV activation as seen in individuals with incomplete rather than complete RBBB. Left ventricular activation times remain slightly prolonged during LBBAP as compared to RBBB individuals.

Evaluation of left ventricular dyssynchrony by ultra-high-frequency ECG in patients with non-LBBB conduction disorder treated with cardiac resynchronization therapy

Abstract Funding Acknowledgements Type of funding sources: None. Introduction LBBB is a reliable left ventricular (LV) electrical dyssynchrony indicator. Patients with RBBB/IVCD are a heterogeneous group, where even with "larger" QRS complex expansion, LV dyssynchrony may not be present. Ultra-high-frequency (UHF) 14-lead ECG is a non-invasive method based on signal averaging that allows better assessment of local electrical activation of the ventricles than standard ECG. Our study aims to test the hypothesis of the usefulness of UHF ECG to select non-LBBB patients for cardiac resynchronization therapy (CRT) based on evidence of electrical dyssynchrony. Methods Using UHF ECG we analysed patients who underwent CRT implantation. The groups of patients with RBBB, IVCD, and LBBB were compared and the presence of electrical dyssynchrony (e-DYS) as a parameter of global ventricular activation, and delayed activation of the left ventricular lateral wall (LVLWd) as a marker of LV intravenricular dyssynchrony was assessed. Results UHF ECG was recorded in 49 patients treated with CRT. IVCD patients had lower e-DYS compared to LBBB patients (26±17 ms vs. 86±20 ms; p<0.0001) and lower LVLWd (26±16 ms vs. 83±22 ms; p<0.0001). In RBBB patients, e-DYS was -52±22 ms, corresponding to right ventricular delay. Delayed left ventricular free wall activation ("RBBB masking LBBB" activation pattern) was not found in any RBBB patient. Conclusion UHF ECG appears to be a promising tool to detect LV electrical dyssynchrony in non-LBBB candidates for cardiac resynchronization therapy. Delayed left ventricular free wall activation was not found in any RBBB patient. Our findings are consistent with the lack of effect of CRT in this group of patients.

Left bundle branch area pacing: feasible, safe and successful

Abstract Funding Acknowledgements Type of funding sources: None. Background Frequent conventional pacing of the right ventricle (RVP) can be deleterious. In the last 3 years, pacing of the left bundle branch area (LBBAP) has experienced great development for the specific conduction system stimulation, displacing His bundle pacing. Methods Prospective study of consecutive patients who received LBBAP for bradicardia or heart failure indications (bailed-out strategy). A 3830-69 lead was implanted using a C-315-His sheath, aiming for left bundle branch pacing (LBBP) in all procedures. We used current criteria to define LBAPP, LBBP (selective or non-selective), and left ventricle septal pacing (LVSP). The purpose of our study was to analyze the feasibility of changing from RVP to LBBAP in bradycardia indication, or LBBAP after sinus coronary lead failure, focusing on the safety and success of the technique. Results We enrolled 149 consecutive patients from our hospital who underwent a LBBAP attempt between Feb/20 and Jan/22. Baseline characteristics and pacing indications are shown in table 1. Mean baseline QRS width was 119.3 ± 29.5 ms. 48.3% of patients showed wide (>120 ms) QRS complex. LBBAP was considered successful in 97.3% of the patients: 78.9% was interpreted as LBBP (44.4% considered selective), and 21.1% as LVSP. Regarding the achievement of criteria to define LBBAP, R´ wave in V1 was obtained in 83% of patients, left bundle branch potential (LBBPo) in 44%, with a mean interval time of LLBPo-local ventricular electrogram of 18.1 ± 6.0 ms. The left ventricular activation time (LVAT) in V5/V6 was 80.1 ± 11.3 ms, and in aVL was 83.7 ± 14.7 ms. Mean procedure time was 21.3 ± 18.0 minutes and the fluoroscopy time was 9.9 ± 10.1 minutes. Mean paced QRS was 115.5 ± 14.8 ms, with mean variation from the baseline QRS of + 4.31 ± 24.7 ms. Mean implant parameters were: R wave amplitude 10.9 ± 5.4 mV, impedance 1004.1 ± 233.6 ohms (monopolar), and threshold 0.94 ± 0.65 V (0.4 ms). In the first follow-up (85.2 ± 38.0 days), parameters were similar or better (Table 1). There were only two patients (1.1%) who presented complications related to the technique: one lead dislodgement and one significant threshold increase. When comparing the first 30 cases with the following ones (Table 2), there was a significant difference in the percentage of implant success (90% vs. 99.1%, p = 0.026), in the LVAT-aVL (94.8 ± 13.6 vs. 81.1 ± 13.7 ms, p <0.001) and a marked trend in the LVAT-V5/V6 (83.8 ± 11.8 vs. 79.3 ± 11.1 ms, p = 0.06). A trend towards a shorter duration of paced QRS was found in the initial cases (110.9 ± 11.8 vs. 116.6 ± 15.2, p = 0.07), which could be explained by the lower percentage of SLBPP (23.5% vs. 48%, p = 0.05). Conclusions LBBAP as elective type of ventricular pacing is feasible, with a high success rate, which improves with the learning curve, showing safety and efficacy. The procedure and fluoroscopy times seem acceptable, considering that know-how may help reduce them.

Comparison between his-bundle pacing and biventricular pacing as cardiac resynchronization therapy for heart failure patients: a systematic review and meta-analysis

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac resynchronization therapy (CRT) has demonstrated significant improvements in cardiovascular outcomes of selected heart failure patients. However, conventional biventricular CRT implantation can be challenging due to unfavorable coronary sinus anatomy, leads to lead instability, poor capture, and insufficient cardiac resynchronization. His-bundle pacing has gained interest as alternative strategy for patients underwent biventricular CRT implantation when coronary sinus lead implantation is unsuccesful or in non-responder cases. Purpose This study aims to compare the efficacy of his-bundle pacing and biventricular pacing in improving electrocardiographic, echocardiographic, and clinical parameters of heart failure patients that required resynchronization therapy. Methods A search for eligible studies was conducted until August 2021 on three databases (PubMed, ScienceDirect, ProQuest). Included studies were evaluated for risk of bias. Our primary outcomes of interest were mean difference in QRS duration, left ventricular ejection fraction (LVEF), and change in systolic blood pressure (SBP). We also investigated left ventricular activation time, left ventricular dyssynchrony index, left ventricular end-systolic volume (LVESV), New York Heart Association (NYHA) functional class, 6-minute walk test, quality of life, heart failure hospitalization and cardiovascular or all cause death. Review Manager (RevMan) 5.4 was utilized to compute mean differences. Results We identified five studies from 2010 to 2019, involving 95 heart failure patients underwent CRT implantation. Pooled analysis showed that his-bundle pacing resulted in significant narrowing of QRS duration compared to biventricular pacing [Mean Difference -23.17 ms (95% CI -36.10, -10.24; p=0.0004; I2=0.63)]. Left ventricular activation time and left ventricular dyssynchrony index were significantly improved in his bundle pacing. There were no significant differences of changes in LVEF, LVESV, and SBP. Clinical parameters such as NYHA functional class, 6-minute walk test, and quality of life were significantly improved in both pacing modality. No significant difference in heart failure hospitalization and cardiovascular or all cause mortality. Conclusion His-bundle pacing delivers better decrease of QRS duration, also reduction in left ventricular activation time and left ventricular dyssynchrony index compared to biventricular pacing. These suggests that his-bundle pacing is a reasonable alternative option for cardiac resynchronization therapy.

Echocardiographic outcomes of left bundle branch versus deep septal pacing

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Left bundle branch area pacing (LBBAP) is a rising technique that aims to preserve physiologic activation of the left ventricle. However, left bundle branch capture (LBBC) is not always achieved despite good progression of the lead into the interventricular septum, leading to what has been called deep septal pacing (DSP). In the latter, the conduction system is not captured, whose consequences on systolic function are not well known. The goal of the present work is to evaluate the repercussion on transthoracic echocardiogram (TTE) of capturing or not the left bundle branch. Methods Unicentric prospective study where patients in whom LBBAP was performed were consecutively included if: Previous TTE was available with a left ventricular ejection fraction (LVEF) > 40% A follow-up TTE performed >30 days after the implant was available Ventricular pacing was >40% of the time at the device follow-up LBBC was accepted if any of the following were present: Sudden change of QRS morphology during ventricular threshold test Left bundle potential was registered with an interval to left ventricular activation time (LVAT) equal to stimulus-LVAT time. T-test was used to compare means between continuous variables and chi-squared to test differences between groups in the categorical ones. Two-tailed p value <0.05 was considered statistically significant. Results 20 patients were included, 12 (60%) males, with a mean age of 74.4±10.6 years. Half of the patients (n=10) fulfilled LBBC criteria whereas the rest received DSP. Image 1 summarizes baseline characteristics and differences observed in the control TTE. After a median follow-up of 322 (interquartile range 114-325) days, LVEF increased in LBBC group whereas it decreased in DSP patients. Image 2 shows a slopegraph of the evolution of LVEF by type of stimulation. Indexed LVEDV increased in DSP group, but it was diminished in LBBC patients (p=0.03). Control TTE showed no significant differences in other parameters. Conclusions In non-selected patients with comparable pre-implant baseline characteristics, deep septal pacing was associated with a decrease in LVEF and an increase in LVEDV, while LBB capture showed better outcomes in these two parameters.

Longer left ventricular activation time is associated with lower mortality and risk of heart failure hospitalization in CRT recipients

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): ALF Governmental Funding within the Swedish health care system Introduction Cardiac resynchronization therapy (CRT) is an established treatment for heart failure in selected patients. Longer QRS duration has been showed to correlate to clinical outcome, but measures global activation time, rather than the left ventricular dyssynchrony that CRT aims to correct. This study therefore evaluated the incremental value of using Left Ventricular Activation Time (LVAT) for prediction of outcome after CRT. Methods Medical records of 445 patients receiving CRT implants at a large-volume tertiary care center were retrospectively evaluated. Digital electrocardiograms (ECG) before and after CRT implantation were collected and ECG parameters were analysed in relation to a primary composite endpoint of time to heart failure hospitalisation or death from any cause. LVAT was defined as time from QRS onset to maximum positive deflection in lead V6 (Figure 1). Results Patients were followed for up to 6 years (median 2.7), during which 147 patients (33%) reached the primary endpoint (93 deaths and 103 heart failure hospitalisations). LVAT was measured pre-implant (median 71ms [58-88]) and post-implant (median 74ms [57-96]). There was no CRT-mediated reduction in LVAT (delta -2.3ms +/-31ms, p=0.27). When divided into quartiles, preoperative LVAT had a significant association with clinical outcome (HR 0.76 [0.64-0.90] per increasing quartile, p=0.001), also shown in a median-split Kaplan Meier curve (Figure 2, log rank p=0.001). Multivariate hazard ratio (adjusted for relevant clinical variables) was 0.83; [0.69-0.99]; p=0.047). There was an interaction between LVAT and ECG morphology (p=0.033), and when ECG groups were analysed separately, there was only a significant result for those with native left bundle branch block morphology. Post-implant LVAT, or change in LVAT, did not correlate with the primary endpoint (p=0.25 and p=0.38 respectively. Conclusion In CRT recipients, longer pre-implant LVAT was associated with lower risk of heart failure hospitalisation and death during a follow-up of up to 6 years. This association was mainly seen in patients with native LBBB prior to implant. No association was seen with post-CRT LVAT and clinical outcome. If confirmed in prospective trials, evaluation of preoperative LVAT may help optimise patient selection for CRT.

Preliminary experience of permanent left bundle branch area pacing using stylet-directed pacing lead without delivery sheath.

Left bundle branch area pacing (LBBAP) aims to capture the cardiac conduction system in area of the left bundle branch. Currently, LBBAP is mainly performed using lumen-less pacing leads (LLLs) with preshaped sheath. However, the data on LBBAP with stylet-driven leads (SDLs) without sheath is limited. This study presents the feasibility, safety, and pacing characteristics of LBBAP using SDLs without the support of sheath. A total of 25 patients with bradycardia indications who received LBBAP implantation with an attempt of SDL (FINELINE II 4471 lead, Boston Scientific, MA, US) between August 2020 and April 2021 at Sir Run Run Shaw Hospital were included in this retrospective cohort study. Twenty of them finally were paced with SDL in priority (SDL-LBBAP group). Twenty propensity score matching patients who underwent LBBAP with LLL (Select Secure 3830 lead, Medtronic, MN, US) and 20 right ventricular septal pacing (RVSP) with regular active fixation lead respectively in the same period (the LLL-LBBAP group and RVSP group) were compared using ECG characteristics, pacing parameters and complications during 6-month follow-up. LBBAP was successful with SDL in 23 of 25 patients (92%) and 20 of them were paced with SDL first. In the SDL-LBBAP group, the average age was 70.4 ± 8.2 years, and 55% of patients were male. Paced QRS duration and the stimulus to peak left ventricular activation time (Sti-LVAT) in SDL-LBBAP group were similar with those in LLL-LBBAP group and significantly shorter than those in RVSP group (126.1±14.1ms vs. 124.8±10.9ms, p=1.00; 77.7±11.2ms vs. 73.5±9.3ms, P=.75; 126.1±14.1ms vs. 147.7±22.5ms, P<.001; 77.7±11.2ms vs. 97.0±13.2ms, P<.001). The pacing threshold and R-wave amplitude of SDL-LBBAP group were 0.53±0.18V and 11.53±3.63mV at baseline respectively, which were comparable with the other two groups. During the 6-month follow-up, the pacing parameters remained stable and no lead-related complications were recorded. It is feasible and safe to use stylet-directed pacing lead for permanent LBBAP without a delivery sheath. Similar to LLL, LBBAP using SDL showed stable parameters and narrower paced QRS duration compared with RVSP, which could be an alternative to LLL in LBBAP.

Left bundle branch area pacing: predictors of success

Abstract Funding Acknowledgements Type of funding sources: None. Background Frequent conventional pacing of the right ventricle can be deleterious. In the last three years, left bundle branch area pacing (LBBAP) has experienced a great development as a tool for the specific conduction system stimulation. Methods Single-center prospective study of consecutive patients with attempted LBBAP for bradycardia or heart failure indications (bailed-out strategy). A 3830-69 lead was implanted using a C-315-His sheath, and we aimed for left bundle branch pacing (LBBP) in all patients. Current criteria to define LBAPP, LBBP (selective or non-selective), and left ventricle septal pacing (LVSP) were used. The goal of our study was to analyze clinical, electrical, and echocardiographic variables that may predict the achievement of LBBP. Results We included 149 patients between Feb/20 and Jan/22. Baseline characteristics and pacing indications are shown in table 1. We had success in 145 patients (97.3%): 78.9% were considered LBBP (44.4% SLBBP), and 21.1% LVSP. Paced QRS was significantly higher in patients with wide basal QRS (120.9 ± 15.2 ms vs 110.7 ± 12.6 ms, p&amp;lt;0.001). Likewise, left ventricular activation time (LVAT) in V5/V6 and aVL was shorter in the group with narrow basal QRS (77.2 ± 10.5 vs 83.3 ± 11.4, p&amp;lt;0.001, and 80.0 ± 14.1 vs 87.6 ± 14.4, p &amp;lt;0.001, respectively), being much more frequent to achieve an LVAT &amp;lt;80 ms in the group with narrow QRS (64.9% vs 42.2%, OR 2.6, p = 0.004). Logically, the variation of the paced QRS compared to baseline was also different in both groups (-25.4 ± 12.5 ms in the wide QRS group and + 16.2 ± 13.8 ms in the narrow QRS group). LBBP was achieved to a greater extent in the narrow QRS group (89.2% vs 67.6%, OR 3.9, p=0.002); the difference between selective and non-selective LBBP based on baseline QRS was not significant. Regarding the clinical variables, the presence of hypertension, diabetes mellitus, heart failure or COPD did not show a significant difference in the achievement of LBBP. In contrast, it was significantly less frequent to achieve LBBP in patients with LV systolic dysfunction of any degree (62.0% vs 83.2%, p=0.02), or chronic ischemic heart disease (61.1% vs 82.1%, p=0.04), with a trend in patients with CKD (67.7% vs 82.6%, p=0.06). Also, the bradycardia pacing indication had a significant influence, with the percentage of LBBP being lower in patients with atrioventricular conduction system disease compared to sick sinus syndrome (72.0% vs 85.1%, p=0.04). On the other hand, there was no significant association between the achievement of LBBP and echocardiographic parameters such as interventricular septum thickness, and left atrial volumen. Conclusions LBBAP as elective ventricular pacing is feasible, with a high success rate, and in most cases, it is possible to capture the conduction system. However, there appear to be factors that a priori may pose a greater challenge in its achievement, highlighting the electrical conduction system and myocardial disease.

Can peak left ventricular activation time measured in aVL identify left bundle capture during left bundle branch area pacing?

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Two main types of capture are observed during left bundle branch area pacing (LBBAP): LBB pacing (selective-LBBP or non-selective LBBP) and LV septal (LVS) capture. Several criteria are used to distinguish between both types. Methods Prospective study of patients who received LBBAP device for bradycardia or heart failure indications (bailed-out strategy). LBBP was defined if monopolar paced QRS had a right bundle branch conduction delay pattern, at least one of the following criteria: (a) Demonstration of LB potential with LB-local ventricular electrogram interval of 10–35 ms. (b) Demonstration of transition in QRS morphology from non-selective to selective LB capture or non-selective to LVS capture (sudden decrease in LVAT of 10 ms) with decrementing output. (c) Peak LV activation time time as measured in leads V5–V6 &amp;lt;80 ms. Patients not fulfilling criteria for LBBP were catalogued as LVS pacing. We analyzed the role that peak LVAT in the lead aVL (measured from the onset of the pacing spike to the peak of the R wave) had to discriminate between LBBP and LVS pacing and its correlation with LVAT measured in V5-V6. Results 154 consecutive LBBAP procedures were included. Success was achieved in 150 patients (97,4%). Mean age at implant was 79.4±9.3 years, native QRS duration was 118.7±29.4 ms, and LVEF was ≤ 40% in 16 (10,5%). A narrow (&amp;lt; 120 ms) QRS complex was present in 82 patients (53,2%) and LBBB was present in 21 patients. Indications for pacing were second- or third-degree AV block (n=57), slow AF (n=22), bifascicular or trifascicular block (n=12), sinus node disease (n=56) and need for resynchronization therapy (n=6). A Medtronic 3830-69 lead was implanted using a C-315-His sheath in all procedures. We did not perform His mapping to select the target delivery zone. LBBP was achieved in 117 patients (NSLBBP in 67 and SLBBP in 50) while LVS was achieved in the remaining 30 patients. Paced QRS duration after LBBAP was 115.3±14.7 ms, with a mean LVAT (measured at V5/V6) of 79.8±11.3 ms and mean LVAT in aVL of 83.6±14.6 ms. Left bundle potential was seen in 64 patients (44.4% of total population. LVAT in both V5/V6 and aVL was longer in LBBP patients compared to LVS patients (table 1). Accuracy of LVAT measured in aVL for the differential diagnosis of LBBP and LVS capture was good (AUC 84,6%). The diagnostically optimal value for discrimination among the two types of capture was 84 ms (sensitivity and specificity of 65.5% and 93.3%, respectively) (Panel A, figure 1). Moreover, ROC curve for discrimination between patients with LVAT in V5/V6&amp;lt;80 ms and &amp;gt;80 ms was also good (AUC 87.8%). A cut-off point for LVAT in aVL &amp;lt; 84 ms was also the diagnostically optimal value with a sensitivity and specificity of 80.2% and 80%, respectively). (Panel B, figure 1) Conclusions Peak LVAT measured in aVL lead might be a useful tool during LBBAP for differentiation between LBB capture and LVS capture.

Initial experience of left bundle branch area pacing using stylet-driven pacing leads: a multicenter study

Abstract Funding Acknowledgements Type of funding sources: None. Background Left bundle branch area pacing (LBBAP) has been performed exclusively using lumen-less pacing leads (LLL) with fixed helix design. This study is the first to explore in a multicenter population the safety and feasibility of LBBAP using stylet-driven leads (SDL) with extendable helix design. Methods This study prospectively enrolled all consecutive patients who underwent LBBAP for anti-bradycardia pacing or heart failure indications at 8 Belgian hospitals. LBBAP was attempted either using SDL or LLL delivered through dedicated delivery sheaths. Implant success, complications, procedural and pacing characteristics were recorded at implant and follow-up. Results The study enrolled 412 patients (mean age 74 ± 38 years, 44% female). LBBAP with SDL and LLL was successful in 334/353 (94%) and 52/59 (88%) respectively (p=0.058). Implant success for LBBAP using SDL varied from 93 to 100% among centers. Mean paced QRS duration and stimulus to left ventricular activation time were comparable for SDL and LLL (126 ± 21ms versus 125 ± 22ms, p=0.861 and 74 ± 17 and 75 ± 21ms, p=0.756). SDL LBBAP resulted in low pacing thresholds (0.6 ± 0.4V at 0.4ms), which remained stable at 1, 6 and 12 months of follow-up. Lead revisions for SDL LBBAP occurred in 5(1.4%) patients: 2 dislodgements at day 1, 1 late septal perforation at week 3, 1 Twiddler’s syndrome at 5 months, 1 lead fracture at 6 months. Conclusion This multicenter study confirms the safety and feasibility of LBBAP using SDL, which is characterized by high implant success, low complication rate and low and stable pacing thresholds.

Left bundle branch pacing with normal paced QRS axis produce more physiological left ventricular lateral wall depolarization than its pacing resulting in heart axis deviation

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Health of the Czech Republic Background Left bundle branch pacing is defined as the pacing of the trunk or its proximal fascicles, usually with septal myocardial pacing at low output. It preserves physiological left ventricular activation; however, it is unknown if there is a difference between captures with normal or deviated axes and pacing in proximal vs. distal locations. Objective To study ventricular activation during nonselective LBB pacing (nsLBBp) resulting in different paced QRS axes and proximal vs. distal pacing positions using ultra-high-frequency ECG (UHF-ECG). Methods This was a retrospective analysis of patients with bradycardia in which nsLBBp was archived during an implant procedure, and UHF-ECG analysis of ventricular activation was performed. nsLBBp captures were classified according to paced QRS axis as with superior (-30°;-90°), normal (-29°;60°), or inferior (61°;120°) axis deviation and proximal (LBbpo to ventricular EGM signal distance ≥ 26 ms) vs. distal (LBBpo to ventricular EGM signal distance &amp;lt; 26 ms). UHF-ECG electrical dyssynchrony parameters – e-DYS (difference between the first and last ventricular activation), local depolarization durations in precordial leads (V1-V8d), and their mean value (Vdmean) were calculated. Results We have studied 79 nsLBBp, of which 35 had superior, 28 normal, and 16 had inferior paced QRS axes. There was no difference in LBBpo to V distance, QRSduration, V5 RWPT, or e-DYS (-27 ms vs. – 22 ms vs. -25 ms for superior vs. normal vs. inferior axes; p = NS) between them. However, nsLBBp with normal paced QRS axis had shorter Vdmean (43 ±6 ms) compared to captures with superior (48 ± 7 ms) and inferior axis deviation (48 ± 6 ms); p &amp;lt; 0.05. It was mainly due to shorter V7-8d during nsLBBp with normal axis (mean difference of - 10 ms; p &amp;lt; 0.05) than in captures with superior or inferior axes. No difference in any of the studied parameters was noted when comparing proximal vs. distal pacing locations. Conclusion Nonselective capture of the left bundle branch resulting in normal paced QRS axis produces more physiological LV activation compared to captures with superior or inferior axes deviations.

The acute haemodynamic response with endocardial biventricular pacing: comparing RV paced and LBBB patients

Abstract Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Boston Scientific Background A third of patients that receive cardiac resynchronisation (CRT) are non-responders. Predictors of positive response include broader QRS duration, non-ischaemic aetiology and sinus rhythm, but it is still unclear whether lead placement site determines a positive responder. Purpose We assessed the acute haemodynamic response of endocardial biventricular pacing in patients with intrinsic left bundle brunch block (LBBB) versus LBBB due to pre-existing right ventricular pacing (RVP). Methods Patients who fulfilled standard criteria for CRT implantation but had failed conventional (coronary sinus) left ventricular (LV) lead placement (primary or revision) or were deemed clinical ‘non-responders after &amp;gt; 6 months of conventional CRT were enrolled. The acute haemodynamic response during endocardial biventricular pacing was assessed with a roving LV lead at 9 different locations (basal and mid: septal, anterior, posterior and lateral walls and apex). Acute changes in beat-to-beat systolic blood pressure (SBP) in the left ventricle were recorded and analysed. Results We recruited 23 patients across 10 UK centres: 14 intrinsic LBBB and 9 dependent on RVP. Patient characteristics were comparable: age (mean 67 + 10.6 years vs. 62 + 15.4 years), ischaemic (63% vs 50%), QRS (160 + 18ms vs. 190 + 36ms, p =0.07). Of the RVP group 5/9 had septal RV leads (the remainder apically positioned). There was no difference in the SBP improvement between the groups: change in SBP ranged from -5.25 – 19.91mmHg (median 3mmHg) in RVP patients vs -5.92 – 23.03mmHg (median 3mmHg) for intrinsic LBBB. However, the improvement in SBP was more consistent across the different segments in the patients with RVP (group A), as compared to intrinsic LBBB (group B), where the lateral wall and then non-septal walls provided the greatest haemodynamic improvement. Figure 1: depicts SBP improvement (in mmHg) during endocardial biventricular pacing in different positions within the LV for patients with RVP (A) vs underlying intrinsic LBBB (B): 9 segment model of the LV: Ant (anterior wall), Lat (lateral wall), Post (posterior wall), Sept (septum). Outer ring represents the four basal LV locations, middle ring the mid LV locations and centre ring the apex. Scale depicts mmHg improvement in SBP. Conclusion When implanting an LV lead for patients who are RV pacing dependent any position within the LV provides an acute haemodynamic improvement, compared with those with intrinsic LBBB, where a targeted lateral wall approach is more important. This finding corroborates the key differences in LV activation patterns for induced versus intrinsic LBBB.

Targeting the latest site of left ventricular mechanical activation is associated with improved long-term outcomes for recipients of cardiac resynchronization therapy.

BackgroundPrevious studies have suggested that targeting the site of latest mechanical activation of the left ventricle (LV) results in improved cardiac resynchronization therapy (CRT) outcomes. It is not known whether these benefits are sustained over medium-term follow-up.ObjectiveTo assess the clinical outcome of imaging-guided LV lead position.MethodsWe sought to assess the medium-term clinical outcome by performing a patient-level meta-analysis of 2 previously published randomized controlled trials (the “STARTER” trial and the “CRT Clinic” trial). These 2 trials compared imaging-guided LV lead placement in the latest activated scar-free segment (intervention group) to standard of care (control). Mortality and heart failure hospitalization outcomes over extended follow-up were gathered from the medical records and merged. Results were stratified for native electrocardiogram (ECG) morphology.ResultsA total of 289 patients were followed for a median of 6.3 years. Seven years post implant, 47 (28%) in the intervention group had died, vs 47 (38%) in the control group (P = .13); 49 (30%) vs 53 (42%) had been hospitalized for heart failure (P = .035); and 47% vs 59% (P = .057) had reached the combined endpoint. In Kaplan-Meier analysis, patients in the intervention group had better survival free of heart failure hospitalization (P = .045) and lower risk of heart failure hospitalization (P = .019).ConclusionTargeting the latest mechanically activated segment in CRT results in better medium-term clinical outcome, mainly driven by a reduced risk of hospitalization for heart failure. The effect was seen regardless of native ECG morphology.

Dyssynchronous Left Ventricular Activation is Insufficient for the Breakdown of Wringing Rotation.

Cardiac resynchronization therapy is a valuable tool to restore left ventricular function in patients experiencing dyssynchronous ventricular activation. However, the non-responder rate is still as high as 40%. Recent studies suggest that left ventricular torsion or specifically the lack thereof might be a good predictor for the response of cardiac resynchronization therapy. Since left ventricular torsion is governed by the muscle fiber orientation and the heterogeneous electromechanical activation of the myocardium, understanding the relation between these components and the ability to measure them is vital. To analyze if locally altered electromechanical activation in heart failure patients affects left ventricular torsion, we conducted a simulation study on 27 personalized left ventricular models. Electroanatomical maps and late gadolinium enhanced magnetic resonance imaging data informed our in-silico model cohort. The angle of rotation was evaluated in every material point of the model and averaged values were used to classify the rotation as clockwise or counterclockwise in each segment and sector of the left ventricle. 88% of the patient models (n = 24) were classified as a wringing rotation and 12% (n = 3) as a rigid-body-type rotation. Comparison to classification based on in vivo rotational NOGA XP maps showed no correlation. Thus, isolated changes of the electromechanical activation sequence in the left ventricle are not sufficient to reproduce the rotation pattern changes observed in vivo and suggest that further patho-mechanisms are involved.

Evaluation of the shortening of the stimulus-to-peak left ventricular activation time at continuous low output to confirm left bundle branch capture.

BackgroundLeft bundle branch area pacing (LBBAP) is a physiological pacing method for treatment of atrioventricular block. However, there is a need for a new convenient and safe method for performing left bundle branch pacing (LBBP) and to confirm left conduction system capture.ObjectiveThis study aimed to explore a new convenient and safe method for performing selective LBBP.MethodsA total of 28 patients who had indications for pacing therapy and received LBBAP were recruited retrospectively. Demographic and baseline patient characteristics, electrocardiograms, pacing parameters, and intracardiac electrogram pattern were evaluated. Continuous unipolar pacing at low output (2 V / 0.5 ms) was performed during the whole period of LBBP lead implantation. Successful left bundle branch (LBB) capture was defined as the abrupt change of the pacing stimulus to the peak of R wave in lead V5 during continuous pacing at low output (2 V / 0.5 ms).ResultsThe parameters of the 2 shortenings (stimulus-to-peak left ventricular activation time [S-peak LVAT] before shortening, S-peak LVAT after shortening, and the duration of shortening) all showed a significant positive correlation (Pearson product-moment correlation coefficient [PCC] = 0.915, P < .001; PCC = 0.897, P < 0.001; PCCs = 0.765, P < 0.001). Shortening of the S-peak LVAT with continuous low output had a 100% sensitivity and 33.3% specificity for predicting stimulus-ventricular potential interval (S-V interval).ConclusionAbrupt shortening of the S-peak LVAT at continuous low output was associated with abrupt shortening of the S-peak LVAT at low and high output. High rate of selective LBB capture can be achieved with the method of continuous low output, shortening the S-peak LVAT.

BS-400-45 LEFT BUNDLE-BRANCH PACING POST-ATRIOVENTRICULAR JUNCTION ABLATION FOR ATRIAL FIBRILLATION: PROPENSITY-SCORE MATCHING WITH HIS BUNDLE PACING

Left bundle branch pacing (LBBP) has emerged as a promising pacing modality to preserve physiological left ventricular activation but has limited prospective data evaluating long-term safety and efficacy in pacing-dependent patients following atrioventricular junction (AVJ) ablation.

Influence of Capture Selectivity and Left Intrahisian Block on QRS Characteristics During Left Bundle Branch Pacing.

This study sought to examine QRS and intracardiac characteristics during selective (S) and nonselective (NS) left bundle branch pacing (LBBP) from direct left septal recordings. Criteria for S-LBBP and NS-LBBP have not been validated with intracardiac mapping. Pacing was performed from multielectrode Purkinje recordings below the left-sided His. S-LBBP and NS-LBBP were performed in patients with narrow QRS (n=9), right bundle branch block (n=3), intraventricular conduction delay (n=5), and left bundle branch block (n=10). QRS duration was measured from stimulus onset (QRSst) and from the intrinsicoid deflection of the R-wave in V1-V2 (QRSid) to QRS end. Retrograde left bundle branch conduction was assessed by stimulus-to-retrograde His intervals. Among 27 patients analyzed, 20 demonstrated both NS- and S-LBBP and were studied in paired comparisons. NS-LBBP resulted in narrower QRS compared to S-LBBP (QRSst: 163ms [interquartile range (IQR): 144-179ms] vs 181ms [IQR: 173-203 ms]; P< 0.001; QRSid: 125ms [IQR: 117-142 ms] vs 150ms [IQR: 135-157 ms]; P< 0.001). Left ventricular activation time was also significantly shorter for NS-LBBP compared to S-LBBP (88ms [IQR: 75-111 ms] vs97ms [IQR: 82-123 ms]; P = 0.019). Leftintrahisian block was bidirectional in 10 patients with long retrograde stimulus-to-His intervals. QRSst duration was significantly longer in patients with complete conduction blockcomparedto those with intact Purkinje activation during NS-LBBP (181ms [IQR: 162-195 ms] vs 157ms [IQR: 139-168 ms]; P =0.022). In contrast to His-bundle pacing, S-LBBP predominantly yields a wide QRS as a result of delayed RBB synchronization, whereas NS-LBBP results in shorter QRS duration because of recruitment of the basal right ventricular septum. A wider-paced morphology of LBBP was noted in patients with complete conduction block caused by bidirectional left intrahisian block. Achievement of narrow QRS during LBBP is predicated upon capture nonselectivity or programmed atrioventricular fusion, rather than intrinsic physiologic synchrony from left bundle branch stimulation.

PO-628-07 LEFT BUNDLE-BRANCH PACING POST-ATRIOVENTRICULAR JUNCTION ABLATION FOR ATRIAL FIBRILLATION: PROPENSITY-SCORE MATCHING WITH HIS BUNDLE PACING

Left bundle branch pacing (LBBP) has emerged as a promising pacing modality to preserve physiological left ventricular activation but has limited prospective data evaluating long-term safety and efficacy in pacing-dependent patients following atrioventricular junction (AVJ) ablation.

Computed tomography imaging-identified location and electrocardiographic characteristics of left bundle branch area pacing in bradycardia patients.

Left bundle branch area pacing (LBBAP) is a novel physiological pacing modality. The relationship between the pacing lead tip location and paced electrocardiographic (ECG) characteristics remains unclear. The objectives are to determine the lead tip location within the interventricular septum (IVS) and assess the location-based ECG QRS duration (QRSd) and left ventricular activation time (LVAT). This multicenter study enrolled 50 consecutive bradycardia patients who met pacemaker therapy guidelines and received LBBAP implantation via the trans-ventricular septal approach. After at least 3 months postimplant, 12-lead ECGs and pacing parameters were obtained. Cardiac computed tomography (CT) imaging was performed to assess the LBBAP lead tip distance from the LV blood pool. Among the 50 patients, analyzable CT images were obtained in 42. In 23 of the 42 patients, the lead tips were within 2 mm to the LV blood pool (the LV subendocardial (LVSE) group), 13 between 2and 4 mm (the Near-LVSE group), and the remaining 6 beyond 4 mm (the Mid-LV septal (Mid-LVS) group). No significant differences in paced QRSd were found among the three groups (LVSE, 107 ± 15 ms; Near-LVSE, 106 ± 13 ms; Mid-LVS, 104 ± 15 ms; p = .87). LVAT in the LVSE (64 ± 7 ms) was significantly shorter than in the Mid-LVS (72 ± 8 ms; p < .05), but not significantly different from that in the Near-LVSE (69 ± 8 ms; p > .05). In routine LBBAP practice, paced narrow QRSd and fast LVAT, indicative of physiological pacing, were consistently achieved for lead tip location in the LV subendocardial or near LV subendocardial region.