Atrioventricular Conduction Research Articles

Transient Atrioventricular Conduction Disturbance During Vein of Marshall Alcohol Ablation

Transient Atrioventricular Conduction Disturbance During Vein of Marshall Alcohol Ablation

Increased interleukin-6 levels are associated with atrioventricular conduction delay in severe COVID-19 patients.

Severely ill patients with coronavirus disease 2019 (COVID-19) show an increased risk of new-onset atrioventricular blocks (AVBs), associated with high rates of short-term mortality. Recent data suggest that the uncontrolled inflammatory activation observed in these patients, specifically interleukin (IL)-6 elevation, may play an important pathogenic role by directly affecting cardiac electrophysiology. The aim of our study was to assess the acute impact of IL-6 changes on electrocardiographic indices of atrioventricular conduction in severe COVID-19. We investigated (1) the behavior of PR-interval and PR-segment in patients with severe COVID-19 during active phase and recovery, and (2) their association with circulating IL-6 levels over time. During active disease, COVID-19 patients showed a significant increase of PR-interval and PR-segment. Such atrioventricular delay was transient as these parameters rapidly normalized during recovery. PR-indices significantly correlated with circulating IL-6 levels over time. All these changes and correlations persisted also in the absence of laboratory signs of cardiac strain/injury or concomitant treatment with PR-prolonging drugs, repurposed or not. Our study provides evidence that in patients with severe COVID-19 and high-grade systemic inflammation, IL-6 elevation is associated with a significant delay of atrioventricular conduction, independent of concomitant confounding factors. While transient, such alterations may enhance the risk of severe AVB and associated short-term mortality. Our data provide further support to current anti-inflammatory strategies for severe COVID-19, including IL-6 antagonists.

Novel insight into atrioventricular node conduction.

Novel insight into atrioventricular node conduction.

Effect of Maternal Ursodeoxycholic Acid Treatment on Fetal Atrioventricular Conduction in Patients with Intrahepatic Cholestasis of Pregnancy.

The aim of this study was, first, to investigate the difference in fetal atrioventricular conduction in patients with and without intrahepatic cholestasis of pregnancy (ICP) by measuring the fetal PR interval; second, to evaluate the altering effect of ursodeoxycholic acid (UDCA) treatment on the fetal PR interval in ICP patients. The study consisted of 42 ICP patients and 48 healthy pregnant women. Fetal echocardiography was performed to measure the mechanical PR interval. The fetal PR interval and the clinical characteristics were compared between the two groups. The effect of UDCA treatment on the fetal PR interval in ICP patients was evaluated. In ICP patients, significantly longer fetal PR intervals were observed than in the control group (123.21 ± 8.54 vs. 115.13 ± 5.95 ms, p < 0.001). In the ICP group, there was a positive correlation between the fetal PR interval and maternal fasting total bile acid (TBA) levels (r = 0.514, p = 0.001). After 1 week of treatment with UDCA in patients with ICP, the PR interval was shorter than before, although the reduction was not statistically significant (120.98 ± 6.70 vs. 123.21 ± 8.54 ms, p = 0.095). In patients with severe ICP (TBA >40 mmol/L, n = 10), a significant reduction in the fetal PR interval was observed after treatment with UDCA (127.5 ms [IQR, 118.0-134.75] before vs. 122 ms [IQR, 109.5-126.5] after, p = 0.037). Fetal PR interval increased in ICP patients in correlation with maternal serum TBA concentration. Treatment with UDCA may have limited positive effects on the fetal AV conduction system. The beneficial effects of UDCA on the fetal PR interval may be more pronounced in patients with higher bile acid levels.

Cardiac Manifestations in Inherited Metabolic Diseases.

Inherited metabolic diseases (IMDs) stem from genetic defects affecting enzyme function within specific metabolic pathways, collectively constituting rare conditions with an incidence of less than 1/100,000 births. While IMDs typically manifest with multisystemic symptoms, cardiac manifestations are common, notably hypertrophic cardiomyopathy. Additionally, they can lead to dilated or restrictive cardiomyopathy, as well as noncompacted left ventricular cardiomyopathy. Rhythm disturbances such as atrioventricular conduction abnormalities, Wolff-Parkinson-White syndrome, and ventricular arrhythmias, along with valvular pathologies and ischemic coronary issues, are also prevalent. This study aims to provide a narrative review of IMDs associated with cardiac involvement, delineating the specific cardiac manifestations of each disorder alongside systemic symptoms pivotal for diagnosis.

Biallelic variants in POPDC2 cause a novel autosomal recessive syndrome presenting with cardiac conduction defects and variable hypertrophic cardiomyopathy.

ABSTRACTPOPDC2encodes for the Popeye domain-containing protein 2 which has an important role in cardiac pacemaking and conduction, due in part to its cAMP-dependent binding and regulation of TREK-1 potassium channels. Loss ofPopdc2in mice results in sinus pauses and bradycardia and morpholino knockdown ofpopdc2 inzebrafish results in atrioventricular (AV) block. We identified bi-allelic variants inPOPDC2in 4 families that presented with a phenotypic spectrum consisting of sinus node dysfunction, AV conduction defects and hypertrophic cardiomyopathy. Using homology modelling we show that the identifiedPOPDC2variants are predicted to diminish the ability of POPDC2 to bind cAMP. Inin vitroelectrophysiological studies we demonstrated that, while co-expression of wild-type POPDC2 with TREK-1 increased TREK-1 current density, POPDC2 variants found in the patients failed to increase TREK-1 current density. While patient muscle biopsy did not show clear myopathic disease, it showed significant reduction of the expression of both POPDC1 and POPDC2, suggesting that stability and/or membrane trafficking of the POPDC1–POPDC2 complex is impaired by pathogenic variants in any of the two proteins. Single-cell RNA sequencing from human hearts demonstrated that co-expression of POPDC1 and 2 was most prevalent in AV node, AV node pacemaker and AV bundle cells. Sinoatrial node cells expressed POPDC2 abundantly, but expression of POPDC1 was sparse. Together, these results concur with predisposition to AV node disease in humans with loss-of-function variants inPOPDC1and POPDC2 and presence of sinus node disease inPOPDC2,but not inPOPDC1related disease in human. Using population-level genetic data of more than 1 million individuals we showed that none of the familial variants were associated with clinical outcomes in heterozygous state, suggesting that heterozygous family members are unlikely to develop clinical manifestations and therefore might not necessitate clinical follow-up. Our findings provide evidence forPOPDC2as the cause of a novel Mendelian autosomal recessive cardiac syndrome, consistent with previous work showing that mice and zebrafish deficient in functionalPOPDC2display sinus and AV node dysfunction.GRAPHICAL ABSTRACT

Assessment the Incidence of Inferior Wall Myocardial Infarction, its Association with Right Ventricular Infarction and Function and its Clinical Outcome

Introduction: Myocardial infarction is one of the most common diagnoses in hospitalized patients. Myocardial infarction was previously thought to be a disease of mainly the left ventricle. Right ventricular infarction was just a pathological entity. Myocardial infarction may go undetected or may lead to catastrophic events leading to sudden cardiac death or causing severe hemodynamic derangements. Objective: To find out the Assessment the incidence of Inferior Wall Myocardial Infarction, its association with right ventricular infarction and function and its clinical outcome. Methods: The hospital based observational cross-sectional study was contacted at Department of Cardiology, Mymensingh Medical College Hospital, Bangladesh from 1st January 2022 to 30th January 2024. Conducted in intensive care unit, on an in-patient basis, consist of 50 cases of inferior wall MI. In patients with RVMI, the hospital death is high and major complications are greater. Right ventricular infarction leads to hemodynamic instability, atrio-ventricular conduction blocks, and in-hospital mortality in patients with inferior wall myocardial infarction. Results: Out of the total 150 cases of acute MI were included. The incidence of IMI among all the cases of AMI was 33.3%. In our study group of IMI RVI incidence was 30%. So, the incidence of RVI in all cases of AMI was 10%. There is a significant association between IWMI and RVMI and RVMI is seen in about 20% of cases and most common complication encountered was hypotension followed by complete heart block. The mean age of participants was 58.33 and maximum number of patients was in the age group of 40-60 (43%) and consists of 80% males and 20% females. Among them 51.4% was hypertensive, 22.8% were diabetic, 74.3% smokers, 11.42% were alcoholics. In this study 58.33% of patients with RVMI and 2% of patients without RVMI were presented with hypotension at the time of admission. Complete heart block seen in 13.33% of IWMI patients and Hypotension seen in 20% IWMI patients RVMI group. Right ventricular myocardial infarction seen in 20% of IWMI cases and TR is seen 66% of patients of IWMI with RVMI and 4% of patients of IWMI without RVMI. Conclusion: The incidence of mortality and complications can be reduced only when we are fully aware of the diagnosis and the complications that can occur in RVI. So, in all cases of IMI, RVI should be looked for by using simple and specific investigation like RPLs of ECG. Involvement of the right ventricle in inferior wall myocardial infarction significantly affects the mortality and morbidity and complications.

Predictive factors of atrioventricular conduction disorders

Atrioventricular conduction disorders represent an alteration in the normal function of the heart’s electrical conduction system, a system that connects the atria and ventricles through the atrio-ventricular node and the His-Purkinje system. Consequently, bradycardia can develop and lead to the occurrence of symptoms (dizziness, loss of consciousness, tachyarrhythmias, heart failure phenomena). Identifying patients at risk of developing atrioventricular conduction disorders will allow early interventions on risk factors and improvements in prognosis. This narrative review explores the risk factors that determine the development and progression of atrioventricular conduction disorders. We will discuss traditional risk factors (age, sex, arterial hypertension, ischemic cardiac disease, diabetes, chronic kidney disease), but also risk factors that are currently being researched (genetic predisposition and inflammatory markers). Finally, we will discuss the limitations and challenges of predicting risk factors for atrioventricular conduction disorders.

Fasciculoventricular accessory pathway masked extensive atrioventricular conduction system disease in a patient with PRKAG2 syndrome

Fasciculoventricular accessory pathway masked extensive atrioventricular conduction system disease in a patient with PRKAG2 syndrome

ALSTER-TAVR 2024: clinical results at one year following optimized self-expanding, transcatheter aortic valve peplacement employing the cusp-overlay technique.

Atrioventricular (AV) conduction disturbances are still common following transcatheter aortic valve replacement (TAVR). The study evaluates the feasibility and clinical effect of self-expanding (SE)-TAVR employing an optimized cusp-overlay technique (COT) at 1 year in a German all-comers population. We analyzed 1-year clinical outcomes in patients who received a SE valve employing the optimized COT. Consecutive patients who underwent SE-TAVR (EvolutR, EvolutPRO) after introduction of the COT as the default implantation technique in 2020 were included (n = 101). Consecutive TAVR patients from the same operators using the conventional implantation technique (CIT) served as the control group (n = 116). The COT was successfully performed in more than 80% of the patients in the COT group. (81.2%, n = 82/101). At discharge, no difference regarding AV block of at least II (CIT 19.47% vs COT 21%; P = .86) and permanent pacemaker (PPM) implantation (CIT 17.5% vs COT 19%; P = .73) was observed between the cohorts. New left bundle branch block (LBBB) was significantly less frequent in the COT group (CIT 40.71% vs COT 26%; P = .029). Paravalvular leakage (PVL) greater than I° was reduced in the COT cohort (CIT 8.62% vs COT 0.99%; P = .012). There was no significant difference in mortality (CIT 18.27% vs COT 13.83%; P = .44), stroke (CIT 9.62% vs COT 15.96%; P = .16) or cardiovascular rehospitalization after 1 year (CIT 25.96% vs 24.47%; P = .92) between the groups. Implementation of COT-TAVR was feasible and safe, and it resulted in an improvement of TAVR outcomes regarding PVL greater than I° and new onset LBBB. However, with respect to PPM, no difference was observed 1-year post-TAVR.

Should Physicians Be Aware of Rhythm Disturbances in Adults with Systemic Autoimmune Diseases and Anti-Ro52 Antibodies? A Cross-Sectional Study.

Objectives: The association between anti-Ro/SSA antibodies and the appearance of cardiac rhythm disorders in adults is discussed. We aim to study this relationship, together with active treatments and comorbidities, and its impact on daily clinical practice in adults with systemic autoimmune diseases (SADs). Methods: This cross-sectional single-center study was conducted in a tertiary hospital between January 2021 and March 2022. A sample of adult patients followed up in the SAD Unit with a diagnosis of a SAD and previously tested for anti-Ro/SSA and anti-La/SSB were recruited. All of them underwent a 12-lead electrocardiogram. Results: 167 patients were included. 90 (53.9%) were positive for anti-Ro60, 101 (60.5%) for anti-Ro52, and 45 (26.9%) for anti-La/SSB; 52 (31.3%) were triple-negative. 84% were women, and the mean age was 59 years (standard deviation 12.8). The most common SAD was primary Sjögren's syndrome (34.8%), followed by systemic lupus erythematosus (24.6%) and rheumatoid arthritis (22.8%). A statistically significant relationship was found between anti-Ro52 positivity and cardiac rhythm disorders (relative risk = 2.007 [1.197-3.366]), specifically QTc prolongation (relative risk = 4.248 [1.553-11.615]). Multivariate regressions showed a significant association, with diabetes mellitus being the most related comorbidity. The association between anti-Ro52 antibodies and atrioventricular conduction disorders was not significant. Conclusions: The presence of anti-Ro52 antibodies in adult patients with SADs is associated with an increased risk of QTc prolongation. Electrocardiographic screening of patients with SAD, anti-Ro52 antibodies, and other risk factors, like diabetes mellitus or QT-prolonging drugs, seems advisable. Those with baseline electrocardiogram abnormalities or additional risk factors should undergo electrocardiographic monitoring.

A GABAergic system in atrioventricular node pacemaker cells controls electrical conduction between the atria and ventricles

Physiologically, the atria contract first, followed by the ventricles, which is the prerequisite for normal blood circulation. The above phenomenon of atrioventricular sequential contraction results from the characteristically slow conduction of electrical excitation of the atrioventricular node (AVN) between the atria and the ventricles. However, it is not clear what controls the conduction of electrical excitation within AVNs. Here, we find that AVN pacemaker cells (AVNPCs) possess an intact intrinsic GABAergic system, which plays a key role in electrical conduction from the atria to the ventricles. First, along with the discovery of abundant GABA-containing vesicles under the surface membranes of AVNPCs, key elements of the GABAergic system, including GABA metabolic enzymes, GABA receptors, and GABA transporters, were identified in AVNPCs. Second, GABA synchronously elicited GABA-gated currents in AVNPCs, which significantly weakened the excitability of AVNPCs. Third, the key molecular elements of the GABAergic system markedly modulated the conductivity of electrical excitation in the AVN. Fourth, GABAA receptor deficiency in AVNPCs accelerated atrioventricular conduction, which impaired the AVN’s protective potential against rapid ventricular frequency responses, increased susceptibility to lethal ventricular arrhythmias, and decreased the cardiac contractile function. Finally, interventions targeting the GABAergic system effectively prevented the occurrence and development of atrioventricular block. In summary, the endogenous GABAergic system in AVNPCs determines the slow conduction of electrical excitation within AVNs, thereby ensuring sequential atrioventricular contraction. The endogenous GABAergic system shows promise as a novel intervention target for cardiac arrhythmias.

Computational study of transcatheter aortic valve replacement based on patient-specific models-rapid surgical planning for self-expanding valves.

Transcatheter aortic valve replacement (TAVR) is a minimally invasive interventional solution for treating aortic stenosis. The complex post-TAVR complications are associated with the type of valve implanted and the position of the implantation. The study aimed to establish a rapid numerical research method for TAVR to assess the performance differences of self-expanding valves released at various positions. It also aimed to calculate the risks of postoperative paravalvular leak and atrioventricular conduction block, comparing these risks to clinical outcomes to verify the method's effectiveness and accuracy. Based on medical images, six cases were established, including the aortic wall, native valve and calcification; one with a bicuspid aortic valve and five with tricuspid aortic valves. The parameters for the stent materials used by the patients were customized. High strain in the contact area between the stent and the valve annulus may lead to atrioventricular conduction block. Postoperatively, the self-expanding valve maintained a circular cross-section, reducing the risk of paravalvular leak and demonstrating favorable hemodynamic characteristics, consistent with clinical observations. The outcomes of the six simulations showed no significant difference in valve frame morphology or paravalvular leak risk compared to clinical results, thereby validating the numerical simulation process proposed for quickly selecting valve models and optimal release positions, aiding in TAVR preoperative planning based on patients'geometric characteristics.

Complementary use of conduction system pacing techniques for the “pace and ablate” strategy in permanent atrial fibrillation - a case report

Abstract Introduction The feasibility of the conduction system pacing combined with atrioventricular node ablation was demonstrated in patients with atrial fibrillation in whom rate control can’t be achieved with medication and heart failure. Clinical case We present a case of an 82-year-old man with a personal history of permanent atrial fibrillation, admitted with symptoms of heart failure. The resting electrocardiogram showed a very fast ventricular response, and the echocardiography showed a depressed left ventricular function, raising the suspicion of a tachycardia-mediated cardiomyopathy. Since the patient was on maximum doses of atrioventricular nodal-blocking drugs, we opted for a physiological pacing and atrioventricular node ablation strategy. First, the His bundle capture was achieved at low pacing thresholds, and ablation of the atrioventricular node was attempted. Unfortunately, after several failed attempts, an acute increase in the His bundle capture threshold was noted, suggesting inadvertent tissue ablation beneath the pacing lead. In this scenario, we removed the lead from the His bundle area and achieved optimal left bundle branch area pacing. With the lead in this position, atrioventricular node ablation was performed during the first attempt. At the six-month follow-up, there was no recovery of atrioventricular node conduction. Device interrogation revealed stable pacing and sensing parameters, and there was a significant improvement in clinical status and left ventricular function. Conclusions Mastering both His bundle pacing and left bundle branch area pacing offers the potential to overcome intraprocedural challenges, giving alternative strategies to achieve physiological pacing. These approaches can be used interchangeably based on the evolving dynamics of the procedure and the patient’s specific needs.

Nurses’ Knowledge and Attitudes toward Pacemaker: A Cross-Sectional Study

Despite the critical role of pacemakers in managing symptomatic atrioventricular and ventricular conduction abnormalities, there remains a significant gap in the knowledge and attitudes of nurses towards these devices. This study assesses the understanding and perceptions of pacemakers among nurses in Al-Basrah Governorate hospitals, exploring associations with demographic factors such as age, gender, educational level, years of experience, and training. Employing a descriptive methodology, a non-probability sample of 200 nurses from five hospitals (Abi Al-Khasib General Hospital, Umm Qasr General Hospital, Al-Zubair General Hospital, Al-Shifaa Hospital, and Al-Mawani Teaching Hospital) was surveyed from October 15, 2022, to August 15, 2023. Content validity was ensured by engaging eleven professionals, while reliability was assessed using Cronbach's Alpha. Results indicate a concerning deficiency in pacemaker-related knowledge, with 79.5% of nurses demonstrating poor knowledge, 18% showing intermediate knowledge, and only 2.5% exhibiting high knowledge. Similarly, attitudes were predominantly negative, with 81.5% of nurses expressing low enthusiasm towards pacemakers, while 11% and 7.5% displayed intermediate and high attitudes, respectively. These findings highlight the need for targeted educational interventions aimed at enhancing nurses' competence and attitudes concerning pacemakers to improve postoperative care and management outcomes for patients with these devices. Highlights: Knowledge Gap: A significant 79.5% of nurses show insufficient knowledge of pacemakers, indicating a critical need for improved medical education. Attitudinal Barriers: Over 81% of nurses have negative attitudes towards pacemakers, which may affect patient care quality. Training Requirement: There's a clear need for specialized training programs for nurses on pacemakers to enhance their knowledge and attitudes, ultimately improving patient care. Keywords: Pacemaker Knowledge, Nursing Attitudes, Educational Interventions

LEFT BUNDLE BRANCH AREA PACING IN COMPLETE ATRIOVENTRICULAR BLOCK DUE TO LYME CARDITIS

Lyme disease, also known as Lyme borreliosis, is caused by Borrelia bacteria. In Europe, 0.3–4% of untreated cases end up with cardiovascular complications known as Lyme carditis which are often associated with atrioventricular conduction disorders. We present the case of a 26-year-old male who was diagnosed with a complete atrioventricular block in the course of Lyme carditis. After a full course of antibiotic therapy, the block did not resolve, so the patient was qualified for permanent pacing. In the course of the procedure, the left bundle branch area pacing was achieved with no early or long-term complications. This is the first reported case of a left bundle branch area pacing in the atrioventricular complete block due to Lyme carditis.

Comparative analysis of classical artificial intelligence and deep learning models for atrial fibrillation detection in electrocardiograms

Abstract Background/Introduction Early diagnosis of atrial fibrillation (AF) presents a challenging yet critical task for appropriate interventions aimed at reducing disease-related burden. In this context, strategies employing classical artificial intelligence (CAI) and deep learning (DL) have emerged as promising approaches to optimize cardiac disorder screening and detection. Purpose This study aimed to compare a CAI model and a DL model for the detection of AF in patients undergoing electrocardiographic (ECG) examinations in tertiary healthcare centers. Methods Between December 2022 and November 2023, a total of 135,476 ECGs were performed, comprising 5,067 with AF and 130,409 without AF. The ECGs were analyzed using both artificial intelligence models. The obtained results were then compared to the gold standard (cardiologist's report). In the CAI model, signals were extracted from ECG images, analyzing five key parameters: cardiac rhythm, atrial depolarization, atrioventricular conduction, ventricular depolarization, and ventricular repolarization (figure 1A). These parameters were benchmarked against the standard values from the Brazilian Society of Cardiology guidelines for detecting cardiac anomalies. Conversely, the DL model utilized a one-dimensional ResNet-based Convolutional Neural Network (CNN). This model was trained using ADAM optimization and binary cross-entropy loss, enabling the learning of complex patterns in the data (figure 1B). Results The mean age was 54.6 years (71.9 years with AF and 53.9 without AF). In the AF population, 52.2% were male (46% were male in the overall sample). In the analysis conducted, the CAI model showed a sensitivity and specificity of 90% and 62%, respectively, while the DL model had 90% and 69%, respectively. ROC curves were generated for both models, demonstrating the superior performance of the DL model (figure 2A). Conclusions Although the sensitivity remained similar between the models, the DL model distinguished itself with higher specificity. These results suggest that artificial intelligence, particularly the deep learning approach, holds promise as a supportive resource in AF diagnosis. However, further studies are needed to evaluate the models more thoroughly and determine their clinical applicability in a broader context.Artificial intelligence modelsROC curves

Real life experience with point by point pulsed field ablation for recurrent ventricular arrhythmias

Abstract Introduction The safety and effectiveness of electroporation/point by point pulsed field ablation (PP PFA) as emerging technoloy for catheter ablation (CA) of ventricular arrhythmias (VAs) has been described till now only in case reports. Purpose The aim of this observational retrospective study is to present real life data concerning the overall performance of PP PFA for CA of recurrent VA. Methods A total number of 13 consecutive patients (11 VTs and 2 PVCs), in whom recurrent VTs after RF ablation documented, were included. In all patients the substrate location was documented beforehand based on cardiac MRI or CT with myocardial thinning. For substrate mapping a high resolution multipoint mapping catheter was used. A complete success was defined as non inducibility of any arrhythmia at the end of procedure respectively lack of VA recurrence at follow – up. Results Excepting 2 patients, all other had a non ischemic cardiomyopathy as underlying heart disease (mean age 63 ± 8 y/o, mean LVEF 42 % ± 9 %). In every patient at least one conventional RF CA has been performed previously (mean 2 ± 1) and 38 % of patients had a previous epicardial RF VT ablation. The PP PFA VT ablation was performed endocardialy in 11 patients (84 %), respectively epicardialy in 2 patients. The ablation sites had a septal location in 53 % of patients and other localisation in 47 % of patients. The applied energy was 25 A. The overall acute complete success was achieved in 77 % patients. At medium 6 ± 3 months follow up a complete success was present in 46 % cases. Most frequently a VT recurrence after PP PFA ablation was encountered in patients with combined septal and nonseptal substrate distrubution. After PP PFA, the RF CA strategy due to recurrent VAs was endocardial in 2 patients, respectively epicardial 2 in cases and bipolar in 1 case. No PP PFA redos were undergone. Three major complications have been documented (1 tamponade, 1 AV block III° and 1 complete LBBB). Conclusion As bailout strategy in patients with failed conventional CA, PP PFA represents a safe strategy. Specific complications like temporary atrioventricular or intraventricular conduction disturbancies are extremely rare, reversible but not life threathening. The midterm success is satisfactory but still limited in patients with intramural substrate.

Effectiveness of dynamic atrioventricular optimization during patient exercise in cardiac resynchronization therapy

Abstract Background Cardiac resynchronization therapy (CRT) is considered the standard treatment for patients with heart failure and prolonged QRS duration. Recent studies suggest that atrioventricular delay (AVD) optimization can play a key role in QRS narrowing, thus improving CRT outcomes. For this purpose, device-based algorithms have been developed. In particular, the SyncAV algorithm continuously monitors the patient’s intrinsic AVD and dynamically adjusts the pacing AVD to allow fusion of the left ventricle pacing with intrinsic right ventricle depolarization. SyncAV optimization is usually performed in a single patient condition, i.e. at rest, and in a single operating scenario of the device, i.e. during atrial sensing. Purpose This study aims to compare QRS narrowing after AVD optimization using SyncAV in CRT-treated patients at rest, during moderate exertion, and during an increase in the atrial pacing rate. Methods This is a prospective, non-randomized, non-blinded, multicenter study. The study population consisted of patients in sinus rhythm, PR interval < 350 ms, and rest ventricular rate < 100 bpm. Within one month from the implant, patients were assessed for AVD optimization with SyncAV, selecting the offset (i.e. 10 to 40% AVD) that resulted in the shortest QRS duration (QRSd). Subsequently, patients performed moderate physical activity using a bicycle ergo-meter while a surface ECG was collected. QRSd was assessed once patients achieved a heart rate over 20 bpm to baseline heart rate, up to 100 bpm. Finally, QRSd narrowing was evaluated during a programmed increase in atrial pacing (i.e. >20 bpm of baseline atrial rate). Results Nine patients were treated with CRT and enrolled (age 67,3 ± 13,2 years; 66% male; LV ejection fraction 33,7±2,9 %; intrinsic QRSd 155,6 ± 12,7 ms) with intact atrioventricular conduction (PR interval 170,6±25,8 ms). The median SyncAV offset that provided the best QRSd reduction was 20 % (10 - 35%). Intrinsic QRSd was reduced to 132,7 ± 10,0 ms (-14,2±9,4%) with standard biventricular pacing and to 122,0 ± 11,2 ms (-21,2±8,5%) with SyncAV optimization. During exercise the mean heart rate was 88,1 bpm, the QRSd was reduced to 132,7 ± 10,0 ms (-14,2±9,4%) with standard biventricular pacing and to 124,9 ± 14,9 ms (-19,3±10,8 %) with SyncAV optimization. The mean heart rate during atrial pacing was 90 bpm with paced QRSd of 126,0 ±13,9 ms (-18,9±7,3% from baseline) with SyncAV optimization and paced PR interval of 198,2±22,7ms. Conclusion We evaluated the effectiveness of SyncAV for AVD optimization in out-of-clinic. This study demonstrates the possibility of narrowing the QRSd using SyncAV at several activity levels. Nevertheless, a deeper evaluation is needed to confirm our findings, investigating the SyncAV role in a larger population of patients.

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<120 ms: 97±15 ms, QRS>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<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.