Baseline QRS Duration Research Articles

'Pacing System Analyzers to guide Conduction System Pacing implantation procedures: A comparison study of intracardiac and surface signals with an Electrophysiological Recording System'.

Left bundle branch area pacing (LBBAP) needs confirmation of left conduction system capture assessed by testing of different electrical parameters. Guidelines recommend the use of an electrophysiological recording-system (EP-RS) to guide conduction system pacing (CSP) procedures. However, some experienced centers perform LBBAP procedures without an EP-RS. We aimed to assess whether LBBAP criteria can be measured using the signals provided by the pacing system analyzers (PSA) as a surrogate for the EP-RS to simplify and universalize the technique. This was an observational, prospective, multicenter study assessing the current LBBAP criteria using the PSA compared to the EP-RS during CSP procedures. 108 consecutive patients were included. Baseline QRS duration was 130±29 vs 128±29msec in the EP-RS vs PSA (p=0.7). An initial "W" morphology in V1 was noted in 88% patients with the EP-RS vs 86% patients with the PSA (p=0.7) during unipolar pacing. The QRS duration (122±17 vs 123±19 msec, p=0.7), the R-wave peak time interval in V6 (80±13 vs 79±14 msec (p=0.9) and the V6-V1 inter-peak interval (39±16 vs 38±17 msec (p=0.7) were superimposable in the EP-RS compared to the PSA. Pearson coefficient for the last two criteria were 0.85 (p<0.0001) and 0.94 (p<0.0001), respectively. According to the current criteria, 91.5% of patients received a successful LBBAP implant using the EP-RS. Based on the PSA measurements, 96.6% of these patients accomplished LBBAP criteria. Criteria for LBBAP can be assessed by PSAs with high accuracy. These results provide the basis for the usefulness of the PSA to guide LBBAP procedures.

A larger reduction of spatial mean QRS-T angle during cardiac resynchronisation therapy is associated with a lower risk of mortality and heart failure hospitalisation

Abstract Background Predicting clinical outcome in heart failure patients undergoing cardiac resynchronization therapy (CRT) remains challenging, necessitating improved risk stratification for CRT recipients. Previous studies have shown an association between large spatial peak and mean QRS-T angles and cardiovascular disease. Little is known, however, about their relation to clinical outcome following CRT. Purpose To investigate the association between spatial peak and mean QRS-T angles and long-term clinical outcome following CRT initiation. Methods All patients with native LBBB receiving CRT at a large-volume tertiary care center between 2015 and 2020 were retrospectively evaluated. Spatial peak and mean QRS-T angles were derived from digital pre- and post-CRT 12-lead ECGs that were processed using Glasgow algorithm and Kors’ regression transformation. The QRS-T angles and their change after CRT were analyzed in relation to the primary composite endpoint of heart failure hospitalisation or all-cause mortality using Cox regression analysis adjusted for clinical covariates (age, gender, CRT-P or CRT-D, secondary ICD indication, ischemic etiology, NYHA class, LVEF, diabetes, atrial fibrillation, baseline QRS duration, NT-proBNP, and eGFR). Results The study group comprised 250 patients (a median age [Q1–Q3] of 72.2 years [64.5–76.3]; 22% female; 58% New York Heart Association (NYHA) class III-IV; LVEF 27% [22–30]) who were followed over a median follow-up time of 4.5 years [3.2–5.8] after CRT implantation. The median post-CRT spatial peak and mean QRS-angles were 142° [116–160] and 152° [127–166], and the median angle was decreased by 16° [-0.6–41] and 14° [-0.4–38], respectively. Both a larger post-CRT mean QRS-T angle (HR 1.20, 95%CI 1.08-1.33, p=&amp;lt;.001) and peak QRS-T angle (HR 1.08, 95%CI 1.01-1.17, p=0.046) were associated with the primary endpoint. A larger reduction of mean QRS-T angle, but not peak QRS-T angle, was associated with a risk reduction (HR 0.87, 95%CI 0.79-0.95, p&amp;lt;0.003). In Kaplan-Meier analysis, patients with a post-CRT mean QRS-T angle above median had a higher risk of reaching the endpoint (log-rank p=0.002, Figure 1). Conclusion Our results show that a larger magnitude of the post-CRT spatial peak and mean QRS-T angles, and a larger reduction of the latter, are associated with long-term heart failure hospitalisation and death. These findings suggest that spatial QRS-T angle may have a potential role in refined risk stratification of CRT patients.Figure 1.K-M curve spatial mean QRS-T

Assessment of mechanical dyssynchrony can improve the new ESC-2021 guidelines for cardiac resynchronization therapy

Abstract Background In 2021, new guidelines for cardiac resynchronization therapy (CRT) were published by the European society of cardiology (ESC-2021), where the different classes of recommendations were based on a new ECG-based definition of left bundle branch block (LBBB). However, its association with reverse LV remodeling and additive prognostic value remain unknown. Aim To investigate (1) the association between the ESC-2021 CRT guidelines and reverse LV remodeling at follow up, and (2) the additive prognostic value of baseline assessment of mechanical dyssynchrony to the ESC-2021 guidelines. Methods We investigated 244 heart failure patients in sinus rhythm treated with CRT in two European centers. 70% of the population were males. Mean age was 69 ± 10 years, QRS duration: 154 ± 24 msec. Mechanical dyssynchrony at baseline was defined as the presence of apical rocking or septal flash (ApRock/SF) in 2D transthoracic echocardiography. LV volumes were measured at baseline and at 12 ± 6 months after CRT, where the amount of CRT induced reverse LV remodeling was calculated as the percent change of LVESV at follow-up compared to baseline. Results Applying the ESC-2021 LBBB definition, only 18% (n=45) of patients had LBBB. Applying the guidelines, only 14% (n=35) had class I recommendation (LBBB + QRS ≥ 150 msec), 44% (n=107) had class IIa (LBBB + QRS 130-149 msec or non-LBBB + QRS ≥ 150 msec), 29% (n=70) had class IIb (Non-LBBB + QRS 130-149 msec), and 13% (n = 33) were not recommended according to the ESC-2021 because of having baseline QRS duration between 120 and 129 msec. On the other hand, ApRock/SF was evident in 57% (n=140) of the patients. There was non-significant difference in the relative decrease in LVESV at follow up between patients with LBBB and non-LBBB applying the new LBBB definition (44% [IQR: 32-63], vs. 39%, IQR [20-57], P = 0.08, panel A). Similarly, there was no significant difference in the relative decrease in LVESV at CRT follow up among the four guideline recommendation classes, panel B. We combined presence of mechanical asynchrony at baseline with each of the guideline recommendation classes. The combination of ApRock/SF with classes IIa and IIb improved the prediction of reverse LV remodeling significantly (P&amp;lt;0.001 and &amp;lt;0.01 respectively), while adding mechanical asynchrony did not significantly improve prediction in the class I and the not-recommended subgroups. However, results of these last 2 may have been impacted by a small number of patients, panel C. Conclusion The new ESC-2021 definition of LBBB is associated with few patients with LBBB and consequently small number of patients with class I recommendation according to the new guidelines. There was weak association between the new ESC-2021 guideline classes of recommendation and reverse LV remodeling after CRT. However, baseline assessment of ApRock and SF can significantly improve the guidelines in predicting CRT outcome.

Conduction system pacing and atrioventricular node ablation for atrial fibrillation - a systematic review and meta-analysis

Abstract Background/Introduction Biventricular pacing (BVP) has been shown to reduce the risk of heart failure following atrioventricular node ablation (AVNA) for the management of medically refractory atrial fibrillation (AF) when compared with conventional right ventricular pacing.[1] Conduction system pacing (CSP) is an emerging cardiac synchronization alternative to BVP[2], however, its evidence in AVNA for AF is limited. Purpose To evaluate the effect of CSP on left ventricular ejection fraction (LVEF), QRS duration (QRSd), pacing threshold and New York Heart Association (NYHA) class score following AVNA for AF. Methods We conducted a literature review of PUBMED, MEDLINE, EMBASE, Cochrane Library, and Web of Science for randomized clinical trials (RCTs) and observational studies evaluating CSP (His bundle pacing and left bundle branch pacing) post AVNA for AF. Out of 14 studies comprising 1112 patients, we conducted meta-analyses evaluating the impact of CSP on LVEF and QRS. Ten studies were pooled to assess outcomes pre- and post-implantation of CSP following AVNA. Three observational studies and one RCT were included in the meta-analysis comparing outcomes in CSP versus BVP post AVNA. Results CSP resulted in a significant QRSd reduction (-11.01 ms, 95% CI 5.07 - 16.95, p &amp;lt;0.01), improved LVEF (+10.28%, 95% CI 7.03 - 13.52; p &amp;lt;0.01) and improved NYHA score (-1.09; 95% CI -1.41 - -0.78; p &amp;lt;0.01) during follow-up of 6-36 months (Figure 1) from baseline (peri-implantation). There was no significant pacing threshold rise (0.11V; 95% CI -0.14 - 0.36; p= 0.39) observed during the same period. CSP was associated with statistically significant shorter QRSd (-49.81ms; 95% CI, -70.57 - -29.06; p &amp;lt;0.01) when compared to BVP. For LVEF, there was a statistically significant improvement of +8.96% (95% CI 2.55 - 15.37%; p &amp;lt;0.01) with CSP versus BVP. Limited data prohibited comparison of threshold and NYHA outcomes between CSP and BVP. Conclusion Conduction system pacing appears effective in improving baseline LVEF, QRSd and NYHA score in AVNA for AF, and may be a viable alternative to further optimising LVEF and QRSd in comparison to BVP. Further studies are required to evaluate the long-term impact and clinical outcomes of CSP in post AVNA patients.

A mcgyvering way to left bundle branch area pacing : using the treadmill test machine ECG system and modified V1 / V6 leads connected to the pacing system analyser for left bundle branch area pacing

Abstract Background Left bundle branch area pacing (LBBaP) is a novel pacing modality which provides physiological synchronisation of both the ventricles. However, its use and adoption requires the presence of a standardised electrophysiological (EP) system with 12 lead ECG to show left bundle branch area capture. Purpose The aim of the study was to assess the feasibility and outcomes of using the conventional treadmill test (TMT) machine 12 lead ECG system and modified V1 and V6 leads connected to the pacing system analyser (PSA) to demonstrate conduction system capture during left bundle branch area pacing (LBBaP). Methods LBBaP was attempted by a single operator in a mixed cohort of patients at peripheral hospitals lacking the standardised EP system. The presence of LBB area capture was tested with the aid of the 12 lead ECG system connected to the standard TMT machine (1). Conduction system capture was also assessed using modified V1 and V6 leads connected to the PSA for measurement of V6 left ventricular activation time (LVAT)(2) . The baseline clinical, procedural, pacing, electrocardiographic parameters, echocardiographic response (&amp;gt; 10% improvement in ejection fraction {EF}) and clinical response to LBBaP were assessed. Results LBBaP was attempted in 19 patients and was successful in 18 patients (94.7%). Patient characteristics include age 66.7 +/- 11.47 years, female 47.37%, male 52.63%, ischaemic cardiomyopathy 10.52% and non-ischaemic cardiomyopathy 5.26% .The mean baseline EF and QRS duration was 45%+/-14% and 130.18 +/-10.45 milliseconds(ms) respectively. LBBaP threshold was 0.59 +/-0.168 volts and R wave amplitude was 12+/-3.5 millimetres , which remained stable during the mean follow up of 15.9 +/-13.67 months. The mean fluoroscopic duration was 11.57 +/-2.58 minutes and procedural time was 108.78+/-29.20 minutes. LBBaP resulted in impressive narrowing of the QRS duration to 102.39 +/-10.55 ms (p&amp;lt;0.001) with LVAT of 68.94 +/-9.94 ms. LVEF improved in the patients with cardiomyopathy from 33.4 +/- 5.77 % to 48.2+/-12.37 % (p=0.028) .Clinical and echocardiographic response was noted in 87.5% of patients with cardiomyopathy. Conclusion The 12 lead ECG system with the standardised TMT machine in conjunction with the modified V1 and V6 leads connected to the PSA is a feasible alternative to the EP system to perform successful left bundle branch area pacing.ECG leads connected during LBBapClinical profile of patients

Larger QRS but better hemodynamic function after high output His bundle pacing in patients with heart failure and narrow QRS. A paradox or a new concept?

Abstract Background QRS duration is an important factor in determining Cardiac Resynchronisation Therapy (CRT) response and a useful surrogate for electromechanical dyssynchrony. However, we don’t have studies confirming this concept in conduction system pacing. Purpose We performed His Bundle Pacing (HBP) with high output (3.5V/1msec) in HF patients with dilated or ischemic cardiomyopathy and narrow QRS to evaluate hemodynamic benefit independent of the QRS duration or AV delay shortening. Methods 14 patients with dilated (7 patients) or ischemic (7 patients) cardiomyopathy (EF&amp;lt;35%) and narrow QRS (&amp;lt;120ms) were referred for implantation of a defibrillator. We implanted an ICD- HBP system, and we collected clinical, echocardiographic, and electrocardiographic data. Results We obtained HBP in all 14 patients successfully. PQ after implantation was shorter from 172±48 to 143±16 (P=0.048) so as to pace the ventricle. Baseline QRS duration increased after pacing from 110±15 to 123±16ms (P=0.008) as measured by ECG analyzer. Despite this increase in QRS duration basal mean EF increased from 30±4% to 46±10% (P&amp;lt;0.001) after a median follow-up of 17 months. Left ventricular end-diastolic diameter and left ventricular end-diastolic volume decreased from 62±5 to 57±5mm (P=0.013) and from 195±69 to 126±27ml (P&amp;lt;0.001), respectively. Left ventricular end-systolic volume decreased from 139±58 to 69±27 (P&amp;lt;0.001). TAPSE increased from 19±4 to 27±4. NYHA class decreased by one class in every patient after only one month. HBP threshold was 1.05V±0.7/1msec and raised to 1.33±0.93/1msec (due mainly to 2 patients with very high threshold). The impedance was 588±109 and decreased to 484±69 Ohms. R-wave at implant was 3.2±1.8mV. In 2 out of 14 patients, threshold increased but was still less than 3.5V/1msec. Conclusions HBP in HF patients with dilated or ischemic cardiomyopathy and narrow QRS improves hemodynamic function in right and left ventricle and decreases NYHA class. This benefit appears to be produced by a higher stimulation output despite a larger QRS after pacing. We exclude that a very short AV delay could be favorable, by measuring acute EF changes only after increasing the pacing output without AV delay modifications. To our knowledge these are the first cases of beneficial HBP in HF patients with narrow QRS. Interestingly, larger QRS corresponds to higher EF in patients with high output HIs Bundle Pacing.

Prognostic value of the right coronary venous anatomy in patients undergoing cardiac resynchronization therapy

Abstract Background The size and distribution of the coronary veins (CV) reflect both intracavitary pressure and myocardial blood flow, and therefore, in patients with cardiomyopathy, CV anatomy could potentially become a biomarker of disease severity. While the left coronary veins have been well described, there are few descriptions of the right CV system. Purpose Given these considerations, the aim of the study was to evaluate the anatomy of the right CV system and its potential prognostic significance in patients with advanced cardiomyopathy. Methods We analyzed CV angiograms from 121 patients (age 67±14 years) undergoing cardiac resynchronization therapy (CRT). The right ventricular (RV) veins were seen to fill during the injection of contrast through multiple connections with the left sided venous system. Patients were followed for a median of 43 [IQR 3-73] months, during which 12 patients expired. Results Anterior cardiac veins (ACV), which overlay the RV wall were observed in 85 (70%) patients and had a maximum ostial diameter of 2.04±0.8 mm. Multiple ACVs were seen in 62 patients. These veins were observed to empty directly into the venous sinus of right atrium (VSRA), into the RV, the right atrium (RA), or into the small cardiac vein (SCV) in 68, 9, 5, and 3 patients respectively. The right marginal vein (RMV) was visualized in 21 (17%) patients, had a diameter of 2.3±1.2 mm, and ran a course along the right border of the RV, emptying directly into RV, RA or into VSRA in 9, 4 and 8 patients respectively. The VSRA present in 91 (75%) patients, coursed parallel to the right coronary sulcus, collecting blood from the ACV’s and RMV’s and drained into the RA (Figure A); in 7 patients, 2 VSRA ostia were noted. VSRA lengths and diameters varied (11-119 mm, mean 41±25 mm) and (1.2-6.9mm, mean 2.7±1.2mm) respectively. The VSRA lengths correlated significantly with RV fractional area change, RV systolic pressure, tricuspid regurgitation severity evaluated by echocardiography, and P wave amplitude in ECG lead II (r=-0.65; p=0.041, r=0.88; p=0.019, r=0.52; p=0.030, and r=0.79; p=0.031 respectively). The VSRA diameters, which were significantly larger in patients with obstructive sleep apnea (3.6±1.5 vs. 2.3±1.2mm; p=0.021) correlated significantly with RV systolic pressure, and tricuspid regurgitation severity by echocardiography (r=0.77; p=0.009, and r=0.63; p=0.006 respectively). Patients who expired during follow-up had a significantly longer VSRA than patients who remained alive (Figure B). The VSRA length, RV fractional area change, and baseline QRS duration independently predicted survival in a Cox multivariate model that also included age and left ventricular ejection fraction. Conclusions RV venous system demonstrates a highly variable anatomy that has not been previously well described. The size of the VSRA correlated with parameters of RV function and predicted survival in patients undergoing CRT.Figure

Multicenter Hemodynamic Assessment of the LOT-CRT Strategy: When Does Combining Left Bundle Branch Pacing and Coronary Venous Pacing Enhance Resynchronization?: Primary Results of the CSPOT Study.

Left bundle branch area pacing (LBBAP) may be an alternative to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT). We sought to compare the acute hemodynamic and ECG effects of LBBAP, BVP, and left bundle-optimized therapy CRT (LOT-CRT) in CRT candidates with advanced conduction disease. In this multicenter study, 48 patients with either nonspecific interventricular conduction delay (n=29) or left bundle branch block (n=19) underwent acute hemodynamic testing to determine the change in left ventricular pressure maximal first derivative (LV dP/dtmax) from baseline atrial pacing to BVP, LBBAP, or LOT-CRT. Atrioventricular-optimized increases in LV dP/dtmax for LOT-CRT (mean, 25.8% [95% CI, 20.9%-30.7%]) and BVP (26.4% [95% CI, 20.2%-32.6%]) were greater than unipolar LBBAP (19.3% [95% CI, 15.0%-23.7%]) or bipolar LBBAP (16.4% [95% CI, 12.7%-20.0%]; P≤0.005). QRS shortening was greater in LOT-CRT (29.5 [95% CI, 23.4-35.6] ms) than unipolar LBBAP (11.9 [95% CI, 6.1-17.7] ms), bipolar LBBAP (11.7 ms [95% CI, 6.4-17.0]), or BVP (18.5 [95% CI, 11.0-25.9] ms), all P≤0.005. Compared with patients with left bundle branch block, patients with interventricular conduction delay experienced less QRS reduction (P=0.026) but similar improvements in LV dP/dtmax (P=0.29). Bipolar LBBAP caused anodal capture in 54% of patients and resulted in less LV dP/dtmax improvement than unipolar LBBAP (18.6% versus 23.7%; P<0.001). Subclassification of LBBAP capture (European Heart Rhythm Association criteria) indicated LBBAP or LV septal pacing in 27 patients (56%) and deep septal pacing in 21 patients (44%). The hemodynamic benefit of adding left ventricular coronary vein pacing to LBBAP depended on baseline QRS duration (P=0.031) and success of LBBAP (P<0.004): LOT-CRT provided 14.5% (5.0%-24.1%) greater LV dP/dtmax improvement and 20.8 (12.8-28.8) ms greater QRS shortening than LBBAP in subjects with QRS ≥171 ms and deep septal pacing capture type. In a CRT cohort with advanced conduction disease, LOT-CRT and BVP provided greater acute hemodynamic benefit than LBBAP. Subjects with wider QRS or deep septal pacing are more likely to benefit from the addition of a left ventricular coronary vein lead to implement LOT-CRT. URL: https://www.clinicaltrials.gov; Unique identifier: NCT04905290.

Mid-term clinical outcomes of left bundle branch area pacing compared to accurate right ventricular septal pacing.

Although left bundle branch area pacing (LBBAP) reportedly results in fewer adverse outcomes after implantation than conventional stylet-guided right ventricular septal pacing (RVSP), previous studies have not compared LBBAP with accurate RVSP using a delivery catheter. The aim of this study was to compare clinical outcomes between LBBAP and accurate RVSP among patients with atrioventricular block (AVB). This single-center observational study enrolled 160 patients requiring RV pacing due to symptomatic AVB between September 2018 and December 2021. Primary composite outcomes included all-cause death, hospitalization due to heart failure (HF), and upgrading to biventricular pacing. Secondary composite outcomes included any procedural and postprocedural complications. Overall, 160 patients were analyzed (LBBAP, n = 81; RVSP, n = 79). No significant differences in baseline characteristics were observed between the two groups. The RV pacing burden at 1year after implantation was 90.8% ± 20.4% and 86.2% ± 22.6%, respectively (p = 0.21). During a mean follow-up of 840 ± 369days, the incidence of the primary outcome was significantly lower with LBBAP (4.9%) compared to RVSP (22.8%) (Log-rank p = 0.02). There was no significant difference in the incidence of the secondary outcome between the two groups (3.7% vs. 5.1%, p = 0.65). In the multivariate analysis, baseline QRS duration, RV pacing burden, and LBBAP were independently associated with the primary outcome (baseline QRS duration: hazard ratio [HR], 1.01; 95% confidence interval [CI], 1.00-1.02; p < 0.001; RV pacing burden: HR, 1.01; 95% CI, 1.00-1.02; p < 0.001; LBBAP: HR, 0.45; 95% CI, 0.31-0.64; p < 0.001). In patients requiring frequent RV pacing, LBBAP was associated with reduced adverse clinical outcome compared to accurate RVSP using a delivery catheter.

Effectiveness of left bundle branch area pacing to restore narrow QRS in patients with right bundle branch block

Abstract Background/Introduction Left bundle branch area pacing (LBBaP) is an innovative technique used to capture conduction tissue and maintain ventricular synchrony during pacing. There are few data about the efficacy of LBBaP in right bundle branch block (RBBB). Purpose To compare the response to LBBaP, evaluated by the change in QRS duration (QRSd) after pacing, in patients with RBBB, left bundle branch block (LBBB) or without conduction disorder. Methods A total of 162 patients with pacemaker indication underwent LBBaP with stylet driven lead with dedicated sheaths, between November 2020 and April 2023. ECG characteristics were evaluated. Data are presented in mean ± standard deviation (SD) or n (%). Paired sample t-test was used to compare QRSd before and after pacing. Results Indications for pacing were atrioventricular block (AVB) 48,4 %, sinus node dysfunction (SND) 37,7 %, AVB and SND 10,7 % and cardiac resynchronization therapy 3,1 %. LBBaP was successfully performed in 98 % (159/162) of patients (78 ± 10 years, 62 % male). Overall, baseline QRSd was 113,2 ± 26,7 ms and paced QRSd was 112,3 ± 14,8 ms (p = 0,662), with left ventricular activation time (LVAT) of 69 ± 14 ms (table 1). Baseline ECG showed 18 LBBB, 29 RBBB and 11 undetermined conduction disorder. In every kind of conduction disorder, paced QRSd was reduced to &amp;lt; 120 ms (table 2). Notably, paced QRSd was &amp;lt; 120 ms, regardless of baseline QRSd. In patients with most important pre-existing conduction disorder (QRS ≥ 145 ms), an impressive reduction in QRSd was observed (Delta = -40,8 ms , table 1). Conclusion LBBaP with stylet driven lead is an effective approach to obtain short paced QRS regardless of baseline QRSd and of the nature of the initial conduction disorder. This opens new perspectives for cardiac resynchronization in patients with RBBB.

Left bundle branch area pacing in the setting of cardiac amyloidosis: a case series

Abstract Background Cardiac amyloidosis (CA) is a highly prevalent cause of congestive heart failure. It often requires cardiac pacing due atrioventricular conduction (AV) system disorders, often with cardiac resynchronization (CRT) to prevent development/deterioration of left ventricular (LV) dysfunction. Left bundle branch area pacing (LBBAP) is an emerging alternative to CRT, offering a strict physiological LV activation and very limited use of iodinated contrast. The feasibility of LBBAP in CA is considered limited due to the presence of septal pseudohypertrophy which theoretically limits left-sided conduction system engagement. Purpose To evaluate the feasibility and effectiveness of LBBAP in cardiac amyloidosis. Methods Consecutive patients with CA (both light-chain -AL- or wild-type transtiretin -wtATTr) with a pacing indication for AV conduction disorders were enrolled. Patients underwent baseline echocardiographic examination. LBBAP was achieved by means of stylet-driven leads advanced transeptally (right ventricle (RV) to LV) via dedicated delivery systems, with continuous monitoring of 12-lead electrocardiographic morphology and impedance until a typical QRS morphology in V1 was obtained (usually rSr’ or Sr’). Standard measures for left bundle (LB) capture were used (stimulus to peak R in V6 – S-RV6, V6-V1 interpeak interval, presence of transition in these measures during threshold testing, presence of fascicular signal during spontaneous QRS). Results Between January 2022 and June 2023, among 63 patients undergoing LBBAP, 7 patients (11%) had CA, 2 AL (28%) and 5 (72%) wtATTR. Patients were prevalently old (78±7 y) males (6, 85%); LV mean septal thickness was 17±2 mm (min 16, max 20 mm) and mean LV ejection fraction (LVEF) was 45±6%. Indications were PR prolongation in 3, bradycardic atrial fibrillation and LB branch block (LBBB) in 2, primary LBBB in 1 and chronic RV pacing in 1. Baseline QRS duration was 145±47 ms (QRS&amp;lt;120 ms: 97±15 ms, QRS&amp;gt;120 ms: 182±13 ms). LBBAP success was 100%. Fascicular electrograms were observed in ¾ of patients without LBBB; S-RV6 interval was 74 ±11 ms (³70 ms in 3), RV6-RV1 interpeak interval was 47±9 ms (³ 30 ms in 6 patients). DQRS in baseline broad QRS was -52 ms and +32 ms in narrow. No complications were observed. Over a short follow up of 6 months, an increase in average LVEF was observed (LVEF at 6 months: 51±3%, p&amp;lt;0.05). Conclusions In patients with CA, LBBAP is easily achievable with stylet-driven systems with frequent selective engagement of conduction system. QRS narrowing in baseline broad QRS is significant while QRS broadening in baseline narrow QRS is limited. Early results regarding follow-up of surrogate endpoint such as LVEF are promising.

Multicenter hemodynamic assessment of the LOT-CRT strategy: when is one lead enough for resynchronization?

Abstract Background Left bundle branch area pacing (LBBAP) has been postulated as an alternative to traditional cardiac resynchronization therapy via biventricular pacing (BiV) in heart failure patients with wide QRS. Limited data is available regarding the acute hemodynamic response of LBBAP and the combination of LBBAP and coronary venous (LVcv) pacing (LOT-CRT). Purpose We sought to compare the acute hemodynamic and ECG effects of traditional CRT (BiV or LV-only) versus LBBAP and LOT-CRT in CRT candidates with advanced conduction disease. Methods In this multi-centre study (5 EU and 7 US centres), 48 subjects (mean age 65.8 years, 67% males, LV ejection fraction 29.4%) with either nonspecific interventricular conduction delay (NIVCD, n = 29) or left bundle branch block (LBBB; n =19; based upon strict criteria AHA/ACC/HRS plus Strauss) underwent an acute hemodynamic study to determine the % change in +LV dP/dtmax from baseline atrial pacing versus BiV, LBBAP, or LOT-CRT. Each therapy pacing configuration was applied 4 times at 5 different atrioventricular (AV) delays. QRS shortening was assessed using standard 12-lead ECG. Results Successful LBBAP lead implantation was achieved in 27 patients (56%) using current EHRA criteria. Twenty-one patients (44%) were categorized as deep septal pacing (DSP), due to suboptimal lead penetration or advanced left conduction system disease with broad paced QRS complexes and absent V1-r-wave. The increase in AV-optimized dP/dtmax for the different pacing configurations is displayed in the Figure, left panel. LOT-CRT dP/dtmax % improvement was 25.8%, significantly higher than LBBAP configurations (p&amp;lt;0.01), either unipolar-LBBAP (19.3%), or bipolar-LBBAP (16.4%), but not different from BiV (26.4%). QRS shortening was greater in LOT-CRT (29.5ms) vs. unipolar-LBBAP (11.9ms), bipolar-LBBAP (11.7ms), or BiV (18.5ms), all p&amp;lt;0.01. Sub-group analysis indicated the hemodynamic benefit of adding LVcv pacing when LBBAP strategy was pursued (Figure, right panel) depended on obtaining LBBAP rather than DSP (p &amp;lt; 0.01) and baseline QRS duration (p = 0.03). The largest benefit was observed among subjects with a baseline QRS wider than the observed cohort mean (171ms) and DSP only, where LOT-CRT provided 14.5% (5.0-24.1%) greater dP/dtmax improvement and 20.8ms (12.8-28.8ms) greater QRS duration shortening than unipolar DSP. Conclusions In a CRT cohort with advanced conduction disease, LOT-CRT provided greater acute hemodynamic benefit than LBBAP strategy (i.e. including also DSP cases). Patients with wider QRS or suboptimal outcome of LBBAP strategy (DSP) are more likely to benefit from addition of a LVcv lead to implement LOT-CRT.Figure 1

Retrograde Conduction in Left Bundle Branch Block: Insights From Left Bundle Branch Pacing.

Biventricular pacing is a well-established therapy for patients with heart failure (HF), left bundle branch block (LBBB) and left ventricular (LV) dysfunction. Left bundle branch pacing (LBBP) has emerged as an alternative to biventricular pacing. The aim of this study was to assess the retrograde conduction properties of the left bundle branch in patients with nonischemic cardiomyopathy and LBBB during LBBP and its clinical implications. Patients undergoing successful LBBP for nonischemic cardiomyopathy with LV ejection fraction (LVEF)≤35% and LBBB were included. Continuous recording of His potential was performed using a quadripolar catheter. Unidirectional block was defined as retrograde His bundle activation during LBBP with stimulus to His potential (SH) duration less than or equal to antegrade HV interval and bidirectional block as VH dissociation or SH duration greater than HV interval. HF hospitalization, ventricular arrhythmias, and mortality were documented. A total of 165 patients were included. The mean follow-up duration was 21.8 ± 13.1months. Bidirectional block (group I) was observed in 82% (n=136), and these patients were noted to have advanced HF stage and prolonged baseline QRS duration. Unidirectional block (group II) with intact retrograde conduction was observed in 18% (n=29) and was associated with narrow paced QRS duration and higher LVEF during follow-up. Super-response (LVEF≥50%) was observed in 54.4% (n=74) in group I compared with 73.3% (n=22) in group II (P=0.03). The OR for LVEF normalization was 4.1 (95%CI: 1.26-13.97; P=0.02), with unidirectional block compared with bidirectional block in patients with LBBB and LV dysfunction. Adverse clinical outcomes as measured by a composite of HF hospitalization, ventricular arrhythmias, and mortality were significantly higher in group I compared with group II (12.5% vs 0%; P=0.04). Bidirectional block in LBBB was characterized by advanced HF symptoms, while unidirectional block was associated with better clinical outcomes after cardiac resynchronization therapy by LBBP.

Impact of left bundle branch block morphology in predicting response to left bundle branch area pacing for cardiac resynchronization therapy

Abstract Background Left bundle branch area pacing (LBBAP) is a novel pacing technique with an emerging role in resynchronization therapy [1-4]. QRS morphology has shown to significantly influence cardiac resynchronization therapy (CRT) response [5-6]. Purpose The aim of this study was to assess whether different left bundle branch block (LBBB) definitions are associated with response to LBBAP resynchronization therapy. Methods 40 consecutive CRT candidates with previously unsuccessful biventricular (BiV) pacing or in which effective CRT could not be achieved with BiV pacing based on anatomical or functional criteria were selected for this study. Both ischemic and non-ischemic heart failure (HF) patients were included. Patients were divided into two groups according to LBBB morphology. Group 1 included 20 patients (45% ischemic HF) with strict LBBB definition according to Strauss criteria [7], while 20 patients in Group 2 (55% ischemic HF) had conventional LBBB morphology. Response to CRT was defined for (1) reduction in QRS duration; (2) increase in left ventricular ejection fraction (LVEF) ≥ 5% and (3) decrease in left ventricular end systolic volume (LVESV) ≥ 15%. Results LBBAP was successfully achieved in all patients (mean age: 72.0 years; male: 29). The mean baseline QRS duration before implantation was 178.6±13.8 in the Group 1 and 170.8±29.4 in the Group 2, without a statistically significant difference. Over a mean follow-up of 5.6 months, LBBAP resulted in QRS narrowing in both groups, with a greater reduction in Group 1 (-40.6 ms) compared to Group 2 (-15.1 ms), (p 0.002). Pre-implantation ventricular systolic function did not show significant differences between the two groups, with a mean of 30.1±3.5% in the Strauss LBBB group and 31.0±6.0% in the conventional LBBB group. After implantation LVEF was 42.1±8.5 % in the true LBBB patients and 33.2±7.5 in the conventional LBBB group. Echocardiographic response was observed in 65% of patients with a statistically significant difference between Group 1 (90% of responders) and Group 2 (40% of responders), (p 0,001). HF etiology did not impact the response to LBBAP CRT. Conclusions Strict LBBB definition is associated to a greater electrocardiographic and echocardiographic response in patients receiving LBBAP CRT compared to conventional LBBB criteria.\

Prognosis and Predictor Factors of Permanent Pacemaker Implantation after Transcatheter Aortic Valve Replacement: A Retrospective Analysis of the Post-Transcatheter Aortic Replacement Clairval Hospital Registry.

Background/Objectives: Despite procedural improvements, post-transcatheter aortic valve replacement (TAVR) conduction disorders remain high. Analyzing the data from a monocentric TAVR registry, this study aims to determine predictive factors for PPI (primary outcome), the indication for PPI, and long-term outcomes among these patients (secondary outcomes). Methods: Conducted at Clairval Hospital in Marseille, France, this retrospective study included all consecutive patients from June 2012 to June 2019. Clinical, electrocardiographic, echocardiographic, and procedural data were collected, with outcomes assessed annually. Logistic regression identified PPI predictors and survival analyses were performed. Results: Of the 1458 patients initially considered, 1157 patients were included. PPI was needed in 21.5% of patients, primarily for third-degree atrioventricular block (46.4%). Predictor factors for PPI included baseline right bundle branch block (ORadj 2.49, 95% CI 1.44 to 4.30; p = 0.001), longer baseline QRS duration (ORadj 1.01, 95% CI 1.00 to1.02, p = 0.002), and self-expandable valves (ORadj 1.82, 95% CI, 1.09 to 3.03; p = 0.021). Seven-year estimated mortality was higher in PPI (43.3%) vs. non-PPI patients (30.9%) (log rank p = 0.048). PPI was an independent predictive factor of death (ORadj 2.49, 95% CI 1.4 to 4.3; p = 0.002). Conclusions: This study reveals elevated rates of PPI post-TAVR associated with increased mortality. These results underscore the pressing necessity to refine our practices, delineate precise indications, and enhance the long-term prognosis for implanted patients.

Association between QRS shortening and mortality after cardiac resynchronization therapy: Results from the DANISH study

BackgroundChanges in QRS duration (∆QRS) are often used in the clinical setting to evaluate the effect of cardiac resynchronization therapy (CRT), although an association between ∆QRS and outcomes is not firmly established. We aimed to assess the association between mortality and ∆QRS after CRT in patients from the DANISH (Danish Study to Assess the Efficacy of ICDs in Patients with Non-Ischemic Systolic Heart Failure on Mortality) study. MethodsWe included all patients from DANISH who received a CRT device and had available QRS duration data before and after implantation. Cox proportional hazards models were used to assess associations between ∆QRS (post-CRT QRS minus pre-CRT QRS) and mortality. ResultsComplete data were available in 572 patients. Median baseline QRS duration was 160 ms (IQR [146;180]). Post-CRT QRS was recorded a median of 48 days (IQR [33;86]) after implantation, and the median ∆QRS was −14 ms (IQR [−38;-3]). During a median follow-up of 4.1 years (IQR [2.5;5.8]), 106 patients died. In crude Cox regression, all-cause mortality was reduced by 6% per 10 ms shortening of QRS (HR 0.94; CI: 0.88–1.00, p = 0.04). The effect did not remain significant after multivariable adjustment (HR 1.01, CI: 0.93–1.10, p = 0.77). Further, no association was found between ∆QRS and improvement of New York Heart Association functional class at 6 months (OR 1.03, CI: 0.96–1.10, p = 0.42). ConclusionIn a large cohort of patients with non-ischemic cardiomyopathy, reduction of QRS duration after CRT was not associated with changes in mortality during long-term follow-up.

Comparing the impact of left bundle branch area pacing and traditional left ventricular pacing on right heart function following dual-chamber pacemaker implantation

Objective: To compare the effects of left bundle branch area pacing (LBBaP) versus traditional right ventricular pacing (RVP) on left ventricular function in patients after dual-chamber pacemaker implantation. Methods: A retrospective cohort study was conducted on patients who underwent dual-chamber pacemaker implantation from March 2017 to April 2021 in Beijing Anzhen Hospital. The patients were divided into the LBBaP group and RVP group based on the placement of the ventricular lead. Follow-up was conducted until March 2022, comparing baseline and follow-up echocardiographic parameters, pacing parameters, and the incidence and timing of complications between the two groups. The complications included ventricular electrode perforation, dislocation, pericardial effusion, tricuspid valve perforation, etc. Results: A total of 163 patients aged (68.3±13.5) years were included, including 82 (50.3%) men, with 80 patients in the LBBaP group and 83 in the RVP group. Baseline left ventricular end-diastolic diameter ((50.49±4.95) mm vs. (47.43±8.15) mm, P=0.01) and left atrium (LA) ((33.14±5.94) mm vs. (30.18±3.92) mm, P=0.001) in the LBBaP group were significantly higher than those in the RVP group. Follow-up LA diameter ((37.10±6.70) mm vs. (40.10±8.90) mm, P=0.016) showed a statistically significant difference in the LBBaP group compared to the RVP group. There was no statistically significant difference between the two groups in baseline QRS duration(P=0.490). Postoperative QRS duration in the LBBaP group was significantly lower ((110.69±24.01) ms vs. (139.65±29.85) ms, P<0.010). Intraoperative threshold in the LBBaP group was significantly higher ((0.83±0.32) V/0.48 ms vs. (0.71±0.23) V/0.48 ms, P=0.004), while impedance was lower ((754.53±205.59) Ω vs. (905.41±302.75) Ω, P<0.01). Comparing with the RVP group, postoperative ventricular pacing ratio (VP) ((87.39±20.92) % vs. (79.49±25.76) %, P=0.034), threshold ((0.90±0.38) V/0.48 ms vs. (0.69±0.27) V/0.48 ms, P<0.01) in the LBBaP group were higher, and impedance ((507.45±77.37) Ω vs. (620.52±197.29) Ω, P<0.01) in the LBBaP group was lower. Postoperative follow-up period was 5 to 51 months, with a median follow-up time of 17 months. No statistically significant difference in overall complications between the LBBaP and RVP groups was found (13.8% (11/80) vs. 7.2% (6/83), P>0.05). The median time to occurrence of complications after surgery was significantly earlier in the LBBaP group (29.74 (95%CI 27.21-32.26) months vs. 46.17 (95%CI 42.48-49.86) months, P=0.030). Conclusion: LBBaP demonstrates more stable pacing parameters, substantial improvement in clinical left ventricular function, with a relatively higher threshold compared to traditional RVP, and complications occurs relatively early.

Feasibility of Conduction System Pacing in Patients with Baseline Bundle Branch Block-A Single-Center Mid-Term Follow-Up Study.

The primary prerequisite for a successful conduction system pacing (CSP) procedure is the integrity of the conduction system, which may be impaired if a baseline bundle branch block (BBB) is present. This study aimed to evaluate the feasibility and mid-term performance of permanent CSP in patients with baseline BBB and to compare the results between left bundle branch block (LBBB) and right bundle branch block (RBBB) patterns. A total of 101 patients with typical BBB and an attempt at CSP were retrospectively reviewed. Procedural characteristics, pacing, sensing parameters, and complications at baseline and after a mid-term follow-up were analyzed. The global procedural success for CSP was 93%. His bundle pacing (HBP) had a significantly lower success rate than left bundle branch area pacing (LBBAP) (50.5% vs. 86%). The paced QRS duration was significantly narrower with HBP. The pacing and sensing thresholds were significantly better with LBBAP. Procedural complications occurred only in the LBBAP group (two acute perforations in the LV cavity and one acute chest pain during lead fixation) without long-term sequelae. The HBP and the LBBAP procedural success rates were higher in the RBBB versus the LBBB group (62.5% vs. 44.9% and 100% vs. 81.5%, respectively). Baseline QRS duration, atrial volumes, and right ventricular diameters were significantly associated with HBP procedural failure. The follow-up pacing and sensing thresholds were similar to the baseline values for all pacing methods and BBB morphology. Only one device-related complication leading to pacing interruption was recorded. In patients with bundle branch blocks, CSP is a feasible procedure associated with a high success rate, stable pacing and sensing parameters, and low complication rates over a mid-term follow-up.

His bundle pacing in nodal versus infranodal atrioventricular block: a mid-term follow-up study

IntroductionThis study evaluated the feasibility of His bundle pacing (HBP) in consecutive, unselected patients with advanced atrioventricular block (AVB) over a medium-term follow-up period, comparing procedural characteristics between nodal and...

His bundle pacing versus right ventricular pacing: A comparative study.

Pacing is the most effective and dependable method for treating complete atrioventricular block (AVB). The purpose of this study is to investigate the use of His bundle pacing (HBP) in patients with atrioventricular block. Patients who underwent HBP or right ventricular pacing (RVP) were enrolled and divided into two groups: the HBP group and the RVP group, respectively. We compared baseline clinical data, fluoroscopy duration, operation duration, pacing electrode parameters during the operation or follow-up, baseline QRS duration, and pacing QRS duration. HBP was attempted in 48 patients and was successful in 34 patients who were included in the HBP group. In addition, 30 RVP patients were included in the RVP group. Fluoroscopy duration and operation duration were significantly longer in the HBP group compared to the RVP group. Compared to the RVP group, the HBP group had a higher pacing threshold, a lower R wave amplitude, and a shorter pacing QRS duration. At 6 months of follow-up, the pacing threshold remained higher, the R wave amplitude was significantly lower, and the end-diastolic diameter of the left ventricle was smaller in the HBP group. HBP was safe and effective for atrioventricular block despite the longer fluoroscopy and operation duration in the HBP group when compared to the RVP group.