Right Ventricular Pacing Research Articles

Abstract 4134305: Intraoperative indicators depending on QRS morphology are required to narrow QRS width during CRT implantation

Introduction: Various indicators to detect the most delayed electrical or mechanical activation site of left ventricular (LV) have been studied using intracardiac electrocardiogram or speckle tracking echocardiogram to narrow QRS width in patients with cardiac resynchronization therapy (CRT). Hypothesis: Unusual intraoperative indicators are required to narrow QRS width in patients with non-LBBB (left bundle branch block) during CRT implantation. Methods: Nineteen patients (14 men, 71±12yrs, 7 with left bundle branch block: LBBB / 10 non-LBBB / 2 pacing-depend, 6 ischemic cardiomyopathy, LVEF 29.6±8.9%, QRS 152±28ms) underwent CRT implantation. Q-LV (an interval from QRS onset to LV potential), RV-LV (from RV to LV), RVp-LV (from RV pacing to LV), and S-QRS (from LV pacing stimulation to QRS onset) were measured in multi-sites of coronary sinus (CS) veins using a 5 mm spacing 2Fr 8-polar catheters. Q-peak strain (an interval from QRS onset to peak radial strain) was evaluated by speckle tracking echocardiogram in each LV segment during sinus rhythm (SR) and RVp. QRS narrowing was defined as the difference between the QRS interval during SR (or RVp) and the QRS interval with biventricular pacing. Results: Parameters were evaluated in 17±7 (8-32) sites of 1.9±0.9 (1-4) CS branches in each patient. In LBBB patients, longer Q-LV during SR, extended RV-LV during SR, and lengthy Q-peak strain during SR were associated with QRS narrowing. Shorter S-QRS during LVP and longer RVP-LV during RVP were related to QRS narrowing in non-LBBB patients. (Table) Conclusion: Suitable indicators depending on QRS morphology are required for QRS narrowing in CRT implantation. The parameters using speckle tracking echocardiogram to detect mechanical LV delay sites might not be useful in patients with non-LBBB.

Acute Electrical Synchronization Achieved with Dynamic Atrioventricular Delays during Biventricular and Left Ventricular MultiPoint Pacing

BackgroundCardiac resynchronization therapy (CRT) response relies on two factors: when and where to pace. These factors may be enhanced by dynamic atrioventricular delays (AVDs) (e.g., SyncAV CRT, Abbott) and multi-site left ventricular (LV) pacing (e.g., MultiPoint Pacing [MPP], Abbott). Their individual and combined synchronization contributions have not been evaluated across a comprehensive spectrum of pacing configurations. The objective is to distinguish the acute electrical synchrony achieved by (i) static vs. dynamic AVDs, (ii) single- vs. multi-site LV pacing, and (iii) with vs. without RV pacing. MethodsCRT-indicated patients with LBBB and intact AV conduction (PR<250ms) were enrolled and evaluated during implant. Acute changes in 12-lead ECG QRS duration (QRSd) were evaluated during: intrinsic conduction, biventricular pacing (BiV), biventricular MPP, LV-only single-site pacing (LVSS), and LV-only MPP (LVMPP). CRT modes were evaluated with static AVDs and optimized SyncAV AVDs. ResultsCRT implant and QRSd evaluation were completed in 85 patients (71% male, 34% ischemic, 179ms PR). The median intrinsic QRSd of 165ms was reduced by BiV, MPP, LVSS, and LVMPP without SyncAV to 144ms (by 14%), 142ms (16%), 155ms (8%), and 149ms (12%), respectively (P<0.01 vs. intrinsic). BiV+SyncAV, MPP+SyncAV, LVSS+SyncAV, and LVMPP+SyncAV reduced the intrinsic QRSd significantly further to 128ms (by 23%), 124ms (26%), 131ms (21%), and 129ms (24%) (P<0.0001, each corresponding pair). ConclusionsMPP combined with SyncAV achieved the narrowest QRSd, in the overall population and in the most patients, by delivering ventricular pacing from all available sites (RV+LV1+LV2) while timed with dynamic AVDs.

Mitigation of pacing-induced cardiomyopathy with superficial right ventricular mid-septal pacing: A long-term retrospective comparison with apical pacing.

It remains unclear if pacing induced cardiomyopathy (PICM) may be minimized by standard pacing of the right ventricle (RV) at sites other than the RV apex. The purpose of this study is to compare the relative frequency of PICM in a population of patients paced at either the superficial RV mid septum (RVMS) or RV apex (RVA), and other outcomes that may differ between these sites. A retrospective evaluation was performed on all patients undergoing pacemaker implantation between 2011 and 2022. Potential study patients were those with Medtronic 3830 superficial RVMS leads placed with septal specific guidance catheters, and any with RVA leads. Patients were included if they had ≥20% RV pacing, available baseline and follow-up measurements of left ventricular ejection fraction (LVEF) at least 6 months postimplantation, and a baseline LVEF ≥50%. PICM was defined as a decline in the LVEF of at least 10%, resulting in LVEF <50%. Patients were excluded for Biventricular devices, and for alternative causes of cardiomyopathy. The study criteria were met in 324 patients, with 220 RVMS and 104 RVA paced patients. PICM occurred in 4.5% of RVMS patients, and 22.1% of RVA patients (p < .001). Additional differences were demonstrated in paced QRS duration (144 ± 15.5 ms in RVMS, 166 ± 19.4 ms in RVA; p < .001); QRS axis (2.3 ± 64.9 in RVMS, -65.2 ± 49.5 in RVA; p < .001), and various qualitative QRS morphologic characteristics. Patients with normal LVEF experienced significantly less PICM with superficial RVMS pacing performed via septal specific guidance catheters than similar counterparts with RVA pacing. Narrower paced QRS duration and less left axis deviation was also demonstrated.

The effect of afterload on right ventricular pacing-induced left ventricular dysfunction: a translational study

Abstract Introduction Right ventricular (RV) pacing (RVP) impairs left ventricular (LV) function. Nevertheless, the interaction between arterial afterload and RVP-associated LV dysfunction has not been investigated yet. Purpose We sought to examine the effect of afterload on RVP-evoked LV hemodynamic changes in patients with aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI) as well as in a small animal model of sustained LV pressure overload (PO). Methods Thirty-five patients with AS and a previously implanted pacemaker underwent detailed echocardiographic examination immediately before TAVI and also on the second postoperative day. The ultrasound measurements were carried out during intrinsic, narrow QRS rhythm and during frequency-matched RVP as well. Global myocardial work index (GMWI) was calculated to assess LV contractility. In parallel, LV pressure-volume analysis was performed in Wistar rats with transverse aortic constriction (TAC) or sham operation (Sham) during intrinsic narrow QRS rhythm (termed as TAC-Vsense and Sham-Vsense) as well as during RVP (termed as TAC-Vpace and Sham-Vpace). RVP was achieved in rats by an octopolar electrophysiology catheter placed in the RV. Results RVP decreased LV contractility in AS patients before and after TAVI as well. Nevertheless, the extent of RVP-evoked LV dysfunction was alleviated following pressure unloading (ΔGMWI: -37±7 vs. -25±8%, before TAVI vs. after TAVI, P&amp;lt;0.05). Similarly, although RVP was associated with reduced LV contractility in both the TAC (the slope of the maximum rate of LV pressure rise-end-diastolic volume relation [dPdtmax-EDV]: 92±8 vs. 53±6mmHg/s/µl, TAC-Vsense vs. TAC-Vpace; P&amp;lt;0.05) and Sham groups (dPdtmax-EDV: 74±5 vs. 60±9 mmHg/s/µl, Sham-Vsense vs. Sham-Vpace; P&amp;lt;0.05), the negative inotropic effect of RVP was found to be stronger in the TAC compared to the Sham group (ΔdPdtmax-EDV: -42±4 vs. -19±6%; TAC vs. Sham, P&amp;lt;0.01). Furthermore, reduction of the maximal rate of LV pressure decrease (ΔdPdtmin: -20±3 vs. -5±5%, TAC vs. Sham, P&amp;lt;0.01) and prolongation of the active relaxation time constant (Δτ: 22±3 vs. 6±3%, TAC vs. Sham, P&amp;lt;0.01) also occurred to a greater extent in case of sustained LV PO, indicating augmented diastolic dysfunction. Conclusion Our translational results indicate that RVP-induced LV dysfunction might be afterload dependent.

Hemodynamic effects of right and biventricular pacing during exercise in hypertrophic obstructive cardiomyopathy

Abstract Background One third of patients with hypertrophic cardiomyopathy present with dynamic left ventricular outflow tract obstruction (LVOTO), referred to as hypertrophic obstructive cardiomyopathy (HOCM). Symptomatic treatment aims at reducing LVOTO with either medications, invasive septal reduction, or pacing. The importance of pacing site is unclear, and effects of pacing during physical activity have not been investigated. Purpose To determine the effect of right ventricular (RV) and biventricular (BiV) pacing, respectively, on LVOTO and cardiac output (CO) during exercise in patients with HOCM. Methods Patients with symptomatic HOCM, sinus rhythm, and no bundle branch block, scheduled for alcohol septal ablation (ASA), were eligible for inclusion. The day before ASA, we placed temporary pacing leads in the right atrium, the RV apex, and on the left ventricle’s lateral wall via the coronary sinus. LVOTO was assessed by echocardiography, and CO was measured by thermodilution with a pulmonary artery catheter. Patients performed supine cycling for 2 minutes until heart rate (HR) increased ≥20 bpm. We measured LVOTO and CO in sinus rhythm, and during cycling with atrial sensed RV pacing, and atrial sensed BiV pacing. The order of pacing sites was randomized, and the personnel performing echocardiography and CO measurements were blinded to the order of pacing. Results We included six patients (54±15 years) with a mean maximal left ventricular wall thickness of 16.7±1.8 mm. Resting LVOTO was 55.7±30.9 mmHg. The figures show LVOTO and CO in sinus rhythm (HR 85±10 bpm), RV pacing (HR 90±10 bpm), and BiV pacing (HR 91±9 bpm) during supine cycling. The LVOTO declined from 56±34 mmHg in sinus rhythm to 27±12 mmHg and 25±5 mmHg respectively for atrial sensed RV and BiV pacing. CO remained unchanged during sinus rhythm (9.0±1.2 L/min), atrial sensed RV pacing (9.0±1.7 L/min), and BiV pacing (8.9±1.5 L/min). Conclusion In this ongoing study evaluating cardiac pacing in HOCM, preliminary data indicate that both RV and BiV pacing are effective in reducing LVOTO during exercise, without compromising CO.

A novel formula to assess the QT interval in ventricular paced rhythm

Abstract Background QT interval measurement in the presence of right ventricular pacing (RVP) represents a clinical challenge due to altered ventricular activation resulting in a prolonged QT-interval. The aim of this study is to compare the QT interval in patients before and after ventricular pacing to develop a new formula for QT interval assessment in patients with RVP. Methods and results All patients presenting to our pacemaker clinic with single- or dual chamber device were included in this prospective observational study. Inclusion criteria were no permanent right ventricular stimulation, an intrinsic QRS interval of &amp;lt;120 ms, and ventricular rate &amp;gt;35 bpm and &amp;lt;150 bpm. Three 12-lead electrocardiograms were recorded for each patient: during intrinsic rhythm and 2 following an atrial paced and a ventricular paced QRS at the same rate. The intrinsic QRS and QT time/JT time (QTi/JTi) were measured during intrinsic and subsequent RVP. To obtain the formula, all measurements were performed on 100 patients (mean age 74 ± 11.3, male 33%) (RV apical lead 30% and non-apical lead 70%). Based on our measurements, a new formula QT (non-paced) = 139.23 + 0.55 xQT (paced) was derived. A population of 482 individuals (mean age 75.5±13.2 years (SD), 64% male) with permanent RV pacing were used as a validation group. The intrinsic QRS and QT time were measured during SR and subsequent RVP. To assess the relationship between the predicted QT with RVP and the measured QT without RVP, linear correlations analyses were performed. Our formula had a strong correlation with the irrespective QT without RVP (r=0.50) Conclusion We proposed a new simple formula to accurately estimate QT during RVP. This formula can be easily utilized in clinical practice. Figure 1: MAD characteristic value via plots stands for Median Absolute Difference (i.e. by how many ms the prediction is estimated on average). Figure 2: "Forest Plot" illustrates the correlation coefficients in the form of a forest plot. The dot r represents r and the bars the 95% confidence intervalsMAD characteristic value via plots standForest Plot" illustrates the correlation

Conduction system versus right ventricular pacing for atrioventricular block: a reconstructed individual participant data meta-analysis

Abstract Background Right ventricular pacing (RVP) is typically offered to patients with established or impending atrioventricular block (AVB) in the absence of left ventricular systolic dysfunction. Direct stimulation of His-Purkinje fibres via conduction system pacing (CSP) is an emerging alternative to RVP to prevent pacing-induced cardiomyopathy. Purpose To perform a systematic review and meta-analysis testing CSP versus RVP in patients with AVB and a left ventricular ejection fraction ≥35%. Methods Observational studies comparing CSP with RVP that reported clinical outcomes were systematically identified. The primary outcome was time-to-first all-cause mortality, heart failure hospitalisation (HFH) or upgrade to biventricular pacing. Secondary endpoints included the individual components of the primary endpoint. Individual participant time-to-event data (IPD) was obtained through data-sharing agreements or reconstructed from digitisation of Kaplan-Meier curves where available. Mixed-effects Cox proportional hazards regression that modelled between-study heterogeneity as a random intercept to account for differing baseline hazards between distinct study populations was performed on these data. Conventional pairwise random effects meta-analyses were also performed. This analysis was prospectively registered. Results 12 eligible studies enrolling 4627 patients were included. In reconstructed IPD pooled survival analyses, CSP associated with a 38% reduced hazard of the primary endpoint compared with RVP [hazard ratio 0.62, 95% CI 0.51 to 0.76, p&amp;lt;0.001] (Figure 1). In pairwise meta-analyses, CSP associated with a 46% risk reduction in the primary endpoint [relative risk (RR) 0.54, 95% CI 0.41 to 0.71, p&amp;lt;0.001] (Figure 2A). CSP also associated with reductions in risk of all-cause mortality [RR 0.60, 95% CI 0.45 to 0.80, p&amp;lt;0.001], HFH [RR 0.39, 95% CI 0.28 to 0.55, p&amp;lt;0.001] and upgrade to biventricular pacing [RR 0.19, 95% CI 0.07 to 0.52, p=0.001] compared with RVP (Figure 2B-D). Conclusions In reconstructed IPD pooled survival analyses, CSP associated with reductions in the primary composite endpoint of all-cause mortality, heart failure hospitalisation or upgrade to biventricular pacing compared with RVP, independent of ventricular pacing burden. This was mirrored in conventional meta-analyses of the primary composite endpoint, and when individual components of the composite were analysed. It may not be necessary to predict which patients will have an elevated pacing burden when applying this therapy. Until randomised data from the PROTECT-HF trial becomes available, this analysis offers the most precise summary estimate of the comparative effects of CSP versus RVP in patients with an AVB indication for pacing, but no evidence of heart failure.Kaplan-Meier plot comparing CSP vs RVPForest plots for major endpoints

Traditional dual-chamber right ventricular pacing versus conduction system pacing in the US medicare population

Abstract Introduction Conduction system pacing (CSP) has emerged as an alternative therapy to traditional right ventricular (RV) pacing. However, the majority of CSP studies reflect small cohorts or single-center experience. Purpose This analysis aimed to compare CSP to dual chamber (DC) RV pacing in a large, population-based cohort utilizing data from the Micra Coverage with Evidence Development (CED) study. Methods Medicare administrative claims data were used to identify patients implanted with a DC RV pacemaker. Lead placement data from Medtronic’s device registration system was used to identify patients with treated with CSP (N=6,197) using a 3830 catheter-delivered lead or DC RV (non-3830 lead, non-CSP placement) (N=16,989) at the same centers. CSP patients were stratified into left bundle branch area pacing (LBBAP) (N=4,738) and His-bundle pacing (HBP) (N=1,459). Incident heart failure hospitalizations (iHFH), all-cause mortality, complication rates and reinterventions at 6 months were analyzed. Results CSP (LBBAP and HBP) patients with a 3830 catheter-delivered lead experienced significantly lower rates of iHFH (HR: 0.70, P=0.02) and all-cause mortality at 6 months compared with DC RV patients (HR: 0.66, P&amp;lt;.0001) (figure). There was no difference in complications (HR: 0.89, P=0.06) or need for reintervention (HR: 0.83, P=0.08) with LBBAP compared to DC RV, though HBP patients experienced significantly higher rates of complications (HR: 1.41, P=0.001) compared to LBBAP. Conclusion Patients treated with CSP with a 3830 catheter-delivered lead experienced significant all-cause mortality and HFH benefits compared to DC RV pacing. LBBAP had lower complications compared to HBP. These real-world results in a large cohort of Medicare patients align with findings in small clinical studies demonstrating the benefits of LBBAP. Future research will focus on understanding patient selection for CSP.Figure

Cardiac resynchronization therapy in adult congenital heart disease: single center cohort study

Abstract Introduction Cardiac resynchronization therapy (CRT) is a recommended therapeutic measure for patients with heart failure. Heart failure is a major morbidity amongst patients with adult congenital heart disease (ACHD). However, the data on the efficacy and safety of CRT amongst ACHD is limited. Methods Data was analyzed from a retrospective cohort of patients with a known diagnosis of ACHD and implantation of CRT between 2015-2022. The primary outcome was echocardiographic response to CRT. This was defined as either:1) an increase in systemic ventricular ejection fraction (EF) of ≥5% in patients with EF &amp;lt;50% (therapeutic) or 2) maintenance of EF in patients with EF≥50% (preventative). Secondary outcomes included change in QRS duration, heart failure admissions, death and CIED (cardiovascular implantable electronic devices) infection during follow up. The outcomes were also assessed by subgroup of systemic left or right ventricle systemic ventricle. Results Our cohort included 46 patients, 96% male and average age was 54±14 years. 26 patients had a systemic left ventricle (56.6%) and 20 patients had a systemic right ventricle (44.4%). The indication for CRT implantation was 1) Reduced EF with wide QRS (n=10, 22%), 2) Reduced EF and RV (right ventricular) pacing (n=22, 49%), and 3) Normal EF with RV pacing (n=14, 33%). 25 patients (55%) had an implanted defibrillator at baseline. Primary outcome amongst patients with preserved EF at baseline was achieved in 22/32 patients (68.7%) and was achieved in 12/14 patients (85.7%) amongst patients with reduced EF at baseline. During follow up, QRS duration was shortened in 68.7%, 13 patients had heart failure admissions (30%), 4 patients underwent heart transplants/mechanical support device implantation (8.6%), death occurred in 11 patients (24%) and 3 had CIED infection (7%). There was no significant difference in complication or efficacy rates between the left systemic and right systemic group. Conclusion CRT is effective in patients with ACHD both as a therapeutic and as a preventative measure for heart failure. There was no difference in clinical response to CRT between patients with SRV compared to SLV. The percentage of patients with a safety outcome was relatively high in this subpopulation due to advanced ACHD.

Mechanical dyssynchrony and response to cardiac resynchronization therapy in heart failure patients with right ventricular pacing: a pre-specified subgroup analysis of the BUDAPEST CRT Upgrade trial

Abstract Introduction The BUDAPEST CRT Upgrade trial has established the strong clinical benefit of upgrading heart failure patients with a reduced left ventricular (LV) ejection fraction (HFrEF) and a high right ventricular pacing (RVP) burden to cardiac resynchronization therapy with defibrillator (CRT-D). Importantly, however, the CRT upgrade response is not homogeneous regarding LV reverse remodeling and associated clinical outcomes. The presence of mechanical dyssynchrony (MD) assessed by echocardiography has been linked to more CRT benefits; still, its change in response to CRT and added prognostic value in HFrEF patients with high RVP are scarcely investigated. Purpose Accordingly, we aimed to assess the prevalence, clinical characteristics, CRT response rate, and prognostic value of RVP-induced MD in the BUDAPEST CRT Upgrade cohort. Methods The multicentre, randomized, controlled trial enrolled 360 HFrEF patients with a pacemaker or implantable cardioverter defibrillator (ICD) and significant RVP (≥ 20%) who were randomly assigned to receive CRT-D upgrade or ICD in a 3:2 ratio. Protocol echocardiography was performed at baseline and at 12-month follow-up visits and was evaluated at a central core lab. Beyond LV end-diastolic (EDV) and end-systolic volumes (ESV), longitudinal strain-derived septal deformation patterns by speckle tracking were assessed to determine the presence of RVP-induced MD. The endpoints were volumetric non-response (defined by a relative decrease in LV ESV &amp;lt;15%) and the composite of volumetric non-response or HF hospitalization. Results The echocardiographic assessment was feasible in 325 patients at baseline; 133 (41%) patients presented with MD. Females were more likely to present with MD (female vs. male, 65% vs. 38%, p=0.003). MD patients had higher LV EDV (MD vs. no-MD, 248±78 vs. 219±78 mL, p=0.001) and LV ESV (190±67 vs. 165±64 mL, p&amp;lt;0.001) at baseline. In the CRT-D group, 126 (75%) patients were volumetric responders, and 41 (25%) were non-responders at 12 months. CRT patients with baseline MD were less likely to experience volumetric non-response (OR 0.35 [95% CI 0.15-0.82], p=0.015) or the composite endpoint (OR 0.37 [95% CI 0.17-0.77], p=0.008). Out of 57 CRT patients with baseline MD who had follow-up assessment available, 52 (91%) patients had a favorable change: the MD pattern disappeared. Patients with MD resolution at 12 months were less likely to experience volumetric non-response or the composite endpoint (OR 0.39 [95% CI 0.17-0.93], p=0.034; OR 0.38 [95% CI 0.16-0.86], p=0.021, respectively). CRT patients with resolved MD were less likely of ischemic etiology and had 100% posterior or lateral LV lead location. Conclusions The presence of RVP-induced MD and its resolution is associated with better clinical response in HFrEF patients undergoing CRT-D upgrade. MD assessment can refine patient selection algorithms of CRT.Figure 1

Impact of left ventricular lead position on echocardiographic response after upgrading from right to biventricular pacing - Insights from the BUDAPEST CRT Upgrade Trial

Abstract Introduction Left ventricular (LV) lead position is strongly associated with the long-term outcome of patients undergoing de novo cardiac resynchronization therapy (CRT) implantation. However, data is scarce about patients who undergo upgrade CRT from right ventricular (RV) pacing. Aims To investigate the impact of the LV lead location on the primary outcome of heart failure (HF) hospitalization, all-cause mortality, or echocardiographic reverse remodelling in the BUDAPEST CRT Upgrade trial cohort. Methods Heart failure patients with reduced ejection fraction (HFrEF), with previously implanted pacemaker (PM) or implantable cardioverter defibrillator (ICD) and intermittent or permanent RV pacing, who were randomly assigned to the CRT-D arm (n=215) and those who were cross-overs from the ICD arm (n=27) were investigated. Short-axis position (anterior / posterior / lateral) of the LV lead was assessed. Primary endpoint encompassed HF hospitalization, all-cause mortality, and the end-systolic volume (ESV) decrease less than 15% from baseline to 12 months follow-up. Echocardiographic response was evaluated by percent change of ESV and LVEF. Results LV lead location was available for 223 patients (age 72.8 ± 8 years, 14% female, 38% diabetic, 49% with prior myocardial infarction, 30% with prior ICD) with a median follow-up time of 12.4 months. There was no difference in the occurrence of the primary endpoint by the lead positions (anterior vs. lateral OR 0.33; 95%CI 0.09-1.22, p=0.10, anterior vs. posterior OR 0.58; 95%CI 0.14-2.50, p=0.47). However, LVEF change was more pronounced in those with lateral LV lead location compared with anterior position (adjusted LVEF difference 7.43%, 95%CI 1.25 – 13.62; p=0.02), while those with posterior leads did not differ from the anterior ones (adjusted LVEF difference 3.00%, 95%CI -3.92 – 9.93; p=0.39). Decrease in ESV was also more remarkable with a lateral position as compared to the other locations (lateral vs. anterior adjusted ESV difference -0.17 mL, 95%CI -0.32 – (-0.01); p=0.03, posterior vs. anterior adjusted ESV difference -0.09 mL, 95%CI -0.26– 0.08; p=0.31). Conclusion Upgrade CRT results in better outcomes as compared to ICD alone; however, lateral LV lead position is associated with the most beneficial mid-term echocardiographic response as compared to other short-axis locations. This finding may translate into better clinical outcomes in the long term.

A comparative analysis of conduction system pacing and biventricular pacing in patients undergoing atrioventricular node ablation: a systematic review and meta-analysis

Abstract Background Atrioventricular node ablation (AVNA) with concomitant permanent pacemaker implantation is a well-established management strategy for patients with atrial fibrillation demonstrating refractory and uncontrolled ventricular rates. Conduction system pacing (CSP) utilising His bundle pacing (HBP) or left bundle branch area pacing (LBBAP), has emerged as an alternative to conventional pacing (CP) (including right ventricular pacing (RVP) and biventricular pacing (BVP). The aims and objectives of this systematic review and meta-analysis is to provide a comprehensive summary and synthesis of clinical outcomes in the literature for CSP in comparison to BVP when facilitated with AVNA. Methods This study protocol was registered in the PROSPERO registry and the review was conducted as per the PRISMA guidelines. MEDLINE, EMBASE and Cochrane Library were searched for relevant studies from inception till January 11th, 2024. Results were synthesised using a random effects meta-analysis. Risk of bias (ROB) assessment was carried out with the RoB 2 and ROBINS-I tool. Results From a total of 259 references identified, 122 full texts were assessed and 5 studies (1 randomised control trial, 2 prospective observational studies, and 2 retrospective observational studies) were included in the review. A total of 738 patients (HBP-294 and LBBAP-444) received CSP and BVP implantation with AVNA, respectively. All devices were implanted successfully with a cumulative total of 4 patients in the HBP population demonstrating acute threshold hold increase following AVN. There was no loss of capture on follow-up in either treatment groups. HBP resulted in a narrower QRSd with a reduction of -35.3 ms (95% confidence interval [CI] -63.8 to -6.78; P&amp;lt;0.05; I2=96.6%) vs BVP. For left ventricular ejection fraction (LVEF), a weighted mean increase of 3.50% (95% CI -0.55%-7.54%; P=0.02, I2=65.8%) was observed following HBP implantation in comparison to BVP (Figure 1). Furthermore, LBBAP also demonstrated a weighted mean increase in LVEF of 6.02% (95%CI -4.05%-16.1%; P&amp;lt;0.05; I2=90.7%) in comparison to BVP. The mean NYHA score was reduced by -0.54 (95% CI -1.07 to -0.02; P=0.05, I2=65.5%) after HBP implantation when compared to BVP. There was a cumulative total of 45 and 65 events of heart failure associated hospitalisation in the HBP and BVP, respectively (OR 0.69; 95% CI 0.19-1.18; P=0.99, I2 =0.00). Conclusion To our knowledge, this is the first methodologically robust systematic review and meta-analysis evaluating the outcomes of CSP with AVNA. Overall, both CSP modalities demonstrated feasibility and application as an effective CRT alternative to facilitate AVNA along with a narrower QRSd ,improved LVEF and trend of better clinical outcomes. While these preliminary findings are promising, further RCTs will be necessary to establish the long-term efficacy and safety of this approach.

Vector Field Heterogeneity (VFH) as a novel quantitative marker of electrical disarray in Arrhythmogenic CardioMyopathy (ACM) with ventricular tachycardia

Abstract Background ACM is a hereditary condition characterized by fibrofatty infiltration and replacement of cardiac myocytes predominantly presenting with ventricular arrhythmias (VA). Cardiac imaging allows for detailed structural phenotyping of scar patterns in ACM. Yet, there is a lack of tools to objectively quantify the electrical substrate alterations that may enable a more precise identification of critical sites that predispose to VA. Purpose To quantify locally disorganized cardiac electrical propagation wavefronts using the Vector Field Heterogeneity (VFH) metric from high-density multi-electrodes in patients with ACM with VT and compare to healthy controls. Methods High density epicardial substrate maps acquired with a 16-pole grid catheter during SR or RV pacing in patients with ACM with VA, who underwent clinically indicated catheter ablation, were retrospectively reviewed. Patients with structurally normal heart and idiopathic VA with epicardial ablation were analysed as a control group. Unipolar contact mapping data was exported &amp; processed offline. From the 4×4 electrode array EGMs, vector maps of the directions of electrical propagation for recorded sites were computed. The VFH was then computed as a quantitative measure of local heterogeneity of propagation, with higher VFH expected to correlate with sites of (micro)structural tissue alterations. VFH was compared between ACM and control patients as well as at sites of normal, border zone &amp; scar based on omnipolar voltage in ACM patients (&amp;gt;1.5mV, 0.5mV–1.5mV, &amp;lt;0.5mV, respectively). Results 10 patients with ACM (70% male, aged 52 ±18 years, ARVC 70%, biventricular 30%, RVEF 40.7±4.7%, LVEF 66±12%) and 2 patients with structurally normal heart (female, 38 &amp; 61 years) were included. Epicardial maps had an average of 9258 ±5412 EGM points. Median VFH was statistically significantly higher in the ACM cohort compared to control for global maps (0.33±0.33 vs 0.13±0.22, p&amp;lt;0.001) and at sites with voltage &amp;gt;1.5mV (i.e. greater disorganization in ACM, p&amp;lt;0.001). In ACM, assessment of VFH according to omnipolar voltage sites (as a surrogate of scar) showed a quantifiable statistically significant increase in electrical disorganized propagation at sites of lower voltage (&amp;lt;0.5mV, median VFH 0.53±0.36) compared to borderzone (0.5-1.5mV, VFH 0.29±0.41) and normal voltage (&amp;gt;1.5mV, VFH 0.15±0.26), p &amp;lt;0.001 respectively. Conclusion Heterogenous electrical propagation as quantified by VFH is significantly increased in patients with ACM at sites of scar, but importantly also in areas of normal voltages when compared to non-ACM controls, possibly indicating microstructural alterations that are missed in traditional assessments of the arrhythmogenic substrate. Identifying and quantifying disorganized conduction patterns by VFH is a promising new mapping approach that could allow improved substrate characterization. Its diagnostic value to guide ablation therapy is currently being validated.VFH Metric ACM and ControlVFH Map Examples

Study of right atrial and right ventricular function in dual chamber pacemaker patients

Abstract Background Unlike left ventricular function, right ventricular (RV) function in pacemaker patients is less well studied with less studies comparing septal versus apical pacing effects on the RV function and almost none on the right atrial (RA) function. Purpose To assess the effect of RV pacing on the echocardiographic and clinical parameters of the RV and RA function and their correlation with the site of right ventricular lead implantation. Methods The study assessed 59 patients in need of permanent dual chamber pacemaker implantation using clinical and echocardiographic data of the RV and RA size and function using tricuspid annular plane systolic excursion (TAPSE), S wave velocity of the tricuspid annulus and fractional area change (FAC), free wall strain (FWSL), global longitudinal strain (GLS) of the RV, RA strain including reservoir, conduit and contraction phases and 3D ejection fraction of the RV using Epiq 7 Ultrasound machine (Philips Healthcare) by the same echocardiographer before implantation and 6 months after. All programming parameters were recorded postoperative and 6 months later. Results 31 patients had the RV lead in the RV apex whereas 28 had it in the septum and all patients had their RA lead in the right atrial appendage, with no significant difference between both groups regarding baseline demographic, clinical nor echocardiographic data. At 6 months, there was a significant decline of the 3D RVEF from a mean of (58.57% ± 6.35%) to (56.41% ± 6.17%), TAPSE from (2.61 cm ± 0.51) to (2.35 cm ± 0.52) and S wave from (13.73 cm/sec ± 2.84) to (12.64 cm/sec ± 2.61) but none showed a significant difference between septal and apical pacing, on the other hand, the RV strain showed a significant decline 6 months after implantation in both the FWSL from (-31.75% ± 5.39) to (-27.82% ± 5.73) and the GLS from (-25.89% ± 5.17) to (-21.65% ± 4.51) with more decline in the septal group compared to the apical (-20.33% ± 4.70 versus -22.84% ± 4.04 regarding the GLS and -26.11% ± 6.41 versus -29.37% ± 4.62 in the FWSL, respectively). There was no difference in the FAC, tricuspid regurgitation severity, gradient nor the estimated pulmonary artery pressure at 6 months. The RA size showed a significant decline at 6 months but no difference in any of the strain parameters. No clinical RV failure symptoms nor signs were observed. Programming revealed a mean percentage of ventricular pacing of (97.92% ± 2.67%) with a minimum of 91% and atrial pacing of (10.41% ± 12.52%), and the thresholds, impedance and atrial high-rate episodes were comparable postoperatively and 6 months after, with no difference between the septal and apical groups. Conclusion At 6 months follow-up after pacemaker implantation, right ventricular function starts to show decline in both the septal and apical groups with only the right ventricular strain more affected in the septal group compared to the apical.3D right ventricular ejection fraction3D right ventricular strain

Impact of Multidirectional Pacing on Activation and Repolarization Parameters to Localize Ischemic Ventricular Tachycardia Circuits.

In ventricular tachycardia (VT), optimal substrate mapping strategies identifying arrhythmogenic sites are not established. This study sought to evaluate multidirectional pacing on the distribution of specific conduction and repolarization metrics to localize re-entrant VT sites in a porcine infarct model. Substrate maps were created in 13 pigs with chronic myocardial infarction using the Advisor HD Grid (Abbott) during right ventricular (RV), left ventricular, biventricular pacing (BIV), and sinus rhythm (SR). Critical VT sites of early-, mid-, and late-diastolic signals were delineated. Vulnerable sites to re-entry were defined as sites of latest activation timing within and post-QRS complex, largest activation and activation-recovery interval gradients. Distances between the 20 most vulnerable sites and diastolic VT points were measured, and identification of VT points was assessed using the area under the receiver-operating characteristic curve. A total of 34 VTs were mapped, and 48 sinus and pacing maps were obtained (10 BIV, 13 left ventricular, 13 RV, 12 SR). Late potential mapping in SR was taken as the established clinical standard for comparison. Latest activation time with BIV pacing provided the closest localization for VT isthmus (median 5.5mm; IQR: 7.15mm; P< 0.005). The gradient of activation-recovery interval using RV pacing had closest localization for VT exit and entrance (median 10.6mm; IQR: 5.0mm; P< 0.005 and 9.4mm; IQR: 8.0mm; P< 0.05). Global sensitivity and specificity analysis showed that gradient of activation-recovery interval in SR achieved the highest area under the receiver-operating characteristic curve, with similar results from the gradient of activation timing. Multidirectional pacing in combination with conduction and repolarization parameters enables better localization of VT diastolic critical sites vs SR late potentials.

TCT-124 Timing of Intraprocedural Conduction Disturbances in TAVR: Predicting Subsequent Pacemaker Implantation and RV Pacing

TCT-124 Timing of Intraprocedural Conduction Disturbances in TAVR: Predicting Subsequent Pacemaker Implantation and RV Pacing

Detailed analysis of electrogram peak frequency to guide ventricular tachycardia substrate mapping.

Differentiating near-field (NF) and far-field (FF) electrograms (EGMs) is crucial in identifying critical arrhythmogenic substrate during ventricular tachycardia (VT) ablation. A novel algorithm annotates NF-fractionated signals enabling EGM peak frequency (PF) determination using wavelet transformation. This study evaluated the algorithms' effectiveness in identifying critical components of the VT circuit during substrate mapping. A multicentre, international cohort undergoing VT ablation was investigated. VT activation maps were used to demarcate the isthmus zone (IZ). Offline analysis was performed to evaluate the diagnostic performance of low-voltage area (LVA) PF substrate mapping. A total of 30 patients encompassing 198 935 EGMs were included. The IZ PF was significantly higher in sinus rhythm (SR) compared to right ventricular paced (RVp) substrate maps (234 Hz (195-294) vs. 197 Hz (166-220); P = 0.010). Compared to LVA PF, the IZ PF was significantly higher in both SR and RVp substrate maps (area under curve, AUC: 0.74 and 0.70, respectively). The LVA PF threshold of ≥200 Hz was optimal in SR maps (sensitivity 69%; specificity 64%) and RVp maps (sensitivity 60%; specificity 64%) in identifying the VT isthmus. In amiodarone-treated patients (n = 20), the SR substrate map IZ PF was significantly lower (222 Hz (186-257) vs. 303 Hz (244-375), P = 0.009) compared to amiodarone-naïve patients (n = 10). The ≥200 Hz LVA PF threshold resulted in an 80% freedom from VT with a trend towards reduced ablation lesions and radiofrequency times. LVA PF substrate mapping identifies critical components of the VT circuit with an optimal threshold of ≥200 Hz. Isthmus PF is influenced by chronic amiodarone therapy with lower values observed during RV pacing.

Right ventriculography to guide left bundle branch pacing in pacing-induced cardiomyopathy: a novel case report

Abstract Background There is emerging evidence for the potential utility of left bundle branch area pacing (LBBAP), as an alternative to conventional cardiac resynchronization therapy (CRT). The utility of right ventriculography by way of power injector to facilitate lead placement has not yet been reported in the literature. Case summary A 79-year-old female, with a background of poorly rate-controlled atrial fibrillation, presented with worsening dyspnoea. She had recently undergone single-chamber pacemaker insertion prior to an atrioventricular nodal (AVN) ablation, owing to failure in achieving successful CRT coronary sinus lead placement. She had clinical evidence of volume overload, and her electrocardiogram demonstrated right ventricular pacing. Echocardiography demonstrated left ventricular (LV) impairment, with an ejection fraction (EF) of 35%, and severe functional mitral regurgitation (MR). Her diagnosis was overall consistent with pacing-induced cardiomyopathy (PIC). In this patient, the use of right ventriculography, using power-injector-delivered contrast, successfully facilitated placement of an LBBAP lead, with confirmation of good threshold and sensing parameters. Following an upgrade to conduction system pacing, the patient recovered well. On recent follow-up, repeat echocardiography (24 months post initial presentation) demonstrated improved LV function (EF 45% from 35%) and only mild-to-moderate MR. Discussion In conclusion, we demonstrate the utility of right ventriculography to facilitate placement of an LBBAP lead, successfully treating a patient who developed PIC from chronic right ventricular pacing following AVN ablation.

Assessment of ventricular electrical heterogeneity in left bundle branch pacing and left ventricular septal pacing by using various electrophysiological methods.

Left bundle branch area pacing (LBBAP) comprises pacing at the left ventricular septum (LVSP) or left bundle branch (LBBP). The aim of the present study was to investigate the differences in ventricular electrical heterogeneity between LVSP, LBBP, right ventricular pacing (RVP) and intrinsic conduction with different dyssynchrony measures using the ECG, vectorcardiograpy, ECG belt, and Ultrahigh frequency (UHF-)ECG. Thirty-seven patients with a pacemaker indication for bradycardia or cardiac resynchronization therapy underwent LBBAP implantation. ECG, vectorcardiogram, ECG belt and UHF-ECG signals were recorded during RVP, LVSP and LBBP, and intrinsic activation. QRS duration (QRSd) was measured from the ECG, QRS area was calculated from the vectorcardiogram, LV activation time (LVAT) and standard deviation of activation time (SDAT) from ECG belt and electrical dyssynchrony (e-DYS16) from UHF-ECG. Both LVSP and LBBP significantly reduced ventricular electrical heterogeneity as compared to underlying LBBB and RV pacing in terms of QRS area (p < .001), SDAT (p < .001), LVAT (p < .001) and e-DYS16 (p < .001). QRSd was only reduced as compared to RV pacing(p < .001). QRS area was similar during LBBP and normal intrinsic conduction, e-DYS16 was similar during LVSP and normal intrinsic conduction, whereas SDAT was similar for LVSP, LBBP and normal intrinsic conduction. For all these variables there was no significant difference between LVSP and LBBP. Both LVSP and LBBP resulted in a more synchronous LV activation than LBBB and RVP. Especially LBBP resulted in levels of LV synchrony comparable to normal intrinsic conduction.

Left ventricular volumes and function in successful and failed His-BundLe Pacing. A comparative prospective study.

Initial data suggest that His Bundle Pacing (HBP) could preserve long-term cardiac structure and function better than Right Ventricular Pacing (RVP), but evidence is limited. We studied consecutive patients with baseline ejection fraction (EF) ≥ 50% who underwent HBP attempt, either successful (HBP group) or failed (RVP group). Two-dimensional (2D) and three-dimensional (3D) echocardiography were carried out at baseline and after 6 months of ventricular pacing burden > 20%. Among 68 patients, 40 underwent successful HBP, and 28 RVP. The HBP and RVP groups did not differ for age, sex and pacing indication. At baseline, the HBP and RVP groups did not differ for 2D EF (62% vs. 62%), 3D EF (60% vs. 63%), 2D (-19% vs. -19%) and 3D global longitudinal strain (GLS) (-15% vs. -16%). After 6 months, 2D EF (-3.86%) and 3D EF (-5.71%) significantly decreased in the RVP group and did not change in the HBP group (p for interaction .006 and <.001, respectively). 2D GLS (3.08%) and 3D GLS (2.22%) significantly increased in the RVP group, but did not change in the HBP group (p for interaction .013 and <.016, respectively). Pacing induced cardiomyopathy (PICM) (EF drop ≥ 10% and EF < 50%) occurred in 14% (RVP) versus 0% (HBP) of patients (p = .025). Successful HBP was superior to RVP in preserving LV systolic function despite a high ventricular pacing burden, and was less frequently associated with PICM.