Left Ventricular Endocardial Pacing Research Articles

Left ventricular electrical delay predicts volumetric response to leadless Cardiac Resynchronization Therapy

BackgroundLeadless left ventricular (LV) endocardial pacing is an emerging cardiac resynchronization therapy (CRT) technology. Predictors of response to leadless CRT are poorly understood. Implanting the LV endocardial pacing electrode in sites with increased electrical latency (Q-LV) may improve response rates. ObjectiveTo examine the association between Q-LV and echocardiographic remodelling response to leadless CRT delivered with the WiSE-CRT system. MethodsA post-hoc analysis (n=122) of the SOLVE-CRT trial examined the relationship between LV pacing site Q-LV with rate of LV end-systolic volume (LVESV) reduction >15% at 6 months. Multivariable regression analysis, adjusting for age, sex, prior CRT non-response, cardiomyopathy aetiology, QRS morphology and QRS duration was performed, followed by ROC analysis and analysis of variance by Q-LV quartile. A subgroup analysis of the ischaemic cardiomyopathy cohort was undertaken. ResultsComplete Q-LV data was available in 122/153 (80%) of patients in the active arms SOLVE-CRT. Overall, the 6-month LVESV response rate was 46%. Logistic regression identified Q-LV as an independent response predictor with borderline significance (adjusted odds ratio 1.015, p=0.05). Analysis by Q-LV quartile demonstrated a significant improvement in response rate in quartile 4 (longest Q-LV, 64%) compared to quartile 1 (shortest Q-LV, 28%), p<0.01. This association was primarily driven by strong Q-LV-response correlation in patients with ischaemic cardiomyopathy, demonstrated by subgroup logistic regression (adjusted odds ratio 1.034, p=0.004). ConclusionIncreased Q-LV was associated with improved reverse remodelling following leadless CRT. Targeting LV endocardial sites of high Q-LV may deliver additional benefit compared to empirical LV electrode implantation.

Leadless Ultrasound-Based Cardiac Resynchronization System in Heart Failure

Approximately 40% of patients with heart failure (HF) who are eligible for cardiac resynchronization therapy (CRT) either fail to respond or are untreatable due to anatomical constraints. To assess the safety and efficacy of a novel, leadless, left ventricular (LV) endocardial pacing system for patients at high risk for a CRT upgrade or whose coronary sinus (CS) lead placement/pacing with a conventional CRT system failed. The SOLVE-CRT study was a prospective multicenter trial enrolling January 2018 through July 2022, with follow-up at 6 months. Data were analyzed from January 17, 2018, through February 15, 2023. The trial combined data from an initial randomized, double-blind study (n = 108) and a subsequent single-arm part (n = 75). It took place at 36 centers across Australia, Europe, and the US. Participants were nonresponders, previously untreatable (PU), or high-risk upgrades (HRU). All participants contributed to the safety analysis. The primary efficacy analysis (n = 100) included 75 PU-HRU patients from the single-arm part and 25 PU-HRU patients from the randomized treatment arm. Patients were implanted with the WiSE CRT System (EBR Systems) consisting of a leadless LV endocardial pacing electrode stimulated with ultrasound energy delivered by a subcutaneously implanted transmitter and battery. The primary safety end point was freedom from type I complications. The primary efficacy end point was a reduction in mean LV end systolic volume (LVESV). The study included 183 participants; mean age was 68.1 (SD, 10.3) years and 141 were male (77%). The trial was terminated at an interim analysis for meeting prespecified stopping criteria. In the safety population, patients were either New York Heart Association Class II (34.6%) or III (65.4%). The primary efficacy end point was met with a 16.4% (95% CI, -21.0% to -11.7%) reduction in mean LVESV (P = .003). The primary safety end point was met with an 80.9% rate of freedom from type I complications (P < .001), which included 12 study device system events (6.6%), 5 vascular events (2.7%), 3 strokes (1.6%), and 7 cardiac perforations which mostly occurred early in the study (3.8%). The SOLVE-CRT study has demonstrated that leadless LV endocardial pacing with the WiSE CRT system is associated with a reduction in LVESV in patients with HF. This novel system may represent an alternative to conventional CRT implants in some HF patient populations. ClinicalTrials.gov Identifier: NCT0292203.

Optimizing electrical efficacy of leadless cardiac resynchronization therapy and leadless left ventricular septal pacing: Insights on left and right ventricular activation from electrocardiographic imaging

BackgroundLeadless cardiac resynchronization therapy (CRT) using the WiSE-CRT system is an emerging heart failure treatment. An implanted electrode delivers lateral or septal endocardial left ventricular pacing (LVP) upon detection of a right ventricular pacing (RVP) stimulus from a co-implanted device, thus generating biventricular pacing (BiVP). Electrical efficacy data regarding this therapy, particularly leadless LV septal pacing (LVSP) for potential conduction system capture, is limited. ObjectiveTo evaluate the acute performance of leadless CRT using electrocardiographic imaging (ECGi), and assess the optimal pacing modality (OPM) of LVSP based on RV and LV activation. MethodsTen WiSE-CRT recipients underwent an ECGi study testing: RVP; BiVP; LVP only; and LVP with an optimised atrioventricular delay (LV-OPT). BiV, LV and RV activation times (BIVAT-90, LVAT-95, RVAT-90), plus LV and BiV dyssynchrony index (LVDI, BIVDI) were calculated from reconstructed epicardial electrograms. The individual OPM yielding the greatest improvement from baseline was determined. ResultsBiVP generated a 23.7% improvement in BiVAT-90 (p=0.002). An improvement of 43.3% was observed at OPM (p=0.0001), primarily through reductions in RVAT-90. At OPM, BiVAT-90 improved in patients with lateral (43.3%, p=0.0001, n=5) and septal LV implants (42.4%, p=0.009, n=5). The OPM varied by individual. LVP or LV(OPT) were mostly superior in patients with LVSP, and for those in SR and LBBB (n=4). ConclusionLeadless CRT significantly improves acute ECGi-derived activation and dyssynchrony metrics. Using an individualised OPM improves efficacy in selected patients. Effective LVSP is feasible, with fusion pacing at LV(OPT) mitigating the potential deleterious effects on RV activation.

Cardiac resynchronization therapy using endocardial versus trans-coronary sinus, epicardial left ventricular pacing: the Epi-Endo study

Abstract Aims Some studies have suggested that cardiac resynchronization therapy (CRT) using endocardial left ventricular (LV) pacing (Endo-CRT) is superior to a conventional transvenous, epicardial CRT (Epi-CRT). To determine whether, in CRT recipients, endocardial LV pacing is haemodynamically superior to trans-coronary vein (trans-CV) LV epicardial pacing. Methods and results At implantation patients (n=16; aged 68.9±8.32 years; 13 male) underwent Epi-CRT and Endo-CRT in basal, mid and apical myocardial segments, delivered using the trans-CS lead and an intra-cavitary, roving EP catheter to achieve juxtapositions of the epicardial and endocardial side of the LV free wall respectively. Myocardial scar was quantified using cardiovascular magnetic resonance. An acute haemodynamic response (AHR) was defined as a ≥10% increase in the maximal rate of rise of LV pressure (%LV dP/dtmax) in relation to RV pacing (DOO). When the 84 paired segments were taken together, the %ΔLV dP/dtmax was higher with Endo-CRT than with Epi-CRT (9.9±8,6% vs 7.9±8.3% respectively, p&amp;lt;0.002; 52.3% vs 28.6% responders [p&amp;lt;0.045). However, Endo-CRT was not always superior to epi-CRT in individual patients. For example, in basal segments, only 5/10 (50%) patients were converted from non-responders with epi-CRT to responders with endo-CRT whereas 1/4 (25%) epi-CRT responder was converted to a non-responder with endo-CRT (Figure). There was no difference in ΔLV dP/dtmax between Epi-CRT and endo-CRT in segments with myocardial scar. Conclusions On average, endo-CRT provides a better AHR than epi-CRT. Within patients, however, endo-CRT is not always better.Epicardial versus Endocardial CRT

Optimising electrical performance of leadless cardiac resynchronisation therapy and leadless LV septal pacing

Abstract Introduction Leadless left ventricular (LV) endocardial pacing with the WiSE-CRT System is an emerging form of cardiac resynchronisation therapy (CRT). The system was designed to provide lateral wall LV pacing (LVP) via an endocardial receiver electrode in response to detection of a right ventricular pacing (RVP) stimulus from a co-implanted device, thereby delivering near-simultaneous biventricular pacing (BiVP). However, it is unclear whether BiVP generates the optimal electrical performance in this system, particularly in the context of leadless LV septal pacing, a novel use for leadless CRT. Aim We aimed to characterise the acute performance of leadless CRT at different pacing modalities using electrocardiographic imaging (ECGi). Methods Patients with the leadless CRT underwent an acute ECGi study. The following pacing modalities were tested: RVP; BiVP; LVP; and LVP with an electrically optimised atrioventricular delay (LV-OPT) in patients with sinus rhythm (SR). Reconstructed epicardial electrograms (Figure 1) were used to calculate BiV activation time (BIVAT-90), LV activation time (LVAT-90), RV activation time (RVAT-90), LV dyssynchrony index (LVDI), and BiV dyssynchrony index (BIVDI). For each metric, the improvement compared to baseline rhythm was calculated, and the optimal pacing modality (OPM) in each patient was determined. Results Ten patients were studied, 5 receiving septal LVP, and 5 receiving lateral LVP. The underlying rhythm in 4 patients was SR with left bundle branch block (LBBB), and atrial fibrillation (AF) with complete heart block (CHB) in the remaining 6. BiVP generated a 23.7% improvement in BiVAT-90 compared to baseline (p=0.002). An individualised OPM resulted in a 43.3% BiVAT-90 improvement compared to baseline (p=0.0001), thus a 19.6% improvement compared to BiVP (p=0.02, Figure 2A). Using an OPM, BiVAT-90 was significantly improved in both patients with lateral (43.3%, p=0.0001) and septal LVP (42.4%, p=0.009). The BiVAT-90 OPM varied between patients (Figure 2B). BiVP was the OPM in 4/10 patients, all of whom had AF with CHB. BiVP was the OPM in 1/5 patients receiving LV septal pacing, with LVP or LV-OPT performing best in the remaining 4. In 3/4 patients in SR, LV-OPT was the OPM. Choosing the OPM increased performance primarily through significant improvements in RVAT-90 compared to BiVP (36.5% versus -8.2%, p =0.002). Conclusion Leadless CRT, both with lateral and septal LVP, significantly reduces electrical activation times and improves electrical dyssynchrony. Individualised selection of the OPM may be required with leadless CRT to accommodate for varying conduction disease phenotypes and implant locations.

Optimization of A 12-lead ECG subset for Automated Early Left-Ventricular Activation Localization Approach based on Pace-Mapping Technology.

We previously developed an automated approach based on pace-mapping to localize early left-ventricular (LV) activation origin. To avoid a singular system, we require pacing from at least 2 more known sites than the number of ECG leads used. Fewer leads used means fewer pacing sites required. To identify an optimal minimal ECG-lead set for the automated approach. We used 1715 LV endocardial pacing sites to create derivation and testing datasets. The derivation dataset, consisting of 1012 known pacing sites pooled from 38 patients, was used to identify an optimal 3-lead set using random-forest regression (RFR), and a second 3-lead set using exhaustive search. The performance of these sets and the calculated Frank leads was compared within the testing dataset with 703 pacing sites pooled from 25 patients. The RFR yielded III, V1, and V4, while the exhaustive search identified leads II, V2 and V6. Comparison of these sets and the calculated Frank leads demonstrated similar performance when utilizing ≥ 5 known pacing sites. Accuracy improved with additional pacing sites, achieving mean accuracy of < 5 mm, after including up to 9 pacing sites when they were focused on a suspect area of ventricular activation origin (radius < 10 mm). The RFR identified the quasi-orthogonal leads set to localize the source of LV activation, minimizing the training set of pacing sites. Localization accuracy was high using these leads, and was not significantly different from using leads identified by exhaustive search, or empiric use of Frank leads.

PO-03-013 ELECTRO-ANATOMICAL CHARACTERIZATION OF LEADLESS LEFT BUNDLE BRANCH AREA PACING

Leadless left ventricular (LV) endocardial pacing with the WiSE-CRT System (EBR Systems Inc) is an emerging treatment in the field of cardiac resynchronization therapy (CRT). Whilst the system was designed to provide LV lateral wall endocardial pacing, modifications to the implant technique have recently enabled positioning of the pacing electrode in the LV septum to perform left bundle branch area pacing (LBBAP). The electrical performance of leadless LBBAP is yet to be determined. We aimed to electro-anatomically characterize the biventricular (BiV) activation patterns of leadless LBBAP in patients with heart failure receiving CRT with the WiSE-CRT system. Four patients with the WiSE-CRT System, all with the pacing electrode located in the LV septum, underwent an electrocardiographic imaging (ECGi) study. The following pacing modalities were tested: Right Ventricular Pacing (RVP); BiV pacing (RVP + LV); LV only; and LV only with an electrically optimised atrioventricular delay (AVD) in patients with sinus rhythm. Reconstructed epicardial electrograms from ECGi were used to calculate LV activation time (LVAT-90), RV activation time (RVAT-90), BiV activation time (BIVAT-90), LV dyssynchrony index (LVDI), and BiV dyssynchrony index (BIVDI). For each metric, the percentage improvement compared to RVP was calculated. At the optimal pacing modality, CRT using leadless LV septal endocardial pacing achieved significant improvements in: LVAT-90 (33.9% ± 24.6, p=0.01); RVAT-90 (51.7% ± 24.1, p=0.003); BiVAT-90 (31.3% ± 30.8, p=0.03) and LV-DI (39.7% ± 39.7, p=0.03), see figure. There was individual variability in optimal pacing modality (see table). For 2 patients with sinus rhythm (SR) and left bundle branch block (LBBB), the optimal modality was LV only pacing with optimised AVD. Two patients had AF and complete heart block (CHB). For these cases, BiV pacing achieved the optimal results for 1 patient, whereas LV only pacing performed best for the other. Leadless LV LBBAP endocardial pacing significantly improves ECGi-derived activation metrics at the optimal pacing modality in both patients in SR and AF. For those with underlying SR and LBBB, LBBAP with AVD optimisation may be the optimal modality as this allows RV activation via native conduction. As each patient required a different protocol to achieve the optimal result, personalisation may be important for LV LBBAP.Tabled 1Optimized pacing setting by activation metric (PO-03-013)PatientUnderlying RhythmBiVAT-90LVAT-90RVAT-90LV-DIBiV-DI1AF, CHBLV onlyLV onlyLV onlyLV onlyLV only2SR, LBBBLV with optimized AVD 80msLV with optimized AVD 100msLV with optimized AVD 130msLV with optimized AVD 80msLV with optimized AVD 100ms3AF, CHBBiVLV onlyBiVLV onlyBiV4AF, LBBBLV only with optimized AVD 180msLV only with optimized AVD 160msLV only with optimized AVD 160msLV only with optimized AVD 160msLV only with optimized AVD 160ms Open table in a new tab

Cardiac resynchronization therapy: present and future.

Cardiac resynchronization therapy (CRT) via biventricular pacing (BVP) is a well-established therapy for patients with heart failure with reduced ejection fraction and left bundle branch block, who remain symptomatic despite optimal medical therapy. Despite the long-standing clinical evidence, as well as the familiarity of cardiac electrophysiologists with the implantation technique, CRT via BVP cannot be achieved or may result ineffective in up to one-third of the patients. Therefore, new alternative techniques, such as conduction system pacing and left ventricular pacing, are emerging as potential alternatives to this technique, not only in case of BVP failure, but also as a stand-alone first choice due to several potential advantages over traditional CRT. Specifically, due to its procedural characteristics, left bundle branch area pacing appears to be the most convincing technique, showing comparable efficacy outcomes when compared with traditional CRT, not increasing short-term device-related complications, as well as improving procedural times. However, transvenous leads remain a major limitation of all these pacing modalities. To overcome this limit, a leadless left ventricular endocardial pacing has been developed as an additional tool to achieve a left endocardial activation, although being still associated with non-negligible pitfalls, limiting its current use in clinical practice. This article focuses on the current state and latest progresses in cardiac resynchronization therapy.

Comparison of methods for delivering cardiac resynchronization therapy: electrical treatment targets and mechanisms of action

ABSTRACT Introduction Cardiac resynchronization therapy (CRT) has been developed as a treatment for patients with conduction system dysfunction and impairment of ventricular performance. The aim is to restore more physiological cardiac activation and thereby improve cardiac function, symptoms, and outcomes. Areas covered In this review, we discuss potential electrical treatment targets for patients with heart failure and how these electrical treatment targets may determine the optimal pacing approach for delivering CRT. Expert Opinion The most well-established method for delivering CRT is biventricular pacing (BVP). BVP improves symptoms and reduces mortality in patients with left bundle branch block (LBBB). However, patients continue to suffer from heart failure symptoms and decompensations despite receiving BVP. There may be scope to deliver more effective CRT since BVP does not restore physiological ventricular activation. Furthermore, the results with BVP in patients with non-LBBB conduction system disease have been generally disappointing. Alternative pacing approaches to BVP are now available, including conduction system pacing and left ventricular endocardial pacing. These newer pacing approaches offer exciting potential to not only offer an alternative to coronary sinus lead implantation in the case of implant failure but to potentially deliver more effective treatment in LBBB and maybe even extend the indications for CRT beyond LBBB.

Pacing interventions in non-responders to cardiac resynchronization therapy.

Non-responders to Cardiac Resynchronization Therapy (CRT) represent a high-risk, and difficult to treat population of heart failure patients. Studies have shown that these patients have a lower quality of life and reduced life expectancy compared to those who respond to CRT. Whilst the first-line treatment for dyssynchronous heart failure is "conventional" biventricular epicardial CRT, a range of novel pacing interventions have emerged as potential alternatives. This has raised the question whether these new treatments may be useful as a second-line pacing intervention for treating non-responders, or indeed, whether some patients may benefit from these as a first-line option. In this review, we will examine the current evidence for four pacing interventions in the context of treatment of conventional CRT non-responders: CRT optimization; multisite left ventricular pacing; left ventricular endocardial pacing and conduction system pacing.

A Continuous Pacing and Recording Technique for Differentiating Left Bundle Branch Pacing From Left Ventricular Septal Pacing: Electrophysiologic Evidence From an Intrapatient-Controlled Study.

Left bundle branch pacing (LBBP) is a promising approach for achieving near-physiologic pacing. However, differentiating LBBP from left ventricular septal endocardial pacing (LVS(e)P) remains a challenge. This study aimed to establish a simple and effective method for differentiating LBBP from LVS(e)P and to evaluate their electrophysiologic characteristics. LBBP, using continuous uninterrupted pacing and real-time monitoring of electrocardiograms along with intracardiac electrograms, was performed in 97 consecutive patients. We evaluated the electrophysiologic characteristics observed during LBBP using 6 modalities: right ventricular septal pacing (RVSP), intraventricular septal pacing (IVSP 1 and 2), LVS(e)P, nonselective LBBP (NSLBBP), and selective LBBP (SLBBP). Of the 97 patients, 87 (89.7%) met the criteria (abrupt change in paced QRS morphology with a transition from Qr to QR/qR in lead V1 and shortening of stimulus to V6 R-wave peak time [Stim-V6RWPT] of ≥ 10 ms with constant output while rather than after lead screwing) for nonselective left bundle branch (LBB) capture. Selective LBB capture was observed in 82 patients (84.5%). The Stim-V6RWPT of NSLBBP and SLBBP were significantly shorter than LVS(e)P (respectively, 67.1 ± 8.7 ms, 67.0 ± 9.3 ms, and 82.1 ± 10.9 ms). Stim-QRSend was the narrowest in IVSP2 (136.6 ± 15.2 ms) instead of NSLBBP (140.0 ± 17.1 ms). The uninterrupted pacing technique for differentiating LBBP from LVS(e)P in the same group of patients is feasible. Electrophysiologic evidence from our intrapatient-controlled study shows that LBBP and LVS(e)P differ in ventricular electrical synchronization.

Leadless left ventricular endocardial pacing for cardiac resynchronization therapy: A systematic review and meta-analysis.

Leadless left ventricular (LV) endocardial pacing to achieve cardiac resynchronization therapy (CRT) is a novel procedure for treatment of patients with dyssynchronous heart failure. Current evidence is limited to observational studies with small patient numbers. The purpose of this systematic review and meta-analysis was to assess the safety and efficacy of leadless LV endocardial pacing. A literature search was conducted through PubMed, EMBASE, and Cochrane databases. Mean differences (MDs) in New York Heart Association (NYHA) functional class and LV ejection fraction (LVEF) from baseline to 6 months postprocedure were combined using a random effects model. Heterogeneity was evaluated using the Cochrane Q test, I2, meta-regression, and sensitivity analysis. Funnel plots were constructed to detect publication bias. Five studies with 181 patients were included in the final analysis. Procedural success rate was 90.6%. Clinical response rate was 63%, with mean improvement in NYHA functional class of 0.43 (MD -0.43; 95% confidence interval [CI] -0.76 to -0.1; P = .01), with high heterogeneity (P <.001; I2 = 81.1%). There was a mean increase in LVEF of 6.3% (MD 6.3; 95% CI 4.35-8.19; P <.001, with low heterogeneity (P = 0.84; I2 <0.001%). The echocardiographic response rate was 54%. Procedure-related complication and mortality rates were 23.8% and 2.8%, respectively. The efficacy of leadless LV endocardial pacing for CRT supports its use as a second-line therapy in patients in whom standard CRT is not possible or has been ineffective. Improvements in safety profile will facilitate widespread uptake in the treatment of these patients.

Leadless Left Bundle Branch Area Pacing in Cardiac Resynchronisation Therapy: Advances, Challenges and Future Directions.

Leadless left bundle branch area pacing (LBBAP) represents the merger of two rapidly progressing areas in the field of cardiac resynchronisation therapy (CRT). It combines the attractive concepts of pacing the native conduction system to allow more physiological activation of the myocardium than conventional biventricular pacing, with the potential added benefits of avoiding long-term complications associated with transvenous leads via leadless left ventricular endocardial pacing. This perspective article will first review the evidence for the efficacy of leadless pacing in CRT. We then summarise the procedural steps and pilot data for leadless LBBAP, followed by a discussion of the safety and efficacy of this novel technique. Finally, we will examine how further mechanistic evidence may shed light to which patients may benefit most from leadless LBBAP, and how improvements in current experience and technology could promote widespread uptake and expand current clinical indications.

Left Ventricular Endocardial Pacing: Update and State of the Art.

Initially, left ventricular (LV) endocardial pacing was performed as a bailout procedure after unsuccessful transvenous cardiac resynchronization therapy implantation in the presence of surgical contraindications. Additional possible advantages of endocardial LV pacing are a more physiologic activation, being less arrhythmogenic, more effective on the hemodynamic level, with better thresholds, and without the risk of phrenic stimulation. Different techniques have been proposed to stimulate the LV endocardium in humans, with feasibility and safety studies involving limited numbers of patients. In this review, we will describe the different techniques proposed to allow LV endocardial pacing, the results observed, and then we will discuss the reasons why LV endocardial pacing seems to be out of fashion today and what are the possible perspectives for development.

Pacing Optimized by Left Ventricular dP/dtmax.

Left ventricular (LV) dP/dtmax provides a sensitive measure of the acute hemodynamic response to cardiac resynchronization therapy (CRT) and can predict reverse remodeling on echocardiography. Its use to guide LV lead placement has been shown to improve outcomes in a multicenter randomized trial. Given the invasive protocol required for measurement, it is unlikely to be universally beneficial for patients undergoing CRT but may be useful for patients who do not respond to conventional CRT, or in those who have borderline indications or risk factors for non-response. In such cases, LV dP/dtmax may help guide LV lead placement, optimize device programming, and select the best alternative method of delivering CRT, such endocardial LV pacing or conduction system pacing.

Endocardial pacing results in better electrical resynchronization and hemodynamic improvement than epicardial pacing in CRT

Abstract Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The original study was financially supported by Medtronic (Minneapolis, Minnesota). The investigation of the current abstract is unrelated to the original financial support. Background Cardiac resynchronization therapy (CRT) is conventionally applied by means of a transvenous epicardial left ventricular (LV) lead. Studies suggest that endocardial LV pacing may result in better resynchronization and LV function than epicardial LV pacing. Purpose To investigate whether endocardial pacing results in better electrical resynchronization and hemodynamic improvement compared to epicardial pacing. Methods Patients with an indication for CRT were prospectively included from two hospitals. In all patients, LV pacing was performed endocardially and epicardially in the postero-lateral region. QRS area was calculated from vectorcardiograms that were synthesized from 12-lead ECGs. Acute hemodynamic improvement was assessed as the change in maximum rate of rise of LV-pressure (%ΔLVdP/dtmax). We assessed the effects of endocardial and epicardial LV pacing on the change in QRS area (∆QRS area) and LVdP/dtmax (%ΔLVdP/dtmax). Results A total of 16 patients (age 66 ± 11 years, 56% male, 31% ischemic cardiomyopathy, QRS duration 166±18ms, LBBB in 88%) were included. Endocardial pacing resulted in greater ∆QRS area than epicardial pacing (-51 ± 34 µVs vs. -24 ± 37 µVs, p = 0.021, Panel A). In addition, endocardial pacing led to a larger %ΔLVdP/dtmax as compared to epicardial pacing (21 ± 12% vs. 18 ± 9%, p = 0.025, Panel B). Conclusion Compared to conventional epicardial LV pacing in CRT, endocardial LV pacing results in better electrical resynchronization and acute hemodynamic improvement.

Leadless left bundle branch pacing: feasibility in an animal model

Abstract Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): EBR Systems Inc. Introduction Epicardial cardiac resynchronization therapy (CRT) is an established treatment for heart failure; left bundle branch (LBB) pacing has been proposed to overcome epicardial CRT limitations. In this study, we report on the first implants of a leadless electrode for endocardial pacing of the LBB in a porcine model. Methods The implant of the leadless, left ventricular endocardial pacing system (WiSE-CRT System) was attempted by transeptal approach in two porcines. Fluoroscopic and transoesophageal echocardiographic guidance were used to navigate the Delivery Sheath to the LBB area; the targeted implant site was selected by analysis of the electrograms from the implanting Electrode. At the end of the procedure, the animals were sacrificed and the hearts were isolated and analysed. Results In both animals, the Delivery System was successfully navigated to the LV septum. The target sites showed LBB electrograms preceding the far field ventricular electrogram by 15ms. The Electrode was successfully implanted on both animals with pacing threshold &amp;lt;2.0V @ 0.5ms. The implant of the pacing electrode was associated with minimal, multifocal haemorrhage; Purkinje fibers components of the LBB were observed in the on both sides of the site of implantation site. The lesion was 1.7 mm large and 2 mm deep. Conclusions This study supports the feasibility of leadless LBB pacing. Anatomical evaluation showed a close relationship between the Electrode and the LBB, with absence of significant damage to the conduction system from the implanted Electrode.

Endocardial left ventricular pacing.

Cardiac resynchronization therapy (CRT) is an effective treatment for dyssynchronous heart failure; however, 30–50% of patients fail to improve after implant. Endocardial left ventricular (LV) pacing is an alternative therapy for patients who do not respond to conventional CRT or in whom placement of a lead via the coronary sinus is not possible. It enables pacing at a wide variety of sites, without restrictions due to coronary sinus anatomy, and there is evidence of superior electrical resynchronization and hemodynamic response compared with conventional epicardial CRT. In this article, we discuss the potential advantages and disadvantages of endocardial LV pacing compared with conventional CRT, review the evidence for the delivery of endocardial LV pacing using both lead-based and leadless systems, and explore possible future directions of this novel technology.

Leadless left ventricular endocardial pacing for CRT upgrades in previously failed and high-risk patients in comparison with coronary sinus CRT upgrades.

AimsCardiac resynchronization therapy (CRT) upgrades may be less likely to improve following intervention. Leadless left ventricular (LV) endocardial pacing has been used for patients with previously failed CRT or high-risk upgrades. We compared procedural and long-term outcomes in patients undergoing coronary sinus (CS) CRT upgrades with high-risk and previously failed CRT upgrades undergoing LV endocardial upgrades.Method and resultsProspective consecutive CS upgrades between 2015 and 2019 were compared with those undergoing WiSE-CRT implantation. Cardiac resynchronization therapy response at 6 months was defined as improvement in clinical composite score (CCS) and a reduction in LV end-systolic volume (LVESV) ≥15%. A total of 225 patients were analysed; 121 CS and 104 endocardial upgrades. Patients receiving WiSE-CRT tended to have more comorbidities and were more likely to have previous cardiac surgery (30.9% vs. 16.5%; P = 0.012), hypertension (59.2% vs. 34.7%; P < 0.001), chronic obstructive airways disease (19.4% vs. 9.9%; P = 0.046), and chronic kidney disease (46.4% vs. 21.5%; P < 0.01) but similar LV ejection fraction (30.0 ± 8.3% vs. 29.5 ± 8.6%; P = 0.678). WiSE-CRT upgrades were successful in 97.1% with procedure-related mortality in 1.9%. Coronary sinus upgrades were successful in 97.5% of cases with a 2.5% rate of CS dissection and 5.6% lead malfunction/displacement. At 6 months, 91 WiSE-CRT upgrades and 107 CS upgrades had similar improvements in CCS (76.3% vs. 68.5%; P = 0.210) and reduction in LVESV ≥15% (54.2% vs. 56.3%; P = 0.835). ConclusionDespite prior failed upgrades and high-risk patients with more comorbidities, WiSE-CRT upgrades had high rates of procedural success and similar improvements in CCS and LV remodelling with CS upgrades.

Endocardial left ventricular pacing Where are we a systematic review

Abstract Funding Acknowledgements Type of funding sources: None. Background Endocardial left ventricular pacing is a technique used in cardiac resynchronization therapy (CRT), when a coronary sinus implant is not possible, conventional CRT was an unsuccess and in CRT nonresponders. We performed a systemic review to evaluate its risks and benefits. Objective Review the evidence regarding the efficacy and safety of endocardial left ventricular pacing. Methods A systemic research on MEDLINE and PUBMED with the term "endocardial left ventricular pacing", "biventricular pacing" or "endocardial left pacing". 1038 results were identified, however, just publish papers (excluding abstract) with more than 16 patients was admitted in these analyses. Comparisons pre and post CRT regard New York Heart Association (NYHA) functional classification, left ventricular ejection fraction (LVEF) and QRS width was performed. Mean differences (MD) and confidence interval (CI) was used as a measurement of treatment. Results Eleven studies were selected, including a total of 560 patients. The studies were performed with different techniques, trans-atrial septal technique, trans-ventricular septal technique and transapical technique. Mean age 66.93 years old, 90.54% male, median ejection fraction of 28.86%, NYHA class of 3.03, QRS width 167,50 mseg. Ischemic etiologic in 43.88%, atrial fibrillation in 45.35% and left bundle branch block in 55.20%. Was reported several complications after the procedure, 8 pocket infection (7 studies), 17 transient ischemic attacks (10 papers), 17 ischemic stroke (all), 35 tromboembolic events (all) and 115 deaths, nevertheless, follow up in the different studies was diverse and heterogeneous. Significant improvement was registered in NYHA class (MD 0.64, CI 0.56-0.72, p &amp;lt; 0.00001, I2 = 89%) (reported in 7 studies), LVEF (MD 6.20, CI 5.09-7.32, p = 0.002, I2 = 69%) %) (reported in 8 studies) and QRS width (MD 31.35, CI 26.11-36.60, p &amp;lt; 0.00001, I2 = 89%) %) (reported in 5 studies), (all p &amp;lt; 0.00001). Conclusions Left ventricular endocardial pacing is a feasible alternative to conventional CRT, when the last one is not possible. With clinical, electrocardiogram and echocardiogram improvement in several series. First data regarding this procedure were associated with higher stroke incidence, something contrary to the last study’s results. Nevertheless, at the moment just small series present this technique with heterogenous results and different approaches, being important further investigation.