Left Bundle Branch Block Morphology Research Articles

Impact of left bundle branch area pacing on right cardiac chambers dimensions and function. a medium term single center echocardiographic study

Abstract Introduction Left bundle branch area pacing (LBBAP) has become, in the last years, the preferred method for physiological pacing due to a wider target area, optimal pacing and sensing thresholds, and stable parameters over time. LBBAP ensures rapid and synchronous left ventricular (LV) activation through the left-sided conduction system. On the other hand, there is little data on right ventricular (RV) activation in LBBAP. The purpose of this study was to evaluate the impact of LBBAP on the right heart anatomy and function over a mid-term follow-up period. Material and methods All consecutive patients with successful LBBAP for bradyarrhythmic indications between February 2021 and July 2022 at our institution were eligible for this study. Left bundle branch capture was defined as a paced QRS complex of right bundle branch block morphology, and proof of transition from non-selective to selective capture with differential pacing maneuvers. To avoid confounders, patients with LV ejection fraction below 40% and with severe valvular disease were excluded. In the end, 57 patients were prospectively evaluated. Patient and procedural characteristics were recorded at baseline and follow-up. Also, right atrial (RA) volume, RV basal diameter, tricuspid annulus peak systolic elevation (TAPSE), RV S` wave (RVS`W), and tricuspid regurgitation (TR) were evaluated before the procedure and at the end of the follow-up period. Results The mean age of the patients was 68.9± 10 years, and 70% were males. 29.8% had a baseline right bundle branch block, and 22.8% had a left bundle branch block morphology. The baseline LV ejection fraction was 54.3 ± 9.9 %. The paced QRS duration was similar to the baseline values (128.5 ± 16.3 vs. 134.4 ± 30.4 msec, p=0.119). The pacing and sensing thresholds were 0.7 ± 0.3 V at 0.4 ms pulse duration and 9.7 ± 4.2 mV, respectively. The mean LV activation time (measured as the R wave peak time in V6) was 80.9 ± 12 msec, and the mean RV activation time (measured as the difference between QRS duration and LV activation time) was 51.9 ± 24.2 msec. The patients were followed over a mean period of 591.2 ± 150.3 days. There were no complications over the follow-up period that led to pacing interruption. The follow-up pacing (0.6 ± 0.2 V, p=0.003) and sensing (11.7 ± 6 mV, p= 0.023) thresholds showed significant improvement compared to the procedural values. The right heart echocardiographic evaluation showed non-statistically significant changes between the follow-up and the baseline values for RA volumes (57.9 ± 33.7 vs. 51.5 ± 28.4 ml, p=0.122), RV basal diameter (32.8 ± 5.4 vs. 31.8 ± 6.4 mm, p=0.31), RVS`W (12.8 ± 3.2 vs. 12.85 ± 2.7 cm/sec, p=0.933), and TR (1.8±0.8 vs. 2±1, p=0.07). On the other hand, there was a significant improvement in the TAPSE (22.2±4.3 vs. 20.7±3.6 mm, p=0.021). Conclusions LBBAP was associated with preserved dimensions and function of the right cardiac chambers over a medium-term follow-up period.

Unfolding the transition ratio: insight into the diagnostic criteria for the diagnosis of the origin of outflow tract ventricular arrhythmias

Abstract Background algorithms for the diagnosis of the site of origin of ventricular outflow tract arrhythmias (OTVA) share the rationale that more posterior structures (LVOT) produce a greater vector approaching the precordial leads than anterior structures (RVOT), i.e. R waves in V1-V3 of greater amplitude and duration, a transition generally earlier than the QRS in sinus rhythm (SR), and vice-versa. Methods in a retrospective cohort of 45 patients (53.3% LVOT, 46.7% RVOT) with OTVA (left bundle branch block morphology, transition in lead V3, absence of conduction aberrancy in SR, who underwent successful catheter ablation were retrospectively analyzed, comparing the diagnostic yield of the main literature criteria. a) The V2 transition ratio, (TR) calculated with the formula [(R\R+S)PVC : (R\R+S)SR] (LVOT if > 0.6) [1]. b) The V1-V2 S-Rd, calculated as [(V1S + V2S) – (V1R + V2R)] (LVOT if < 1.625) [2]. c) The V2S\V3R amplitude ratio (LVOT if < 1.5) [3]. d) The transition zone index (TZI), obtained by subtracting the transition zone of the PVC with that of the SR (LVOT if < 0) [4]. We extended the use of these criteria to the precordial leads V1 to V3; for TR the equation was applied to amplitude as well as duration measurements. Results Comparison of PVC QRS morphology with that of SR. 1. The diagnostic accuracy of the TR showed incremental values moving from lead V1 to V3, both using amplitude and duration measurements; compared to the modest accuracy of the V2 TR (AUC 0.630, 0.727), the V3 TR (LVOT if > 1) showed an accuracy of 85.3% (AUC 0.804, 0.855). 2. Simplifying the complex TR equation, comparing R or S waves of the PVC with those of the SR, we again found incremental values of accuracy moving from lead V1 to V3, with better results for the SVT\SSR compared to the RVT\RRS; the V3 SVT\SRS) (LVOT if < 1) showed an accuracy of 86.6% (AUC 0.917). 3. The TZI showed in our series a lower diagnostic yield compared to that of the literature (AUC 0.748, accuracy 73.3%) Comparison of PVC QRS morphology between two contiguous leads: 4. Compared to the V1-V2 S-Rd (AUC 0.830), the V2-V3 S-Rd (AUC 0.855), calculated as [(V2S + V3S) – (V2R + V3R)] showed greater accuracy (82.2%). 5. Similarly, compared to the V1S\V2R amplitude ratio (AUC 0.774), the V2S\V3R (AUC 0.930) showed the greatest accuracy (88.8%, with a more balanced sensitivity and specificity moving the cut-off for the diagnosis of origin from LVOT to < 2), resulting the criterion with the highest diagnostic yield. Conclusions variables that compare the morphology of the QRS of the PVC of two contiguous leads have greater accuracy than those that compare the morphology of the QRS of the PVC with that of the SR, with greater diagnostic yield when applied from lead V1 to V3; the V2S\V3R ratio represents the best criterion, with high sensitivity, like the V3 transition ratio; the simple ratio (SVT\SSR) can virtually replace the more complex TR, with similar accuracy but high specificity.

Artificial intelligence enabled electrocardiogram for mortality and ventricular arrhythmia prediction

Abstract Background Artificial intelligence-enhanced electrocardiograms (AI-ECG) can be used to predict risk of events but existing models suffer from lack of actionability, explainability and biological plausibility, and therefore are not used clinically. Purpose We sought to address these limitations of previous AI-ECG approaches by developing the AI-ECG risk estimator (AIRE). Methods AIRE was developed in a dataset of 1,163,401 ECGs from 189,539 patients from a secondary care setting in the USA. Uniquely, AIRE uses deep learning with a residual convolutional neural network with a discrete-time survival loss function to create a subject-specific survival curve using a single ECG. AIRE was trained to predict time-to-mortality and fine-tuned for the additional endpoints described below. Results AIRE outputs a subject-specific survival curve that predicts not only mortality but time-to-mortality, using only a single ECG (Figure 1A). AIRE accurately predicts risk of all-cause mortality (C-index 0.775 (0.773-0.776), Figure 2) and can differentiate prognosis in high and low risk subjects even when only cardiologist reported normal ECGs are considered (Figure 2). AIRE also accurately predicted cardiovascular (CV) death 0.832 (0.831-0.834), future ventricular arrhythmia (0.760 (0.756-0.763)), future atherosclerotic cardiovascular disease (0.696 (0.694-0.698)) and future heart failure (0.787 (0.785-0.889))). In particular AIRE was superior to left ventricular ejection fraction (LVEF) in predicting risk of future ventricular arrhythmias in subjects with LVEF <50% (C-index 0.649 (0.638 – 0.660) vs 0.615 (0.603 – 0.626) p < 0.0001 ) and in dilated cardiomyopathy (C-index 0.690 (0.669-0.711) vs 0.608 (0.584 – 0.631), p < 0.0001). We used a variational autoencoder (VAE) to visualise the features most correlated with the mortality predictions. Features of QRS morphology, particularly broader and more left bundle branch block morphologies, inverted and biphasic T waves as well as ST segment changes were associated with high predicted mortality (Figure 1B). We externally validated our findings in four diverse, transnational cohorts from Brazil and the UK including volunteers and primary care subjects (Figure 2), and found AIRE accurately predicted all-cause mortality in all four external cohorts. Through phenome- and genome-wide association studies, we identified candidate biological pathways for the prediction of increased risk, including changes in cardiac structure and function (LV mass, LVEF, LV trabeculation), and genes associated with cardiac structure, QT interval, biological aging and metabolic syndrome (VGLL2, KCNQ1, CCDC91, TBX3). Conclusion AIRE is an explainable, biologically plausible and actionable AI-ECG risk estimation platform that has the potential for use worldwide across a wide range of clinical contexts for short- and long-term risk estimation.Figure 1Figure 2

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.\

Left bundle branch area pacing optimized cardiac resynchronization therapy (LOT CRT) -comparative results to a CRT implanted patient population

Abstract Background Cardiac resynchronization therapy (CRT) is gold standard treatment option among patients with symptomatic heart failure with reduced left ventricular ejection fraction (LVEF) and intraventricular conduction delay of left bundle branch block (LBBB) morphology. Purpose Left bundle branch area pacing optimized cardiac resynchronization therapy (LOT CRT) is a novel and promising approach for CRT candidate patients even in advanced intraventricular conduction delay, however convincing follow-up data regarding this patient group is still lacking. Methods In our observational registry 35 LOT CRT vs. 35 conventional CRT patients were consecutively implanted according to current guidelines. All the patients had LBBB morphology QRS width of >150 ms. The two compared patient group did not show significant difference in age, gender, baseline non-ischemic etiology, LVEF, NYHA functional class, LBBB QRS width. Results Immediate postoperative results showed significantly increased QRS width reduction (p=.028) and at 6 months of follow-up a significantly greater improvement in LVEF(p=.031), NYHA functional class (p=.04) and Nt-ProBNP levels (p=0.043) were seen in LOT CRT patient group compared to conventional CRT patients. Conclusion Our single center observational study showed significant improvement in prompt postoperative QRS width and clinical follow-up parameters in LOT CRT implanted patients compared to conventional CRT implanted patients.LOTCRTvs.CRTQRSwidthreductionLOTCRTXray

Impact of non-typical LBBB on CRT response

Abstract Introduction Cardiac resynchronization therapy (CRT) benefits have been established in patients with heart failure and reduced left ventricular ejection fraction (HFrEF) who have a broad QRS and remain symptomatic despite optimized medical therapy. Responders typically are female, with LBBB and broader QRS. It remains uncertain to what extent do patients with non-LBBB QRS complex morphology respond to CRT and also if there are differences among various types of intraventricular conduction delays. Purpose To evaluate the impact of non-typical left bundle branch block (LBBB) on reverser remodeling and clinical events. Methods Single center, observational, retrospective study including patients (pts) who implanted CRT in the context of HFrEF, from 2015 to 2020. Evaluation of QRS morphology analysis was conducted. CRT response was defined by a reduction of LVESV≥15% or an increase in LVEF≥10%. Predictors of CRT response were evaluated with Chi-square and Mann- Whitney analysis. Impact on reverse remodeling and clinical outcomes was performed with Kaplan-Meyer analysis. Results A total of 361 pts were included for analysis, of which 184 had non-typical LBBB. Pts had a mean age of 71±9years old, the majority of pts were female (61%), and almost half were ischemic (47.8%). EGC evaluation prior to CRT implantation, revealed an atypical LBBB in 83 (45.1%) pts, typical RBBB in 23 (12.5%) pts, atypical RBBB 94.(9%) pts and nonspecific intraventricular conduction delay in 69 (37.5%) pts. During a mean time of follow-up of 2.9 ±2.4years, 33 pts (18%) had hospitalizations due to HF and 68 (37%) died. In this cohort, 78 pts (42.4%) were deemed as responders, who presented a better clinical outcome when compared to non-responders (p < 0.001, HR 2.629 [95% CI 1.635-4.225]. There was no difference among the four types of intraventricular conduction analyzed in respect to degree of CRT response – figure 1. Regarding clinical events during follow-up, there was once again no significant difference among the different patterns of non-typical LBBB– figure 2. In this subset population we found no independent predictors of CRT response, although non-responders were significantly older than responders (72±8 vs 69±10 years-old (p=0.016). Conclusion Although pts with non-typical LBBB morphology display a lower therapy response to CRT than reported for LBBB pts, the rate of response is not negligible and represents a protective factor for clinical outcomes. Different types of intraventricular conduction delay present no difference regarding long- term prognosis or reverse remodeling.Survival according to CRT response

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.

Immediate pharmacotherapy intensification after cardiac resynchronization therapy: incidence, characteristics, and impact.

Cardiac resynchronization therapy (CRT) is an established treatment for drug-refractory heart failure (HF) in patients with left bundle branch block (LBBB). Acute haemodynamic improvement after CRT implantation may enable the intensification of HF medication soon thereafter. Immediate pharmacotherapy intensification (IPI) after CRT implantation achieves a synergetic effect, possibly leading to a better prognosis. This study aimed to explore the incidence, characteristics, and impact of IPI on real-world outcomes among CRT recipients with a history of hospitalization for acute HF. This multicentre retrospective study enrolled CRT recipients with LBBB morphology, a QRS width ≥120ms, a left ventricular ejection fraction ≤35%, and New York Heart Association II-IV HF symptoms. All patients had previous HF hospitalizations within the previous year and received guideline-directed medical therapy before CRT implantation. Patient baseline characteristics, including HF medication, were collected. IPI was defined as the intensification of beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and mineralocorticoid receptor antagonists within 30days of CRT implantation. The primary endpoint was all-cause death or first hospitalization for HF; the secondary endpoint was all-cause death. We enrolled 194 patients (75% male; mean age, 65±13years; 78% with non-ischaemic cardiomyopathy). One hundred five (54%) patients received IPI. Patients who received IPI exhibited a significantly shorter QRS duration (159±26 vs. 171±32ms; P=0.004), higher estimated glomerular filtration rate (55.2±20.0 vs. 47.8±24.7mL/min/1.73m2 ; P=0.022), and more dilated cardiomyopathy. During a median follow-up period of 29months, 70 (36%) patients reached the primary endpoint and 42 (22%) patients died. Patients with IPI showed significantly better outcomes for the primary and secondary endpoints than patients without IPI. The volumetric responder ratio at 6months after implantation was not significantly different between patients with and without IPI; however, patients who received IPI had reduced mortality even at 6months after implantation. In the multivariate analysis, IPI was an independent predictor of the primary endpoint (hazard ratio, 0.51; 95% confidence interval, 0.27-0.97; P=0.043). Immediate intensification of HF medication was achieved in 54% of CRT recipients and was significantly higher in patients without excessive QRS prolongation, preserved renal function, and dilated cardiomyopathy than others. In patients with LBBB morphology and QRS≥120ms, IPI was associated with a significantly better prognosis and fewer HF hospitalizations after CRT implantation than others.

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...

Role of fragmented QRS complex in the prognosis of patients undergoing cardiac resynchronization therapy. A new red flag to look for?

Abstract Introduction Cardiac resynchronization therapy (CRT) has demonstrated to reduce mortality and hospitalization for heart failure in selected patients with heart failure with reduced ejection fraction (HFrEF). However, there is a significant percentage of readmissions for heart failure (HF) after implantation. In the recent years, several biomarkers and electrocardiographic findings possibly related with prognosis in this group of patients have been identified. Fragmentation of QRS complex (fQRS) has been related with worse prognosis in various cardiac diseases, but the evidence in patients undergoing CRT is limited. Purpose The objective of this study is to evaluate if the presence of pre-implantation fragmented QRS complex has a prognostic role in patients undergoing cardiac resynchronization therapy in terms of hospitalization for HF. Methods Consecutive patients undergoing CRT were prospectively included from October 2009 to December 2022. Demographic clinical, electrocardiographic and echocardiographic variables were recorded. Prospective follow-up variables were collected from electronic clinical records and telephone interview. Fragmentation of the QRS complex was defined by the presence of different RSR′ patterns including an additional R-wave (R′), notching of the R-wave and S-wave or the presence of more than 1R′ in two contiguous leads corresponding to a main coronary artery territory. Results 244 patients were included. Mean age at the implantation of the device was 71.8 years (standard deviation, SD ±9.8 years), 79.5% were male and 40.2% were diabetic. Mean LVEF was 24.9% (SD ±8.9) and the aetiology was non-ischaemic in 50.8% of the patients and ischaemic in 49.2%. 40.2% had prior history of acute myocardial infarction. Pre-implantation fragmented QRS complex was found in 58.6% of the patients and mostly in inferior leads of the surface ECG. Mean QRS duration was 157.9ms and 82.0% had left-bundle branch block morphology. CRT with defibrillator implantation was performed in 71.4% of the patients. The median follow-up time was 27.4 month. After device implantation, mean LVEF was 33.2% and 76.6% presented NYHA class I-II. During this period, 28.7% of the patients died. Additionally, 29.1% of the patients presented at least one hospitalization for heart failure (HF), 22.5% with fQRS and 6.6% without fQRS. A multivariate survival study using Cox regression showed that the presence of pre-implantation fQRS was an independent predictor of HF hospitalization events (HR 2.24; 95% CI 1.20-4.18). Figure 1 presents Kaplan-Meier curves for hospitalization for HF. Conclusions According to our results, pre-implantation fQRS is a strong independent predictor of hospitalization for HF after CRT implantation. Thus, patients with fQRS could benefit from a more rigorous follow-up as they present higher risk of decompensation. Further research is needed to confirm our findings.Figure 1.Kaplan-Meier curves

Significance of left posterior extension of early repolarization in patients with J-wave syndrome

J waves in the inferior or lateral leads are characteristic electrocardiographic (ECG) changes in patients with early repolarizationsyndrome (ERS). However, the presence of J waves in the left posterior region has not yet been evaluated. The purpose of this study was to clarify the significance of J waves in the posterior left ventricle using leads V7-V9 and a body surface mapping (BSM) system. Forty patients diagnosed with ERS were included. All patients exhibited J waves in either the contiguous inferior, lateral, or posterior leads. We evaluated the incidence of J waves in the inferolateral and posterior leads using a 15-lead ECG with synthesized V7-V9 and an 87-lead BSM. Additionally, we assessed the arrhythmogenicity of the posterior regions based on the morphology ofthe premature ventricular complexes (PVCs) associated with ventricularfibrillation (VF). J waves were observed in the lateral, inferior, and posterior leads of 26 (65%), 31 (78%), and 39 (97%) patients, respectively. J waves were found only in the posterior leads of 5 patients. BSM was evaluated in 9 patients, all of whom exhibited a positive area on the posterior region. PVCs associated with VF were recorded in 5 patients. Among patients with inferolateral and posterior J waves, all except 1 patient who displayed left bundle branch block morphology showed PVCs originating from the posterior left ventricular region. Posterior J waves are common in ERS patients. This abnormality can be detected using leads V7-V9 and the BSM system and may be associated with arrhythmogenesis.

Selective and non-selective right bundle pacing for the diagnosis of bundle branch reentry ventricular tachycardia.

Bundle branch reentry ventricular tachycardia (BBRVT) can be seen in patients with conduction disease. In this report, we describe the use of conduction system pacing for its diagnosis. BBRVT was induced in two patients with infra-nodal conduction disease. Bundle branch reentry ventricular tachycardia with a left bundle branch block morphology was observed in the first patient (type A), whereas the second patient had a right bundle branch block morphology (type C).The diagnosis of BBRVT was confirmed in both patients by ventriculo-atrial dissociation, and the interdependence of the conduction system and the ventricular tachycardia cycle length variations.Selective and non-selective RB pacing was observed in the two patients during apical right ventricular pacing for entrainment of BBRVT with evidence of manifest entrainment with non-selective RB capture in the first patient, and concealed entrainment by selective RB capture in the second patient. Other criteria for entrainment including a short post-pacing interval at the right bundle pacing site were noted. Right bundle pacing is feasible in patients with BBRVT and may be a helpful manoeuver for the diagnosis of BBRVT.

Feasibility of Permanent His Bundle Pacing in the Elderly vs the Very Elderly. A Single-Center Mid-Term Follow-Up Study.

Although feasibility studies have included older patients, specific data for His bundle pacing (HBP) in this population is scarce. The aim of this study was to evaluate the feasibility and mid-term performance of HBP in the elderly (70 to 79 years old) versus the very elderly (80 years old and above) patients with conventional indications for pacing. About 105 patients older than 70 years of age with attempted HBP from the 1st of January 2019 to the 31st of December 2021 were reviewed. Clinical and procedural characteristics were recorded at baseline, and after a mid-term follow-up period. The procedural success rate was similar in both age groups (68.49% vs 65.62%). There was no significant difference in pacing or sensing thresholds, impedance, and fluoroscopy times. For both age intervals, patients with a baseline narrow QRS maintained a similar QRS duration after pacing, while in patients with a wide QRS, the paced QRS was significantly shorter. Baseline QRS duration, left bundle branch block morphology, and ejection fraction, were significantly associated with HBP procedural failure. The mean follow-up period was 830.34 days for the elderly and 722.76 days for the very elderly. After the follow-up period, both sensing and pacing thresholds were similar between the groups. Compared to the baseline values, there were no significant changes in both pacing and sensing parameters, irrespective of the age interval. During follow-up, no lead dislodgements were recorded. There were two cases of significant pacing threshold rise in the elderly (4%) and three cases in the very elderly group (14.2%) which were managed conservatively, without lead revision. In elderly and very elderly patients, HBP is a feasible procedure associated with constant pacing and sensing parameters and with low complication rates over mid-term follow-up.

Diagnostic gain of cardiac MR in patients with premature ventricular complexes and structurally normal hearts on echocardiography

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway Background An important part of the diagnostic evaluation of patients with premature ventricular complexes (PVCs) is to identify underlying cardiac disease. The majority of these patients referred to catheter ablation have PVCs with inferior axis and left bundle branch block morphology (I-LBBB). Although this is the most common morphology in patients with idiopathic PVCs, cardiac magnetic resonance (CMR) is recommended to exclude potential other underlying pathology. However, the diagnostic gain of CMR in patients with I-LBBB PVCs is uncertain. Purpose The purpose of this study was to explore the prevalence of cardiac abnormalities identified by CMR in patients with I-LBBB PVCs evaluated for catheter ablation without signs of underlying cardiac disease from resting ECG, stress test, or echocardiography. Methods We retrospectively collected data from consecutive patients with I-LBBB PVCs evaluated for catheter ablation at our tertiary referral centre from 2011 to 2022. We included patients with normal ECG and stress test, and no evidence of functional or structural heart disease by echocardiography. We categorized CMR examinations as normal or as having signs of functional or structural abnormalities. Results We identified a total of 63 patients with I-LBBB PVCs evaluated for catheter ablation, with no signs of underlying conditions from sinus rhythm ECG, stress test or echocardiography. All were studied by CMR at our institution. The median age was 49 years (IQR 36-61), and 39 were females (62 %). The maximum PVC burden recorded in each patient prior to referral was 20 % (IQR 11-29.5). Left ventricular (LV) ejection fraction by echocardiography was 56±4 %. CMR was normal in 52 patients (83 %), while functional or structural abnormalities were detected in 11 patients (17 %). These abnormalities comprised reduced LV systolic function (2 patients), dilated right ventricle (2 patients), dilated LV (1 patient), ventricular septal defect (2 patients), non-compaction cardiomyopathy (1 patient), mitral annular disjunction (2 patients), tricuspidal annular disjunction (1 patient), and myocardial fibrosis by late contrast enhancement (3 patients). Conclusions In patients with I-LBBB PVCs evaluated for catheter ablation, and with no signs of underlying pathology from standard diagnostic work-up, CMR detected abnormalities in 17 %. These results support the routine use of CMR in the evaluation of patients with I-LBBB PVCs referred for catheter ablation.

The feasibility and safety of his-purkinje conduction system pacing in patients with heart failure with severely reduced ejection fraction.

The purpose of this study was to evaluate the feasibility and outcomes of conduction system pacing (CSP) in patients with heart failure (HF) who had a severely reduced left ventricular ejection fraction (LVEF) of less than 30% (HFsrEF). Between January 2018 and December 2020, all consecutive HF patients with LVEF < 30% who underwent CSP at our center were evaluated. Clinical outcomes and echocardiographic data [LVEF and left ventricular end-systolic volume (LVESV)], and complications were all recorded. In addition, clinical and echocardiographic (≥5% improvement in LVEF or ≥15% decrease in LVESV) responses were assessed. The patients were classified into a complete left bundle branch block (CLBBB) morphology group and a non-CLBBB morphology group according to the baseline QRS configuration. Seventy patients (66 ± 8.84 years; 55.7% male) with a mean LVEF of 23.2 ± 3.23%, LVEDd of 67.33 ± 7.47 mm and LVESV of 212.08 ± 39.74 ml were included. QRS configuration at baseline was CLBBB in 67.1% (47/70) of patients and non-CLBBB in 32.9%. At implantation, the CSP threshold was 0.6 ± 0.3 V @ 0.4 ms and remained stable during a mean follow-up of 23.43 ± 11.44 months. CSP resulted in significant LVEF improvement from 23.2 ± 3.23% to 34.93 ± 10.34% (P < 0.001) and significant QRS narrowing from 154.99 ± 34.42 to 130.81 ± 25.18 ms (P < 0.001). Clinical and echocardiographic responses were observed in 91.4% (64/70) and 77.1% (54/70) of patients. Super-response to CSP (≥15% improvement in LVEF or ≥30% decrease in LVESV) was observed in 52.9% (37/70) of patients. One patient died due to acute HF and following severe metabolic disorders. Baseline BNP (odds ratio: 0.969; 95% confidence interval: 0.939-0.989; P = 0.045) was associated with echocardiographic response. The proportions of clinical and echocardiographic responses in the CLBBB group were higher than those in the non-CLBBB group but without significant statistical differences. CSP is feasible and safe in patients with HFsrEF. CSP is associated with a significant improvement in clinical and echocardiographic outcomes, even for patients with non-CLBBB widened QRS.

PO-04-169 DELAYED EFFECT OF CATHETER ABLATION FOR INTRAMURAL OUTFLOW TRACT VENTRICULAR ARRHYTHMIAS

Despite sequentially bilateral outflow tract catheter ablation, intramural septal outflow tract ventricular arrhythmia (OT-VA) can be clinically challenging. The outcome of intramural septal OT-VA without complete elimination after sequentially bilateral ablation remains unknown. We aimed to investigate the outcome of intramural septal OT-VA without complete elimination after sequentially bilateral catheter ablation. During 2008 to 2020, patients with intramural OT-VA undergoing sequentially bilateral ablation were recruited. ECG and electrophysiological parameters were analyzed. The intramural OT-VA was defined by one of the following: 1. Difference of activation time between right and left ventricular outflow tract < 20 ms; 2. Pacemapping at the earliest activation site could not yield 12/12 matched morphology; 3. Catheter ablation at the earliest activation site could not completely eliminate the ventricular arrhythmia. Partial success was defined by a > 80% reduction in ventricular arrhythmia burden immediately after ablation. Delayed resolution was defined by a ventricular arrhythmia burden persistently < 2% of total daily beats during follow-up. In total, 124 patients (76 men, age: 53.5 ± 14) with intramural OT-VA undergoing sequentially bilateral ablation were studied. Acute success, partial success, and failure were found in 85 (68.5%), 26 (21.0%), and 13 (10.5%) patients respectively. For the patients with partial success, after a median follow-up period of 17.4 months (25%-75%, interquartile range: 2.8-53.2), recurrence and delayed resolution were observed in 21 and 5 (19.2 %) patients, respectively. The delayed effect was observed within 3.0 (25%-75%, interquartile range: 1.9-10.6) months after ablation (Figure). Of 5 patients with delayed resolution, the ventricular arrhythmias were characterized by left bundle branch block morphology and dominantly precordial R/S transition at V3, and the activation time of ventricular arrhythmias at right ventricular outflow tract was earlier than those at left ventricular outflow tract. Despite partial success could be achieved immediately after bilateral ablation of intramural OT-VA, the recurrence rate was still high. Delayed resolution of intramural OT-VA could only be observed in 19.2% of patients and the majority of ventricular arrhythmia resolution was observed within 3 months after catheter ablation.

PO-04-015 BIVENTRICULAR ARRHYTHMOGENIC CARDIOMYOPATHY ASSOCIATED WITH A NOVEL HETEROZYGOUS PLAKOPHILIN-2 EARLY TRUNCATING VARIANT

N/A N/A N/A A 31-year-old male patient suffered from palpitations, which occurred particularly during and shortly after physical activity. The patient was very athletic and took part in marathons. His family history was unremarkable. The electrocardiogram showed T wave inversions in V1-V3 (Figure 1A). During bicycle ergometry monomorphic premature ventricular complexes (PVC) and non-sustained ventricular tachycardia episodes (left-bundle branch block morphology, inferior axis) evolved (Figure 1B, black arrow). Of note, under maximal physical stress a second PVC with a right-bundle branch block morphology occurred (Figure 1B, red arrow) suggesting left ventricular (LV) involvement. Echocardiographic evaluation showed a dilated right ventricle (RV) with reduced systolic function, a subtricuspid aneurysm and multiple sacculations of the RV free wall (Figure 1C-D, white markers). Cardiac magnetic resonance imaging (MRI) confirmed the right ventricular findings (Figure 1E, red arrows). In addition, late gadolinium enhancement and fatty deposits were visible in the LV lateral wall (Figure 1F-G, yellow arrows and blue asterix). Genetic testing was performed using a panel covering 173 genes (Agilent, SureSelectQXTTarget Enrichment) and next generation sequencing (NGS) (Illumina MiSeq). It revealed a novel heterozygous nonsense variant in the plakophilin-2 (PKP2) gene (808C>T p. (Gln270Ter) in exon 3) that causes an early truncation, which was confirmed by Sanger sequencing. It was classified as pathogenic (class V). Cascade screening of the asymptomatic patient’s mother (64-y-old), father (70-y-old) and sister (33-y-old) showed that the patient's father and sister harbored the same PKP-2 variant. Both did not report a history of participating in competitive sports, and thorough cardiac evaluation of these two genotype positive family members showed normal findings. Previous studies have indicated that early truncation of the PKP2 C-terminus likely causes arrhythmogenic right ventricular cardiomyopathy (ARVC) irrespective of transcript position. Although desmosomal and non-desmosomal variants create certain genetic potential for the development of ARVC, exercise has an important role in determining the development, severity, and pattern of phenotypic expression. The fact that the only index patient, as a marathon runner, developed ARVC, suggests that the novel PKP2 variant poses a genetic risk, but is not sufficient for inducing an ARVC phenotype by itself.

PO-04-222 OUTFLOW TRACT VERSUS NON-OUTFLOW TRACT VENTRICULAR ARRHYTHMIAS IN ATHLETES: MYOCARDIAL SUBSTRATE AND LONG-TERM CLINICAL OUTCOMES

Outflow tract ventricular arrhythmias (OT-VA) are common in healthy subjects without structural heart disease (SHD), and are generally considered benign. However, athlete-specific data on the clinical meaning of different ventricular arrhythmia (VA) morphologies are scarce. To assess the prevalence of SHD as well as long-term clinical and sports medicine outcomes in a cohort of athletes with OT-VA undergoing a comprehensive diagnostic assessment, by comparing them with athletes with non-outflow tract VAs (nOT-VA). We conducted a multi-center, observational, retrospective study enrolling athletes who were referred because of complex VAs (>500 PVCs/24 h, exercise-induced VAs, nonsustained or sustained ventricular tachycardia). Athletes were categorized into two groups: OT-VA, in case of monomorphic ventricular arrhythmias of left bundle branch block and inferior axis morphology; nOT-VA, in case of polymorphic VAs or monomorphic VAs of right bundle branch block or left bundle branch block and superior/intermediate axis. The two co-primary outcomes were survival free from all-cause death or sustained VAs and sports practice at last follow-up. 175 athletes with complex ventricular arrhythmias (OT-VA,n=82; nOT-VA,n=93) were included in the present analysis; clinical characteristics are resumed in the Table. Remarkably, the prevalence of signs of SHD was higher in nOT-VA compared to OT-VA (Table). A final diagnosis of idiopathic VA was more common in OT-VA compared to nOT-VA and, accordingly, catheter ablation was more commonly performed in the former group. Over a median follow-up of 61(43-85) months, there were 2 cardiac arrests and 1 appropriate ICD shock, all occurring in athletes in the nOT-VA group with in vivo evidence of SHD and polymorphic VAs, for an overall prevalence of a primary outcome event of 0 and 3% in the OT-VA and the nOT-VA groups, respectively (p=0.25). At last follow-up, 31 athletes (18%) practiced competitive sports (OT-VA vs. nOT-VA,p=0.23), while 92 (53%) were leisure-time athletes (OT-VA vs. nOT-VA,p=0.91). Our data confirm that the prevalence of an underlying SHD substrate is lower in athletes with OT-VA than in athletes with nOT-VA, and that all major adverse cardiac events occurred in athletes with polymorphic VAs. Nevertheless, a comprehensive workup with liberal use of cardiac magnetic resonance allowed the identification of SHD in a substantial minority of athletes with OT-VA, with clear implications for sports eligibility assessment.

Comparison of his bundle pacing versus biventricular pacing in heart failure: a systematic review and meta-analysis

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Despite optimal medical treatment, the 5-years mortality and HF readmission rate was 75.3% and 48.5%, respectively. The current guidelines recommended cardiac resynchronization therapy (CRT) by implanting biventricular pacing (BVP) for specific group of patients with HF with reduced ejection fraction (HFrEF) in order to reduce the mortality and the risk of HF events by 34%. However, 20% to 40% patients might not respond or even get clinical deterioration after receiving such device. To overcome the non-responders, His bundle pacing (HBP) emerges recently as one of the therapeutic options. His bundle pacing implantation potentially results in the narrower QRS duration as well as more improvement in left ventricle (LV) function compared with BVP in patients with LBBB. On top of that, HBP might become a more cost-effective solution, compared to CRT, particularly for the majority of developing countries in Asia. Purpose We aim to elaborate the clinical efficacy of HBP in specific patients with HF, compared to BVP. This HBP was implanted either as a primary therapeutic strategy for CRT candidates or as a rescue strategy for BVP non-responders. Methods This study is registered. A structured search was conducted in Pubmed, Embase, and Clinicaltrial.gov. Inclusion criteria were: Age &amp;gt;18 years old, NYHA II-IV, QRS duration ≥120 milliseconds, and left (LBBB) or right bundle branch block (RBBB) morphology. The primary endpoints were change in QRS duration, improvement in LVEF, improvement in NYHA class, and cardiovascular (CV) event. Results A total of 8 final articles involving 361 HF patients were included for analysis, with a male preponderance. The QRS duration was significantly narrower in HBP (MD: -23.44; 95%CI -34.92 to -11.97; P&amp;lt;0.001) compared to BVP. There was no statistically significant LVEF improvement between HBP group and BVP group in HF patients who were CRT candidates (MD: 4.63; 95%CI -4.47 to 13.74; P=0.32). The improvement in NYHA class varied between studies. One study reported comparable improvement between HBP and BVP, while another study reported better improvement in HBP compared to BVP. In terms of CV outcome, there was no significant difference in CV hospitalization and mortality rate. Heart failure hospitalization occurred both in HBP and BVP group, but the difference was not significant between groups. Improvement in QRS duration, LVEF, and NYHA class occurred in both LBBB and RBBB. Conclusion(s) HBP provides better electrical resynchronization compared to BVP. Additionally, some degree of reverse LV remodelling was also observed in HBP group of patients with either LBBB and RBBB patterns. However, the benefits of HBP in reducing HF hospitalization and CV mortality remain indeterminate. Further RCTs with large samples are still required to evaluate the superiority of HBP, compared to BVP for CRT, in reducing mortality and HF hospitalization.

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure