Antitachycardia Pacing Research Articles

Interventional Cardiac Electrophysiology for the Management of Adults With Congenital Heart Disease.

Congenital heart disease (CHD) is the most common congenital anomaly in newborns. Advances in catheter and surgical techniques led to the majority of these patients surviving into adulthood, leading to evolving challenges due to the emergence of long-term complications such as arrhythmias. Interventional electrophysiology (EP) has had remarkable advances over the last few decades, and various techniques and devices have been explored to treat adult patients with CHD. This comprehensive review aims to summarize findings from recent studies exploring advances in the use of interventional electrophysiology to manage adult patients with CHD. While pacemaker therapy has some indications in adults with CHD, various long-term consequences include pacing-induced cardiomyopathy and complications requiring reintervention. Cardiac resynchronization therapy has shown promising results in some studies to treat CHD patients with heart failure, although further research to clarify guidelines is encouraged. Implantable cardiac defibrillators have demonstrated clear benefits in CHD patients and are indicated for primary prevention of sudden cardiac death, although selection criteria for secondary prevention of sudden cardiac death are uncertain. Catheter ablation has also been used for various atrial and ventricular arrhythmias in patients with CHD with high success rates, although the likelihood of success depends on patient characteristics and the type of arrhythmia, and multidisciplinary assessment is encouraged to improve the chance of successful therapy.

Racial and Ethnic Disparities in the Outcomes and Treatment of Patients Admitted with Heart Failure: A Nationwide Analysis

Background/Objectives: Heart failure is the leading cause of hospital admission and mortality. Racial disparities have been demonstrated in various cardiovascular disorders; however, the data for in-hospital outcomes, complications, and procedural rates are limited. Methods: Utilizing the National Inpatient Sample (NIS) database, this retrospective cohort study included adult patients admitted with a principal diagnosis of heart failure. Coding for race and ethnicity in the NIS combines self-reported race and ethnicity provided by the data source into 1 data element (“RACE”). We compared the outcomes between various racial groups, focusing on mortality, the length of stay (LOS), hospital charges, and complications. Differences in the utilization of advanced therapies, including implantable cardiac defibrillators, cardiac resynchronization therapy (CRT), ventricular assist devices (VADs), and heart transplant, were also analyzed. Results: Out of 1,107,860 patients hospitalized with heart failure, 715,345 (64.57%) patients were White, 244,394 (22.06%) patients were Black, and 97,063 (8.31%) patients were Hispanic. Compared to White people, the odds of in-hospital mortality were lower among Black (aOR 0.74; 95% CI 0.68–0.81; p < 0.001) and Hispanic (aOR 0.78; 95% CI 0.69–0.88; p < 0.001) people. Complication rates including cardiogenic shock were found to be significantly lower in Black people (aOR 0.86; 95% CI 0.77–0.96; p < 0.001) and in Hispanic (aOR 0.72; 95% CI 0.63–0.81; p < 0.001) people. The rates of acute respiratory failure were also lower in Black (aOR 0.72; 95% CI 0.69–0.74; p < 0.001) and Hispanic (aOR 0.77; 95% CI 0.73–0.81; p < 0.001) people as opposed to White people. However, Black people were found to have higher rates of acute kidney injury (aOR 1.11; 95% CI 1.07–1.14; p < 0.001) and cardiac arrest (aOR 1.17; 95% CI 1.03–1.34; p = 0.02) compared to White people. Black people were less likely to receive advanced interventions, including cardiac resynchronization therapy (aOR 0.71; 95% CI 0.60–0.83; p < 0001), a ventricular assist device (aOR 0.45; 95% CI 0.34–0.59; p < 0.001), and heart transplants (aOR 0.57; 95% CI 0.42–0.77; p < 0.001), than White people. Hispanic people were found to have lower rates of ventricular assist device (aOR 0.49; 95% CI 0.33–0.72; p < 0.001) use than White people. Conclusions: These findings highlight significant racial disparities in mortality, secondary outcomes, and advanced therapy utilization in heart failure admissions. Further research is needed to identify the root factors for these disparities in order to guide targeted interventions to reduce this racial gap.

A refined, minimally invasive, reproducible ovine ischaemia-reperfusion-infarction model using implantable defibrillators: Methodology and validation.

Ischaemic heart disease remains a leading cause of premature mortality and morbidity. Understanding the associated pathophysiological mechanisms of cardiac dysfunction arising from ischaemic heart disease and the identification of sites for new therapeutic interventions requires a preclinical model that reproduces the key clinical characteristics of myocardial ischaemia, reperfusion and infarction. Here, we describe and validate a refined and minimally invasive translationally relevant approach to induce ischaemia, reperfusion and infarction in the sheep. The novelty and refinement in the procedure stems from utilization of implantable cardiac defibrillators prior to coronary engagement, balloon angioplasty to induce infarction, and intra-operative anti-arrhythmic drug protocols to reduce adverse arrhythmic events. The protocol is readily adoptable by researchers with access to standard fluoroscopic instrumentation, and it requires minimally invasive surgery. These refinements lead to a substantial reduction of intra-operative mortality to 6.7% from previously published values ranging between 13% and 43%. The model produces key characteristics associated with the fourth universal definition of myocardial infarction, including ECG changes, elevated cardiac biomarkers and cardiac wall motility defects. In conclusion, the model closely replicates the clinical paradigm of myocardial ischaemia, reperfusion and infarction in a translationally relevant large animal setting, and the applied refinements reduce the incidence of intra-operative mortality typically associated with preclinical myocardial infarction models.

Inappropriate Therapy and Shock Rates Between the Subcutaneous and Transvenous Implantable Cardiac Defibrillator: A Secondary Analysis of the PRAETORIAN Trial.

Inappropriate therapy (IAT) is an undesirable side effect of implantable cardiac defibrillator (ICD) therapy. Early studies with the subcutaneous ICD (S-ICD) showed relatively high inappropriate shock (IAS) rates. The PRAETORIAN trial demonstrated that the S-ICD is noninferior to the transvenous ICD (TV-ICD) with regard to the combined end point of IAS and complications. This secondary analyses evaluates all IAT in the PRAETORIAN trial. This international, multicenter trial randomized 849 patients with an indication for ICD therapy between S-ICD (n=426) and TV-ICD therapy (n=423). ICD programming was mandated by protocol. All analysis were performed in the modified intention-to-treat population. In both groups 42 patients experienced IAT (48-month Kaplan-Meier estimated cumulative incidence, 9.9% and 10.1%, respectively; hazard ratio (HR), 0.99 [95% CI, 0.65-1.52]; P=0.97). There was no significant difference in patients experiencing IAS between both groups (P=0.14). In the S-ICD group, 81 IAT episodes with 124 IAS and 1 inappropriate antitachycardia pacing occurred versus 89 IAT episodes with 130 IAS and 124 inappropriate antitachycardia pacing in the TV-ICD group. IAT episodes were most frequently caused by supraventricular tachycardias in the TV-ICD group (n=83/89) versus cardiac oversensing in the S-ICD group (n=40/81). In the TV-ICD group, a baseline heart rate >80 bpm (HR, 1.99 [95% CI, 1.05-3.76]; P=0.03), a history of atrial fibrillation (HR, 2.66 [95% CI, 1.41-5.02]; P=0.003), and smoking (HR, 2.46 [95% CI, 1.31-4.09]; P=0.005) were independent predictors for IAT. A QRS duration >120 ms was an independent predictor for IAT caused by cardiac oversensing in the S-ICD group (HR, 3.13 [95% CI, 1.34-7.31]; P=0.008). Post-IAS interventions significantly reduced IAS recurrence in both groups (P=0.046). There was no significant difference in IAT and IAS rates between the S-ICD and TV-ICD in a conventional ICD population, but causes and predictors for IAT differed between the devices. After the first IAS, an intervention significantly reduced the recurrence rate of IAS. URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.

The effects of empagliflozin on ventricular arrhythmias in heart failure patients with an implantable cardioverter-defibrillator: a double-blind randomized controlled trial.

Sodium-glucose transporter 2 (SGLT2) inhibitors such as empagliflozin are one of the main treatments for type 2 diabetes mellitus (DM2) and heart failure (HF). They have also demonstrated anti-arrhythmic effects in some preclinical and clinical studies. The purpose of this study was to assess the effects of empagliflozin on ventricular arrhythmias in HF patients with an implantable cardioverter-defibrillator (ICD). In a prospective double-blinded, randomized controlled trial of Iran County, Mashhad (72 patients 1:1), we compared the frequency and proportion of ventricular arrhythmias and ICD therapies during the 24weeks to the prior 24weeks. Results revealed that empagliflozin significantly reduced the frequency and proportion of ventricular tachycardia (VT)/fibrillation (VF) episodes (P = 0.019 and 0.039, respectively). Moreover, it tended to reduce the frequency and proportion of ICD therapies, including anti-tachycardia pacing (ATP) and shock. Subgroup analysis of patients with or without any antiarrhythmic drugs (digoxin, mexiletine, amiodarone, or sotalol) revealed that only patients who were previously on the antiarrhythmic drugs benefit from empagliflozin antiarrhythmic effects. In conclusion, empagliflozin exhibits anti-arrhythmic effects in HF patients with an ICD. Larger and long-term clinical studies are still needed to investigate and confirm all positive effects of SGLT2 inhibitors in this regard. Trial registration number: IRCT20120520009801N7 (Approval date: June 11, 2022).

Ventricular arrhythmias and the role of antitachycardia pacing in patients with electrical heart disease and hypertrophic cardiomyopathy

Ventricular arrhythmias and the role of antitachycardia pacing in patients with electrical heart disease and hypertrophic cardiomyopathy

Catheter Ablation or Antiarrhythmic Drugs for Ventricular Tachycardia.

Patients with ventricular tachycardia and ischemic cardiomyopathy are at high risk for adverse outcomes. Catheter ablation is commonly used when antiarrhythmic drugs do not suppress ventricular tachycardia. Whether catheter ablation is more effective than antiarrhythmic drugs as a first-line therapy in patients with ventricular tachycardia is uncertain. In an international trial, we randomly assigned in a 1:1 ratio patients with previous myocardial infarction and clinically significant ventricular tachycardia (defined as ventricular tachycardia storm, receipt of appropriate implantable cardioverter-defibrillator [ICD] shock or antitachycardia pacing, or sustained ventricular tachycardia terminated by emergency treatment) to receive antiarrhythmic drug therapy or to undergo catheter ablation. All the patients had an ICD. Catheter ablation was performed within 14 days after randomization; sotalol or amiodarone was administered as antiarrhythmic drug therapy according to prespecified criteria. The primary end point was a composite of death from any cause during follow-up or, more than 14 days after randomization, ventricular tachycardia storm, appropriate ICD shock, or sustained ventricular tachycardia treated by medical intervention. A total of 416 patients were followed for a median of 4.3 years. A primary end-point event occurred in 103 of 203 patients (50.7%) assigned to catheter ablation and in 129 of 213 (60.6%) assigned to drug therapy (hazard ratio, 0.75; 95% confidence interval, 0.58 to 0.97; P = 0.03). Among patients in the catheter ablation group, adverse events within 30 days after the procedure included death in 2 patients (1.0%) and nonfatal adverse events in 23 patients (11.3%). Among the patients assigned to drug therapy, adverse events that were attributed to antiarrhythmic drug treatment included death from pulmonary toxic effects in 1 patient (0.5%) and nonfatal adverse events in 46 patients (21.6%). Among patients with ischemic cardiomyopathy and ventricular tachycardia, an initial strategy of catheter ablation led to a lower risk of a composite primary end-point event than antiarrhythmic drug therapy. (Funded by the Canadian Institutes of Health Research and others; VANISH2 ClinicalTrials.gov number, NCT02830360.).

Abstract 4137564: Management of Atrial Flutter (AFL) Using Intrinsic Antitachycardia Pacing (iATP) Protocol

Background: The recently introduced iATP algorithm augments traditional ventricular antitachycardia pacing (ATP) with programmed stimulation (PS) resulting in greater efficacy terminating ventricular tachycardia than traditional ATP in avoiding ICD shocks. The use of iATP in the atrium may similarly enhance termination of atrial arrhythmias, avoiding prolonged arrhythmia burden or need for cardioversion. Objective: To compare efficacy of 3 atrial ATP protocols (PROT[GS1] ) in either converting AFL to sinus rhythm or accelerating AFL to atrial fibrillation (AF). Methods: Patients presenting in AFL for ablation were recruited. Patents underwent all three pacing protocols, twice, and in random order (6 times total). 1. PROT 1 – Ramp pacing at 91% of tachycardia cycle length (TCL) for 13 beats with 5 or 10ms decrement, avoiding pacing cycle length (CL) <160 ms. 2. PROT 2 – Ramp pacing at 81% of TCL for 13 beats again with 5 or 10ms decrement, avoiding CL <160 ms. 3. PROT 3 (iATP) – Drive train of 88% of TCL for 15 beats with singles, doubles, and triples down to atrial effective refractory period. If AFL terminated, it was re-induced with PS or burst pacing. Termination and CL acceleration to AF are defined as the positive effect. No effect is defined as the negative effect. CL acceleration and termination were treated similarly in the analysis because AF is clinically easier to manage than AFL. Results: Of the 21 patients enrolled, 17 completed the entire protocol. 4 patients (excluded from analysis) did not complete the protocol due to non-inducibility following AFL termination. The TCL of the AFL ranged from 190ms to 290ms. PROT 1 terminated AFL 6 out of 34 attempts (17.6%). PROT 2 terminated AFL 7 out of 34 attempts (20.5%). iATP terminated AFL 13 out of 34 attempts (38%). It also accelerated AFL more frequently than the other two protocols (PROT 1:1, 2:4, 3:8). Conclusion: Atrial iATP was significantly more effective in either terminating or accelerating AFL, compared to ramp pacing protocols.

Abstract 4123563: High Prevalence of Unrecognized Actionable Cardiac Arrhythmias in Patients with Moderate to Severe Chronic Obstructive Pulmonary Disease

Background: Patients with chronic obstructive pulmonary disease (COPD) are at high risk for developing arrhythmias due to hypoxemia, right heart failure and use of beta-agonists inhalers. Symptoms related to arrhythmias can often be masked or confounded by symptoms related to COPD exacerbation and remain undiagnosed. Objective: To identify the incidence of actionable arrhythmias in patients with no prior cardiology follow-up and moderate–severe COPD with continuous monitoring. Methods: An automatic referral for electrophysiology (EP) consult was generated in patients with moderate-severe COPD if they answered yes to one of the following: palpitations, dizziness, abnormal ECG, near syncope. Upon consultation with EP specialist, implantation of loop reorder was discussed (ILR) with the patient. Patients were then monitored for 12 months via remote monitoring. Actionable arrhythmia was defined the arrhythmia that correlated with symptoms triggered by the patient, necessitated adjustment of medications (including initiation of anticoagulation), catheter ablation and implantation of implantable cardiac defibrillator (ICD) or permanent pacemaker (PPM). Results: Out of 62 patients referred 22 (35.5%) agreed to undergo ILR implantation. Of the 22 (50.0% female, 62 ± 9.5 years) patients implanted with an ILR, 15 (68.2%) had an actionable arrhythmia after a mean follow-up of 2.7± .3 months. These included 14 symptomatic events requiring medication adjustment (10 atrial tachycardias, 4 ventricular events), 7 cases of atrial fibrillation (requiring initiation of anticoagulation in all cases and catheter ablation in 1), 1 case of sinus node dysfunction requiring pacemaker implantation, and 1 episodes of sustained ventricular tachycardia requiring ICD implantation. Conclusion: Continuous monitoring had high yield in diagnosing significant arrhythmic events in patients with moderate-severe COPD. Awareness should be raised about the high arrhythmic risk of this population and the role of continuous monitoring should be sought in larger studies.

Abstract 4137113: The Effectiveness of Cardiac Resynchronization Therapy in Patients with Cardiac Sarcoidosis: A Retrospective Analysis

Background: Cardiac sarcoidosis (CS) manifests in a wide range of clinical presentations, including conduction system abnormalities, ventricular arrhythmias, and systolic heart failure. Although cardiac resynchronization therapy (CRT) has shown efficacy in treating select nonischemic cardiomyopathy patients, its specific impact on CS patients remains less explored. This study aimed to evaluate the outcomes of CRT therapy in CS patients, focusing on implantable cardioverter defibrillator (ICD) therapies, heart failure (HF) hospitalizations and mortality. Methods: We retrospectively reviewed all patients with a clinical or histological diagnosis of CS who underwent device implantation (ICD or Permanent Pacemaker (PPM)) with or without CRT therapy at Johns Hopkins Hospital between 2004 and 2024. Baseline characteristics and echocardiographic parameters were assessed. Heart failure hospitalizations, the frequency of ATP (Anti-Tachycardia Pacing) or ICD shocks, and all-cause mortality were also evaluated as the outcomes. Results: The study included 212 patients (40.1% female, average age 52.8 ± 11.1 years). Eighty-five patients underwent CRT implantation (82 CRT-D and 3 CRT-P), whereas the rest received either an ICD or a PPM without CRT therapy. Most CRT devices (58.82%) were upgrades from an initial PPM or ICD. Over a follow-up of 6.15 ± 4.43 years, 27 (12.74%) patients were hospitalized for heart failure (HF), 86 (40.56%) experienced ATP or ICD shocks, and 17 (8.02%) died. The composite outcome was observed in 103 patients (48.5%), with no significant differences between CRT and non-CRT groups ( P = .51). Survival analysis indicated significantly reduced freedom from HF hospitalizations in the CRT group compared to non-CRT group ( P = .01). However, ATP/ICD shocks did not have a significant difference. CRT recipients showed an improvement in left ventricular ejection fraction (LVEF) from 35.3 ± 12.6% to 38.9 ± 13.6% at 6 months ( P = .01). Non-recipients showed no significant change in LVEF ( P = .43). Conclusions: Over an average six-year follow-up period, CRT upgrade does not appear to affect ATP/ICD shock and mortality in CS patients, although it is associated with significantly higher rates of heart failure (HF) hospitalizations compared to CS patients with an ICD or PPM alone. These findings underscore the complex response of CS patients to CRT, highlighting the need for further research to optimize treatment strategies within this subgroup.

Abstract 4123956: Upgrade to Implantable Cardioverter-Defibrillator in Patients Diagnosed with Cardiac Sarcoidosis after Permanent Pacemaker Implantation for High-Grade Atrioventricular Block

Introduction: Unexplained high-grade AV block (AVB) in patients age <65 years is among the salient features of cardiac sarcoidosis (CS). Guidelines recommend that CS patients with high-grade AVB should receive an implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy-defibrillator (CRT-D) rather than a permanent pacemaker (PPM). However, in clinical practice, CS may be recognized after PPM implantation for high-grade AVB. Aims: To evaluate the characteristics and outcomes of patients diagnosed with CS after PPM implantation for high-grade AVB and assess the decision-making and rationale for upgrade to ICD/CRT-D. Methods: Retrospective review of the Mayo Clinic Sarcoid Registry (n=848) was performed to identify all patients for which a PPM was implanted for high-grade AVB prior to the diagnosis of CS. Baseline clinical and imaging characteristics were collected during index evaluation at our institution. Decision-making for ICD upgrade, lead management strategy, immunosuppression initiation, and outcomes were assessed. Results: Overall, 29 of 848 (3.4%) of CS patients (62% probable/definite CS; 77% male; median (IQR) age 56 (48-61) years; and median (IQR) LVEF 58% (50-62) received a PPM for high-grade AVB prior to a CS diagnosis. Median (IQR) interval between PPM implant and index evaluation was 10 (3-23) months. Eight of 29 patients underwent upgrade to ICD (n=4) or CRT-D (n=4). Among them, the pacing lead was extracted in 4. All patients were upgraded for primary prevention of sudden cardiac death (SCD), with 3 of them also having LVEF<50% requiring upgrade to CRT-D. Twenty-two (79%) patients in the total cohort were treated with immunosuppression. During median (IQR) follow-up 37 months (11-74), 1 patient in the upgrade group had sustained VT appropriately treated with anti-tachycardia pacing. No events were documented among patients in the non-upgrade group. At last follow-up, 6 (75%) patients in the upgrade group and 12 (57%) in the non-upgrade group were pacemaker dependent. Median LVEF change was 0% in patients who underwent upgrade to CRT-D and –0.2% in those who underwent upgrade to ICD or no upgrade. Conclusions: In this cohort of patients diagnosed with CS several months after a PPM had been implanted for high-grade AVB, incident VT/VF was infrequent with contemporary CS management. In the absence of other SCD risk factors, CS patients who received a PPM for high-grade AVB prior to their CS diagnosis may not require ICD upgrade.

Abstract 4117406: The Safety and Efficacy of Surgical Cardiac Sympathetic Denervation for Ventricular Arrhythmias: An Updated Systematic Review&Meta-Analysis

Objectives: This meta-analysis sought to explore the long-term arrhythmic outcomes of cardiac sympathetic denervation (CS) by measuring event rates of recurrent ventricular arrhythmias (VA) and implantable cardiac defibrillator shocks (ICD) post CSD. Background: The role of sympathetic nervous system in the beginning and continuation of ventricular arrhythmias (VAs) is well known. CS has been associated with improved arrhythmic outcomes in patients with refractory ventricular arrhythmias. However, whether CSD lowers shock event rates after the procedure is still uncertain and therefore, we performed a systematic review and meta-analysis to evaluate this. Methods&Materials: A comprehensive literature search was performed at Medline and Embase until March 2023. Our primary outcome was event rate of ICD shocks at 30 days, 90 days, and 1 year following CS. All analysis was conducted using Comprehensive Meta-Analysis software. Results: The initial search found 1,324 articles. After all articles were examined, a total of 29 studies fit our criteria. ICD shocks 1 year post CSD had a pooled event rate of 66.5% with a 95% confidence interval (CI) of 57.7% to 74.3% and the I-squared (I2) statistics. ICD shocks at 6 months had an event rate at 61.7% with a 95% confidence interval of 53.3% to 69.4% with I2 at 46. VA in one year post CSD had a pooled event rate of 62.5 with a 95% with a CI of 53.3% to 69.1% and I2 at 22%. At 6 months the event rate was 64.2 with a 95% CI of 56.3% to 71.4% with I2 at 33% Mortality from cardiac arrhythmia and classified 0-30 days (short term), 21-364 days (medium term), and >365 days (long term). The pooled event rate for short term morality was 6.8% with a 95% CI of 4.2%-11.0% with I2 at 0%, medium term was 5.2% with a 95% CI of 2.9% to 8.9% with I2 at 0%, and long term was 5.0% with a 95% CI of 2.7% to 9.2% and I2 at 0%. Conclusion: CSD may be an alternative form of therapy that reduces shock event rates and recurrent VA in patients that are refractory to ablation and medical therapy. However larger prospective studies are needed to further evaluate the usefulness and safety of CSD.

Abstract 4138350: Candidemia in Patients with Left Ventricular Assist Device-A Case Series

Introduction: Candidemia is rare but associated, have significant morbidity and mortality. Outcomes are not well-characterized in patients with left ventricular assist devices (LVADs). With an increasing number of patients living with LVADs, we sought to characterize risk factors to help optimize outcomes for this high-risk population. Methods: We retrospectively reviewed records of 97 patients who underwent LVAD implant between January 2012 to May 2024 at Indiana University Health, Indianapolis Indiana. Demographic and clinical data were extracted. Candidemia was defined as a positive blood culture with candida species. Result: We identified three patients with candidemia, with an overall attack rate of 3.09%. All patients had a HeartMate III (HM3) at the time of infection. The mean age of patients was 40.3 years (Range 29.0 – 58.0 years) and mean BMI was 35.7 kg/m 2 (Range, 30.0 – 42.0 kg/m 2 ). One patient grew Candida auris and Candida tropicana, the other patient grew Candida auris and the third patient grew Candida globrata. All patients had an automatic implantable cardiac defibrillation, a peripherally inserted central catheter line, and right heart failure. Two patients had driveline infections (one fungal, one bacterial) while one patient developed LVAD endocarditis with a right ventricular outflow tract vegetation. Two patients had persistently positive blood cultures despite treatment with a multi-drug anti-fungal regimen (Flucytosine, Amphotericin B and micafungin) and expired. The third patient initially cleared her blood cultures after treatment with IV micafungin only but was re-admitted with muti-organ failure and expired. Summarily, all patients with candidemia died with a mortality rate of 100%. None of the patients were candidates for heart transplantation. Average survival from the time of diagnosis of candidemia was 5 months (Range 1.0 – 11.0 months). RHF, chronic DL infection and high BMI were associated with candidemia in our series. Conclusion: Candidemia in LVAD patients, while less common than bacterial infections, carry high mortality without cardiac transplantation (100% mortality in our cohort). Its rare occurrence makes it challenging to identify reversible risk factors, leading to poor survival. Multicenter registries are needed to fully elucidate these risk factors and determine effective treatment strategies.

Abstract 4119658: Catheter Ablation for Ventricular Arrhythmias in Transthyretin Cardiac Amyloidosis: A Single Center Experience

Background: Transthyretin cardiac amyloidosis (ATTR-CA) carries an elevated risk of developing ventricular arrhythmias (VA) but there remains limited evidence supporting the role of catheter ablation in this population. Purpose: To assess the safety and efficacy of catheter ablation for VA in ATTR-CA. Methods: An electronic database was used to identify all patients suspected of having ATTR-CA who underwent catheter ablation for VA at our institution between January 2010 and December 2023. Patients who did not meet the diagnosis of ATTR-CA and had a negative workup who underwent catheter ablation for ventricular tachycardia (VT) or premature ventricular contractions (PVCs) were used to form a control group matched for age, sex and left ventricular ejection fraction at a ratio of 2:1. Results: 20 controls and 10 cases of ATTR-CA were identified. Examining the two groups at baseline (Table 1), the mean age at index ablation was 67.7±7.0 and 68.6±8.1 years (p=0.359), mean follow-up time was 4.1±3.1 and 4.2±2.6 years (p=0.494), and the proportion of males was 100% and 90% respectively. The ATTR-CA group had a significantly higher proportion of chronic kidney disease (90% vs. 50%, p=0.032) and prior stroke or thrombotic events compared to the control group (50% vs. 10%, p=0.026) with similar CHA 2 DS 2 VASc scores (4.2±1.6 vs. 3.8±1.3, p=0.233). Both groups had comparable left ventricular ejection fraction (41.4%±14% vs. 46.9%±15.2%, p=0.173), VT/PVCs at presentation (40%/60% vs. 25%/75%, p=0.77), use of antiarrhythmics (70% vs. 60%, p=0.592), and high proportion of atrial fibrillation/flutter (70% vs. 90%, p=0.168). Procedural (261.2±101.2 vs. 265.7±125.6 mins, p=0.449) and total energy delivery time (1442.9±1509.1 vs. 1744.6±956.2 secs, p=0.296) was not significantly different in the two groups. Both groups had a significant decrease in PVC burden postablation with a reduction from 26.8% to 3.8% (p=0.024) and from 27.1% to 13.6% (p=0.028) in the ATTR-CA and control group respectively. A downward trend was seen in antitachycardia pacing events for VT postablation in the ATTR-CA (14.7±9.8 vs. 5.3±6.7, p =0.184) and control (193±387.6 vs. 0.67±1.2. p=0.139) groups. No major complications occurred after ablation (Table 2). Mean time to recurrence post-index ablation was similar between both groups (1620.4±483.8 vs. 1498.8±291.4 days, p=0.987, Figure 1). Conclusions: Catheter ablation appears to be safe and effective for VT and PVCs in patients with ATTR-CA.

Long-term clinical outcomes of remote monitoring for implantable cardioverter-defibrillators in Singapore.

Remote monitoring (RM) for cardiac implantable electronic devices is on the rise and has been shown to reduce the burden of in-clinic follow-up visits. We aimed to investigate the long-term clinical outcomes of RM versus no RM. This was a prospective, single-centre cohort study of consecutive patients with an implantable cardioverter-defibrillator (ICD) or cardiac resynchronisation therapy-defibrillator (CRT-D) followed up from 2018 to 2023. Patients who received non-ICD devices were excluded. In general, RM was offered to all patients, but uptake depended on patient preference. For data analysis, patients were stratified according to whether RM was used. The primary outcome was all-cause mortality; secondary outcomes were hospitalisation for heart failure and device therapy (shocks and electrical storm). Of 551 patients, 284 (51.5%) received RM and 267 (49.5%) did not. Baseline demographics were similar between the two arms. All-cause mortality was significantly lower in RM versus non-RM patients (hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.33-0.60, P <0.001), as was hospitalisation for heart failure (HR 0.39, 95% CI 0.25-0.59, P <0.001); these remained significant after adjustment for baseline covariates. More patients on RM received appropriate antitachycardia pacing (ATP) (17.6% vs. 10.7%, P = 0.035) and appropriate shocks (24.1% vs. 14.7%, P = 0.017). The incidences of inappropriate ATP, inappropriate shocks and electrical storm were similar. More patients on RM underwent pulse generator change (34.1% vs. 10.1%, P <0.001). Remote monitoring was associated with significantly lower mortality in both ICDs and CRT-Ds and in primary and secondary indications, as well as fewer heart failure hospitalisations. This supports current guidelines recommending the use of RM in all patients with ICD or CRT-D.

Sudden cardiac death after acute myocarditis with arrhythmic presentation: hunting for risk predictors − a systematic review and meta-analysis

BackgroundVentricular arrhythmias (VAs) frequently occur in the acute phase of myocarditis. Possible arrhythmic recurrences and the risk of sudden cardiac death (SCD) in this setting are reasons for concern, and...

Efficacy of percutaneous stellate ganglion block according to ventricular arrhythmia cycle length: A post hoc subanalysis of the STAR study

BackgroundData on the predictors of percutaneous stellate ganglion block (PSGB) efficacy in electrical storm are scanty. ObjectiveWe aimed to assess whether PSGB efficacy is influenced by the arrhythmia type and cycle length before the procedure. MethodsThis is a subanalysis of the multicenter STAR study. The population was stratified into 3 groups according to the median cycle length of the latest ventricular arrhythmia before PSGB: ventricular fibrillation (VF), fast ventricular tachycardia (VT), and slow VT. The primary outcome was the number of treated arrhythmic episodes (with antitachycardia pacing or direct current shocks) in the hour immediately after PSGB compared with the hour before. ResultsWe considered 139 PSGBs from 112 patients divided into VF (51 procedures), fast VT (44 procedures, VT cycle <375 ms), and slow VT (44 procedures, VT cycle ≥375 ms). The number of treated arrhythmic episodes in the hour after every PSGB was significantly lower compared with the hour before in all groups (VF: 0 [0–1] vs 5 [2–8], P < .001; fast VT: 0 [0–0] vs 1 [0–6.5], P < .001; slow VT: 0 [0–0] vs 1 [0–4.5], P = .001). In analyzing the reduction of the number of antitachycardia pacing sequences or direct current shocks from the hour before to the hour after PSGB, a significant trend was observed across the groups (Jonckheere-Terpstra trend P < .001), and a significant difference was observed in comparing slow VT vs VF and fast VT vs VF but not in comparing slow VT vs fast VT. VF was independently associated with the probability of reduction of treated events after PSGB. ConclusionPSGB is an effective treatment of electrical storm in patients with all types of ventricular arrhythmias. However, its effectiveness was more pronounced in patients with VF.

Ultra-low-energy defibrillation through adjoint optimization.

This study investigates ultra-low-energy defibrillation protocols using a simple two-dimensional model of cardiac tissue. We find that, rather counter-intuitively, a single, properly timed, biphasic pulse can be more effective in defibrillating the tissue than low energy antitachycardia pacing (LEAP), which employs a sequence of such pulses, succeeding where the latter approach fails. Furthermore, we show that, with the help of adjoint optimization, it is possible to reduce the energy required for defibrillation even further, making it three orders of magnitude lower than that required by LEAP. Finally, we establish that this dramatic reduction is achieved through exploiting the sensitivity of the dynamics in vulnerable windows to promote the annihilation of pairs of nearby phase singularities.

Targeting ventricular tachycardia originating from the anterolateral papillary muscle with stereotactic body radioablation therapy

Abstract Background Ventricular Tachycardia (VT) is prevalent in the setting of non-ischaemic cardiomyopathy (NICM), a heterogeneous group of conditions characterized by myocardial dysfunction in the absence of coronary artery disease. Challenges of catheter ablation to treat VT in NICM patients are well known, and recurrence rates can be as high as 58%. Stereotactic body radioablation therapy (SBRT) involves precise delivery of radiation to arrhythmogenic substrates, and represents a novel treatment to reduce recurrent implantable cardioverter defibrillator (ICD) therapies in patients with refractory VT. Though SBRT has shown preliminary effectiveness in reducing VT episodes, its effectiveness in NICM patients has not been widely evaluated. Purpose To evaluate SBRT effectiveness in NICM patients with scars at the basal anterolateral papillary muscle at a tertiary care center between November-December 2022. Methods Eligible patients had their VT substrate mapped using a single-use ECGI vest and a 4D-CT simulation scan. In addition, MRI scans were used to aid anatomical identification of the anterolateral papillary muscle which could not be seen on the non-contrast diagnostic CTs. SBRT was delivered in a single fraction of 25 Gy under image guidance. Effectiveness of the treatment was evaluated as changes in frequencies of total antitachycardia pacing (ATP) and ICD shock episodes from 6 months pre-, and within to 3, 6, and 12 months follow up post SBRT. Results Participants were 3 males with NICM, aged 56, 60, and 73 with previous dual chamber ICD implantation, 2 of whom had a history of VT ablation/ VT storm and paroxysmal atrial fibrillation. All participants had basal lateral scar, and were receiving beta blockers, mexiletine, and amiodarone with refractory VT before SBRT treatment. Prior to SBRT, ICD device interrogation showed a total of 119 (77, 7, and 35 in patients 1-3 respectively) ATPs, and 27 (10, 1, and 16 in patients 1-3 respectively) ICD shocks delivered. At 12 month follow-up, none of the participants experienced any episodes of ATP or ICD shock. Ejection fraction remained consistent pre-post SBRT. Conclusion SBRT showed remarkable success in reducing ATP and ICD shock episodes, facilitating uncomplicated 1 year follow-up in 3 male patients with NICM and VT from the anterolateral papillary muscle.

Incidence of systolic heart failure and need for implantable cardiac defibrillators in patients with atrial fibrillation who had catheter ablation versus antiarrhythmic medical therapy

Abstract Background The CASTLE-AF trial demonstrated that patients with atrial fibrillation (AF) and heart failure with reduced ejection fraction (HFrEF) who underwent catheter ablation (CA) showed improved patient outcomes. These outcomes included a reduction in all-cause mortality and heart failure hospitalizations along with an improvement in left ventricular ejection fraction, when compared to those receiving medical therapy alone. However, there is no data regarding development of novel HFrEF and the need for implantable cardiac defibrillator (ICD) in patients with AF who underwent CA vs. those on antiarrhythmic therapy (AAD). Purpose This study aims to assess if there is a difference in the development of HFrEF and the need for ICD intervention amongst AF patients who underwent CA vs. those on AAD. We hypothesize that patients with AF who underwent CA will have a decrease in the development of HFrEF and mitigation in the need for ICD intervention compared to AAD alone. Methods A large retrospective, multicentre database was utilized to identify patients aged 18-80 with AF from 2017-2023. Two cohorts were subsequently established based on treatment received: 1) CA vs. 2) AAD (amiodarone, flecainide, dronedarone, dofetilide, propafenone, sotalol). Patients with crossover between the groups were excluded. Student’s t-test was performed to compare baseline characteristics between cohorts. Relevant comorbidities, atrial fibrillation types, and cardiovascular medications were used for propensity matching. Kaplan Meier curves were calculated to compare outcomes at 5 years such as HFrEF development, ICD implantation, mortality, and hospitalizations. Results Patients that underwent CA (n=32,774) and AAD (n=345,882) were propensity matched yielding 32,670 patients per cohort. CA demonstrated a significantly decreased need for ICD intervention compared to AAD (1.69% vs. 3.28%; HR=0.559; 95% CI [0.503, 0.621], log rank p&amp;lt;0.0001). Secondary outcomes showed significant reduction in development of systolic heart failure (4.83% vs. 10.60%; HR=0.499; 95% CI [0.467, 0.533], log rank p&amp;lt;0.0001), overall hospitalizations (12.03% vs. 27.32%; HR=0.440; 95% CI [0.420, 0.461], log rank p&amp;lt;0.0001), and all-cause mortality (2.38% vs. 14.19%; HR=0.188; 95% CI [0.174, 0.203], log rank p&amp;lt;0.0001) with catheter ablation. Conclusions Patients that underwent CA had a significant reduction in development of systolic heart failure and mitigation in the need for ICD implantation when compared to those on AAD alone. Randomized clinical trials are needed to better understand this relationship and to further define which subpopulation of atrial fibrillation patients would derive the most benefit from CA.