Atrioventricular Node Research Articles

Cardioneuroablation for pediatric patients with functional sinus node dysfunction and paroxysmal atrioventricular block.

Severe transitory episodes of bradycardia with subsequent syncope in children are common, and generally portend a benign prognosis. Rarely, patients may experience prolonged asystolic episodes secondary to significant sinus pauses (SP)or paroxysmal atrioventricular block (AVB).Cardioneuroablation (CNA)is a catheter-based intervention, used to identify and ablate the epicardial ganglionated plexi (GP),which results in disruption of the vagal-mediated parasympathetic input to the sinus and atrioventricular node. Describe the methodology and role of CNA for treatment of pediatric patients with functional AVB or SP. This is a single-center, case series study. Patients with SP or AVB, 21 years of age or younger, who underwent CNA between 2015 and 2021 were included. CNA was performed via anatomically guided and high-frequency stimulation methods. Six patients were included. The median age was 18.9 years (range 12.3-20.9 years), 33% female. Two patients had prolonged SP, two had paroxysmal AVB, and two had both SP and AVB. Four patients had prior syncope. The median longest pause was 8.9 s (range 3.9-16.8) with 11 total documented pauses (range 2-231) during the 6 months pre-CNA. Post-CNA,the median longest pause was 1.3 s (range 0.8-2.2) with one documented SP after termination of atrial tachycardia at the 3-month follow-up. At 6 months, the median longest pause was 1.1 s (0.8-1.3) with 0 documented pauses. No patients had syncope post-CNA. CNAmay be an effective alternative to pacemaker implantation in pediatric patients with syncope or significant symptoms secondary to functional SP or AVB.

Hibernation of the Conduction System and Atrioventricular Block Reversibility Following Revascularization in Patients without Acute Coronary Syndrome.

Although myocardial infarction (MI) is a reversible cause of atrioventricular (AV) block, the association of ischemia other than MI with AV block is unclear. The purpose of this study is to investigate this relationship. Among patients nominated for pacemaker implantation due to AV block in two centers from 2017-2020, 120 patients with significant coronary artery disease (CAD) in angiography were included in the study. Patients were divided into two equal groups based on their CAD treatment approach: drug therapy and revascularization. Coronary lesions were divided into three types based on location: left anterior descending artery (type 1), dominant coronary with AV node branch (type 2), and a combination of both (type 3). After coronary disease treatment, all patients were followed up with for 14 months, and AV block reversibility was assessed. There were 7 cases of block reversibility in the revascularization group (11.7%) and 1 case in the medical group (1.7%), which differed significantly (P = .02). A history of acute coronary syndrome, smoking, opium use, chronic kidney disease, hypertension, age, sex, and chronic obstructive pulmonary disease were not significantly associated with reversible block. Also, the type of coronary obstruction had no significant relationship with block reversibility (P = .3, .5, and .8 for type 1, type 2, and type 3, respectively). Hibernation due to ischemia can be a reversible cause of an AV blockage. Therefore, it is recommended that significant coronary artery lesions be revascularized before pacemaker implantation.

Withdrawal Of Atrioventricular Nodal Blocking Agents in Patients Receiving Mavacamten: A Retrospective Single-Center Experience in A Predominantly Asian-American Cohort

Withdrawal Of Atrioventricular Nodal Blocking Agents in Patients Receiving Mavacamten: A Retrospective Single-Center Experience in A Predominantly Asian-American Cohort

Conversion to Sinus Rhythm in Refractory Atrial Fibrillation Patients after Atrioventricular Node Ablation with Conduction System Pacing.

"Ablate and pace" strategy is a reasonable treatment option in refractory atrial fibrillation (AF) when sinus rhythm (SR) cannot be achieved with catheter ablation or pharmacological therapy. Atrioventricular node ablation (AVNA) combined with conduction system pacing (CSP), with left bundle branch pacing (LBBP) or His bundle pacing (HBP), is gaining recognition since it offers the most physiological activation of the left ventricle. However, the incidence of conversion to SR after AVNA with CSP is not known. The purpose of the investigation was to determine the incidence of spontaneous conversion to SR and its predicting factors in patients undergoing CSP and AVNA. Consecutive refractory symptomatic AF patients undergoing AVNA with CSP at our institution between June 2018 and December 2022 were retrospectively analyzed. Twelve lead electrocardiogram (ECG) recordings were analyzed at each outpatient follow-up visit. Echocardiographic and clinical parameters were assessed at baseline and six months after the implantation. Sixty-eight patients (male 42.6%, age 71 8 years, left ventricular ejection fraction 40 15%) were included. Thirty-seven patients (54.4%) received HBP and 31 (45.6%) LBBP. During follow-up, spontaneous conversion to SR was registered in 6 patients (8.8%); 3 in the HBP group and 3 in the LBBP group. Baseline characteristics of patients who converted to SR did not differ from non-sinus rhythm (NSR) patients except for left atrial volume index (LAVI), which was significantly smaller in the SR group (45 mL/ (41-51) vs. 60 mL/ (52-75); p = 0.002). Multiple regression model confirmed an inverse association between LAVI and conversion to SR even after considering other clinically relevant covariates (odds ratio 1.273, p = 0.028). At follow-up, LAVI did not change in any group (SR: p = 0.345; NSR: p = 0.508). Improvement in New York Heart Association (NYHA) class was comparable in both groups. Spontaneous conversion to SR after AVNA combined with CSP is not uncommon, especially in patients with smaller left atria. Further studies are warranted to clarify which patients should be considered for initial dual-chamber device implantation to provide atrio-ventricular synchrony in case of SR restoration.

Pharmacotherapy of Wolff-Parkinson-White (WPW): A Review for Nurse Practitioners

Wolff-Parkinson-White (WPW) is a congenital condition where patients have ≥1 accessory pathways with the ability to bypass the atrioventricular node and cause ventricular preexcitation. These patients are at increased risk of arrhythmia and sudden cardiac death. Atrial fibrillation is a potentially fatal form of arrhythmia. In patients with WPW, atrial fibrillation can degenerate to ventricular fibrillation. This report provides acute care nurse practitioners with an updated outline of the diagnostic criteria for WPW and sheds some light on its pharmacotherapy.

Diagnostic accuracy of Apple Watch Series 6 recorded single-lead ECGs for identifying supraventricular tachyarrhythmias: a comparative analysis with invasive electrophysiological study.

The advancements in wearable technology have made the detection of arrhythmias more accessible. While smartwatches are commonly used to detect patients with atrial fibrillation, their effectiveness in the differential diagnosis of supraventricular tachycardias (SVT) lacks consensus. A study was conducted on 47 patients with documented SVTs on a 12-lead ECG. All patients in the cohort underwent electrophysiology study with induction of SVT. A 6th generation Apple Watch was used to record ECG tracings during baseline sinus rhythm and during induced SVT. Cardiology residents and attending cardiologists evaluated these recordings to diagnose the differential diagnosis of SVT. The evaluation revealed 27 cases of typical atrioventricular nodal reentrant tachycardia (AVNRT), 11 cases of atrioventricular reentrant tachycardia (AVRT), and 9 cases of atrial tachycardia/atrial flutter (AT/AFL) among the induced tachycardias. Attending physicians achieved an accuracy of 66.0 to 76.6%, and residents demonstrated accuracy rates between 68.1 and 74.5%. Interrater reliability was assessed using Fleiss's Kappa method, resulting in a moderate level of agreement between residents (Kappa = 0.465, p < 0.001, 95% CI 0.30-0.63) and attendings (Kappa = 0.519, p < 0.001, 95% CI 0.35-0.68). The overall Kappa value was 0.417 (p < 0.001, 95% CI 0.34-0.49). Smartwatch recordings demonstrate moderate feasibility in diagnosing SVT when following a pre-specified algorithm. However, this diagnostic performance was lower than the accuracy obtained from 12-lead ECG tracings when blinded to procedure outcomes.

Muscarinic acetylcholine receptors M2 are upregulated in the atrioventricular nodal tract in horses with a high burden of second-degree atrioventricular block.

Second-degree atrioventricular (AV) block at rest is very common in horses. The underlying molecular mechanisms are unexplored, but commonly attributed to high vagal tone. To assess whether AV block in horses is due to altered expression of the effectors of vagal signalling in the AV node, with specific emphasis on the muscarinic acetylcholine receptor (M2) and the G protein-gated inwardly rectifying K+ (GIRK4) channel that mediates the cardiac IK,ACh current. Eighteen horses with a low burden of second-degree AV block (median 8 block per 20 h, IQR: 32 per 20 h) were assigned to the control group, while 17 horses with a high burden of second-degree AV block (median: 408 block per 20 h, IQR: 1,436 per 20 h) were assigned to the AV block group. Radiotelemetry ECG recordings were performed to assess PR interval and incidence of second-degree AV block episodes at baseline and on pharmacological blockade of the autonomic nervous system (ANS). Wenckebach cycle length was measured by intracardiac pacing (n = 16). Furthermore, the expression levels of the M2 receptor and the GIRK4 subunit of the IKACh channel were quantified in biopsies from the right atrium, the AV node and right ventricle using immunohistochemistry and machine learning-based automated segmentation analysis (n = 9 + 9). The AV block group had a significantly longer PR interval (mean ± SD, 0.40 ± 0.05 s; p < 0.001) and a longer Wenckebach cycle length (mean ± SD, 995 ± 86 ms; p = 0.007) at baseline. After blocking the ANS, all second-degree AV block episodes were abolished, and the difference in PR interval disappered (p = 0.80). The AV block group had significantly higher expression of the M2 receptor (p = 0.02), but not the GIRK4 (p = 0.25) in the AV node compared to the control group. Both M2 and GIRK4 were highly expressed in the AV node and less expressed in the atria and the ventricles. Here, we demonstrate the involvement of the m2R-IK,ACh pathway in underlying second-degree AV block in horses. The high expression level of the M2 receptor may be responsible for the high burden of second-degree AV blocks seen in some horses.

Feasibility and Safety Study of Concomitant Left Bundle Branch Area Pacing and Atrioventricular Node Ablation with Same-Day Hospital Dismissal.

Left bundle branch area pacing (LBBAP) has rapidly emerged as a promising modality of physiologic pacing and has demonstrated excellent lead stability. In this retrospective study, we evaluate whether this pacing modality can allow concomitant atrioventricular node (AVN) ablation and same-day dismissal. Twenty-four consecutive patients (female 63%, male 37%) with an average age of 78 ± 5 years were admitted for pacemaker (75%)/defibrillator (25%) implantations and concomitant AVN ablation. Device implantation with LBBAP was performed first, followed by concomitant AVN ablation through left axillary vein access to allow for quicker post-procedure ambulation. The patients were discharged on the same day after satisfactory post-ambulation device checks. LBBAP was successful in 22 patients (92% in total, 20 patients had an LBBP and two patients had a likely LBBP), followed by AVN ablation from left axillary vein access (21/24, 88%). All patients had successful post-op chest x-rays, post-ambulation device checks, and were discharged on the same day. After a mean follow up of three months, no major complications occurred, such as LBBA lead dislodgement requiring a lead revision. The LBBA lead pacing parameters immediately after implantation vs. three-month follow up were a capture threshold of 0.8 ± 0.3 V@0.4 ms vs. 0.6 ± 0.3 V@0.4 ms, sensing 9.9 ± 3.9 mV vs. 10.4 ± 4.1 mV, and impedance of 710 ± 216 ohm vs. 544 ± 110 ohm. The QRS duration before and after AVN ablation was 117 ± 32 ms vs. 123 ± 14 ms. Mean LVEF before and three months after the implantation was 44 ± 14% vs. 46 ± 12%. LBBA pacing not only offers physiologic pacing, but also allows for a concomitant AVN ablation approach from the left axillary vein and safe same-day hospital dismissal.

Cardioneuroablation for symptomatic bradyarrhythmia: for whom it fails?

Abstract Background Cardioneuroablation (CNA) has been proposed as a new therapeutic approach in selected patients with symptomatic functional bradyarrhythmia including recurrent neurally-mediated syncope. Purpose In patients after CNA, we investigated the potential predictors of the recurrence of clinically significant bradyarrhythmia. Methods A retrospective study included 187 consecutive patients (age: 40±12 years; 57 % of males; predominant AV nodal phenotype of the disorder in 37 % of patients; post-atropine sinus rate acceleration by 72±31 %) who underwent their first CNA at our centre from 2014 to 2022 and were followed for the minimum of 3 months. Biatrial radiofrequency ablation was performed under general anaesthesia by irrigated-tip catheter at empirical sites of ganglionated plexi (GP) with the navigation by 3D electroanatomic mapping system and intracardiac echocardiography. Anterior right GP and posteromedial left GP were always targeted to modulate the innervation of both sinoatrial and atrioventricular nodes, irrespective of the clinical manifestation of the disease. The loss of responsiveness of both nodes to extracardiac vagus nerve stimulation (frequently bilateral) was the procedural endpoint. The association of baseline, procedural, and early follow-up characteristics with the recurrence of clinically significant bradyarrhythmia was analyzed. Results CNA with the procedural duration of 154±32 min and radiofrequency time of 14±7 min resulted acutely in sinus rate acceleration by 27±13 bpm, shortening of AH interval by 16±28 ms, an increase of Wenckebach point by 26±28 bpm, shortening of AV node effective refractory period by 114±128 ms, and sinus node recovery time by 462±867 ms. At the 3-month visit, the sinus rate was still significantly higher (83±14 bpm) than at baseline (61±13 bpm); with acceleration by 23±14 bpm. During a median follow up of 33 months (IQR: 18-48 months), recurrence of clinically significant bradyarrhythmia was documented in 18 (10 %) patients. Re-CNA was performed in 11 patients and was scheduled in 3 patients. In 6 (3 %) patients, a pacemaker was finally implanted. Compared to the rest of the population, patients with bradyarrhythmia recurrence were non-significantly younger (36±12 vs. 40±12 years, P=0.16) and had non-significantly less acceleration of sinus rate at the 3-month post-CNA visit (by 18±11 vs. 23±13 bpm, P=0.10) suggesting a trend to more pronounced reinnervation of the sinus node. Conclusion Long-term clinical efficacy of CNA is reasonably high. We did not identify practically useful predictors of CNA failure. This investigation was significantly limited by the low rate of clinical events.

High-power short-duration ablation of the atrioventricular node

Abstract Introduction There are limited studies that compare different radiofrequency ablation catheters in atrioventricular node (AVN) ablation. Our study compared the effectiveness of several radiofrequency ablation catheters in AVN ablation. Methods We identified patients who underwent AVN ablation at our institution. Data related to patients and procedures were collected through retrospective chart review. The radiofrequency catheters compared were plain non-irrigated, externally irrigated (EI), and contact force sensing in two different settings: low-power long duration (LPLD) and high-power short duration (HPSD). We compared the different catheters in terms of success rate using logistic regression and lesion time using linear regression. Results We identified 66 patients who underwent AVN ablation, out of which 31 were female (47%). The patients were elderly, with a mean age of 73.27 years. The indications were resistant atrial fibrillation in 74%, atrial flutter in 18%, and other atrial tachycardias in 8% of patients. Types of catheters used were plain non-irrigated in 48%, EI in 2%, LPLD in 16%, and HPSD in 34% of patients. All ablation procedures were successful with no immediate post-procedure complications. Regarding lesion time, HPSD was significantly shorter compared to plain catheters by 403.42s[-631.67, -175.17] as shown in table 1. Conclusions While plain catheter, LPLD, and HPSD were equally safe and effective, HPSD catheter had significantly shorter lesion time and thus procedure time.

Diffusion tensor imaging identifies atrial regional changes associated with atrial fibrillation remodelling

Abstract Background Structural remodeling in the context of persistent atrial fibrillation (PAF) has been mainly characterized by imaging techniques focused on fibrosis detection. Diffusion tensor imaging (DTI) has demonstrated its direct relationship with histological properties and myocyte organization, which may provide a more complete structural information. However, the potential of DTI in the characterization of the AF-related structural substrate remains unknown. Purposes To evaluate the performance of DTI-derived parameters to characterise the structural remodelling derived from persistent AF and its relationship with specific atrial regions associated with AF maintenance (i.e., driver regions). Methods Two experimental groups of pigs were studied: control (n=7) and PAF (n=10). The PAF swine model was developed using rapid atrial pacing until the animals reached a stage of self-sustained PAF. The AV node was ablated to prevent heart failure due to fast ventricular activation rates. A second lead in the right ventricular was used for ventricular pacing at 60-110 bpm. Animals with PAF were studied after ≥ 6 months in self-sustained persistent AF. AF animals underwent invasive electroanatomical to identify driver regions based on instantaneous frequency modulation maps. After euthanasia, explanted hearts from AF animals and controls underwent DTI including 15 diffusion weighted images with a b-value of 600 s/mm² plus a non-DWI volume (isotropic resolution, 0.6 mm³). DTI images were segmented and divided into 13 atrial anatomical regions. Driver regions in AF animals were also segmented and classified as functional regions of interest (ROIs) (Figure 2B). Afterwards, diffusion tensors were estimated and scalar features were analyzed (Figures 1A and 2A) according to both anatomical and functional ROIs. Results DTI analysis in AF animals revealed region-specific structural remodelling (Figure 1B). Compared to controls, PAF animals showed an increased fractional anisotropy (FA) in both right and left atrial free walls (Figure 1C). Other anatomical regions, such as the superior vena cava (SVC), the coronary sinus (CS) or the left atrium roof developed higher axial diffusivities in AF compared to controls (Figure 1D), without significant alterations in FA (Figure 1C). AF driver regions were frequently located in the CS, the SVC and the LAA (Figure 2C). AF driver ROIs into the CS and the SVC showed intracase increased diffusivities and decreased linear indexes compared to non-driver regions. However, AF driver ROIs in the LAA showed increased intervoxel main eigenvector dispersion in contrast to non-driver ROIs (Figure 2C). Conclusion DTI sequences provide atrial structural information associated with functional tissue properties relevant for AF maintenance.

Paradigm shift of catheter ablation of atypical atrioventricular nodal tachycardia: 3D mapping-based ablation of exits of slow pathway

Abstract Background In current practice, the ablation target of atypical atrioventricular nodal tachycardia (AVNRT) is the earliest atrial activation site in the coronary sinus (CS) or conventional slow pathway (SP) region. Objectives The purpose of this study was to map the site of earliest retrograde atrial activation using electroanatomic 3D mapping during atypical AVNRT and to evaluate successful ablation sites. Methods Forty-two patients with a total of 49 AVNRTs (slow/fast 30; fast/slow 15; slow/slow 4) underwent EP study and ablation. Among them there were 14 patients (10 women, 60±19 y/o) in whom 19 atypical AVNRT (fast/slow 15; slow/slow 4) were induced. Results The intracardiac electrocardiograms or 3D mapping of the exit site during tachycardia revealed that 7 patients had exit sites solely inside the CS (left inferior extension=LIE), 3 solely in the right postero-septal tricuspid annulus (TA) (right inferior extension=RIE), and 4 had both LIE and RIE exits. The distance from the CS ostium to LIE exits was 14±6 mm. RIE exits were located on the TA posterior to the CS ostium (between 5 and 6 o’clock in the LAO projection). Ablation targeting these exits or traditional SP succeeded in long term elimination of AVNRT in 13 of the 14 patients (93%). There were no complications. Conclusions Catheter ablation targeting the exit sites of LIE or RIE mapped at the CS or TA holds promise as an effective and safe alternative approach to the current targets of ablation for atypical AVNRT cases.Distribution of exit sites during atypicthe circuit of atypical AVNRT：the exit s

Duration of type 2 diabetes mellitus is associated with third-degree atrioventricular block - A Danish nationwide registry study

Abstract Introduction Type 2 diabetes mellitus (T2DM) is associated with third-degree atrioventricular block, but whether duration of T2DM is an important factor of the association is unknown. Aim To investigate the association between duration of T2DM and third-degree atrioventricular block. Method This nested case–control study, based on nation-wide Danish cohort registries, included patients older than 18 years, diagnosed with third-degree atrioventricular block between 1 July 1995 and 31 December 2018. Five controls, from the risk set of each case of third-degree atrioventricular block, were matched on age and sex to fit a conditional logistic regression with time-dependent exposure and time-dependent covariates. Duration of T2DM was split into four groups: 0–5 years, 6–10 years, 11–15 years, and &amp;gt;15 years. Results We included 24 177 cases with third-degree atrioventricular block who were matched 1:5 on sex and birth year with 120 915 controls without third-degree atrioventricular block. Median age was 73.8 years, 62% were males in both cases and controls, whereas 19% of cases and 9.7% of controls had T2DM respectively. After adjusting for atrioventricular nodal blocking agents and comorbidities known to be associated with third-degree atrioventricular block, patients with T2DM duration 0–5 years, 6–10 years, 11-15 years, and &amp;gt;15 years had a higher hazard ratio of third-degree atrioventricular block of 1.24 (95% CI 1.16-1.33), 1.41 (95% CI 1.31-1.52), 1.79 (95% CI 1.64-1.95), and 2.20 (95% CI 2.01-2.40), respectively, compared to patients with no T2DM (Figure 1). Conclusion This study shows a stepwise increase in the hazard ratio of third-degree atrioventricular block along with duration of T2DM, which is independent of atrioventricular nodal blocking agents and comorbidities known to be associated with third-degree atrioventricular block.Figure 1

Incidence and predictors of sudden cardiac arrest in cardiac amyloidosis: a 5-year retrospective analysis

Abstract Background Despite recent advances in treatment, cardiac amyloidosis (CA) portends a poor outcome. Clinical manifestations of CA are variable and often nonspecific, which makes the diagnosis challenging. Failure to recognize early cardiac involvement may result in devastating complications such as sudden cardiac arrest (SCA). Electrocardiography (ECG) is a widely available and affordable modality that can aid with risk stratification. Purpose We aimed to study patient demographics and identify clinical and electrocardiographic (ECG) predictors of SCA in patients with CA. Methods We queried the Nationwide Inpatient Sample database between 2016–2020 to identify hospitalizations for CA who were then subcategorized based on SCA, using the ICD-10 diagnosis code. The primary outcome was to assess clinical and ECG predictors of SCA. Both groups were compared for association using the chi-square test, following which multivariate regression analysis was performed to identify predictors of SCA. In addition, we performed a temporal trends analysis of CA hospitalizations and SCA during this study period. Results A total of 103,620 weighted hospitalizations for CA were identified of which 1935(1.9%) suffered a SCA. Baseline characteristics and comorbidities were largely equivalent except for a history of heart failure which was significantly higher in the SCA group(63.3% vs 46.8%, p &amp;lt; 0.001). Interestingly, traditional cardiac risk factors like smoking, hypertension, diabetes, and obesity did not correlate with increased risk of SCA. African American (AA) race had a higher incidence of SCA(30.2% vs 23.4%, p &amp;lt; 0.001). A multivariate regression analysis was performed to identify predictors of SCA and account for potential clinical as well as demographic confounders. Higher rates of SCA were observed in male sex, age &amp;lt; 40 years, and AA race as outlined in figure 1. The presence of heart failure with reduced ejection fraction (HFrEF), heart failure with preserved ejection fraction (HFpEF), and tachyarrhythmias such as atrial fibrillation, atrial flutter, ventricular tachycardia and ventricular fibrillation were associated with significantly higher odds of SCA. In addition, right bundle branch block, left bundle branch block, first-degree AV block, complete heart block and fascicular blocks were independently predictive of higher rates of SCA. As expected, the rates of ICD implantation were higher in the SCA group (7.2% vs 0.9%, p &amp;lt; 0.001. There is an increasing trend in hospitalizations for cardiac amyloidosis from 2017 to 2020 as highlighted in figure 2. Conclusion Among patients with cardiac amyloidosis, young age, AA race, ECG evidence of AV nodal dysfunction, distal conduction disease, and tachyarrhythmias is associated with an elevated risk of SCA. These findings could improve risk stratification, prompt further targeted evaluation with advanced imaging modalities and help in early identification of amyloid patients with cardiac involvement.Figure 1Figure 2

Atrial fibrillation virtual ward - a hospital is not always the best place to be

Abstract Background Atrial fibrillation (AF) continues to represent a global health challenge. Our ability to prolong our lives has inevitably led to an increase in the incidence of AF, with subsequent increase in AF-related hospitalisations. With at least 92% of the global population having access to a digital telecommunication medium, virtual wards could be the way forward for managing acute AF patients. Purpose We implemented a virtual ward for hospital patients presenting with fast AF or atrial flutter (AFL), aiming to provide remote hospital-level care. Methods Patients presenting acutely with AF/AFL to the hospital were onboarded to the virtual ward and managed remotely at home, after being given access to a single-lead ECG device, a blood pressure monitor and pulse oximeter with instructions to record daily ECGs, blood pressure, oxygen saturations and to complete an online AF symptom questionnaire via a smartphone app. Data were uploaded to a digital platform for daily review by the clinical team. Admissions were either "step-up", where patients were onboarded to the virtual ward instead of hospitalisation, or "step-down" where early hospital discharge was facilitated through virtual ward support. Outcomes included hospitalisations avoided, bed-days saved and destination therapy plans (defined as electrical cardioversion, catheter ablation, or AV nodal ablation). Patients' satisfaction was assessed using the NHS Friends and Family test (FFT) and free-text narrative feedback. Results There were 118 virtual admissions between Jan 2022 – Jan 2023. Sixty-six (55%) of them avoided initial hospital admission as patients were directly enrolled to the virtual ward from outpatient settings. A further 61 re-admissions were appropriately prevented during virtual surveillance. Hence, avoiding a total of 127 unplanned hospitalisations, saving a median of 444 days (assuming a median hospital stay of 3.5 days per AF admission). The mean age on onboarding to the virtual ward was 66 ± 10 years. Mean HR at the time of onboarding and offboarding was 124 ± 22 and 84 ± 24 bpm respectively (P&amp;lt;0.0001; 95% CI= -47 to -34). A rhythm control strategy was pursued in 75% (n=88, P&amp;lt;0.0001), and 65% (n=75, P&amp;lt;0.0001) were referred for destination therapy. The FFT questionnaire yielded 100% positive responses among participants. Positive feedback themes focused on avoiding hospital stay and active participation in care plans, whilst the main negative comments addressed initial difficulty with technology and expressed the need for more instant communication. There were 5 unplanned discharges from the virtual ward requiring hospitalisation. Conclusion Our preliminary outcomes demonstrate a promising foundation for a reproducible model of healthcare delivery that provides an alternative to the traditional in-patient care for patients with AF. Thus, reducing the huge associated economic burden on healthcare without compromising on patients’ care or safety.AF virtual ward referral criteriaThe new Clinical Pathway

Real-time interactive 3d simulation of Atrial Fibrillation for education

Abstract Background The mechanistic understanding of atrial fibrillation (AF) has burgeoned over the past decades. However, the interplay between triggers, reentry, drivers and therapies is rarely fully appreciated despite being ultimately fundamental to patient care. Readily accessible, high-fidelity interactive simulation has the potential to address this knowledge gap across healthcare providers. Objective To develop a, interactive simulation system to allow deep understanding of AF mechanisms and therapies. Methods An application for e-Training was developed to be accessible on consumer smartphones and tablets, based on a validated electromechanical simulation model of the heart, with real-time interactive 3D image output. A virtual heart is represented in normal and arrhythmic states, enabled with simulated models for administering antiarrhythmic drugs, performing Pulmonary Vein Isolation (PVI), AV Node ablation, ventricular pacing, DC Cardioversion, plus the formation of atrial thrombus leading to a stroke event. Electrogram and ECG signals are generated from the underlying simulation and respond realistically to drugs, pacing and ablation. A self-study tutorial introduces the arrhythmia and treatment procedures. Learning outcomes are assessed with MCQ tests and receive Continuous Professional Development CPD credits. Results The AFib Sim app has received CPD accreditation in the UK and has so far been used at the Universities of Oxford, Cambridge and Leeds medical schools. All trainees and medical students followed the self-study tutorials and took the interactive MCQ test, which are embedded within the AFib Sim app. Development was based on Unity 3D and was made available on iOS, Android, macOS, MS Windows and WebGL platforms. Conclusion This project meets an urgent training need whilst expanding expertise and market scope into clinical training. The impact on clinical training was high and the societal benefit came from better and quicker trained staff. Learning Objective Upon completion of this session, the attendee will be able understand how a simulation of Atrial Fibrillation can be used for training and deepening the clinical understanding of atrial fibrillation.

Cardiac resynchronosation and left ventricular ejection fraction improvement with single ventricular conduction pacing system lead

Abstract Background Conduction system pacing is a new modality to obtain physiologic pacing (PP) and normal to near normal cardiac synchrony; they often obtain shorter QRS durations and they could replace the need of Bi-V (CRT) implants if LVEF improves as much with less leads implanted. Methods From our cohort of 340 physiologic pacing attempts (2019-2023), we extracted all patients (pts) with available ultrasounds before and after implants, aiming to describe the variation of Left Ventricular Ejection Fraction (LVEF) over time; all attempts, including failures were analyzed. Results A total of 146 pts completed follow-up LVEF evaluation. Pts were 36,8% females; median age was 79 +/- 8.5 years. Indications were: SSS 25%, AV block 41% (including 11 post TAVR), Pacemaker induced cardiomyopathy (PIMC) 27% and AV node ablation in 7%. Success to achieve cardiac resynchronisation (defined as a QRS shorter than 140ms and a LVAT shorter than 90ms, or 20% reduction in QRS width) was obtained in 82,6% of pts (higher success rate achieved with LBB-P: 88,4% vs 55,5% for His-P). Procedural time (pts in-out) was 88min (+/- 37min). Pts with a QRS larger than 150ms (CRT indication) were 49% of the cohort. Patients with a LVEF less than 50% accounted for 54,8% of the cohort. Mean QRS duration was 141,9ms (+/-36) pre-implant and 129,3ms (+/- 19) post implant. Mean LVEF was 43,6% (+/- 14) before implant and increased to 50,2% (+/-12) post implant for the entire cohort, in pts with CRT indication, variation persisted: mean LVEF improved from 33,2 to 43,8% and QRS duration from 172,9 to 136,8ms. Pts with less than 50% LVEF had a response rate of 75,5% (increase in LVEF from 4-41%), and 33% of patients increase their LEVF between 10-30% (deemed super responders), only one pt decrease 10% her LVEF (a His failure implant). Conclusion Cardiac resynchronisation is feasible with only one ventricular lead, potentially with longer duration of batteries and lesser costs. Response rate is similar to CRT historical controls but super responders are twice to three times higher than historical controls.

Abstract 12422: Does a Jump in the Atrioventricular Conduction Curve Really Indicate a Switch From Fast Pathway to Slow Pathway Conduction?

Introduction: A jump in the atrioventricular (AV) conduction curve (aka, a discontinuous curve) remains the current clinical criterion for diagnosing dual pathway AV nodal electrophysiology. However, it has never been proven that a jump in the AV conduction curve indicating a transition from fast pathway (FP) to slow pathway (SP) conduction, as it has been assumed. Hypothesis: A jump in the AV conduction curve may not reflect the transition from FP to SP conduction, as assumed it does by the current clinical criterion. Methods: Eighty-one experimental records from rabbit AV nodal preparations containing the following data were analyzed. 1. had at least one AV conduction curve, and 2. had intracellular action potential recordings from AV nodal fibers and/or recording of His electrogram alternans (a validated new index of dual pathway conduction). Results: There were 11 (13%) of 81 preparations showing a jump in the AV conduction curve. In these preparations, the transition from FP to SP conduction was smooth. The jumps always occurred after the FP to SP transition at a much shorter prematurity (Figure). On average, the FP-SP transition occurred at prematurity of 196±39ms versus the jump at 117±9ms (P&lt;0.001). Complex intranodal/nodal-atrial reentries were detected after the FP to SP transition. The jumps were always associated with and most likely caused by the intranodal/nodal-atrial reentry and its subsequent conduction to the His bundle, rather than a direct conduction by the premature beat itself. Conclusions: The transition from FP to SP conduction does not produce a jump in the AV conduction curve. A jump in the AV conduction curve is likely caused by induction of intranodal/nodal-atrial reentry by the premature beat and the subsequent conduction of the reentrant beat to the His bundle, rather than a direct conduction by the premature beat itself. Thus, a jump in the AV conduction curve as the current clinical criterion of dual pathway conduction should be invalidated.

Abstract 15446: Impact of Patient Demographics on Optimal Beta-Blocker Use After New-Onset Heart Failure: Analysis of the HF-OPT Study (Heart Failure Optimization Study)

Background: While beta-blockers (BB) have helped to improved outcomes in patients with heart failure and a low ejection fraction (HFrEF), the titration to target doses has been suboptimal and it is not clearly understood why. The Heart Failure Optimization Study (HF-OPT) study in newly diagnosed HF patients (pts) collected baseline data, arrhythmias during wearable cardioverter defibrillator (WCD), as well as medications and dosing. Purpose: The objective was to assess which factors were associated with receiving BB at target doses by day 180. Methods: Data from pts with newly diagnosed HFrEF during WCD use was collected from 487 pts (54% from US, 72% male, age 59±13) in the HF-OPT study. Target dose of BB were defined as the lowest maximum dose from either the ESC or ACC/AHA/HFSA guidelines. Supraventricular tachycardia (SVT) was used to label all dysrhythmias originating at or above the atrioventricular node and captured by the WCD. Association between BB and other variables were assessed using logistic regression. Results: 6 months after a new diagnosis of HFrEF, 97% of pts were prescribed BB, but only 25% were on target doses. Univariate analysis showed that only BMI, age, sex, black race, a history of hypertension, and no history of PCI or angina, were associated with receiving target doses of BBs by 180 days. Having episodes of SVT during the first 180 days were also associated with receiving target BB doses (Table). In multivariate analysis, all were significantly associated with target BB dose except BMI, SVT during WCD use and history of PCI. Conclusions: The full beneficial effects of BB may not be achieved in patients with HFrEF if the patients are not recieving target doses. In the HF-OPT study, factors positively associated with reaching target BB doses included younger age, black race, being male, and a history of hypertension. Having a history of angina was associated with not achieving target BB doses. The significance of these differences should be further explored.

Abstract 15934: Trends and Disparities in Patients Admitted With Bradyarrhythmias: Insights From the National Inpatient Sample 2016-2020

Introduction: Bradyarrhythmias are caused by a dysfunction in the cardiac conduction system at the level of the sinus node, the atrioventricular node, or the His/Purkinje system. We aimed to investigate national trends and outcomes in patients with bradyarrhythmias, grouped as sinus node dysfunction, atrioventricular block, and conduction disorder (with 1:1 AV conduction). Methods: We utilized the National Inpatient Sample (NIS) Database 2016-2020 to identify the cohort with principal diagnosis of sinus node dysfunction (SND), atrioventricular block (AVB), and conduction disorder with 1:1 AV conduction using ICD-10-CM codes. For inpatient mortality analysis, COVID-19 patients were excluded from NIS 2020. Outcome analysis included hospitalization rates per 10,000 admissions and adjusted inpatient mortality rate utilizing predictive margins, during each calendar year stratified by sex, age, race, and median household income (MHOI). Results: There were a total of 1,557,806 hospitalizations (713,321 with SND; 297,037 with AVB and 547,448 with conduction disorder with 1:1 AV conduction) with a principal diagnosis of bradyarrhythmia from 2016-2020. Adjusted rates for hospitalizations per 10,000 admissions significantly increased throughout the years 2016-2020 for all three types of bradyarrhythmias, as demonstrated in Figure 1. Between the years 2016 and 2020, adjusted inpatient mortality rates amongst admissions with SND, AVB and conduction disorder with 1:1 AV conduction were similar, p-trend 0.201, 0.823 and 0.965 respectively; demonstrated in Figure 2. Conclusion: Our findings indicate that, throughout the years of 2016-2020, there was a trend suggesting an increase in hospitalization rates for bradyarrhythmias including sinus node dysfunction, atrioventricular block, and conduction disorder with 1:1 AV conduction. These findings may help the healthcare system recognize and decrease the healthcare burden of bradyarrhythmias.