Ventricular Tachycardia Research Articles

Magnetic Resonance Myocardial Imaging in Patients With Implantable Cardiac Devices: Challenges, Techniques, and Clinical Applications.

Cardiovascular magnetic resonance imaging (MRI) in patients with cardiac implants, such as pacemakers and defibrillators, has gained importance in recent years with the development of modern cardiac implantable electronic devices. The increasing clinical need to perform MRI examinations in patients with cardiac implants has driven the development of new advanced MRI sequences to mitigate image artifacts associated with cardiac implants. More specifically, advances in imaging techniques, such as wideband late gadolinium enhancement imaging, wideband T1 mapping, and wideband perfusion, have been designed to improve image quality and examinations in patients with cardiac implants, enabling a comprehensive and more reliable diagnosis, which was previously unattainable in these patients. This review article explores recent developments and applications of wideband techniques in the field of cardiovascular MRI, offering insights into their transformative potential. Clinical applications of wideband cardiovascular MRI are highlighted, particularly in assessing myocardial viability, guiding ventricular tachycardia ablation, and characterizing myocardial tissue.

BOATMAP: Bayesian Optimization Active Targeting for Monomorphic Arrhythmia Pace-mapping

Recent advances in machine learning and deep learning have presented new opportunities for learning to localize the origin of ventricular activation from 12-lead electrocardiograms (ECGs), an important step in guiding ablation therapies for ventricular tachycardia. Passively learning from population data is faced with challenges due to significant variations among subjects, and building a patient-specific model raises the open question of where to select pace-mapping data for training. This work introduces BOATMAP, a novel active learning approach designed to provide clinicians with interpretable guidance that progressively assists in locating the origin of ventricular activation from 12-lead ECGs. BOATMAP inverts the input–output relationship in traditional machine learning solutions to this problem and learns the similarity between a target ECG and a paced ECG as a function of the pacing site coordinates. Using Gaussian processes (GP) as a surrogate model, BOATMAP iteratively refines the estimated similarity landscape while providing suggestions to clinicians regarding the next optimal pacing site. Furthermore, it can incorporate constraints to avoid suggesting pacing in non-viable regions such as the core of the myocardial scar. Tested in a realistic simulation environment in various heart geometries and tissue properties, BOATMAP demonstrated the ability to accurately localize the origin of activation, achieving an average localization accuracy of 3.9±3.6mm with only 8.0±4.0 pacing sites. BOATMAP offers real-time interpretable guidance for accurate localization and enhancing clinical decision-making.

A study on QT dispersion and thrombolytic therapy in acute myocardial infarction

Background: Myocardial infarction is a major manifestation of ischemic heart disease, a leading cause of death in developed nations and the third globally. QTc dispersion is an important marker of ventricular repolarization variations and arrhythmogenic risk. This study examines the effects of thrombolytic therapy on QTc dispersion in acute myocardial infarction Materials and methods: 88 patients admitted to Al Ameen Medical College Hospital, Vijayapur, for acute MI were included in the study. Over a period of 8±2 days, all patients underwent monitoring, with standard 12-lead ECGs conducted upon admission and before discharge. QT interval, QTc interval, and QT and QTc dispersion parameters were calculated from these ECGs. Results: Analysis revealed significant variations in QT parameters between patients treated and not treated with thrombolytic therapy. Patients receiving thrombolytic therapy exhibited greater reductions in QT parameters by day 8±2 compared to those without treatment. Additionally, anterior wall infarctions demonstrated significantly higher QT and QTc dispersions compared to inferior wall infarctions, with these differences being statistically significant. Conclusion: In the early stages of acute myocardial infarction, patients, especially those diagnosed with anterior myocardial infarction, exhibited significantly elevated QT and QTc dispersions. Thrombolytic treatment resulted in substantial reductions in these dispersions compared to untreated individuals. Typically peaking within the initial hours of the condition, these dispersions subsequently decline following successful thrombolysis, underscoring their significance in risk assessment for malignant ventricular tachyarrhythmias and reinforcing the efficacy of thrombolytic therapy

Role of ventricular tachycardia cycle length in the outcomes after catheter ablation or antiarrhythmic drugs in the SURVIVE-VT trial

Abstract Background It has been suggested that antiarrhythmic drugs (AAD) are less effective and safe in slow ventricular tachycardia (VT) due to their effect on conduction velocity, which could stabilize reentry. Conversely, catheter ablation aims to disrupt the VT circuit. Because of the distinct mechanisms of action of AAD and catheter ablation on the VT circuit, VT cycle length (VT-CL) may play a crucial role in determining their therapeutic efficacy. Therefore, VT-CL could be important in selecting VT treatment. Purpose The aim of this study was to assess the impact of VT-CL on outcomes following catheter ablation or antiarrhythmic drugs in AAD-naïve patients with ischemic cardiomyopathy presenting with VT. Methods This is a post hoc analysis of the previously published Substrate Ablation vs Antiarrhythmic Drug Therapy for Symptomatic Ventricular Tachycardia (SURVIVE-VT) trial. In summary, 144 patients with ischemic cardiomyopathy and symptomatic VT were randomized to receive either catheter ablation (N=71) or AAD (N=73) as first-line therapy. We analyzed VT recurrence, implantable cardioverter-defibrillator (ICD) therapies, and the incidence of slow/incessant VT/VT storm using Cox proportional hazard models, with treatment and VT-CL interaction terms, adjusted for age. Missing VT-CL data for five patients were imputed using the median value. Results In patients with chronic ischemic heart disease and VT treated with either AAD or catheter ablation, a significant interaction was observed between clinical VT-CL and treatment effect on VT recurrence (p=0.016 for the interaction). Specifically, slower VT cycle lengths were associated with higher rates of VT recurrence (hazard ratio per 10 ms [HR] 1.094, 95% confidence interval [CI] 1.015, 1.179; p=0.037) in patients treated with AAD, while no significant effect was observed in those undergoing catheter ablation (see Figure 1). Survival freedom from VT recurrence in patients with VT-CL ≥300ms was significantly higher in patients treated with catheter ablation (78.8% vs 58.1%, log-rank p=0.044, see Figure 2). As expected, VT-CL was significantly associated with a higher risk of slow/incessant VT/VT storm (HR per 10 ms 1.115, 95% CI 1.017-1.222, p=0.047) but was not associated with ICD therapies (HR per 10 ms 1.082, 95% CI 0.994-1.178, p=0.102). Conclusion VT-CL significantly influences treatment outcomes, with slower VT cycles associated with an increased risk of VT recurrence in patients treated with AAD, but not in those undergoing catheter ablation. Therefore, VT-CL should be taken into consideration when selecting the optimal therapy for patients with ischemic cardiomyopathy and VT.Figure 1Figure 2

Atrial rates during treated ventricular tachycardia in patients with implantable cardioverter defibrillators: clinical implications of a vagal sinus node response

Abstract Introduction Autonomic tone plays an important role in the genesis and sustenance of ventricular tachycardia (VT). Whilst sympathetic hyperactivity is an established driver of ventricular arrhythmias, sinus node response during VT varies broadly between patients, and can be paradoxical. Purpose We hypothesized that device-detected changes in sinus node rate could be an important surrogate of the autonomic response to VT, and may exert significant – and potentially modifiable – haemodynamic consequences independent of ventricular activity. Methods Device electrograms were analysed from consecutive patients with dual chamber implantable cardioverter defibrillators (ICDs) requiring anti-tachycardia pacing (ATP) or defibrillation for sustained monomorphic VT. Atrial rates were measured before VT onset (‘baseline’) and again at the point of detection by the device. Sinus node response was characterized as ‘stable’ (atrial rate remained within 10% of baseline), ‘sympathetic’ (atrial rate increased >10%) or ‘vagal’ (atrial rate decreased >10%). Patients who did not maintain ventriculoatrial dissociation or who presented in atrial tachyarrhythmia were excluded. Symptoms and electrical response to ICD therapies were recorded. Results 172 treated episodes of VT were included from 97 patients (median age: 69 years, 65% male, 31% ischaemic cardiomyopathy, median ventricular rate: 205bpm, median ejection fraction: 30%). Sinus node response was stable in 55%, sympathetic in 24% and vagal in 21%. A vagal response was associated with ATP-refractory VT (OR: 2.2 (1.1-4.8) p=0.03) and, when adjusting for ventricular rate, was independently associated with symptoms of presyncope or syncope (adjusted OR: 6 (2.7-13.7), p<0.0001). Conclusions This preliminary analysis suggests that a vagal sinus node response during VT is associated with adverse outcomes in ICD patients. Vagolytic therapy has recently been demonstrated to improve haemodynamic tolerance during VT ablation; whether supportive atrial pacing during VT could mitigate symptoms and potentiate arrhythmia termination in ICD patients warrants further exploration. Figure 1: Change in sinus node rate during sustained monomorphic ventricular tachycardia in patients with dual chamber ICDs, stratified by the occurrence of presyncopal symptoms or syncopeFigure 1

Stereotactic arrhythmia radioablation - A systematic review and meta-analysis of the prospective clinical studies

Abstract Background Stereotactic arrhythmia radioablation (STAR) is increasingly being evaluated in prospective studies as a new promising treatment option for patients with therapy-refractory ventricular tachycardia (VT). In STAR, the VT substrate is noninvasively treated with a high dose of radiotherapy. Recently, several single-arm prospective studies evaluating the clinical outcomes of STAR were published. Considering that the evidence base consists mainly of retrospective case series, we conducted a systematic review and meta-analysis to synthesize the prospective data on outcomes of STAR. Purpose To perform a systematic review and meta-analysis of prospective studies evaluating clinical outcomes of STAR for VT. Methods This study was registered in PROSPERO and adhered to the PRISMA reporting guidelines. Full-text studies describing prospective studies evaluating the safety and efficacy of STAR for VT were included in this study. Records published until August 2023 were retrieved from OVID MEDLINE, OVID Embase, Web of Science Core Collection, the Cochrane Central Register of Controlled Trials, and Google Scholar search engine (top 200 hits), deduplicated, and screened for eligibility. Abstract screening, full-text screening, data extraction and quality assessment were performed by two reviewers independently. Endpoints were defined as treatment related CTCAE grade ≥3 adverse events within 90 days after treatment, overall survival (OS), time to VT recurrence, and recurrence-free survival. Rates of patients achieving pre-defined 50%, 75% and 95% VT burden reduction thresholds were summarised. Random-effects generalized linear mixed-effects models and inverse variance models were used for the meta-analysis. Results 1861 records were identified, 987 were screened, and 10 full-text manuscripts published between 2019 and 2023 describing the results of STAR in 82 patients were included in this study. The majority were male (n=72; 88%), between 45 and 85 years old, and suffered from ischaemic cardiomyopathy (n=51; 62%). Median left ventricular ejection fraction ranged from 21 to 38% between studies. 20 patients did not undergo a prior catheter ablation for VT. All patients were treated with a single dose of 25 Gy and median planned target volume ranged from 45 to 198 cc between studies. Pooled 12-month OS rate was 0.73, and the proportion of patients experiencing grade ≥3 adverse events within 90 days after STAR was 0.11 (Figure 1). Reduction in VT burden is shown in Table 1. Although these were not pooled because of large heterogeneity in VT reduction time frame definitions, it can be appreciated that most of the patients experienced a reduction in VT burden. Conclusion The increasing evidence from prospective studies on STAR shows acceptable 12-month OS in a population of patients with advanced heart failure and refractory VT. Moreover, there is a modest rate of high-grade adverse events and most patients experience a reduction in VT burden.

Mineralocorticoid receptor antagonist therapy in patients with ischemic heart failure and ventricular tachycardia: a comparative analysis of spironolactone vs. eplerenone

Abstract Background Mineralocorticoid receptor antagonists (MRAs) are a cornerstone of heart failure therapy and have been shown to reduce the incidence of sudden cardiac death. However, a direct comparison between spironolactone and eplerenone in patients who present ventricular tachycardia (VT) is lacking. Purpose This study aimed to compare the effect of spironolactone and eplerenone on VT recurrence in patients with ischemic heart disease (IHD) hospitalized for VT episodes. Methods Our data utilized a registry of 405 patients with IHD and HF, who were hospitalized for an episode of sustained VT and received MRA therapy. We performed propensity score matching based on age, hypertension, diabetes, history of acute myocardial infarction, left ventricular ejection fraction (LVEF) and presentation with incessant VT. The matched population included 200 patients, stratified into two equivalent groups. Cox regression analysis was performed to identify predictors of VT recurrence, with Kaplan-Meier curves facilitating time-to-event analyses. Results The median age was 69 years and the majority (91%) were male. One-third had an ICD, and 41 patients (20%) had CRT. The median LVEF was 30%, 23 patients (12%) presented with an electrical storm, while 18 (9%) had incessant VT. VT led to hemodynamic instability in 91 cases (46%). Ablation was performed in 47 patients (24%), while 1 required mechanical circulatory support. Ablation was performed in 47 patients (24%), while 1 required mechanical circulatory support. Patients were followed for at least a year and median follow-up time was 414 days. A total of 78 patients had VT recurrence and 117 patients died. Eplerenone use significantly reduced the risk of VT recurrence compared to spironolactone (HR: 0.59 [0.37-0.93], p=0.023). This effect was consistent in the multivariate model as well (p=0.007). Conclusions Eplerenone use may confer a greater protective effect against VT recurrence in patients with IHD and sustained VT. Further studies are required to confirm these preliminary findings.

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.

Machine-learning models to predict the risk of recurrent VT following catheter ablation in patients with structural heart disease

Abstract Background Ventricular tachycardia (VT) is a life-threatening arrhythmia that can complicate structural heart disease. While catheter ablation is effective in treating this condition, the recurrence of VT after the procedure continues to be a concern. Consequently, there is a need for a reliable system to evaluate the likelihood of arrhythmia recurrence following an ablation. Objective To predict recurrence or repeat ablation after a VT catheter ablation procedure using machine learning (ML) models. Methods We conducted a single-center, retrospective study of all patients undergoing catheter ablation for scar-related VT between 2012 and 2022. Data collected included demographics, comorbidities, medications, relevant laboratory abnormalities, electrocardiograms, echocardiograms, detailed procedural characteristics, and outcomes. Python version 3.8.5 for exploratory data analysis (EDA) and visualization. Using six different ML models from the training set (90:10 split), we used 34 variables to predict the primary outcome, including VT recurrence or repeat catheter ablation. The accuracy of these models was compared using ROC curves based on their performance on the test set. Results Out of 508 VT ablation procedures, 261 experienced a recurrence. Support Vector Classifier (SVM) performed the best, having an AUC of 0.73, followed by logistic regression at 0.69 (Figure A). SVM yielded sensitivity, specificity, positive and negative predictive values of 0.73, 0.73, 0.79, and 0.67, respectively. The F1 score was 0.70. Among the factors with the highest feature importance in the model, the most influential variable was the proceduralist’s experience level, followed by QRS width at baseline, LVEF, and patient’s age (Figure B). Conclusion Our model can predict recurrent VT after ablation with reasonable accuracy, outperforming the existing clinical risk scores significantly. Larger training sample sizes will help achieve more robust ML models and improve predictive accuracy further.Figure A: ROC curve depicting the AUROCB. Feature importance graph

Comparison of ventricular tachyarrhythmias in HF patients on dapagliflozin versus empagliflozin

Abstract Background Ventricular tachycardia (VT) and ventricular fibrillation (VF) are devastating tachyarrhythmias that can cause sudden cardiac death in patients with heart failure (HF) if not anticipated or treated promptly. Although post-hoc analysis in DAPA-HF showed promise in their benefit, Sodium-glucose transport protein 2 inhibitors (SGLT2i) have not yet been evaluated for their effect on these tachyarrhythmias. This retrospective analysis aims to compare the 2 most commonly used SGLT2i agents, dapagliflozin and empagliflozin, and the incidence of VT in patients with HF. Methods The TriNetX Research network was used for this study. The two initial patient cohorts were created using ICD-10 codes and medication codes from the TriNetX platform. Both cohorts consisted of patients over age 60 with a history of heart failure and either VF or VT. One cohort was on treatment with dapagliflozin and the other with empagliflozin. The cohorts were balanced by propensity score matching and the greedy nearest neighbor algorithm for age, gender, race, ethnicity, hyperkalemia, and the current use of spironolactone, amiodarone, metoprolol, and carvedilol, resulting in 9,841 patients in each arm. The cohorts were then evaluated for the development of VF or VT over the subsequent five years as well as all-cause mortality. Additional cohorts were created to evaluate dapagliflozin vs empagliflozin in diabetics, nondiabetics, and patients with ejection fractions less than 35% Results Dapagliflozin was associated with an increased risk of ventricular arrhythmia in heart failure patients compared to empagliflozin (46.0% vs. 40.8%, RR 1.13, 95% CI (1.09,1.16), P value < 0.0001). It was also associated with higher mortality at five years (RR 1.10, 95% CI (1.03,1.18), P value 0.0034). Conclusions In comparisons between dapagliflozin and empagliflozin in heart failure patients with previously documented ventricular arrhythmias, empagliflozin had 13% less risk of recurrence of ventricular arrhythmias. Secondarily, the empagliflozin cohort also exhibited lower all-cause mortality (14.8% vs 16.3%) at five years from starting the drug. Our analysis does not disprove findings in DAPA-HF, but rather may support the potential class effect of SGLT2 inhibitors in their ability to suppress VT.(1) Importantly, the overall incidence of ventricular tachyarrhythmias is high in both cohort, given we selected a high-risk population. Notably, our documented recurrence rate is similar to past reports of recurrence after VT ablation, the gold standard for treatment of VT. (2) SGLT2 inhibitors have shown clear benefit in multiple placebo-controlled studies in terms of heart failure outcomes like mortality and readmission, but their effect on arrhythmias is one more additional benefit this class may have. (3) Given these associations, empagliflozin may be a more favorable options for HF patients who have already had VT or VF.

3D target definition and initial results from the electroanatomic substrate-guided stereotactic ablative radiotherapy for refractory ventricular tachycardia (ELSTAR-VT)

Abstract Background/introduction Noninvasive stereotactic radiotherapy (STAR) is an emerging transmural ablative therapy for refractory ventricular tachycardia (VT). Delineation of the arrhythmogenic gross target volume (GTV) relies on electrical (exit and isthmus) VT characteristics and anatomical scar detailing. 17-AHA segmental approaches or eyeballing techniques are adopted to transfer the GTV to the treatment planning CT. An individualized 3D GTV delineated with ADAS3D based on the areas of interest of each modality could lead to a smaller GTV compared to 17-AHA segmental approaches. Purpose We investigated whether our workflow using ADAS3D for the delineating of the GTV renders smaller GTV compared to 17-AHA segmental approaches whilst remaining effective for VT treatment during follow-up. Methods We targeted 3D-personalized GTV with STAR in patients with refractory VT in structural heart disease. Electroanatomical detailing was achieved by combining high-resolution invasive and noninvasive (ECG imaging during noninvasive programmed stimulation) mapping, combined with wall thickness analyses by cardiac CT. After coregistration in ADAS3D, a 3D DICOM-radiation therapy file including the delineated target volume was generated and transferred into the free-breathing and respiration-corrected 4D CT scan. Standard STAR using a single-fraction of 20-25 Gy was applied. We compared conventional (17-AHA segmental approaches) versus 3D-based GTV demarcation, and assessed VT burden and procedural safety. Results From January 2023 to February 2024 STAR was successfully performed in three patients (all male, mean age 73±1 years, two ischemic cardiomyopathy, one laminopathy) with persistent VT despite ≥2 catheter-based (endocardial/epicardial) ablation procedures. The 3D-derived GTVs showed a statistical trend towards smaller volumes compared to conventional segmental delineation (11±4 versus 21±3 cm3, p=0.07). VT burden and ICD therapy was reduced by 100% over 9 patients-months (8-week blanking period). No acute or subacute adverse events occurred. One patient died of progressive heart failure. Conclusion 3D-individualized target volume annotation may hold promise for effective and safe STAR employment.ELSTAR workflow

Ventricular tachycardia burden in heart failure with reduced ejection fraction - can we rely on optimized medical therapy

Abstract Introduction Implantation of cardioverter-defibrillator and/or resynchronization (ICD and CRT-D) devices is aimed to prevent sudden cardiac death, fatal complication of heart failure with reduced ejection fraction (HFrEF). Guidelines propose a period of 3 months receiving maximally titrated guideline-directed medical therapy (GDMT) prior to implantation. Ventricular tachycardia (VT) burden in HFrEF has been related to worse outcomes. The effect of GDMT up-titration on VT incidence after device implantation has not yet been fully clarified. Purpose The main goal of this study is to examine the effects of GDMT evidence-based target doses on VT and appropriate device therapy (ADT) incidence in patients with HFrEF implanted with ICD or CRT-D. Methods This registry-based study included patients with HFrEF who were implanted with ICD or CRT-D from January 2021 to November 2023, with at least one follow-up. Titration of GDMT and incidence of VT/ADT were evaluated. We compared VT/ADT incidence in target dose group to incomplete titration group of each drug class. We also compared GDMT titration and VT/ADT incidence in CRT-D to ICD group. The Fisher exact test was used to evaluate the differences between groups. Results Data on 132 patients were collected (mean age 63±26 years, 16% female). Median follow-up time from device implantation was 201 (30-748) days. Target doses were reached for 24.4% beta blockers (BB), 37.8% angiotensin receptor neprilysin inhibitors (ARNI), 73.5% mineralocorticoid receptor antagonists (MRA), 89.5% sodium-glucose contransporter-2 inhibitors (SGLT2I), and 18.8% of complete GDMT. Total VT and ADT incidence was 32.6% and 12.9%, respectively. In target doses vs. incomplete doses groups, VT incidence was 34.4% vs. 32.0% (p=.83) for BB, 28.0% vs. 35.4% (p=.45) for ARNI, 32.0% vs. 34.3% (p=.84) for MRA, 30.1% vs. 50.0% (p=.23) for SGLT2I and 33.3% vs. 32.4% (p=1) for complete GDMT. ADT incidence was 18.8% vs. 11.0% (p=.36) for BB, 12.0% vs. 13.4% (p=1) for ARNI, 12.4% vs. 14.3% (p=.77) for MRA, 11.0% vs. 21.4% (p=.39) for SGLT2i, and 16.7% vs. 12.0% (p=.51) for complete GDMT. In CRT-D vs. ICD group, 31.5% vs. 19,2% (p=.15) BB, 44.4% vs. 33.3% (p=.21) ARNI, 79.6% vs. 69.2% (p=.16) MRA, 98.1% vs. 83.3% (p<0.05) SGLT2I; and 20.4% vs. 16.7% (p=.65) of complete GDMT were maximally titrated. VT incidence was significantly lower in CRT-D group (18.5% vs. 42.3%, p<0.05). ADT was also lower, but without statistical significance (9.3% vs. 15.4%, p=.43). Conclusions Up-titration of any individual drug or complete GDMT to the evidence-based target dose did not directly correlate with a decrease in VT or ADT incidence. Cardiac resynchronization therapy provides more room for target GDMT doses, particularly of BB. We notice only a modest trend in up-titration of GDMT in patients with CRT-D, who had significantly lower incidence of VT.

Median dose area product and fluoroscopy time have stabilized on a low level during the last years: data from the swedish national catheter ablation registry

Abstract Background Despite the utilization of 3D-mapping systems, the use of fluoroscopy is still necessary in most procedures of catheter ablations of arrhythmias, but associated with serious health risks to both patients and operators. However, given the rapid improvement of the 3D-mapping systems, the usage of fluoroscopy has likely decreased during the past 15 years. Purpose The purpose of this study was to explore trends over time in usage of fluoroscopy in catheter ablation for all arrhythmias. Methods The Swedish Catheter Ablation Registry covers virtually all (>97%) catheter ablations performed in Sweden since 2005. Patients >18 years of age undergoing catheter ablation from January 1st 2006 to December 31st 2020 were included. Periprocedural data; median dose area product and fluoroscopy time were analyzed and compared. Periprocedural data were compared between 2006, 2015 and 2020 to find possible trends. Results A total of 61242 procedures were performed during the study period. The breakdown between the different arrhythmias was: 3% ventricular tachycardia (VT), 3% premature ventricular complex (PVC), 5% atrial tachycardia (AT), 7% atrioventricular junction ablation (AVJ), 10% atrioventricular reentry tachycardia (AVRT), 14% cavotricuspid isthmus ablation (CTI), 20% atrioventricular nodal reentry tachycardia (AVNRT) and 39% atrial fibrillation (AF). In 2006, the median fluoroscopy duration for AF, VT and PVC were recorded at 41, 32 and 37 minutes, respectively. Subsequently in 2015 the corresponding times were recorded at 14, 8 and 13 minutes. In 2020 respective procedures had a median fluoroscopy time of 11, 10 and 18 minutes (p< 0.001 for trend for all ablations). In 2006 median dose area product for AF, VT and PVC were 3998 cGycm2, 4300 cGycm2, and 5138 cGycm2, respectively. By 2015 the median dose area product had decreased to 1005 cGycm2, 432 cGycm2 and 1123 cGycm2 respectively. In 2020 the median dose area product had decreased further to 524 cGycm2, 380 cGycm2 and 848 cGycm2 (p<0.001 for trends for all ablations). See figure 1 for all procedures. Conclusion Fluoroscopy time and median dose area product have decreased significantly over a 15-year period and have stabilized on a low level over the last 5 years. Given the associated risks, efforts to further reduce radiation exposure are clearly warranted.Median dose area product

Cardiac motion in patients with ventricular tachycardia: potential implications for the treatment of patients candidates to stereotactic arrhythmia radio-ablation (STAR)

Abstract Background Stereotactic arrhythmia radio-ablation (STAR) has proven to be a valid alternative treatment for refractory ventricular tachycardia (VT) in patients who are unsuitable to undergo standard catheter ablation (CA). It consists in the application of external beam radiotherapy in a single dose of 25 Gy to the target areas. There is increased research activity on better understanding the complex and fast motion of the heart and on reducing radiation toxicity. Purpose In the context of an in silico study to evaluate the feasibility of STAR with protons in patients with VT, the initial findings related to cardiac motion on the first 10 patients are here presented. Methods Prior to CA, each patient underwent ECG gated CT scans in expiratory breath-hold, with and without contrast and reconstructed at 30% (systole) and 80% (diastole) of the cardiac R-R cycle. Contouring of the ablation target as a clinical target volume (CTV) for proton treatment planning was performed based on a standard electrophysiological study with 3D eletroanatomical mapping. Two different treatment plans were created: the first with only the diastolic CTV as target (gated treatment), the second including both diastolic and systolic CTVs to create an Internal Target Volume (ITV) in the hypothesis of non-gated treatment. Robust optimization was used to create the Planning Target Volume (PTV). Results The target volumes used for treatment planning are given in Table 1. The median CTV was 10.90 (2.93-36.94) cm3 for diastole and 14.26 (1.73-36.31) cm3 for systole. These volumes are somewhat smaller than those reported in patients treated previously with STAR: this difference may be due to the fact that no respiratory motion was included in the target contour and that the study population includes many patients referred for ventricular ectopic beats without structural heart disease, where the ablation target is expected to be smaller as compared to patients with VT in structural heart disease. Despite a small median difference between the diastolic and systolic CTV of 0.53 (0.03-9.61) cm3, the ITV approach resulted in a median increase in volume compared to the largest of the two CTVs of 29 % (1%-44%). When considering the proton range uncertainty and potential errors in patient positioning (PTV), the target is this time enlarged by a factor 2.9 (1.9-3.9). This data indicates that both cardiac motion and uncertainties in patient positioning before treatment will have a large impact on the treatment volume thus affecting the amount of surrounding tissue exposed to radiation. Conclusion The ablation target contour at systole and diastole are of similar magnitude but their non-overlap results in a large increase in treated volume when radiation delivery is not gated for cardiac motion. Further analysis shall investigate on a case-by-case basis the potential reduction in risk of healthy tissue toxicity with cardiac-gated proton delivery.Table 1

Endomyocardial biopsy in the diagnosis of cardiac sarcoidosis

Abstract Background Definite diagnosis of cardiac sarcoidosis (CS) requires proof of sarcoid granulomas in the heart. Endomyocardial biopsy (EMB) is considered a risky procedure with poor sensitivity (<25%) in CS (1), although comprehensive studies on its diagnostic performance are not available. Purpose We investigated the sensitivity, complications, and prognostic significance of EMB in a large cohort of patients with CS to help to choose diagnostic strategy when the disease is suspected. Methods We analysed the data of 260 consecutive patients diagnosed with CS in 1988-2022 at our institution. All met the diagnostic criteria of the Heart Rhythm Society (1). The use, findings, and complications of EMB were retrospectively noted in addition to patients’ demographics, presenting phenotype, diagnostic examinations, and future serious cardiac events. The data were retrieved from hospital records and an ongoing CS registry (2). Advanced imaging studies (cardiac magnetic resonance, positron emission tomography) were re-analysed and the follow-up information was updated until June 2023. EMB’s performance was assessed also in 30 cardiac transplant recipients having CS at the histopathologic study of the explanted heart. Results Of the 260 patients (mean age 49, 60% females), 216 (83%) underwent diagnostic EMB, 48 with repeat procedures. The sensitivity of EMB was 38%, rising to 49% after repeats. The predictors of positive EMB (Table 1) included the presenting phenotype and characteristics of the activity, extent, and location of myocardial involvement. Presentation with ventricular tachyarrhythmia, left ventricular (LV) ejection fraction ≤45%, elevation of cardiac troponins, and presence of middle or apical LV septal late gadolinium enhancement on magnetic resonance imaging were independent predictors (p<0.05) of positive biopsy. The sensitivity of EMB was directly related to the count of the predictors present (Figure 1). The rate of procedural complications was 9.7% overall and 0.7% for major events. One pericardial effusion needed drainage, but no deaths or long-term sequels followed the biopsies. Minor complications included 10 paroxysms of ventricular tachycardia and 6 small pericardial effusions. The 10-year rate (95% CI) of the composite of cardiac death, end-stage heart failure, or ventricular tachyarrhythmia was 55% (44-67%) with positive EMB vs 29% (17-44%) with negative EMB (p<0.001). When adjusted for the presenting phenotype and LV ejection fraction, EMB did not predict outcome events. In the 30 patients with CS in explanted hearts, the sensitivity of EMB, including the repeats, was 60%. Conclusion The sensitivity of EMB is better than usually presented in CS and the higher the more extensive myocardial involvement is. Risk of serious complications is <1%. In patients with suspect CS, the pre-test likelihood and value of positive EMB should be weighed against the procedural risks in shared decision-making when choosing the diagnostic pathway.

Risk stratification for a primary prevention ICD: Performance of the MADIT-ICD Benefit Score in contemporary real world patients

Abstract Background We have recently developed the MADIT-ICD Benefit Score to improve risk stratification for primary implantable cardioverter defibrillator (ICD) implantation by assessing the competing risk of life-threatening ventricular tachyarrhythmia (VTA) vs. non-arrhythmic mortality based using simple clinical variables. Patients with a MADIT-ICD Benefit Score of < 50 are more likely to experience non-arrhythmic mortality than life-threatening VTA, and therefore derive limited benefit from a prophylactic ICD. Purpose We aimed to provide data on the performance of the MADIT-ICD Benefit Score in a real world population, comprising patients with HFrEF and either ischemic or nonischemic cardiomyopathy (ICM/NICM) who are treated with contemporary guideline-directed medical therapy (GDMT). Methods The study population comprised 2875 patients who were implanted with a primary prevention ICD and prospectively followed in a large tertiary healthcare system (the University of Rochester Medical Center, including 3 affiliated hospitals in Upstate New York) between 2017 through 2023. Arrhythmic events were captured from device interrogation data, which were blindly adjudicated by 2 electrophysiologists. Results Among the 2875 study patients, mean age was 62 ± 15 years, 1265 (44%) were women, and 1667 (58%) had ICM. Guideline-directed medical therapies, including angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, angiotensin receptor/neprilysin inhibitors, beta-blockers, mineralocorticoid receptor antagonists, and sodium-glucose transport protein 2 (SGLT2) inhibitors, were prescribed to 43%, 36%, 96%, 67% and 32% of study patients, respectively. The 2-year cumulative incidence of VTA, after accounting for the competing risk of death, was 19% vs. 11% in patients with a Score of ≥50 vs. <50, respectively (p<0.001; Figure 1A). Findings regarding ICD shocks were consistent (8% vs. 4%, respectively, p<0.001; Figure 1B) The rate of VTA events at 4 years was directly correlated with increasing quartiles of the MADIT-ICD Benefit Score, while the corresponding rates of non-arrhythmic mortality were inversely correlated with score quartiles (Figure 1C). A similar direct correlation with increasing Benefit Score quartiles was observed when the endpoint of ICD shocks was assessed (Figure 1D). Accordingly, the benefit of the ICD (calculated as the difference between predicted rates of VTA/shock events and corresponding rates of non-arrhythmic mortality) was attenuated with decreasing quartiles of the MADIT-ICD Benefit Score (Figures 1C and 1D; right column). Conclusions We show good performance of the MADIT-ICD Benefit Score in a large cohort of real world ICD recipients who are treated with contemporary GDMT. These data support the use of the MADIT-ICD Benefit Score for improved risk stratification and for shared decision-making in contemporary candidates for a primary prevention ICD.

Impact of SLGT2 inhibitors treatment initiation on the reduction of atrial and ventricular arrhythmias in patients with implanted cardiac defibrillator

Abstract Introduction Sodium-glucose cotransporter type 2 inhibitors (SGLT2i) have been associated with improved prognosis in patients with heart failure; however, their impact on atrial arrhythmic (AA) and ventricular arrhythmic (VA) events is not fully understood. Methods Retrospective multicentric study of heart failure patients with implantable cardiac defibrillator device (ICD) from 2015 to 2020 with or without cardiac resynchronization therapy (CRT) receiving SGLT2 inhibitors. Device-registered arrhythmic events were analyzed and compared in two time periods for each patient: one year before and one year after starting SGLT2i. Relevant VA were defined as the occurrence of any sustained VT (SVT) (>30 seconds), ventricular fibrillation (VF), or appropriate therapy (antitachycardia pacing or shock). All VA included all the relevant VA and the occurrence of non-sustained ventricular tachycardia (NSVT). AA included atrial fibrillation (AF) burden, and episodes of more than 24 hour of AF. Results A total of 195 patients (66.8 [61.3-73.1] years, 18.5% women) were included. A reduction was observed in the percentage of patients with any VA (pre: 52.3% vs post: 30.3%; P < 0.001) and clinically relevant VA (excluding NSVT) (pre: 21.5% vs post 8.7%; P < 0.001) in the post-SGLT2i period. There was also a reduction in the number of episodes per patient/year of NSVT (pre: 2 (1-5) vs post: 1 (0-2); P < .001), and SVT (pre: 1 (1-3) vs post: 0 (0-2); p = 0.046). This protective effect was also observed after controlling confusion factors (Any VA: OR 0.35 (0,24-0,50); p<0.001 and relevant VA: OR 0.30 (0,17-0,52); p<0.001). However, no differences were observed in the prevalence of AA (24.7% vs 18.8%; P = 0.117) or the burden of atrial fibrillation (pre: 0% (0-0.1) vs post 0% (0-0); p = 0.097). Conclusions Following the initiation of SGLT2i treatment, a reduction in the percentage of patients with relevant VA was observed. However, this effect was not observed for AA.Figure 1Figure 2

Speckle tracking echocardiography as a predictor of location of ablation sites in candidates to catheter ablation for recurrent ventricular tachycardia

Abstract Background Preoperative imaging is essential before a ventricular tachycardia (VT) ablation procedure, to improve operative outcomes and reduce procedural times. Although MRI is the gold standard, it has several limitations, including patient compliance, possible presence of non-MRI-compatible devices, and long acquisition time. Speckle tracking echocardiography (STE) is a reliable and appealing technique that quantifies regional and global myocardial deformation, as well as layer-specific (endo-, mid- and epicardial) longitudinal strain, without MRI limitations. Purpose This study aimed to evaluate the efficacy of STE in predicting VT ablation sites. Methods In this study, we compared the bull’s eye segmentation of the left ventricle, global and layer-specific, obtained with STE (TomTec Arena), to investigate whether echocardiography can predict the areas of scar and late potential, as identified by electroanatomic mapping (EnSite X mapping, HD Grid mapping catheter, Abbott). Strain analysis and electroanatomic mapping data were matched segment-by-segment to obtain pairs of endocardial strain and bipolar substrate maps, as well as pairs of midmyocardial/epicardial strain and unipolar substrate maps. Results Twenty-three consecutive patients with an indication for catheter ablation for recurrent VT were enrolled. All patients were being treated with beta-blockers, 52% were taking amiodarone, and only 2 patients were on mexiletine. A total of 1170 pairs of bull’s eye segments were available for analysis. A binary logistic mixed-effects model was used to predict the presence of electroanatomical scar based on strain echocardiography data, to account for interpatient variability. The study findings highlighted a close correlation between the bipolar map and endocardial strain values, and between the unipolar map and midmyocardial strain values. Progressively higher (less negative) values of endocardial strain proved predictive of bipolar electroanatomical scar, with an increase in the odds ratio of bipolar electroanatomical scar equal to 6.2% (95% confidence interval 2.5%-10%) for each unit increase in strain values. Similarly, progressively higher values of midmyocardial strain were predictive of unipolar electroanatomical scar, with an increase in the odds ratio of unipolar electroanatomical scar equal to 6.2% (95% confidence interval 1.2%-11.4%) for each unit increase in strain values. Conclusions The data from our study showed an anatomical correspondence between the areas of low potential identified by electroanatomical mapping and the areas of anomalous longitudinal strain. In particular, the endocardial strain correlates with the bipolar map, and the meso-epicardial strain correlates with the unipolar map. These data may prove useful in the appropriate planning of the procedure in patients with an indication for catheter ablation in the context of recurrent VT.

Clinical profile of patients undergoing percutaneous stellate ganglion block for electrical storm and association with antiarrhythmic efficacy

Abstract Background Percutaneous stellate ganglion block (PSGB) usage for patients with refractory ventricular arrhythmias (VAs) in form of electrical storm (ES) is in quickly expanding. The clinical profile of patients and the potential association with the antiarrhythmic efficacy of the procedure are mostly unexplored. Purpose To better characterize clinical profile and potential association with antiarrhythmic efficacy of patients undergoing PSGB for ES. Methods Patients undergoing PSGB for ES in our Center from 2/2021 to 2/2024 were enrolled; all the dynamic variables were evaluated in a per procedure analysis. Results 45 patients (93% male, 64 ± 10 years) received a total of 80 PSGB performed with the lateral, ultrasound (US) guided technique; most PSGB consisted of a single bolus anesthetic injection (lidocaine + ropivacaine), 26% in an additional continuous infusion, mostly with ropivacaine. All procedures except for 3 in a single patient who had previously received left cardiac sympathetic denervation, were performed on the left side. Most of the patients (60%) suffered ischemic cardiomyopathy (CMP), including 10 with an acute coronary syndrome; the rest had non-ischemic CMP; 60% had an ICD. The type of VAs was ventricular tachycardia (VTs) only in 86% of the procedures (cycle length 404 ± 143 msec), VT and VF in 10% and VF only in 3 (4%). Most PSGB (81%) were performed in the setting of impending or manifest cardiogenic shock (SCAI classification B or more), including 20% with sepsis. Cardiac US performed before (within 12 hours) each PSGB showed a severely depressed left ventricular (LV) function (mean LVEF 22 ± 10%, mean LV outflow tract velocity time integral 12 ± 4 cm), calculated at a mean heart rate of 81 ± 16 bpm. Mean LVEDV was 252 ± 104 ml, 79% had mitral regurgitation (MR) ≥2+/4+ (including 39% severe MR), 50% had ≥ moderate diastolic dysfunction, 29% had right ventricular dysfunction (mean fractional areal change 33± 7%). Most cases (75%) experienced a complete VAs suppression (sustained or treated) in the 12 hours after PSGB; only 3/80 cases required additional urgent antiarrhythmic strategies (intra-aortic ballon pump in one case, urgent pacing in another one, urgent revascularization in the last one). None of the assessed clinical or echocardiographic characteristics was significantly associated with VT cycle length or the response to PSGB. Only 1 (1%) major complication occurred (respiratory arrest), that was quickly and effectively treated with lipid emulsion. Conclusions PSGB in our Center was mostly performed in the setting of primary impending or manifest cardiogenic shock with severely impaired cardiac function, with an excellent safety profile. None of the assessed clinical or echocardiographic variables were associated with response to PSGB. Our data, despite preliminary and requiring confirmation, suggests always considering PSGB in the urgent/emergent setting independently from patients’ characteristics.

In-hospital outcomes of ventricular tachycardia catheter ablation in the presence of intra-cardiac thrombus

Abstract Background Ventricular tachycardia (VT) catheter ablation in the presence of intracardiac thrombi was evaluated in very few studies. Objectives To investigate in-hospital outcomes of VT ablation in the presence of an intracardiac thrombus, in a large inpatient US registry. Methods Using the National Inpatient Sample (NIS) database, patients who underwent non-elective VT catheter ablations in the US between 2016 and 2019 were identified using ICD-10 codes. Sociodemographic, clinical data, in-hospital procedures and outcomes as well as in-hospital mortality were collected. In-hospital outcomes were compared using propensity score (PS) matching analysis with a 1:3 ratio between patients with and without intracardiac thrombus. Results A weighted total of 15,725 admissions for non-elective VT ablation were included in the study, of which 190 (1.2%) had a discharge diagnosis of intracardiac thrombus. Patients with intracardiac thrombus had a higher comorbidity burden and were more likely to have ischemic cardiomyopathy and a diagnosis of cardiac aneurysm. In PS analysis, the presence of intracardiac thrombus was significantly associated with higher rates of any in-hospital complications (42.1% vs 19.3%, P<0.009), driven by higher periprocedural cerebrovascular accident and vascular injury events. In-hospital mortality rates were not significantly different between the groups. Conclusions In patients undergoing non-elective VT ablation, intracardiac thrombus was associated with higher rates of in-hospital complications, but not higher in-hospital mortality. These findings suggest that intracardiac thrombus should not contraindicate VT ablation when deemed necessary, while efforts should be made to decrease potential complications.