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

PURPOSE

Left bundle branch area pacing (LBBAP) has emerged as a physiological and stable form of pacing. We aim to compare the mechanical ventricular synchrony of LBBP, LBFP, and LVSP.

METHODS

Proximal Left bundle branch pacing (LBBP), left bundle fascicular pacing (LBFP) and left ventricular septal pacing (LVSP) were identified in patients with bradycardia who successfully underwent LBBAP. Patients with left ventricular ejection fraction (LVEF) < 50% or QRS duration (QRSd) ≥ 120 ms were excluded. By using electrocardiograms, the left ventricular activation time (LVAT) and QRS duration (QRSd) were measured to examine electrophysiological synchrony. As indications of mechanical synchrony, global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), and peak strain dispersion (PSD) were evaluated by using 2-dimensional speckle tracking echocardiography (2D-STE).

RESULTS

In 56 patients, data were collected during LBBP (n = 18), LBFP (n = 16), and LVSP (n = 22). LVSP resulted in a longer LVAT (91.3 ± 14.9 ms) than LBBP (77.1 ± 10.8 ms, P < 0.05) and LBFP (72.1 ± 9.6 ms, P < 0.05), but all three groups had similar QRSd. There were no differences in GLS, GCS, GRS, or PSD between LBBP, LBFP, and LVSP.

CONCLUSIONS

In patients with normal cardiac function and narrow QRS, though LBBAP with LBB capture resulted in better electrophysiological synchrony than without, the mechanical synchrony of the three groups was comparable.

Optimizing Patient Selection for Physiological Pacing in Bradyarrhythmia: Factors Associated With High Ventricular Pacing Burden

Background

Right ventricular (RV) pacing is established as the most common ventricular pacing (VP) strategy for patients with symptomatic bradyarrhythmia. Some patients with high VP burden suffer deterioration of left ventricular (LV) function, termed pacing-induced cardiomyopathy (PICM). Patients who pace > 20% of the time from the RV apex are at increased risk of PICM, but independent predictors of increased RV pacing burden have not been elucidated in those who have a permanent pacemaker (PPM) inserted for bradyarrhythmia.

Methods

We aimed to identify factors that are associated with increased VP burden > 20%, hence determining those at risk for resultant PICM. In this retrospective cohort study, we identified the most recent 300 consecutive cardiac implantable electronic device (CIED) implants in our center and collected past medical history, electrocardiogram (ECG), echo, medication and pacemaker check data.

Results

A total of 236 individuals met inclusion criteria. Of the patients, 35% had RV pacing burden < 20%, while 65% had VP burden ≥ 20%; 96.2% of patients with complete heart block (CHB) paced > 20% (P = 0.002). Utilization of DDD or VVI (75.2% and 89.2% of patients, respectively) without mode switch algorithms was associated with VP > 20% (P < 0.001). Male or previous coronary artery bypass grafting (CABG) patients also statistically paced > 20%. Other factors trending towards significance included prolonged PR interval, atrial fibrillation or more advanced age.

Conclusion

High-grade atrioventricular (AV) block was associated with an RV pacing burden > 20% over 3 years but this was not consistent in patients with only transient episodes of high-grade AV block. We found a significant association between high VP% and male sex, previous CABG and the absence of mode switching algorithms.

Modern physiological approach to inappropriate ICD shocks due to atrial fibrillation with very fast ventricular response. A case report

BACKGROUND

Fast-conducting atrial fibrillation misinterpreted as ventricular tachycardia is the leading cause for inappropriate shocks in patients with implantable cardiac defibrillators (ICD). These inappropriate shocks are associated with significant morbidity and mortality and cause great discomfort and stress.

CASE PRESENTATION

We report the case of a patient with ischemic cardiomyopathy, permanent atrial fibrillation, and a single-chamber DF-1 ICD implanted for the primary prevention of sudden cardiac death, who presented for multiple inappropriate internal shocks due to very fast-conducting atrial fibrillation, which was mislabeled as ventricular fibrillation by the ICD. Since the patient was under maximal atrioventricular nodal blocking medical therapy (beta-blockers and digitalis) and we didn`t find any reversible causes for the heart rate acceleration, we opted for rate control with atrioventricular node ablation. To counteract the risk of pacing-induced cardiomyopathy in this patient who would become totally pacemaker-dependent, we successfully performed left bundle branch area pacing. Because the patient`s ICD had a DF-1 connection and the battery had a long life remaining, we connected the physiological pacing lead to the IS-1 sense-pace port of the ICD. The 6-month follow-up showed an improvement in left ventricular function with no more inappropriate shocks.

CONCLUSIONS

Left bundle branch area pacing and atrioventricular node ablation in patients with an implantable single-chamber DF-1 defibrillator and fast-conducting permanent atrial fibrillation is a cost-efficient and very effective method to prevent and treat inappropriate shocks, avoiding the use of an additional dual-chamber or CRT-D device.

Comparisons of long-term clinical outcomes with left bundle branch pacing, left ventricular septal pacing, and biventricular pacing for cardiac resynchronization therapy

BACKGROUND

Left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) are referred to as left bundle branch area pacing.

OBJECTIVE

This study investigated whether long-term clinical outcomes differ in patients undergoing LBBP, LVSP, and biventricular pacing (BiVP) for cardiac resynchronization therapy (CRT).

METHODS

Consecutive patients with reduced left ventricular ejection fraction (LVEF <50%) undergoing CRT were prospectively enrolled if they underwent successful LBBP, LVSP, or BiVP. The primary composite end point was all-cause mortality or heart failure hospitalization. Secondary end points included all-cause mortality, heart failure hospitalization, and echocardiographic measures of reverse remodeling.

RESULTS

A total of 259 patients (68 LBBP, 38 LVSP, and 153 BiVP) were observed for a mean duration of 28.8 ± 15.8 months. LBBP was associated with a significantly reduced risk of the primary end point by 78% compared with both BiVP (7.4% vs 41.2%; adjusted hazard ratio [aHR], 0.22 [0.08-0.57]; P = .002) and LVSP (7.4% vs 47.4%; aHR, 0.22 [0.08-0.63]; P = .004]. The adjusted risk of all-cause mortality was significantly higher in LVSP than in BiVP (31.6% vs 7.2%; aHR, 3.19 [1.38-7.39]; P = .007) but comparable between LBBP and BiVP (2.9% vs 7.2%; aHR, 0.33 [0.07-1.52], P = .155). Propensity score adjustment also obtained similar results. LBBP showed a higher rate of echocardiographic response (ΔLVEF ≥10%: 60.0% vs 36.2% vs 16.1%; P < .001) than BiVP or LVSP.

CONCLUSION

LBBP yielded long-term clinical outcomes superior to those of BiVP and LVSP. The role of LVSP for CRT needs to be reevaluated because of its high mortality risk.

Early effects of left bundle branch area pacing on ventricular activation by speckle tracking echocardiography

BACKGROUND

Left bundle branch area pacing (LBBAP) is an emerging cardiac pacing modality that preserves fast electrical activation of the ventricles and provides very good electrical measures. Little is known on mechanical ventricular activation during this pacing modality.

METHODS

We prospectively enrolled patients receiving LBBAP. Electrocardiographic and electrical parameters were evaluated at implantation, < 24 h and 3 months. Transthoracic echocardiography with strain analysis was performed at baseline and after 3 months, when ventricular mechanical activation and synchrony were analyzed by time-to-peak standard deviation (TPSD) of strain curves for both ventricles. Intraventricular left ventricular (LV) dyssynchrony was investigated by LV TPSD and interventricular dyssynchrony by left ventricle-right ventricle TPSD (LV-RV TPSD).

RESULTS

We screened 58 patients with permanent pacing indication who attempted LBBAP. Procedural success was obtained in 56 patients (97%). Strain data were available in 50 patients. QRS duration was 124.1 ± 30.7 ms at baseline, while paced QRS duration was 107.7 ± 13.6 ms (p < 0.001). At 3 months after LBBAP, left ventricular ejection fraction (LVEF) increased from 52.9 ± 10.6% at baseline to 56.9 ± 8.4% (p = 0.004) and both intraventricular LV dyssynchrony and interventricular dyssynchrony significantly improved (LV TPSD reduction from 38.2 (13.6-53.9) to 15.1 (8.3-31.5), p < 0.001; LV-RV TPSD from 27.9 (10.2-41.5) to 13.9 (4.3-28.7), p = 0.001). Ameliorations with LBBAP were consistent in all subgroups, irrespective of baseline QRS duration, types of intraventricular conduction abnormalities, and LVEF.

CONCLUSIONS

Echocardiographic strain analysis shows that LBBAP determines a fast and synchronous biventricular contraction with a stereotype mechanical activation, regardless of baseline QRS duration, pattern, and LV function.

A Study to Analyse the Feasibility and Effectiveness of Left Bundle Branch Area Pacing Used in Young Children

This study aimed to investigate the feasibility and effectiveness of left bundle branch area pacing (LBBaP) in young children. From September 2020 to May 2021, a total of 31 children (≤ 7 years) with complete atrioventricular block were included. All patients were scheduled to undergo LBBaP. Pacing parameters, and cardiac function and synchrony were evaluated during follow-up. LBBaP succeeded in 21 children (3.3 ± 2.1 years old), with a success rate of 70.9%. LBBaP failed in nine children, who eventually received right ventricular septal pacing (RVSP). The average postoperative QRS duration in patients of LBBaP group was narrower than that of RVSP group: 100.9 ± 9.1 versus 114.2 ± 11.9 ms (P = 0.002). The median follow-up duration was 12 [interquartile range (IQR) 6-15] months. At last time of follow-up, the capture threshold of ventricular electrode in patients of LBBaP group were significantly lower than that of RVSP group (0.70 ± 0.25 versus 1.39 ± 0.94 V, P = 0.011). The echo-left ventricular ejection fraction (LVEF) in patients in the LBBaP group was better than that in the RVSP group (66.1 ± 3.3 versus 63.1 ± 2.2%, P = 0.025). LBBaP can be safely and effectively administered in young children. Satisfactory pacing parameters, and narrow QRS durations were obtained.

Complications of left bundle branch area pacing compared with biventricular pacing in candidates for resynchronization therapy: Results of a propensity score-matched analysis from a multicenter registry

BACKGROUND

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is a well-established therapy in patients with reduced left ventricular ejection fraction, heart failure, and left bundle branch block. Left bundle branch area pacing (LBBAP) has recently been shown to be a feasible and effective alternative to BVP. Comparative data on the risk of complications between LBBAP and BVP among patients undergoing CRT are lacking.

OBJECTIVE

The aim of this study was to compare the long-term risk of procedure-related complications between LBBAP and BVP in a cohort of patients undergoing CRT.

METHODS

This prospective, multicenter, observational study enrolled 668 consecutive patients (mean age 71.2 ± 10.0 years; 52.2% male; 59.4% with New York Heart Association class III-IV heart failure symptoms) with left ventricular ejection fraction 33.4% ± 4.3% who underwent BVP (n = 561) or LBBAP (n = 107) for a class I or II indication for CRT. Propensity score matching for baseline characteristics yielded 93 matched pairs. The rate and nature of intraprocedural and long-term post-procedural complications occurring during follow-up were prospectively collected and compared between the 2 groups.

RESULTS

During a mean follow-up of 18 months, procedure-related complications were observed in 16 patients: 12 in BVP (12.9%) and 4 in LBBAP (4.3%) (P = .036). Compared with patients who underwent LBBAP, those who underwent BVP showed a lower complication-free survival (P = .032). In multivariate analysis, BVP resulted an independent predictive factor associated with a higher risk of complications (hazard ratio 3.234; P = .042). Complications related to the coronary sinus lead were most frequently observed in patients who underwent BVP (50.0% of all complications).

CONCLUSION

LBBAP was associated with a lower long-term risk of device-related complications compared with BVP in patients with an indication for CRT.

Conduction system pacing versus biventricular pacing in heart failure with reduced ejection fraction: A systematic review and meta-analysis of randomized controlled trials

Conduction system pacing (CSP) has emerged as a promising alternative to biventricular pacing (BVP) in patients with heart failure with reduced ejection fraction (HFrEF) and ventricular dyssynchrony, but its benefits are uncertain. In this study, we aimed to evaluate clinical outcomes of CSP vs BVP for cardiac resynchronization in patients with HFrEF. PubMed, Scopus, and Cochrane databases were searched for randomized controlled trials comparing CSP to BVP for resynchronization therapy in patients with HFrEF. Heterogeneity was examined with I2 statistics. A random-effects model was used for all outcomes. We included 7 randomized controlled trials with 408 patients, of whom 200 (49%) underwent CSP. Compared to BVP, CSP resulted in a significantly greater reduction in QRS duration (MD -13.34 ms; 95% confidence interval [CI] -24.32 to -2.36, P = .02; I2 = 91%) and New York Heart Association functional class (standardized mean difference [SMD] -0.37; 95% CI -0.69 to -0.05; P = .02; I2 = 41%), and a significant increase in left ventricular ejection fraction (mean difference [MD] 2.06%; 95% CI 0.16 to 3.97; P = .03; I2 = 0%). No statistical difference was noted for left ventricular end-systolic volume (SMD -0.51 mL; 95% CI -1.26 to 0.24; P = .18; I2 = 83%), lead capture threshold (MD -0.08 V; 95% CI -0.42 to 0.27; P = .66; I2 = 66%), and procedure time (MD 5.99 minutes; 95% CI -15.91 to 27.89; P = .59; I2 = 79%). These findings suggest that CSP may have electrocardiographic, echocardiographic, and symptomatic benefits over BVP for patients with HFrEF requiring cardiac resynchronization.

Efficacy of left bundle branch area pacing versus biventricular pacing in patients treated with cardiac resynchronization therapy: Select site - cohort study

BACKGROUND

Cardiac resynchronization therapy (CRT) is typically attempted with biventricular (BiV) pacing. One-third of patients are nonresponders. Left bundle branch area pacing (LBBAP) has been evaluated as an alternative means.

OBJECTIVE

The purpose of this study was to assess the feasibility and clinical response of permanent LBBAP as an alternative to BiV pacing.

METHODS

Of 479 consecutive patients referred with heart failure, 50 with BiV-CRT and 51 with LBBAP-CRT were included in this analysis after study exclusions. Quality-of-Life (QoL) assessments, echocardiographic measurements, and New York Heart Association (NYHA) class were obtained at baseline and at 6-monthly intervals.

RESULTS

There were no differences in baseline characteristics between groups (all P > .05). Clinical outcomes such as left ventricular ejection fraction, left ventricular end-systolic volume, QoL, and NYHA class were significantly improved for both pacing groups compared to baseline. The LBBAP-CRT group showed greater improvement in left ventricular ejection fraction at 6 months (P = .001) and 12 months (P = .021), accompanied by greater reduction in left ventricular end-systolic volume (P = .007). QRS duration < 120 ms (baseline 160.82 ± 21.35 ms vs 161.08 ± 24.48 ms) was achieved in 30% in the BiV-CRT group vs 71% in the LBBAP-CRT group (P ≤ .001). Improvement in NYHA class (P = .031) and QoL index was greater (P = .014). Reduced heart failure admissions (P = .003) and health care utilization (P < .05) and improved lead performance (P < .001) were observed in the LBBAP-CRT group.

CONCLUSION

LBBAP-CRT is feasible and effective CRT. It results into a meaningful improvement in QoL and reduction in health care utilization. This can be offered as an alternative to BiV-CRT or potentially as first-line therapy.

Lead performance of stylet-driven leads in left bundle branch area pacing: Results from a large single-center cohort and insights from in vitro bench testing

BACKGROUND

Left bundle branch area pacing (LBBAP) requires deep septal lead deployment for left-sided conduction stimulation. Advancing leads toward deep septal positions might add mechanical stress on these leads. Concerns about lead performance and reliability remain an unanswered question.

OBJECTIVE

The purpose of this study was to analyze lead performance and integrity of stylet-driven pacing leads (SDLs) for LBBAP.

METHODS

This study assessed lead fracture rates of SDL in a large single-center cohort of adult LBBAP patients. Fluoroscopic analysis of lead bending angulations at the septal insertion point and in vitro bench testing of lead preconditioning were performed to simulate clinical use conditions. Lead performance was compared between LBBAP and conventional right ventricular apical pacing (RVp) sites.

RESULTS

The study included 325 LBBAP patients (66% male; age 71±15 years). During median follow-up of 18 months, 2 patients (0.6%) experienced conductor fracture between tip housing and ring electrode, whereas no such fractures occurred with RVp patients (n = 149; P = .22). X-ray analysis revealed that high lead bending angulations occurred in 1.3% of the patients. Accelerated bench testing of excessive preconditioned leads showcased a higher probability of early conductor fracture compared to standard preconditioned leads.

CONCLUSION

The incidence of early conductor failure in LBBAP seems higher than with conventional RVp sites. The most vulnerable lead part seems to be the interelectrode space between the tip housing and ring electrode. Excessive angulation and preconditioning might contribute to early fatigue fracture.

Treatment strategy for heart failure complicated with complete left bundle branch block and atrial tachycardia: a case report

BACKGROUND

For patients with heart failure combined with complete left bundle branch block, cardiac resynchronization therapy is an important therapeutic method. If these patients also have atrial tachycardia, how to choose a treatment strategy deserves discussion.

CASE PRESENTATION

A Chinese woman in her early 70s was admitted due to recurrent episodes of chest distress and asthma for 1 year. Physical and laboratory examinations showed filling of the jugular vein, lung rales, left enlargement of the heart boundary, edema of the lower limbs and elevation of N-terminal pro b-type natriuretic peptide. An electrocardiogram showed atrial tachycardia and a left bundle branch block. An echocardiography revealed enlargement of the left ventricle and left ventricular systolic dysfunction. After obtaining informed consent, the treatment strategy decided upon by the team was to use biventricular cardiac resynchronization therapy treatment and to not intervene for the atrial tachycardia, with left bundle branch area pacing as a backup. Due to twisted and narrow coronary vein branches, traditional biventricular pacing failed, and then, left bundle branch area pacing was attempted successfully. A follow-up echocardiography at 1 year showed improved systolic function. The outcomes for this patient are favorable, but the choice of interventional strategy is worthy of discussion in this case.

CONCLUSION

For patients with heart failure combined with left bundle branch block and atrial tachycardia, left bundle branch area pacing can replace traditional biventricular pacing for cardiac resynchronization therapy treatment, and the therapeutic effect is significant. However, multiple factors need to be considered when formulating strategies, including whether there is bundle branch block under sinus rhythm, the success and recurrence rate of atrial tachycardia ablation, the response of cardiac resynchronization therapy, the costs of different strategies, and instrument implantation issues.

Conventional biventricular pacing is still preferred to conduction system pacing for atrioventricular block in patients with reduced ejection fraction and narrow QRS

It is well established that right ventricular pacing is detrimental in patients with reduced cardiac function who require ventricular pacing (VP), and alternatives nowadays are comprised of biventricular pacing (BiVP) and conduction system pacing (CSP). The latter modality is of particular interest in patients with a narrow baseline QRS as it completely avoids, or minimizes, ventricular desynchronization associated with VP. In this article, experts debate whether BiVP or CSP should be used to treat these patients.

Result of the Physiologic Pacing Registry, an international multicenter prospective observational study of conduction system pacing

BACKGROUND

Conduction system pacing (CSP), including both left bundle branch area pacing (LBBAP) and His-bundle pacing (HBP) has been proposed as an alternative therapy option for patients with indication for cardiac pacing to treat bradycardia or heart failure.

OBJECTIVE

The purpose of this study was to evaluate implant success, safety, and electrical performances of HBP and LBBAP in the multinational Physiological Pacing Registry.

METHODS

The international prospective observational registry included 44 sites from 16 countries globally between November 2018 and May 2021.

RESULTS

Of 870 subjects enrolled, CSP lead implantation was attempted in 849 patients. Subjects with successful CSP lead implantation were followed for 6 months (5 ± 2 months). CSP lead implantation was successful in 768 patients (90.4%). Implant success was 95.2% (239/251) for LBBAP and 88.5% (529/598) for HBP (P = .002). Procedural duration and fluoroscopy duration were comparable between LBBAP and HBP (P = .537). Capture threshold at implant was 0.69 ± 0.39 V at 0.46 ± 0.15 ms in LBBAP and 1.44 ± 1.03 V at 0.71 ± 0.33 ms in HBP (P <.001). Capture threshold at 6 months was 0.79 ± 0.33 V at 0.44 ± 0.13 ms in LBBAP and 1.59 ± 0.97 V at 0.67 ± 0.31 ms in HBP (P <.001). Pacing threshold rise ≥1 V was observed at 6 months in 3 of 208 (1.4%) of LBBAP and 55 of 418 (13.2%) of HBP (P <.001). Serious adverse events related to implant procedure or CSP lead occurred in 5 of 251 (2.0%) with LBBAP and 25 of 598 (4.2%) with HBP (P = .115).

CONCLUSION

This large prospective multicenter study demonstrates that CSP is technically feasible in most patients with relatively higher implant success and suggests that, with current technology, LBBAP may have better pacing parameters than HBP.

The Zwolle experience with left bundle branch area pacing using stylet-driven active fixation leads

AIMS

Left bundle branch area pacing (LBBAP) is a novel physiological pacing modality and is regarded as a viable alternative to His bundle pacing. LBBAP has mostly been performed with the lumen-less permanent pacing lead (SelectSecure™ Model 3830, Medtronic, Inc.) with a fixed helix. The aim of this study was to compare the non-stylet driven lumen-less lead (LLL) (Medtronic 3830) with a standard stylet-driven active fixation lead (SDL) (Tendril™ STS Model 2088TC-38, Abbott Laboratories) in terms of lead parameters, procedural success and complication rates.

METHODS

Patients receiving a LBBA pacemaker in the Isala Hospital, The Netherlands, were prospectively enrolled. The majority received a standard right ventricular (RV) lead as backup, the implanter chose between LLL and SDL for the LBBAP lead.

RESULTS

The study included 94 patients with a mean follow-up of 30 weeks. 30/31 LLL procedures were successful, compared with 62/63 in the SDL group. Including the participants that lost LBBAP during follow-up resulted in success rates of 90.3% for LLL versus 96.8% for SDL, P = 0.199. Mean number of deployments was significantly lower in the SDL group compared with the LLL group (2 ± 2.3 versus 4 ± 3.4, P = 0.005), implantation and procedural times were comparable. Pacing thresholds were low and remained low in both groups (at last follow-up 0.8 ± 0.30 V for LLL versus 0.6 ± 0.20 V for SDL). Complication rates did not differ significantly between both groups, P = 0.805.

CONCLUSION

LBBAP using SDL is feasible and has comparable success rates with lower number of deployments of the active fixation screw.

Conduction system pacing and defibrillation support using a single-chamber defibrillator - A case report

We present a case of a 67-year-old male with heart failure with reduced ejection fraction due to a previous myocardial infarction, slow-conducting atrial fibrillation with an indication of pacemaker implantation, and sustained ventricular tachycardia, requiring defibrillation support in prevention of sudden cardiac death. Current guidelines recommend biventricular over conventional right ventricular pacing for patients with ejection fraction <40 % and atrioventricular conduction disorders in either sinus rhythm or atrial fibrillation, but in patients with a narrow baseline QRS complex, biventricular pacing still induces a form of electrical dyssynchrony. In our case we combined the advantages of conduction system pacing in form of left bundle branch area pacing, in order to prevent further left ventricular deterioration due to newly induced dyssyncrony, and also defibrillation support, using a single-chamber defibrillator with a DF-1/IS-1 connection.

Conduction System Pacing for Patients with Congenital Heart Disease

For patients with congenital heart disease (CHD), chronic ventricular pacing may lead to progressive cardiomyopathy owing to electromechanical dyssynchrony. Cardiac conduction system pacing (CSP) has been proposed as a physiologic pacing strategy-directly engaging the His-Purkinje system and preserving electromechanical synchrony. CSP may be indicated for a wide variety of children and adults with CHD and has emerged as an important tool in the armamentarium for cardiac implantable electronic device operators. This review provides the rationale, background, and supportive evidence for CSP in patients with CHD and discusses implant strategies and outcomes in the context of dominant ventricular morphologic categories.

Left bundle branch area pacing reduces epicardial dispersion of repolarization compared with biventricular cardiac resynchronization therapy

BACKGROUND

Biventricular endocardial pacing (BiV-endo) and left bundle branch area pacing (LBBAP) are novel methods of delivering cardiac resynchronization therapy. These techniques are associated with improved activation times and acute hemodynamic response compared with conventional biventricular epicardial pacing (BiV-epi); however, the effects on repolarization and arrhythmic risk are unknown.

OBJECTIVE

The purpose of this study was to compare the effects of temporary BiV-epi, BiV-endo, and LBBAP on epicardial left ventricular (LV) repolarization using electrocardiographic imaging (ECGi).

METHODS

Eleven patients indicated for cardiac resynchronization therapy underwent a temporary pacing protocol with ECGi. BiV-endo was delivered via endocardial stimulation of the LV lateral wall. LBBAP was delivered by pacing the LV septum. Epicardial LV repolarization time (LVRT-95; time taken for 95% of the LV to repolarize), LV RT dispersion, mean LV activation recovery interval (ARI), LV ARI dispersion, and RT gradients were calculated.

RESULTS

The protocol was completed in 10 patients. During LBBAP, there were significant reductions in LVRT-95 (94.9 ± 17.4 ms vs 125.0 ± 29.4 ms; P = .03) and LV RT dispersion (29.4 ± 6.3 ms vs 40.8 ± 11.4 ms; P = .015) compared with BiV-epi. In contrast, there were no significant differences between baseline, BiV-epi, or BiV-endo. There was a nonsignificant reduction in mean RT gradients between LBBAP and baseline rhythm (0.74 ± 0.22 ms/mm vs 1.01 ± 0.31 ms/mm; P = .07). There were no significant differences in mean LV ARI or LV ARI dispersion between groups.

CONCLUSION

Temporary LBBAP reduces epicardial dispersion of repolarization compared with conventional BiV-epi. Further study is required to determine whether these repolarization changes on ECGi translate into a reduced risk of ventricular arrhythmia in clinical practice.

Acute performance of stylet driven leads for left bundle branch area pacing: A comparison with lumenless leads

Background

Lumenless leads (LLLs) are widely used for left bundle branch area pacing (LBBAP). Recently, stylet-driven leads (SDLs) have also been used for LBBAP.

Objective

The purpose of this study was to evaluate the acute performance of SDLs during LBBAP in comparison with LLLs.

Methods

Consecutive patients undergoing LBBAP for bradycardia or cardiac resynchronization therapy indications at 2 high-volume, early conduction system pacing adopters, tertiary centers were included from January 2019 to July 2023. Patients received either SDLs or LLLs at the discretion of the implanting physician. Acute performance and follow-up data of both lead types were evaluated.

Results

A total of 925 LBBAP implants were included, 655 using LLLs and 270 using SDLs. Overall, LBBAP acute success was significantly higher with LLLs than SDLs (95.3% vs 85.1%, respectively; P <.001) even after the learning curve (97% vs 86%; P = .013). LLLs were implanted in more mid-basal septal positions in comparison with SDLs, which tended to be implanted in more inferior and mid-apical septal positions. Acute lead-related complications were higher with SDLs than LLLs (15.9% vs 6.1%, respectively; P <.001) with 15 cases of lead damage during implant (4.4% vs 0.5%; P <.001) but decreased with acquired experience and were comparable in the last 100 patients included in each group. Lead implant and fluoroscopy times were shorter for SDLs, with lead dislodgment occurring in 0.9% with LLLs and 1.5% with SDLs (P = .489).

Conclusion

Acute lead performance proved to be different between LLLs and SDLs. A specific learning curve should be considered for SDLs even for implanters with extensive previous experience with LLLs.

A Novel Technique of Placing Desfibrillator Leads in Patients with Persistent Left Superior Vena Cava

Persistent left superior vena cava is the most common thoracic venous anomaly. It is usually asymptomatic, but it can make implanting intracardiac devices difficult.We present a novel technique to facilitate desfibrillator lead implantation in patients with persistent left superior vena cava and the absence of the right superior vena cava. We used a fixed-curve Selectra 3D 65-42 cm sheath (Biotronik), orienting it toward the tricuspid valve (TV) by rotating it counter-clockwise. During follow-up, the electrodes remained stable.Our technique was safe, simple, and feasible for patients with this complex venous anatomy.

Safety and efficacy of left bundle branch area pacing compared with right ventricular pacing in patients with bradyarrhythmia and conduction system disorders: Systematic review and meta-analysis

BACKGROUND

Right Ventricular Pacing (RVP) may have detrimental effects in ventricular function. Left Bundle Branch Area Pacing (LBBAP) is a new pacing strategy that appears to have better results. The aim of this systematic review and meta-analysis is to compare the safety and efficacy of LBBAP vs RVP in patients with bradyarrhythmia and conduction system disorders.

METHODS

MEDLINE, EMBASE and Pubmed databases were searched for studies comparing LBBAP with RVP. Outcomes were all-cause mortality, atrial fibrillation (AF) occurrence, heart failure hospitalizations (HFH) and complications. QRS duration, mechanical synchrony and LVEF changes were also assessed. Pairwise meta-analysis was conducted using random and fixed effects models.

RESULTS

Twenty-five trials with 4250 patients (2127 LBBAP) were included in the analysis. LBBAP was associated with lower risk for HFH (RR:0.33, CI 95%:0.21 to 0.50; p < 0.001), all-cause mortality (RR:0.52 CI 95%:0.34 to 0.80; p = 0.003), and AF occurrence (RR:0.43 CI 95%:0.27 to 0.68; p < 0.001) than RVP. Lead related complications were not different between the two groups (p = 0.780). QRSd was shorter in the LBBAP group at follow-up (WMD: -32.20 msec, CI 95%: -40.70 to -23.71; p < 0.001) and LBBAP achieved better intraventricular mechanical synchrony than RVP (SMD: -1.77, CI 95%: -2.45 to -1.09; p < 0.001). LBBAP had similar pacing thresholds (p = 0.860) and higher R wave amplitudes (p = 0.009) than RVP.

CONCLUSIONS

LBBAP has better clinical outcomes, preserves ventricular electrical and mechanical synchrony and has excellent pacing parameters, with no difference in complications compared to RVP.

Role of conduction system pacing in ablate and pace strategies for atrial fibrillation

With the advent of conduction system pacing, the threshold for performing 'ablate and pace' procedures for atrial fibrillation has gone down markedly in many centres due to the ability to provide a simple and physiological means of pacing the ventricles. This article reviews the technical considerations for this strategy as well as the current evidence, recognized indications, and future perspectives.

Conduction system pacing: overview, definitions, and nomenclature

Pacing from the right ventricle is associated with an increased risk of development of congestive heart failure, increases in total and cardiac mortality, and a worsened quality of life. Conduction system pacing has become increasingly realized as an alternative to right ventricular apical pacing. Conduction system pacing from the His bundle and left bundle branch area has been shown to provide physiologic activation of the ventricle and may be an alternative to coronary sinus pacing. Conduction system pacing has been studied as an alternative for both bradycardia pacing and for heart failure pacing. In this review, we summarize the clinical results of conduction system pacing under a variety of different clinical settings. The anatomic targets of conduction system pacing are illustrated, and electrocardiographic correlates of pacing from different sites in the conduction system are defined. Ultimately, clinical trials comparing conduction system pacing with standard right ventricular apical pacing and cardiac resynchronization therapy pacing will help define its benefit and risks compared with existing techniques.

Procedural outcome and follow-up of stylet-driven leads compared with lumenless leads for left bundle branch area pacing

AIMS

Left bundle branch area pacing (LBBAP) is most often delivered using lumenless leads (LLLs), but may also be performed using stylet-driven leads (SDLs). There are limited reports on the comparison of these tools, mainly limited to reports describing initial operator experience or without detailed procedural data. Our aim was to perform an in-depth comparison of SDLs and LLLs for LBBAP at implantation and follow-up in a larger cohort of patients with experience that extends beyond that of the initial learning curve.

METHODS AND RESULTS

A total of 306 consecutive patients (age 77 ± 11 years, 183 males) undergoing LBBAP implantation at a single centre were prospectively included. The population was split into two groups of 153 patients based on the initial use of an SDL (from 4 manufacturers) or an LLL. After having discounted the initial learning curve of 50 patients, there was no difference in the success rate between the initial use of lead type (96.0% with SDL vs. 94.3% with LLL, P = 0.56). There were no significant differences in success between lead models. Electrocardiogram and electrical parameters were comparable between the groups. Post-operative macro-dislodgement occurred in 4.3% of patients (essentially within the first day following implantation) and presumed micro-dislodgement with loss of conduction system capture or rise in threshold (occurring mostly during the first month) was observed in 4.7% of patients, without differences between groups.

CONCLUSION

Left bundle branch area pacing may be safely and effectively performed using either LLLs or SDLs, which provides implanters with alternatives for delivering this therapy.

Worldwide survey on implantation of and outcomes for conduction system pacing with His bundle and left bundle branch area pacing leads

BACKGROUND

Adoption and outcomes for conduction system pacing (CSP), which includes His bundle pacing (HBP) or left bundle branch area pacing (LBBAP), in real-world settings are incompletely understood. We sought to describe real-world adoption of CSP lead implantation and subsequent outcomes.

METHODS

We performed an online cross-sectional survey on the implantation and outcomes associated with CSP, between November 15, 2020, and February 15, 2021. We described survey responses and reported HBP and LBBAP outcomes for bradycardia pacing and cardiac resynchronization CRT indications, separately.

RESULTS

The analysis cohort included 140 institutions, located on 5 continents, who contributed data to the worldwide survey on CSP. Of these, 127 institutions (90.7%) reported experience implanting CSP leads. CSP and overall device implantation volumes were reported by 84 institutions. In 2019, the median proportion of device implants with CSP, HBP, and/or LBBAP leads attempted were 4.4% (interquartile range [IQR], 1.9-12.5%; range, 0.4-100%), 3.3% (IQR, 1.3-7.1%; range, 0.2-87.0%), and 2.5% (IQR, 0.5-24.0%; range, 0.1-55.6%), respectively. For bradycardia pacing indications, HBP leads, as compared to LBBAP leads, had higher reported implant threshold (median [IQR]: 1.5 V [1.3-2.0 V] vs 0.8 V [0.6-1.0 V], p = 0.0008) and lower ventricular sensing (median [IQR]: 4.0 mV [3.0-5.0 mV] vs. 10.0 mV [7.0-12.0 mV], p < 0.0001).

CONCLUSION

In conclusion, CSP lead implantation has been broadly adopted but has yet to become the default approach at most surveyed institutions. As the indications and data for CSP continue to evolve, strategies to educate and promote CSP lead implantation at institutions without CSP lead implantation experience would be necessary.

Correlations between myocardial injury current and lead performance in His bundle pacing compared with left bundle branch area pacing and right ventricular septum pacing

BACKGROUND

Conduction system pacing by implanting the lead in the His bundle (HBP) region or in the left bundle branch area (LBBAP) has gained popularity. Myocardial injury current (IC) is useful for predicting adequate lead fixation in right ventricular septal pacing (RVSP).

OBJECTIVES AND METHODS

We compared the correlations between IC and lead performance among patients receiving HBP (n = 41), LBBAP (n = 53), and historical RVSP (n = 88). LBBAP was an alternative if optimal HBP was not achieved. A positive IC (STpost-screw-in - STpre-screw-in) was defined as > 0.2 mV or a > 25% ST elevation and prolongation of the ventricular electrograms > 10 ms from baseline.

RESULTS

HBP patients with a positive IC (48%, 0.84 ± 0.4 V/0.4 ms) exhibited a similar pacing threshold to their LBBAP counterparts (76%, 0.75 ± 0.3 V/0.4 ms, p = 0.329), but a higher pacing threshold than their RVSP counterparts (67%, 0.50 ± 0.1 V/0.4 ms, p < 0.001) at implantation. The R-wave (5.70 ± 3.4 mV) and impedance (660.91 ± 140.8 Ω) were both lower than those of LBBAP (10.35 ± 6.0 mV, p = 0.002; 822.36 ± 235.8 Ω, p = 0.005) and RVSP (11.24 ± 4.9 mV, p < 0.001; 754.27 ± 126.4 Ω, p = 0.006) patients respectively at implantation. The trend of electrical parameter comparisons remained unchanged during follow-up (3.56 ± 1.4 months). Notably, HBP patients without ICs had a higher pacing threshold (1.24 ± 0.6 V/0.4 ms) compared to their LBBAP (0.73 ± 0.3 V/0.4 ms, p = 0.009) and RVSP (0.53 ± 0.1 V/0.4 ms, p < 0.001) counterparts at implantation and during follow-up.

CONCLUSIONS

The detection of positive changes of myocardial ICs during HBP was associated with a better capture threshold equivalent to the LBBAP counterpart both at implantation and during short-term follow-up. Further large-scale studies with longer follow-up are necessary to confirm these findings.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

Success and complication rates of conduction system pacing: a meta-analytical observational comparison of left bundle branch area pacing and His bundle pacing

BACKGROUND

Left bundle branch area pacing (LBBAP) and His bundle pacing (HBP) are the main strategies to achieve conduction system pacing (CSP), but only observational studies with few patients have compared the two pacing strategies, sometimes with unclear results given the different definitions of the feasibility and safety outcomes. Therefore, we conducted a meta-analysis aiming to compare the success and complications of LBBAP versus HBP.

METHODS

We systematically searched the electronic databases for studies published from inception to March 22, 2023, and focusing on LBBAP versus HBP. The study endpoints were CSP success rate, device-related complications, CSP lead-related complications and non-CSP lead-related complications.

RESULTS

Fifteen observational studies enrolling 2491 patients met the inclusion criteria. LBBAP led to a significant increase in procedural success [91.1% vs 80.9%; RR: 1.15 (95% CI: 1.08-1.22); p < 0.00001] with a significantly lower complication rate [1.8% vs 5.2%; RR: 0.48 (95% CI: 0.29-0.78); p = 0.003], lead-related complications [1.1% vs 4.3%; RR: 0.38 (95% CI: 0.21-0.72); p = 0.003] and lead failure/deactivation [0.2% vs 3.9%; RR: 0.16 (95% CI: 0.07-0.35); p < 0.00001] than HBP. No significant differences were found between CSP lead dislodgement and non-CSP lead-related complications.

CONCLUSION

This meta-analysis of observational studies showed a higher success rate of LBBAP compared to HBP with a lower incidence of complications.

Diverse QRS morphology reflecting variations in lead placement for left bundle branch area pacing

AIMS

Left bundle branch area pacing (LBBAP) is a potential alternative to His bundle pacing. This study aimed to investigate the impact of different septal locations of pacing leads on the diversity of QRS morphology during non-selective LBBAP.

METHODS AND RESULTS

Non-selective LBBAP and left ventricular septal pacing (LVSP) were achieved in 50 and 21 patients with atrioventricular block, respectively. The electrophysiological properties of LBBAP and their relationship with the lead location were investigated. QRS morphology and axis showed broad variations during LBBAP. Echocardiography demonstrated a widespread distribution of LBBAP leads in the septum. During non-selective LBBAP, the qR-wave in lead V1 indicated that the primary location for pacing lead was the inferior septum (93%). The non-selective LBBAP lead was deployed deeper than the LVSP lead in the inferior septum. The Qr-wave in lead V1 with the inferior axis in aVF suggested pacing lead placement in the anterior septum. The penetration depth of the non-selective LBBAP lead in the anterior septum was significantly shallower than that in the inferior septum (72 ± 11 and 87 ± 8%, respectively). In lead V6, the deep S-wave indicated the time lag between the R-wave peak and the latest ventricular activation in the coronary sinus trunk, with pacemaker leads deployed closer to the left ventricular apex.

CONCLUSION

Different QRS morphologies and axes were linked to the location of the non-selective LBBAP lead in the septum. Various lead deployments are feasible for LBBAP, allowing diversity in the conduction system capture in patients with atrioventricular block.

Pacing of Specialized Conduction System

Right ventricular pacing for bradycardia remains the mainstay of pacing therapy. Chronic right ventricular pacing may lead to pacing-induced cardiomyopathy. We focus on the anatomy of the conduction system and the clinical feasibility of pacing the His bundle and/or left bundle conduction system. We review the hemodynamics of conduction system pacing, the techniques to capture the conduction system and the electrocardiogram and pacing definitions of conduction system capture. Clinical studies of conduction system pacing in the setting of atrioventricular block and after AV junction ablation are reviewed and the evolving role of conduction system pacing is compared with biventricular pacing.

Cardiac resynchronization therapy using conduction system pacing after double-switch surgery for congenitally corrected transposition of the great arteries: a case report

Background

Patients with congenitally corrected transposition of the great arteries (ccTGA) are at risk of developing conduction disease and complete atrio-ventricular block and this risk increases after corrective cardiac surgery. However, the optimum pacing modality remains controversial.

Case summary

Twelve years after a double-switch surgery with ventricular septal defect correction, a 16-year-old ccTGA female was referred with an indication for cardiac resynchronization therapy. In the absence of coronary sinus (CS) or direct access to the conduction system, several therapeutic options were considered. Finally, using a three-dimensional navigation system and customized sheaths, a left bundle branch area pacing (LBBAP) lead was successfully implanted. The implantation resulted in stable pacing parameters and positive haemodynamic changes. At 9-month follow-up, pacing parameters were stable and the patient reported a significant improvement in quality of life.

Discussion

Cardiac resynchronization therapy in adults with repaired congenital heart disease remains challenging, especially in the absence of CS or direct access to the conduction system. In such a situation, LBBAP appears as an attractive alternative pacing modality. However, pre-operative management is critical to the success of the implantation.

Consecutive Experience with Left Bundle Branch Area Pacing in a High-Volume Australian Centre

INTRODUCTION

Left-bundle branch area pacing (LBBAP) is a relatively new technique for conduction system pacing. Australian safety and efficacy data is currently lacking. We aim to evaluate the learning curve, medium-term safety, and lead performance in a high-volume Australian setting.

METHODS

We performed a retrospective cohort study of 200 consecutive LBBAP procedures performed by a single operator at two centres between January 2019 and May 2020. Left bundle branch area pacing was performed predominantly via left subclavian access using a 69 cm Medtronic SelectSecure 3830 pacing lead and a preformed non-steerable C315-His sheath. Procedural success was defined as evidence of left septal or left bundle branch area capture as evidenced by a right bundle branch block-like paced morphology. Procedural characteristics, and follow-up (including lead performance) data were collected. Procedural efficiency over time, as well as safety data, were collected.

RESULTS

Median age was 78.26 years (interquartile range [IQR] 71-85), 37% were female. Atrial fibrillation was present in 22%. The left ventricular ejection fraction <50% in 24%, atrioventricular (AV) block was present in 43.5%, left bundle branch block in 22.5% and right bundle branch block in 24.5%. Acute procedural success was 91.5%. Implant threshold was 0.6V @ 0.5 ms, and 0.75V @ 0.5 ms at 11.9 months of follow-up. The QRS was significant reduced (baseline 134 ms vs implant 114 ms, p<0.001) There was a reduction in procedural time and X-ray dose over the course of the study. There were no complications specific to LBBAP.

CONCLUSION

LBBAP appears to be a safe and effective pacing strategy. The QRS duration was significantly reduced compared to baseline. There appears to be an early learning curve with LBBAP.

Conduction System Pacing Upgrade in Chronic Heart Failure with Severe Left Ventricular Dysfunction and Chronic Atrial Fibrillation

Cardiac resynchronization therapy (CRT) is a standard treatment for patients with severe congestive heart failure. However, one-third of patients receiving CRT are non-responders. Conduction system pacing (CSP), including His-bundle pacing (HBP) and left bundle branch area pacing (LBBAP), has become an alternative to CRT therapy. Furthermore, CRT therapy with CSP has shown to be more effective than CRT alone. When an implantable cardiac defibrillator or CRT-defibrillator is implanted with CSP, the problem of which port the HBP lead and LBBAP lead should be connected to arises. We report 2 cases of upgrading to CRT with CSP by utilizing the atrial ports for HBP and LBBAP leads. The procedure is a simple, reasonable, and effective therapy for end-stage heart failure.

Outcomes of conduction system pacing for cardiac resynchronization therapy in patients with heart failure: A multicenter experience

BACKGROUND

Whether conduction system pacing (CSP) is an alternative option for cardiac resynchronization therapy (CRT) in patients with heart failure remains an area of active investigation.

OBJECTIVE

The purpose of this study was to assess the echocardiographic and clinical outcomes of CSP compared to biventricular pacing (BiVP).

METHODS

This multicenter retrospective study included patients who fulfilled CRT indications and received CSP. Patients with CSP were matched using propensity score matching and compared in a 1:1 ratio to patients who received BiVP. Echocardiographic and clinical outcomes were assessed. Response to CRT was defined as an absolute increase of ≥5% in left ventricular ejection fraction (LVEF) at 6 months post-CRT.

RESULTS

A total of 238 patients were included. Mean age was 69.8 ± 12.5 years, and 66 (27.7%) were female. Sixty-nine patients (29%) had His-bundle pacing, 50 (21%) had left bundle branch area pacing, and 119 (50%) had BiVP. Mean follow-up duration in the CSP and BiVP groups was 269 ± 202 days and 304 ± 262 days, respectively (P = .293). The proportion of CRT responders was greater in the CSP group than in the BiVP group (74% vs 60%, respectively; P = .042). On Kaplan-Meier analysis, there was no statistically significant difference in the time to first heart failure hospitalization (log-rank P = .78) and overall survival (log-rank P = .68) between the CSP and BiVP groups.

CONCLUSION

In patients with heart failure and reduced ejection fraction, CSP resulted in greater improvement in LVEF compared to BiVP. Large-scale randomized trials are needed to validate these outcomes and further investigate the different options available for CSP.

The PhysioVP-AF study, a randomized controlled trial to assess the clinical benefit of physiological ventricular pacing vs. managed ventricular pacing for persistent atrial fibrillation prevention in patients with prolonged atrioventricular conduction: design and rationale

AIMS

In patients with prolonged atrioventricular (AV) conduction and pacemaker (PM) indication due to sinus node disease (SND) or intermittent AV-block who do not need continuous ventricular pacing (VP), it may be difficult to determine which strategy to adopt. Currently, the standard of care is to minimize unnecessary VP by specific VP avoidance (VPA) algorithms. The superiority of this strategy over standard DDD or DDD rate-responsive (DDD/DDDR) in improving clinical outcomes is controversial, probably owing to the prolongation of the atrialventricular conduction (PR interval) caused by the algorithms. Conduction system pacing (CSP) may offer the most physiological-VP approach, providing appropriate AV conduction and preventing pacing-induced dyssynchrony.

METHODS AND RESULTS

PhysioVP-AF is a prospective, controlled, randomized, single-blind trial designed to determine whether atrial-synchronized conduction system pacing (DDD-CSP) is superior to standard DDD-VPA pacing in terms of 3-year reduction of persistent-AF occurrence. Cardiovascular hospitalization, quality-of-life, and safety will be evaluated. Patients with indication for permanent DDD pacing for SND or intermittent AV-block and prolonged AV conduction (PR interval > 180 ms) will be randomized (1:1 ratio) to DDD-VPA (VPA-algorithms ON, septal/apex position) or to DDD-CSP (His bundle or left bundle branch area pacing, AV-delay setting to control PR interval, VPA-algorithms OFF). Approximately 400 patients will be randomized in 24 months in 13 Italian centres.

CONCLUSION

The PhysioVP-AF study will provide an essential contribution to patient management with prolonged AV conduction and PM indication for sinus nodal disease or paroxysmal 2nd-degree AV-block by determining whether CSP combined with a controlled PR interval is superior to standard management that minimizes unnecessary VP in terms of reducing clinical outcomes.

Conduction system pacing in France in 2022: A snapshot survey from the Working Group of Pacing and Electrophysiology of the French Society of Cardiology

BACKGROUND

Conduction system pacing (CSP) is an emerging and promising approach for physiological ventricular pacing. While data from randomized controlled trials are scarce, use of His-bundle pacing (HBP) and left bundle branch area pacing (LBBAP) has increased in France.

AIM

To perform a national snapshot survey for cardiac electrophysiologists to evaluate adoption of CSP in France.

METHODS

An online survey, distributed to every senior cardiac electrophysiologist in France, was conducted in November 2022.

RESULTS

A total of 120 electrophysiologists completed the survey. Eighty-three (69%) respondents reported experience in undertaking CSP procedures and 27 (23%) were planning to start performing CSP in the coming 2 years. The implantation techniques and criteria used for successful implantation differed significantly among operators. The most frequent indications for HBP and LBBAP were high-degree atrioventricular block with left ventricular ejection fraction (LVEF) < 40% (24 and 82%, respectively) or with LVEF ≥ 40% (27 and 74%, respectively), and after failure of a coronary sinus left ventricular lead (27 and 71%, respectively). The limitations respondents most frequently perceived when performing HBP were bad sensing/pacing parameters (45%), increased procedure duration (41%) and risk of lead dislodgement (30%). The most frequently perceived limitations to performing LBBAP were absence of guidelines or consensus (31%), lack of medical training (23%) and increased procedure duration (23%).

CONCLUSIONS

Our national survey-based study supports wide adoption of CSP in France. CSP is currently used as a second-line approach for both antibradycardia and resynchronization indications, with important variations regarding implantation techniques and criteria for measuring success.

Early Experience of Patients with left Bundle Branch Block Corrected through Left Bundle Branch Area Pacing Compared with Conventional Right Ventricular Pacing: A Single-Center Retrospective Study

Background

Left bundle branch area pacing (LBBAP) has the advantages of narrow QRS duration, rapid peak left ventricular (LV) activation, and LV dyssynchrony correction with a low, stable pacing output. Here we report our experience with patients undergoing LBBAP with a left bundle branch block (LBBB) for clinically indicated pacemaker or cardiac resynchronization therapy implantation. We compared the initial follow-up data of these patients and patients undergoing conventional right ventricular pacing (RVP).

Methods

This retrospective study was performed between January 2017 and December 2020 and recruited 19 consecutive patients (mean age: 63 years; 8 women, 11 men) who underwent LBBAP (13 LBBAP only and 6 LBBAP + LV pacing), and 14 consecutive patients (mean age: 75 years; 8 women, 6 men) who underwent RVP. Demographic data, QRS durations, and echocardiographic parameters were compared before and after the procedures.

Results

LBBAP substantially shortened the QRS duration and improved LV dyssynchrony echocardiographic parameters. However, RVP was not significantly associated with prolonged QRS duration and worse LV dyssynchronization. LBBAP improved cardiac contractility in selected patients. We did not find adverse effects of LBBAP on patients with preserved systolic function, possibly due to the limited number of patients and follow-up time. However, two of the 11 patients with preserved systolic function at baseline who underwent conventional RVP developed heart failure after implantation.

Conclusions

In our experience, LBBAP improves LBBB-related ventricular dyssynchrony. However, LBBAP requires greater skill, and doubts remain about lead extraction. LBBAP may be an option for patients with LBBB when performed by an experienced operator, however further studies are needed to verify our findings.

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.

Pacing of the specialized His-Purkinje conduction system: 'back to the future'

The conduction system of the human heart is composed of specialized cardiomyocytes that initiate and propagate the electric impulse with consequent rhythmic and synchronized contraction of the atria and ventricles, resulting in the normal cardiac cycle. Although the His-Purkinje system (HPS) was already described more than a century ago, there has been a recent resurgence of conduction system pacing (CSP), where pacing leads are positioned in the His bundle region and left bundle branch area to provide physiological cardiac activation as alternatives to the unnatural myocardial stimulation obtained with conventional right ventricular and biventricular pacing. In this review, we describe the fundamental anatomical and pathophysiological aspects of the specialized HPS along with the CSP technique's nuts and bolts to highlight its potential benefits in everyday clinical practice.