Complete Left Bundle Branch Block Research Articles

Comparison of Down Sizing Strategy (HANGZHOU Solution) and Standard Annulus Sizing Strategy in type 0 bicuspid aortic stenosis patients undergoing transcatheter aortic valve replacement: Rationale and design of a randomized clinical trial

BackgroundThere has not been a consensus on the prothesis sizing strategy in type 0 bicuspid aortic stenosis (AS) patients undergoing transcatheter aortic valve replacement (TAVR). Modifications to standard annular sizing strategies might be required due to the distinct anatomical characteristics. We have devised a Down Sizing Strategy for TAVR using a self-expanding valve specifically for patients with type 0 bicuspid AS. The primary aim of this study is to compare the safety and efficacy of Down Sizing Strategy with the Standard Annulus Sizing Strategy in TAVR for patients with type 0 bicuspid AS. Trial designIt is a prospective, multi-center, superiority, single-blinded, randomized controlled trial comparing the Down Sizing and Standard Annulus Sizing Strategy in patients with type 0 bicuspid aortic stenosis undergoing transcatheter aortic valve replacement. Eligible participants will include patients with severe type 0 bicuspid AS, as defined by criteria such as mean gradient across aortic valve ≥40 mmHg, peak aortic jet velocity ≥4.0 m/s, aortic valve area (AVA) ≤1.0 cm², or AVA index ≤0.6 cm2/m2. These patients will be randomly assigned, in a 1:1 ratio, to either the Down Sizing Strategy group or the Standard Sizing Strategy group. In the Down Sizing Strategy group, a valve one size smaller will be implanted if the “waist sign” manifests along with less than mild regurgitation during balloon pre-dilatation. The primary end point of the study is a composite of VARC-3 defined device success, absence of both permanent pacemaker implantation due to high-degree atrioventricular block and new-onset complete left bundle branch block. ConclusionThis study will compare the safety and efficacy of Down Sizing Strategy with the Standard Annulus Sizing Strategy and provide valuable insights into the optimal approach for sizing in TAVR patients with type 0 bicuspid AS. We hypothesize that the Down Sizing Strategy will demonstrate superiority when compared to the Standard Annulus Sizing Strategy. (Down Sizing Strategy (HANGZHOU Solution) vs Standard Sizing Strategy TAVR in Bicuspid Aortic Stenosis (Type 0) (TAILOR-TAVR), NCT05511792)

Prevalence and Clinical Significance of Intraventricular Conduction Disturbances in Hospitalized Children.

Introduction: Data on the prevalence and clinical significance of interventricular conduction disturbances (IVCDs) in children are scarce. While incomplete right bundle branch blocks (IRBBBs) seem to be the most frequent and benign findings, complete bundle blocks and fascicular blocks are often seen in children with congenital/acquired cardiac conditions. This study aims to delineate the prevalence and the diagnostic accuracy of IVCD in children admitted to a paediatric cardiology unit. Methods: Children admitted to the paediatric cardiology unit between January 2010 and December 2020 who had an ECG were included in the study. IVCDs were diagnosed according to standard criteria adjusted for age. Results: Three thousand nine hundred and ninety-three patients were enrolled. The median age was 3.1 years (IQR: 0.0-9.2 years), and 52.7% were males. IVCDs were present in 22.5% of the population: 17.4% of the population presented with IRBBBs, 4.8% with a complete right bundle branch block (CRBBB), 0.1% with a complete left bundle branch block (CLBBB), 0.2% with a left anterior fascicular block (LAFB) and 0.2% with a combination of CRBBB and LAFB. Also, 26% of children with congenital heart disease had an IVCD, and 18% of children with an IVCD had previous cardiac surgery. The overall sensitivity of IVCD in detecting a cardiac abnormality was 22.2%, with a specificity of 75.5%, a PPV of 83.1% and an NPV of 15.1%, but the values were higher for CLBBB and LAFB. Conclusions: IVCDs were present in one-fifth of children admitted to the cardiology unit. IRBBB was the most frequent disturbance, while CRBBB, CLBBB and fascicular blocks were much rarer, though they had a higher predictive value for cardiac abnormalities.

Del Nido versus cold crystalloid cardioplegia for myocardial protection during ventricular septal defect repair in children under one year of age: a prospective randomized trial

Rationale: The choice of strategy for myocardial protection during procedures with cardiopulmonary bypass and cardioplegic arrest in children is not regulated by clinical guidelines due to insufficient data from clinical studies. The issue of methods to assess myocardial injury remains unresolved.
 Aim: To assess the frequency and specifics of the development of intraoperative myocardial injury syndrome in children of the first year of life with ventricular septal defect depending on the strategy for cardioplegia.
 Materials and methods: In a single center, prospective, randomized controlled trial we compared two cardioplegia strategies during surgical closure of ventricular septal defect in infants aged from 1 to 12 months: del Nido blood cardioplegia (n = 102) and cold crystalloid cardioplegia with Custodiol solution (n = 102). The primary endpoint was a persistent over 10-fold increase above the upper limit of the normal in the plasma concentration of high-sensitivity troponin I at 6 hours after surgery persisting after 24 hours. The secondary combined endpoint was myocardial damage verified by persistent increase in troponin I level more than 10-fold above the upper limit of the normal, persisting at 6 and 24 hours, accompanied by new pathological Q waves, acute complete left bundle branch block, abnormalities of the end part of the ventricular complex on the electrocardiography (ST segment elevation 1 mm or ST depression of 1 mm in more than 2 adjacent leads), and a decrease in the global longitudinal strain of the left ventricle by 50% from the initial value at 6 hours after surgery.
 Results: In 53/204 (26%) patients, the increase in troponin I persisted at 24 hours after the surgery and was associated with electrocardiography abnormalities, changes in the parameters of left ventricle longitudinal mechanics, and in some cases required greater inotropic support. By the end of the 1st postoperative 24 hours, the longitudinal strain of the left ventricle showed more negative changes over time in the Custodiol group compared to that in the del Nido group (-10 [-14.1; -6.27] versus -14.8 [- 16.5; -10]%; p 0.0001). The same was true for the left ventricle global strain rate (-0.71 [-0.9; -0.52] s-1 in the del Nido group and -0.57 [-0.760; - 0.44] s-1 in the Custodiol group; p = 0.0049). The primary endpoint was achieved by 21 (20.6%) and 55 (53.9%) patients in the del Nido and Custodiol groups, respectively (p = 0.032). The combined endpoint in the Custodiol group was achieved by 34 (33.3%) versus 19 (18.6%) patients in the del Nido group (p = 0.049, χ2 = 3.875, DF = 1, φ = 0.191).
 Conclusion: Del Nido blood cardioplegia compared to cold crystalloid cardioplegia with Custodiol has advantages in terms of preventing intraoperative myocardial damage and minimizing its severity. When assessing myocardial damage, such indicators as left ventricle global longitudinal strain and left ventricle global strain rate are informative, along with an increase in the troponin I level.

Outcomes with T-wave discordance of left bundle branch block and preserved or mildly reduced ejection fraction.

Left bundle branch block (LBBB) is associated with an increased risk of adverse outcomes for patients with heart failure. The prognosis of LBBB in patients with a preserved ejection fraction (EF) remains controversial. This study investigated the predictive value of T-wave discordance for the prognosis of patients with LBBB and preserved or mildly reduced EF. We enrolled 707 patients with complete LBBB and left ventricular (LV) EF≥40% observed using electrocardiograms (ECGs) and echocardiograms between January 2010 and December 2018. Their serial ECGs were reviewed during the follow-up period. The T-wave pattern was classified as discordant LBBB (dLBBB) or concordant LBBB (cLBBB) according to the 12-lead ECG T-wave morphology. The primary outcome was the composite of cardiovascular death or hospitalization for heart failure during a median follow-up period of 3.1years. A multivariable Cox regression analysis was used to evaluate the independent predictors of the primary outcome. Patients with dLBBB had more comorbidities, a higher heart rate, a longer QRS and QTc duration, a larger LV end-systolic volume and left atrial dimension, a lower LVEF, and a higher mitral E/A ratio and E/e', compared with those with cLBBB. Older age [hazard ratio (HR)=1.023, 95% confidence interval (CI)=1.001-1.046, P=0.023], history of heart failure (HR=2.440, 95% CI=1.524-3.905, P=0.001), chronic kidney disease (HR=1.917, 95% CI=1.182-3.110, P=0.008), larger LV end-systolic volume (HR=1.046, 95% CI=1.017-1.075, P=0.002), lower LVEF (HR=0.916, 95% CI=0.885-0.948, P=0.001), and presence of dLBBB (HR=1.63, 95% CI=1.011-2.628, P=0.032) were independent predictors of the primary outcome in patients with LBBB and LVEF≥40%. The discordant or concordant T-wave morphology of LBBB could transform from one subtype to the other in up to 23% of the study population during the follow-up period, and individuals with persistent or transformed dLBBB faced an increased risk of cardiovascular death or non-fatal heart failure hospitalization. In patients with LBBB and EF≥40%, dLBBB serves as an independent predictor of a higher risk of cardiovascular death or non-fatal heart failure hospitalization.

Assessment of the Impact of Cardiac Implantable Electronic Devices on Patients' Quality of Life.

Assessing the quality of life serves as a crucial metric during various therapeutic or surgical procedures. The rise in cardiac electronic device implantations in recent years underscores the significance of evaluating the quality of life among such patients. We conducted a study focusing on the quality of life of 438 patients with cardiac implantable electronic devices (cardiac pacemakers, cardioverter-defibrillators, cardiac resynchronization therapy devices). These patients were diagnosed with sick sinus syndrome, high-degree atrioventricular (AV) block, or severe heart failure (New York Heart Association (NYHA) classes III- IV (NYHA III-IV)), with left ventricular ejection fraction (LVEF) ≤ 35%, with/without complete left bundle branch block (QRS ≥ 130 μs), or with a history of ventricular tachycardia/ventricular fibrillation. The study utilized the EuroQol 5-Dimension 5-level (EQ-5D-5L) questionnaire and the EQ visual analog scale, which patients completed both prior to cardiac device implantation and during six post-implantation follow-up visits. The analysis of the research findings was conducted using the IBM SPSS Statistics software program (Armonk, NY). Cardiac pacemaker implantation in patients with sick sinus syndrome and high-grade AV block demonstrated significant and highly reliable positive effects on quality of life concerning mobility, self-care, and usual activity. Similarly, cardiac resynchronization device implantation in individuals with severe heart failure with reduced LVEF and wide QRS showed significant positive effects in these areas. However, cardioverter-defibrillator implantation did not yield positive effects on these modules.Regarding pain/discomfort, neither pacemaker nor cardiac resynchronization device implantation resulted in improved quality of life, while there was a somewhat positive effect observed in the cardioverter-defibrillator group. In terms of anxiety/depression, pacemaker implantation in patients with sick sinus syndrome and high-degree AV block had a significant and highly reliable positive impact on quality of life. Additionally, relatively positive impacts were noted at various periods following cardioverter-defibrillator and cardiac resynchronization device implantations. Cardiac implantable electronic devices play a crucial role not only in saving lives but also in positively impacting the quality of life of patients when appropriately selected.

Paced QRS morphology mimicking complete left bundle branch block induced by right ventricular pacing is associated with pacing-induced cardiomyopathy.

Right ventricular (RV) pacing sometimes causes left ventricular (LV) systolic dysfunction, also known as pacing-induced cardiomyopathy (PICM). However, the association between specifically paced QRS morphology and PICM development has not been elucidated. This study aimed to investigate the association between paced QRS mimicking a complete left bundle branch block (CLBBB) and PICM development. We retrospectively screened 2009 patients who underwent pacemaker implantation from 2010 to 2020 in seven institutions. Patients who received pacemakers for an advanced atrioventricular block or bradycardia with atrial fibrillation, baseline LV ejection fraction (LVEF) ≥ 50%, and echocardiogram recorded at least 6 months postimplantation were included. The paced QRS recorded immediately after implantation was analyzed. A CLBBB-like paced QRS was defined as meeting the CLBBB criteria of the American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society in 2009. PICM was defined as a ≥10% LVEF decrease, resulting in an LVEF of <50%. Among the 270 patients analyzed, PICM was observed in 38. Baseline LVEF was lower in patients with PICM, and CLBBB-like paced QRS was frequently observed in PICM. Multivariate analysis revealed that low baseline LVEF (odds ratio [OR]: 0.93 per 1% increase, 95% confidence interval [CI]: 0.89-0.98, p = 0.006) and CLBBB-like paced QRS (OR: 2.69, 95% CI: 1.25-5.76, p = 0.011) were significantly associated with PICM development. CLBBB-like paced QRS may be a novel risk factor for PICM. RV pacing, which causes CLBBB-like QRS morphology, may need to be avoided, and patients with CLBBB-like paced QRS should be followed-up carefully.

Long-term efficacy of left bundle branch pacing and biventricular pacing in patients with heart failure complicated with left bundle branch block.

Left bundle branch pacing (LBBP) can physiologically correct complete left bundle branch block (CLBBB), and has become the best alternative to biventricular pacing (BiVP). To compare the efficacy of LBBP and BiVP in patients with heart failure (HF) complicated with CLBBB. This was a single-center retrospective study. Patients with HF complicated with CLBBB who underwent successful cardiac resynchronization therapy (CRT) in Wuhan Asian Heart Hospital from June 2018 to June 2023 were enrolled and divided into LBBP group and BiVP group according to the pacing method. The primary endpoints were the absolute increase of left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), and echocardiographic response rate. Secondary endpoints were all-cause mortality, heart failure hospitalization (HFH), NT-proBNP, paced QRS duration, pacing threshold, and procedural duration. A total of 120 patients were enrolled in this study, including 60 patients in LBBP group and 60 patients in BiVP group. The median follow-up time was 37 ± 19 months. Compared with BiVP group, LBBP group had a more significant increase in absolute LVEF (ΔLVEF) (14.8 ± 9.9% vs. 10.7 ± 9.0%, P = 0.02), a more significant reduction in LVEDD (56.9 ± 10.9 mm vs. 61.1 ± 10.8 mm, P = 0.03), and a higher echocardiographic super response rate (65% vs. 45%, P = 0.02). There were no significant differences in all-cause mortality (1.7% vs. 10.0%, P = 0.11) and HFH (6.7% vs. 13.3%, P = 0.22). In terms of paced QRS duration (128.7 ± 14.1 ms vs. 137.5 ± 16.5 ms, P = 0.002), pacing threshold (0.72 ± 0.21 V/0.4 ms vs. 1.39 ± 0.51 V/0.4 ms, P < 0.001), procedural duration (134.1 ± 32.2 min vs. 147.7 ± 39.4 min, P = 0.04), the LBBP group was superior to the BiVP group. In nonischemic cardiomyopathy (NICM) patients with HF combined with CLBBB and LVEF ≤ 35%, LBBP is better than BiVP.

Redefining left bundle branch block from high-density electroanatomical mapping

BackgroundThe existing ECG criteria for diagnosing left bundle branch block (LBBB) are insufficient to distinguish between true and false blocks accurately. MethodsWe hypothesized that the notch width of the QRS complex in the lateral leads (I, avL, V5, V6) on the LBBB-like ECG could further confirm the diagnosis of true complete left bundle branch block (t-LBBB). We conducted high-density, three-dimensional electroanatomical mapping in the cardiac chambers of 37 patients scheduled to undergo CRT. These patients' preoperative electrocardiograms met the ACC/AHA/HRS guidelines for the diagnosis of complete LBBB. If the left bundle branch potential could be mapped from the base of the heart to the apex on the left ventricular septum, it was defined as a false complete left bundle branch block (f-LBBB). Otherwise, it was categorized as a t-LBBB. We conducted a comparative analysis between the two groups, considering the clinical characteristics, real-time correspondence between the spread of ventricular electrical excitation and the QRS wave, QRS notch width of the lateral leads (I, avL, V5, V6), and the notch width/left ventricular end-diastolic diameter (Nw/LVd) ratio. We performed the ROC correlation analysis of Nw/LVd and t-LBBB to determine the sensitivity and specificity for diagnostic authenticity. ResultsTwenty-five patients were included in the t-LBBB group, while 12 patients were assigned to the f-LBBB group. Within the t-LBBB group, the first peak of the QRS notch correlated with the depolarization of the right ventricle and septum, the trough corresponded to the depolarization of the left ventricle across the left ventricle, and the second peak aligned with the depolarization of the left ventricular free wall. In contrast, within the f-LBBB group, the first peak coincided with the depolarization of the right ventricle and a majority of the left ventricle, the second peak occurred due to the depolarization of the latest, locally-activated myocardium in the left ventricle, and the trough was a result of delayed activation of the left ventricle that did not align with the usual peak timing. The QRS notch width (45.2 ± 12.3 ms vs. 52.5 ± 9.2 ms, P < 0.05) and the Nw/LVd ratio (0.65 ± 0.19 ms/mm vs. 0.81 ± 0.17 ms/mm, P < 0.05) were compared between the two groups. After conducting the ROC correlation analysis, a sensitivity of 56% and a specificity of 91.7% for diagnosing t-LBBB using Nw/LVd were obtained. ConclusionBy utilizing the current diagnostic criteria for LBBB, an increased Nw/LVd value can enhance the effectiveness of diagnosing LBBB.

Predictors for new-onset conduction block in patients with pure native aortic regurgitation after transcatheter aortic valve replacement with a new-generation self-expanding valve (VitaFlow Liberty™): a retrospective cohort study

BackgroundNew-generation self-expanding valves can improve the success rate of transcatheter aortic valve replacement (TAVR) for severe pure native aortic regurgitation (PNAR). However, predictors of new-onset conduction block post-TAVR using new-generation self-expanding valves in patients with PNAR remain to be established. Therefore, this study aimed to identify predictors of new-onset conduction block post-TAVR using new-generation self-expanding valves (VitaFlow Liberty™) in patients with PNAR.MethodsIn this retrospective cohort study, patients were categorized into pacemaker and non-pacemaker groups based on their need for new postoperative permanent pacemaker implantation (PPI). Based on the postoperative presence of either new-onset complete left bundle branch block (cLBBB) or high-grade atrioventricular block (AVB), patients were further classified into conduction disorder and non-conduction disorder groups. Laboratory, echocardiographic, computed tomography, preoperative and postoperative electrocardiography, and procedural and clinical data were collected immediately after TAVR and during hospitalization and compared between the groups. Multivariate logistic regression analysis was performed incorporating the significant variables from the univariate analyses.ResultsThis study examined 68 consecutive patients with severe PNAR who underwent TAVR. In 20 patients, a permanent pacemaker was fitted postoperatively. Multivariate logistic regression analysis revealed an association between the need for postoperative PPI and preoperative complete right bundle branch block (cRBBB) or first-degree AVB, as well as a non-tubular left ventricular outflow tract (LVOT). In addition, valve implantation depth and angle of aortic root were independent predictors of new-onset cLBBB or high-grade AVB developing post-TAVR. The predictive value of valve implantation depth and angle of aortic root was further supported by receiver operating characteristic curve analysis results.ConclusionsIn patients with PNAR undergoing TAVR using self-expanding valves, preoperative cRBBB or first-degree AVB and a non-tubular LVOT were indicators of a higher likelihood of PPI requirement. Moreover, deeper valve implantation depth and greater angle of aortic root may be independent risk factors for new-onset cLBBB or high-grade AVB post-TAVR. Valve implantation depth and angle of aortic root values may be used to predict the possibility of new cLBBB or high-grade AVB post-TAVR.

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

BackgroundFor 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 presentationA 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.ConclusionFor 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.

Real-time three-dimensional transthoracic echocardiography in quantification of left ventricular dyssynchrony

Aim. To compare endocardial and epicardial left ventricular (LV) pacing using real-time electrocardiography (ECG)-synchronized three-dimensional echocardiography (3DE).Methods. Experimental intraoperative study included 88 points obtained from 12 patients with compensated heart failure of II-IV functional class NYHA (LV ejection fraction &lt; 35%) and cardiac resynchronization therapy indications - ECG pattern of complete left bundle branch block (LBBB) and QRS complex duration &gt; 150 ms. During isolated LV pacing as part of cardiac resynchronization therapy implantation procedure endocardial and epicardial stimulation points matched under fluoroscopic control using quadripolar coronary sinus leads and endocardial electrodes for temporary pacing were obtained. The overall number of corresponding pacing sites included 44 endocardial and 44 epicardial stimulation positions. The mean age of patients was 68.5 [63; 73.5] years, 83% males (n=10). Before study enrollment, 12-channel ECG, echocardiography, and a six-minute walk test were performed for all participants along with cardiac magnetic resonance imaging and control coronary angiography if indicated. The prevalence of coronary heart disease was 50% (n=6) while dilated cardiomyopathy was the most common etiology of chronic heart failure in other cases. Intraoperative ECG with estimation of paced QRS complex morphology at each point was registered via LabSystem Pro Electrophysiological Recording System (Bard Electrophysiology, USA). 3DE was performed using TomTec and Philips Qlab 3DQ Advanced software (Philips Medical Systems, USA).Results. Three-dimensional parametric imaging of LV regional segmental excursion and myocardial contractility using 3DE revealed statistically significant difference in semi-quantative parameters such as ExcAvg (p&lt;0.001), ExcMax (p=0.001), ExcMin (p&lt;0.001) and LV ejection fraction based on 3D modelling (p=0.003) while endocardial pacing was more beneficial. During the course of endocardial stimulation, the 3DE dyssynchrony index estimated at the 2nd stimulation site was also significantly lower (p=0.03). Identical dyssynchrony parameters valid for the 16 and 12-segment 3D models (SDI-16, Tmsv-12SD) (at p=0.06) demonstrated only a tendency for significant difference. The duration of QRS complex at the time of endocardial pacing was significantly shorter (&lt;190 [179;215] ms) (p=0.0008). Semi-quantitative and quantitative 3DE parameters showed the benefit of endocardial pacing resulting in cardiac contractility improvement with less dyssynchrony and LV volume reducing during intraoperative period.Conclusion. Endocardial pacing has potential benefit over the epicardial pacing represented by intraoperative dynamics of LV global and local contractility, intraventricular dyssynchrony estimated by 3DE and also ECG criteria. 3DE is helpful in more precise and reproducibile determing of late activation zone for target LV lead placement that is more manoeuvrable in case of endocardial stimulation.

R-Rʹ interval in the left bundle branch block predicts long-term outcomes after cardiac resynchronization therapy by estimating greater mechanical dyssynchrony and viable myocardium

BackgroundTypical left bundle branch block (LBBB) shows 2 peaks of the R wave, which reflect activation reaching the interventricular septum (R) and posterolateral wall (Rʹ) sequentially. ObjectiveThe purpose of this study was to investigate the relationship among R-Rʹ interval (RRʹ), mechanical dyssynchrony, extent of viable myocardium, and long-term outcomes in cardiac resynchronization therapy (CRT) candidates. MethodsThe study enrolled 49 patients (34 men; mean age: 69 ± 11 years) with LBBB who received CRT. The LBBB definition used requires the presence of mid-QRS notching in leads V1, V2, V5, V6, I, and aVL. Baseline evaluations were QRS duration (QRSd) and RRʹ measured from the 12-lead electrocardiogram; eyeball dyssynchrony (apical rocking and septal flash) and opposing-wall delay by speckle tracking from echocardiography, and extent of viable myocardium assessed by thallium-201 single-photon emission computed tomography. Primary outcomes included the combination of all-cause death and heart failure–related hospitalization. ResultsRRʹ predicted volumetric response better than QRSd (area under the curve 0.73 vs 0.67, respectively). The long RRʹ group (≥48 ms) revealed more frequent eyeball dyssynchrony and significantly greater radial (SL) and circumferential dyssynchrony (AP and SL) and %viable segment than the short RRʹ group. In multivariate regression analysis, only RRʹ ≥48 ms was independently associated with higher event-free survival rates following CRT (hazard ratio 0.21; P = .014). ConclusionThese findings suggest that RRʹ in complete LBBB was associated with mechanical dyssynchrony, extent of viable myocardium, and long-term outcomes following CRT.

Three-dimensional vector ECG analysis in the diagnosis of the left bundle branch block

The complete left bundle branch block (CLBBB) leads to the development of severe heart failure and requires resynchronization therapy(CRT). It is known that one third of patients do not respond to CRT. In this regard, it is necessary to search new diagnostic criteria for patient selection for CRT.Aim. Determination of the criteria for CLBBB using three-dimensional vectorcardiography data with analysis of the rate of vector loop formation.Material and research methods. The study included 137 patients. The main group consisted of 57 patients with CLBBB, which was based on D. G. Strauss et al. (2011) criteria. Causes of CLBBB and comorbidities were not considered. The control group included 80 healthy individuals. All patients underwent synchronous registration of 12 standard ECG leads and reconstruction of a three-dimensional vectorcardiogram (VCG) using the McFee-Parungao system.Research results. The following signs are characteristic for CLBBB according to three-dimensional VCG data: • fracture of the spatial vector loop due to a change in the direction of the excitation front in its middle part; • reduction in planarity index (PI) less than 80%; • a sharp, by a factor of 2 or more, decrease in the speed of tracing a spatial vector loop in its middle part with the formation of a “claw-shaped” curve with two peaks R and L.Conclusion. Three-dimensional VCG allows you to reliably determine the «true» CLBBB, based on the “fracture” of the spatial vector loop with a reduction in PI less than 80% and a significant decrease in the speed of tracing the vector loop in its middle part with the formation of a “clawshaped” curve and carry out a differential diagnosis with “false” СLBBB, in which changes on the ECG are associated with a combination of left ventricular hypertrophy and left anterior fascicular block, when there is no “fracture” of the loop, a reduction in PI, and the routing speed decreases at the end of the loop without forming a “claw-shaped” curve.

Complete Left Bundle Branch Block in Acute Coronary Syndrome with ST Segment Elevation: Epidemiological Features

Background: Complete left bundle branch in acute coronary syndrome with ST segment elevation is not common, but known as a sign of poor prognosis. Several international studies had reported its incidence and related mortality, but its epidemiological data is lacking in Algeria. Aims: The main objective of our study is the determination of the frequency of complete left bundle branch block in acute coronary syndrome with ST segment elevation, the secondary objective was the analysis of its predictive factors and related mortality. Methods and materials: In this prospective study, conducted in the cardiology department of Hussein Dey hospital (Algiers-Algeria), 467 patients with acute coronary syndrome with elevated ST segment (87 women and 380 men) were enrolled between 28 February 2014 and 16 July 2015. The average age is 60 ± 13 years; at admission, a Holter recorder was attached for continuous ECG monitoring during 48 hours. Kruskal’s ANNOVA or H tests were used for comparison of quantitative variables, χ2 test or Fisher’s exact test, were used for qualitative variables, all tests were performed with 1st species risk of 5%. Results: The frequency of complete left bundle brunch block is 1.7 % (8 patients), CI 95%: [0.5%-2.9%], multivariate analysis identified the two independent predictors: diabetes type 1, and Angiotensin Receptor-Blockers as current treatment. Despite the risk of mortality expressed by Hazard Ration (HR) is 4.7, but remains not significant: CI95%: [0.62-36], p = 0.134; however, the risk of ventricular fibrillation occurrence is high, with relative risk (RR) at 7.17, CI 95 %: [2.70-19.03], p = 0.007. Conclusion: Complete left bundle brunch block is not common in acute coronary syndrome with elevated ST segment, its predictive factors according to our study are: Diabetes type 1 and Angiotensin Receptor-Blockers as current treatment. The high-risk mortality in the left bundle brunch block group isn’t significant; however the risk of ventricular fibrillation occurrence is high.

Obesity and Cardiac Conduction Block Disease in China

Although a high body mass index (BMI) has been found to be associated with increased risk of cardiac conduction block (CCB) in older adults, no further studies have investigated the association between obesity and CCB in the general population. To investigate the association between obesity and CCB, including its subtypes. This cohort study used data from participants in the Kailuan Study in China (2006-2018) who had completed a physical examination in 2006 (baseline) and had not experienced CCB before baseline. Data analysis was conducted from March to September 2023. Obesity status was defined by BMI in 3 groups: normal weight (18.5 to <24), overweight (24 to <28), and obesity (≥28). The primary outcome was CCB, which was diagnosed from standard 12-lead electrocardiography. The primary end point included high-grade atrioventricular block (HAVB), complete right bundle branch block, complete left bundle branch block, left anterior fascicular block (LAFB), and left posterior fascicular block. First-degree atrioventricular block (FAVB), second-degree type 1 AVB, HAVB, complete and incomplete right and left bundle branch block, LAFB, and left posterior fascicular block were considered separately as secondary end points. Among 86 635 participants (mean [SD] age, 50.8 [11.9] years; 68 205 males [78.7%]), there were 33 259 individuals with normal weight (38.4%), 37 069 individuals with overweight (42.8%), and 16 307 individuals with obesity (18.8%). The mean (SD) follow-up was 10.6 (3.07) years. In the multivariable Cox proportional hazards regression analysis, obesity was associated with an increased risk of incident CCB (hazard ratio [HR], 1.21; 95% CI, 1.04-1.42) vs normal BMI. In secondary analysis, obesity was associated with an increased risk of FAVB (HR, 1.44; 95% CI, 1.21-1.73), HAVB (HR, 1.99; 95% CI, 1.03-3.82), and LAFB (HR, 1.29; 95% CI, 1.03-1.62) vs normal BMI. There was no association between obesity and other CCB subtypes. Obesity was associated with a greater increase in risk of CCB vs normal BMI in older (aged ≥65 years; HR, 1.44; 95% CI, 1.05-1.96) vs younger (aged <65 years; HR, 1.13; 95% CI, 0.96-1.34) participants (P for interaction < .001) and those with diabetes (HR, 2.16; 95% CI, 1.24-3.76) vs without diabetes (HR, 1.19; 95% CI, 1.02-1.39) (P for interaction = .02). This study found that obesity was associated with an increased risk of CCB, with greater increases in risk for FAVB, HAVB, and LAFB. Individuals who were older and those who had diabetes had larger increases in risk.

Abstract 18352: Impact of Approach Site on Conduction Defect in Right Ventricular Biopsy

Introduction: Myocardial biopsy is a fundamental procedure for diagnosing myocarditis and cardiomyopathy. Complete right bundle branch block (CRBBB) is a potential complication of right ventricular biopsy (RV-EMB) that occurs at a certain rate. Consequently, patients with complete left bundle branch block (CLBBB) often exhibit reluctance to undergo RV-EMB due to the risk of complete atrioventricular block. However, it is precisely in such cases that the diagnosis of CLBBB through myocardial biopsy becomes crucial and concerns clinicians.Although there are two approaches to RV-EMB, namely the transfemoral vein and transjuglar vein approaches, and each institution has its preferred method, no study has investigated the variation in complication rates, particularly the occurrence of CRBBB, based on the different approach sites for RV-EMB. AIMS:This study aims to analyze the disparity in complication rates, primarily CRBBB, attributable to differences in the approach site during the RV-EMB procedure. METHODS/RESULTS: Over all 266 cases who underwent RV-EMB at Kanazawa University between January 2017 and December 2022 including 87 cases with transfemoral venous approach (Group TF) and 179 cases with transjugular venous approach (Group TJ) were enrolled in this retrospective single-center study. Group TF exhibited a higher usage of warfarin (15.1% vs. 3.4%, p=0.001) and obtained fewer specimens compared to Group TJ (2.97±0.98 vs. 3.90±0.65 pieces, p&lt;0.001).Transient CRBBB was observed in 26 (29.9%) patients in Group TF and 13 (7.3%) patients in Group TJ (p&lt;0.001); CRBBB persisted beyond 24 hours in 8 (9.1%) and 2 (1.1%) patients(p=0.004), respectively. One case of cardiac tamponade occurred in Group TF, and two cases of VF were reported in Group TJ, with no instances of stroke, permanent pacemaker implantation, or mortality.Multivariate logistic regression analysis identified approach cite (Group TF/TJ) as an independent predictor of CRBBB (p&lt;0.001, odds ratio 0.43). CONCLUSIONS: The transjugular venous approach in RV-EMB demonstrates potential in reducing the occurrence of CRBBB as a complication. In cases where complete atrioventricular block is a concern, such as those with CLBBB, the transjugular vein approach may be preferable.

Association Between Left Ventricular Apical-to-Basal Strain Ratio and Conduction Disorders after Aortic Valve Replacement

The aim of the study was to evaluate whether left ventricular apical-to-basal longitudinal strain differences, representing advanced basal interstitial fibrosis, are associated with conduction disorders after aortic valve replacement (AVR) in patients with severe aortic stenosis. Patients with aortic stenosis undergoing AVR were included. The apical-to-basal strain ratio was calculated by dividing the average strain of the basal segments by the average strain of the apical segments. Values >1.9 were considered abnormal, as previously described. All patients were followed-up for the occurrence of complete left or right bundle branch block, or permanent pacemaker implantation within 2 years after AVR. Subgroup analysis was performed in patients undergoing transcatheter AVR. Two hundred seventy-four patients were included (74 years (IQR 65, 80), 46.4% male). During a median follow-up of 12.2 months (IQR 0.2, 24.3), 74 patients (27%) developed complete bundle branch block or were implanted with a permanent pacemaker. These patients more often had an abnormal apical-to-basal strain ratio. Cumulative event-free survival analysis showed worse outcome in patients with an abnormal apical-to-basal strain ratio (Log rank χ2 7.258, p = 0.007). In multivariable cox regression analysis, an abnormal apical-to-basal strain ratio was the only independent factor associated with the occurrence of complete bundle branch block or permanent pacemaker implantation after adjusting for other factors previously shown to be associated with conduction disorders after AVR. Subgroup analysis confirmed the independent association of an abnormal apical-to-basal strain ratio with conduction disorders after transcatheter AVR. The apical-to-basal strain ratio is independently associated with conduction disorders after AVR and could guide risk stratification in patients potentially at risk for pacemaker implantation.

Catheter-induced right bundle branch block: Practical implications for the cardiac electrophysiologist.

The right bundle branch (RBB), due to its endocardial course, is susceptible to traumatic block caused by "bumping" during right-heart catheterization. In the era of cardiac electrophysiology, catheter-induced RBB block (CI-RBBB) has become a common phenomenon observed during electrophysiological studies and catheter ablation procedures. While typically transient, it may persist for the entire procedure time. Compared to pre-existing RBBB, the transient nature of CI-RBBB allows for comparative analysis relative to the baseline rhythm. Furthermore, unlike functional RBBB, it occurs at similar heart rates, making the comparison of conduction intervals more reliable. While CI-RBBB can provide valuable diagnostic information in various conditions, it is often overlooked by cardiac electrophysiologists. Though it is usually a benign and self-limiting conduction defect, it may occasionally lead to diagnostic difficulties, pitfalls, or undesired consequences. Avoidance of CI-RBBB is advised in the presence of baseline complete left bundle branch block and when approaching arrhythmic substrates linked to the right His-Purkinje-System, such as fasciculo-ventricular pathways, bundle branch reentry, and right-Purkinje focal ventricular arrhythmias. This article aims to provide a comprehensive practical review of the electrophysiological phenomena related to CI-RBBB and its impact on the intrinsic conduction system and various arrhythmic substrates.

Myocardial Fibrosis and Left Bundle Branch Block Complicating an Athlete's Heart Syndrome Treated Homeopathically: A Case Report

Abstract Background During 2013, a 59-year-old male patient, a medical practitioner and lifelong sportsperson, complained of being constantly conscious of his heart action, and left sternal heave, as well as retrosternal heaviness at rest. On October 23, 2013, an electrocardiogram (ECG) showed some signs of an athlete's heart syndrome. An ECG on 11 January, 2019, shockingly showed a complete left bundle branch block (LBBB), a broad complex QRS sinus rhythm ECG, without ever experiencing angina pectoris after doing four sets of 20 push-ups. Methods A complication of an athlete's heart may be myocardial fibrosis (MF). MF is the primary pathology to treat, as well as its comorbidities synergistically, when they obstruct progress. Thus, Calcarea fluorata (Calc-f) was prescribed for endocardial fibrosis, Iberis amara (Iber) for endomyocardial fibrosis, Cactus grandiflorus (Cact) for pulmonary arterial hypertension and right ventricular strain, and Crataegus laevigata (Crat) for subendocardial ischaemia. Results After 17 months on Calc-f, the LBBB was unchanged. Iber was again prescribed on February 13, 2022. On February 23, 2022, after 10 days on Iber, a narrow complex QRS sinus rhythm (SR) ECG was recorded with a QRS of 90 milliseconds. This was the first SR ECG after having had a permanent complete LBBB for at least 3 years. Conclusions This case report documents via ECGs the biological effectiveness of Calc-f and Iber for MF. SR returned after the employment of, respectively, Iber and Cact. After employing Crat, the abnormal inverted T waves in most leads became positive. Since October 16, 2022 and beyond, there is a stable SR, but any intense exertion causes an LBBB.

Hyperacute T Wave in the Early Diagnosis of Acute Myocardial Infarction.

The diagnostic performance of T-wave amplitudes for the detection of myocardial infarction is largely unknown. We aimed to address this knowledge gap. T-wave amplitudes were automatically measured in 12-lead ECGs of patients presenting with acute chest discomfort to the emergency department within a prospective diagnostic multicenter study. The final diagnosis was centrally adjudicated by 2 independent cardiologists. Patients with left ventricular hypertrophy, complete left bundle branch block, or paced ventricular depolarization were excluded. The performance for lead-specific 95th-percentile thresholds were reported as likelihood ratios (lr), specificity, and sensitivity. Myocardial infarction was the final diagnosis in 445 (18%) of 2457 patients. In most leads, T-wave amplitudes tended to be greater in patients without myocardial infarction than those with myocardial infarction, and T-wave amplitude exceeding the 95th percentile had positive and negative lr close to 1 or with confidence intervals (CIs) crossing 1. The exceptions were leads III, aVR, and V1, which had positive lrs of 3.8 (95% CI, 2.7 to 5.3), 4.3 (95% CI, 3.1 to 6.0) and 2.0 (95% CI, 1.4 to 2.9), respectively. These leads normally have inverted T waves, so T-wave amplitude exceeding the 95th percentile reflects upright rather than increased-amplitude hyperacute T waves. Hyperacute T waves, when defined as increased T-wave amplitude exceeding the 95th percentile, did not provide useful information in diagnosing myocardial infarction in this sample.