Ventricular Tachycardia Research Articles

Emotion-Related Syncope in A Young Female Patient

Abstract A female patient in her 20s presented to our medical center with recurrent attacks of transient loss of consciousness that were essentially related to severe emotional situations. During hospital admission, she suffered an exercise-related presyncope while performing a stress ECG which recorded a transition from regular sinus rhythm into a bidirectional ventricular tachyarrhythmia which is a characteristic pattern of catecholaminergic polymorphic ventricular tachycardia.

The Impact of Coronary Ischemia Assessment on Outcomes in Those With Scar-Dependent Ventricular Tachycardia.

Guidance and outcomes of coronary ischemia assessment (IA) in those with structural heart disease (SHD), presenting with monomorphic ventricular tachycardia (MMVT) is unclear. To assess the impact of IA on arrhythmic and non-arrhythmic outcomes in those with SHD. Patients presenting with MMVT over a 6-year period to a tertiary center were retrospectively analyzed. Propensity score-matched analysis was performed comparing those undergoing IA to those who did not. The primary endpoint was a composite of VT recurrence, appropriate ICD therapy, heart failure hospitalization, and death. Secondary analysis of the individual components of the composite was performed. Kaplan-Meier, univariate and multivariate analysis was performed to compare the two groups and derive predictors of poor outcomes. Two hundred and seventeen patients (57.6% ICM) were analyzed. 55.8% underwent IA. Following propensity score-matching, 120 patients remained. At 12 months, freedom from the primary endpoint was 68.3% of those undergoing IA versus 43.3% who did not, p < 0.001, multivariate HR 0.56 (0.34-0.92). This was driven by a reduction in all-cause mortality, with a 12-month survival of 98.3% in those undergoing IA versus 86.5% in those not undergoing IA (p < 0.01). Coronary intervention was associated with a significantly higher event-free 12-month survival compared to those who did not undergo intervention (82.4% vs 51.5%, respectively, p = 0.01). Patients with SHD presenting MMVT who undergo an IA have significantly improved freedom from VT recurrence, appropriate ICD therapies, HF hospitalization, and death compared to those who do not, driven by a reduction in mortality.

Effect of Ischemia Testing and Coronary Revascularization on Mortality and Ventricular Tachycardia Recurrence in Patients With Monomorphic Ventricular Tachycardia Without Acute Coronary Syndrome: A Meta-Analysis and Systematic Review.

Studies show mixed results regarding the effect of coronary revascularization on mortality benefit and ventricular tachycardia (VT) recurrence in patients with monomorphic VT without acute coronary syndrome (ACS). This meta-analysis aimed to assess the effect of ischemia testing and/or coronary revascularization on mortality and VT recurrence in a pooled data set. Databases including PubMed, Google Scholar, and the Cochrane Library were searched from January 2000 to December 2023 for studies reporting event data on mortality and VT recurrence in patients without ACS who presented with monomorphic VT. Data were pooled and analyzed using random effects meta-analysis. The pooled sample consisted of a total of five studies, with 1062 patients, of whom 433 underwent ischemia testing and/or coronary revascularization and 629 did not. There was no statistically significant difference in the mortality and VT recurrence in the patients who underwent ischemia testing and/or revascularization versus those who did not (mortality odds ratio [OR]: 0.98; [95% confidence interval (CI): 0.62 to 1.53]; p = 0.92; VT recurrence OR: 1.07; [95% CI: 0.51 to 2.26]; p = 0.86). No publication bias was detected by examination of the funnel plot, Begg-Mazumdar's test (p = 0.80), and Egger's test (p = 0.91). In conclusion, in patients with sustained monomorphic VT in the absence of ACS, ischemia testing and/or revascularization does not lead to improved mortality or a decrease in the incidence of VT recurrence.

The Significance of rS Change in the V2 Lead for Diagnosing Ventricular Tachycardia Deserves Attention: A Case Report

Abstract Occasionally, incessant ventricular tachycardia (VT) exhibits a narrow QRS complex pattern that could be misdiagnosed as supraventricular tachycardia. In this case, a 66-year-old woman was referred to the emergency department due to the worsen hemodynamic and incessant VT manifesting as a narrow QRS complex pattern that was initially misdiagnosed as supraventricular tachycardia (SVT), which was unresponsive to antiarrhythmic drugs. The electrocardiogram manifestation of VT was characterized by an rS configuration in lead V2 with Rs pattern in leads V1 and V3, and the R-wave amplitude of lead V1 and V3 was greater than that of lead V2, which was different from the typical electrocardiogram features of right bundle branch block. The patient was subsequently found to have suspected acute myocarditis when the cause of the disease was investigated. A combination of high-dose methylprednisolone, immunoglobulin and intra-aortic balloon pump was given immediately. Hemodynamics gradually stabilized, and ventricular tachycardia did not recur. The rS change in the V2 lead may be helpful to distinguish VT from supraventricular tachycardia.

Prognostic Significance and Associations of Neural Network-Derived Electrocardiographic Features.

Subtle, prognostically important ECG features may not be apparent to physicians. In the course of supervised machine learning, thousands of ECG features are identified. These are not limited to conventional ECG parameters and morphology. We aimed to investigate whether neural network-derived ECG features could be used to predict future cardiovascular disease and mortality and have phenotypic and genotypic associations. We extracted 5120 neural network-derived ECG features from an artificial intelligence-enabled ECG model trained for 6 simple diagnoses and applied unsupervised machine learning to identify 3 phenogroups. Using the identified phenogroups, we externally validated our findings in 5 diverse cohorts from the United States, Brazil, and the United Kingdom. Data were collected between 2000 and 2023. In total, 1 808 584 patients were included in this study. In the derivation cohort, the 3 phenogroups had significantly different mortality profiles. After adjusting for known covariates, phenogroup B had a 20% increase in long-term mortality compared with phenogroup A (hazard ratio, 1.20 [95% CI, 1.17-1.23]; P<0.0001; phenogroup A mortality, 2.2%; phenogroup B mortality, 6.1%). In univariate analyses, we found phenogroup B had a significantly greater risk of mortality in all cohorts (log-rank P<0.01 in all 5 cohorts). Phenome-wide association study showed phenogroup B had a higher rate of future atrial fibrillation (odds ratio, 2.89; P<0.00001), ventricular tachycardia (odds ratio, 2.00; P<0.00001), ischemic heart disease (odds ratio, 1.44; P<0.00001), and cardiomyopathy (odds ratio, 2.04; P<0.00001). A single-trait genome-wide association study yielded 4 loci. SCN10A, SCN5A, and CAV1 have roles in cardiac conduction and arrhythmia. ARHGAP24 does not have a clear cardiac role and may be a novel target. Neural network-derived ECG features can be used to predict all-cause mortality and future cardiovascular diseases. We have identified biologically plausible and novel phenotypic and genotypic associations that describe mechanisms for the increased risk identified.

Gain-of-Function and Loss-of-Function Mutations in the RyR2-Expressing Gene Are Responsible for the CPVT1-Related Arrhythmogenic Activities in the Heart

Mutations in the ryanodine receptor (RyR2) gene have been linked to arrhythmia and possibly sudden cardiac death (SCD) during acute emotional stress, physical activities, or catecholamine perfusion. The most prevalent disorder is catecholaminergic polymorphic ventricular tachycardia (CPVT1). Four primary mechanisms have been proposed to describe CPVT1 with a RyR2 mutation: (a) gain-of-function, (b) destabilization of binding proteins, (c) store-overload-induced Ca2+ release (SOICR), and (d) loss of function. The goal of this study was to use computational models to understand these four mechanisms and how they might contribute to arrhythmia. To this end, we have developed a local control stochastic model of a ventricular cardiac myocyte and used it to investigate how the Ca2+ dynamics in the mutant RyR2 are responsible for the development of an arrhythmogenic episode under the condition of β-adrenergic (β-AR) stimulation or pauses afterward. Into the model, we have incorporated 20,000 distinct cardiac dyads consisting of stochastically gated L-type Ca2+ channels (LCCs) and ryanodine receptors (RyR2s) and the intervening dyadic cleft to analyze the alterations in Ca2+ dynamics. Recent experimental findings were incorporated into the model parameters to test these proposed mechanisms and their role in triggering arrhythmias. The model could not find any connection between SOICR and the destabilization of binding proteins as the arrhythmic mechanisms in the mutant myocyte. On the other hand, the model was able to observe loss-of-function and gain-of-function mutations resulting in EADs (Early Afterdepolarizations) and variations in action potential amplitudes and durations as the precursors to generate arrhythmia, respectively. These computational studies demonstrate how GOF and LOF mutations can lead to arrhythmia and cast doubt on the feasibility of SOICR as a mechanism of arrhythmia.

Abstract 4113336: Characteristics and Outcomes of Ventricular Tachycardia Ablation in Patients with the HeartMate 3 Left Ventricular Assist Devices: Results From a Large Single-Center Registry

HeartMate 3 (HM3) is a fully magnetically levitated continuous flow left ventricular assist device (LVAD). In patients with HM3 and recurrent ventricular tachycardia (VT), data on the outcomes of catheter ablation (CA) are insufficient. We report our institutional experience with CA of VT in patients with the HM3.Consecutive patients with HM3 and recurrent drug-refractory VT undergoing CA were included. Ablation sites were identified using activation/entrainment mapping (stable VTs) and/or late/fractionated potential ablation and pace-mapping (unstable VTs). Between 2016-2023 a total of 431 patients (age 58±13, INTERMACS 3±0.98, 44% ischemic cardiomyopathy) received an HM3 LVAD at our institution. Of these, 15 (3.4%) underwent CA for recurrent VT despite therapy with 1.3±0.8 antiarrhythmic drugs a median of 700 days from the LVAD surgery (2 patients &lt;1 month from the surgery). The LV access was transseptal in 12 (80%) cases, retrograde aortic in 2 (13%) and both in 1 (7%). A total of 23 distinct VTs were targeted. Of these, 21 (91%) were mapped with activation/entrainment mapping, always utilizing an intracardiac RV reference due to excessive surface ECG noise, and 2 (9%) were hemodynamically unstable with reduced LVAD flows and targeted with substrate-based ablation. A total of 3 (13%) VTs were targeted adjacent to the HM3 inflow cannula, and 20 (87%) from substrate remote from the HM3 cannula. At post-procedural programmed ventricular stimulation, non-inducibility of all targeted VTs was achieved in 13 (87%) patients, 1 patient had residual inducible clinical VT, and in 1 patient no post-procedural programmed stimulation was performed. Periprocedural complications occurred in 1 (7%) case (small pericardial effusion not requiring intervention). At 12 months follow-up following the index procedure, no death occurred and one patient received heart transplantation. Of the remaining 14 patients, 6 (42%) remained free from VT (2 with VT ablation &lt;1 month post-LVAD and 12 with VT ablation &gt;=1 month post-LVAD). In this large single-center HM3 registry, a minority of patients underwent CA for recurrent drug-refractory VT (3.4% over a 7-year period). CA of VT in HM3 recipients is feasible and appears safe also when performed soon after LVAD surgery. Myocardial scar from the underlying cardiomyopathic process rather than the apical cannula is the dominant substrate responsible for VT in these patients.

Abstract 4148095: The Impact of Body-Mass Index on Ventricular Tachycardia Outcomes Post-Catheter Ablation

Background: In recent years, catheter ablation has emerged as a sustainable, first-line therapy for the management of ventricular tachycardia (VT). Given the rise of the “obesity paradox” theory in atrial ablation outcomes, we sought to study the effect of BMI on patients undergoing structural VT ablation. Purpose: To assess the outcomes of VT ablation, specifically VT recurrence, in patients with elevated vs. normal BMI. Methods: Clinical characteristics and demographic data were collected for VT patients who underwent ablation at Mayo Clinic Rochester from 2012-2022. Patient BMI was classified as non-obese (&lt;30 kg/m2), obese (30-40 kg/m2), and morbidly obese (≥40 kg/m2). The endpoint was a composite of initial monomorphic VT recurrence and repeat ablation after adjusting for age, sex, and comorbidities. Results: A total of 399 patients underwent 508 ablations. 51.4% of ablations had a BMI &lt;30, 39.2% were between 30-40, and 9.4% were ≥40. There was a greater prevalence of hypertension and type 2 diabetes mellitus in morbidly obese patients (p &lt;0.01). Morbidly obese individuals also had a significantly increased rate of general anesthesia during ablation and long VT cycle lengths. The Kaplan-Meier curve demonstrates no statistically significant differences in time to VT recurrence among the three BMI groups (p = 0.324). Neither morbid-obesity (aHR= 1.20; CI = 0.94-1.56, p = 0.14) nor nonmorbid-obesity (aHR = 0.92; CI = 0.76-1.10, p = 0.4), compared to non-obesity was a significant independent predictor of VT recurrence or repeat ablation on multivariate regression after adjusting for age, sex and comorbidities. Conclusion: There was no significant association between BMI groups and VT recurrence or repeat ablation, and no difference in complications. We did not find the obesity paradox to be relevant for VT ablation in our patient population. Further study would be needed with larger samples to corroborate these findings.

Abstract 4143264: A Case of Spike-on-T Phenomenon and Polymorphic Ventricular Tachycardia

Background: R-on-T phenomenon occurs when an electrical stimulus is delivered at a critical point during ventricular repolarization. This can initiate ventricular arrhythmias like polymorphic ventricular tachycardia (PMVT). We describe a case of ventricular pacemaker spikes delivered on the T wave causing PMVT. Case: A 53-year-old female with CAD s/p stent, postpartum cardiomyopathy s/p Bi-V CRT-D (Boston Scientific G124), and paroxysmal atrial fibrillation presented for elective endoscopy and colonoscopy to evaluate her dysphagia and abdominal pain. Her CRT-D was reprogrammed from DDD pacing with lower rate limit (LRL) 50 bpm to an asynchronous Bi-V DOO mode at 50 bpm (‘electrocautery mode’) for the procedure (tachy therapy disabled). Her LV-RV offset was 40 msec. Prior to receiving sedation or medications, she was found unresponsive. Telemetry showed Spike-on-T phenomenon which initiated PMVT. She was externally defibrillated with 200J and received magnesium and an IV amiodarone bolus. She returned to sinus rhythm, but one minute later had another Spike-on-T event initiating PMVT. She was successfully defibrillated with 360J. Post-shock EKG showed an asynchronous Bi-V paced rhythm at 50 bpm. Decision Making: The patient was admitted to the CCU for post-resuscitation care. Her electrolytes and cardiac enzymes were unremarkable. Her CRT-D was reprogrammed to DDD 80-140 bpm. Transthoracic echocardiogram showed normal biventricular systolic function. Cardiac catheterization did not show obstructive CAD. After reprogramming of her device, she had no further events. After initial treatment with IV amiodarone load, she was discharged home on oral magnesium gluconate. Discussion: The only intervention prior to her procedure was device reprogramming (DDD 50 bpm to DOO 50 bpm). Telemetry showed pacer spikes initiating PMVT. Given the LV-RV offset of 40 msec, she would have received these two tightly coupled pacemaker spikes in an asynchronous mode, in this unfortunate instance during her T wave. While her bowel preparation may have led to electrolytes abnormalities, post-resuscitation electrolytes were normal. Fortunately, she received prompt therapy and was reprogrammed with increased LRL. Conclusion: We described a case of Spike-on-T PMVT prior to colonoscopy without obvious provocation other than asynchronous pacemaker spikes. Reprogramming devices in DOO mode with increased LRL may prevent PVCs and asynchronous pacemaker spikes from triggering PMVT.

Catheter Ablation for Ventricular Tachycardias: Current Status and Future Perspectives

Catheter ablation for ventricular tachycardia (VT) in patients with systolic heart failure remains a critical yet challenging area of non-pharmacological therapy. Despite positive outcomes in atrial fibrillation, evidence for the efficacy of VT ablation in reducing cardiac mortality is inconclusive due to the absence of standardized ablation strategies. The primary challenges include difficulties in identifying suitable ablation targets and their deep locations within myocardial tissue. Current techniques, such as voltage mapping, provide valuable insights; however, they are limited by the presence of numerous bystander areas and the occurrence of incomplete transmural scarring. Recent advancements in functional substrate mapping have focused on identifying critical isthmuses without requiring hemodynamic stabilization during VT, thereby shifting the emphasis to the analysis of potentials during baseline rhythm. While methods like isochronal late activation mapping have improved target identification, they primarily address conduction abnormalities without adequately considering repolarization heterogeneity. This review highlights emerging technologies that utilize unipolar potentials to assess repolarization heterogeneities and identify VT isthmuses. Furthermore, novel ablation sources such as pulsed-field ablation, bipolar ablation, and ultra-low temperature cryoablation are being explored to create deeper and more durable lesions, addressing the limitations of traditional radiofrequency ablation. These advancements aim to reduce VT recurrence and improve overall treatment efficacy. Ultimately, understanding these innovative strategies is expected to optimize procedural outcomes and significantly enhance the management of patients with scar-related VT.

Abstract 4132217: Comorbidities Associated with One Year Mortality and Hospital Readmission After Ventricular Tachycardia Ablation

Introduction: Many studies have evaluated outcomes after ventricular tachycardia (VT) ablation though few studies have evaluated outcomes past thirty days. This study aimed to determine which comorbidities are associated with one-year readmissions and mortality after VT ablation, including socioeconomic disadvantage (SED) via the Area Deprivation Index (ADI). Methods: Patients ages ≥18 were identified in the Healthcare Cost and Utilization Project State Inpatient Databases in New York and Florida from 2016-2019 with follow-up into 2020. These states were chosen due to availability for linkage of the 2020 ADI (1-100, higher scores representing more disadvantage). International Classification of Diseases 10 codes for VT and VT ablation were used. Patients undergoing pacemaker placement or with other arrhythmias were excluded. The risk of readmission and mortality was assessed using Cox proportional hazards first in an unadjusted fashion for each comorbidity in the Charlson Comorbidity Index. In addition to demographic variables, only significant variables from the unadjusted analysis were included in the final adjusted multivariable models. Results: 1,798 patients met inclusion criteria. The readmission and mortality rates at one, three, and twelve months were 18.5%, 27.4%, 41.4% and 3.5%, 4.1%, 6.5%, respectively. Common diagnoses for readmission were VT (24.8%) and dyspnea/chest pain (10.7%). After adjustment, African American race, federal insurance, heart failure (CHF), vascular disease, renal disease (CKD), severe liver disease (SLD), and higher ADI were associated with increased risk for twelve-month readmissions. Federal insurance, CHF, cerebrovascular disease, dementia, peptic ulcer disease, CKD, and SLD were associated with increased risk for twelve-month mortality. Conclusion: CHF and CKD increased the risk of readmission and mortality. Recurrent VT was the most common cause of readmission. Patients of SED are at increased risk of readmissions within one year.

Abstract 4135194: Safety and Efficacy of Mechanical Circulatory Support during VT ablation

Introduction: Ventricular arrythmias are prevalent in patients with advanced heart failure and associated with increased mortality. Outcomes of electrophysiology ablation on patients requiring mechanical circulatory support (MCS) are not well described. We aimed to analyze the safety and efficacy of ventricular tachycardia (VT) ablation in patients requiring MCS at the Emory system. Methods: Patients were identified via retrospective chart review from October 2022 through August 2023. Patients who underwent VT ablation with the support of Impella, left ventricular assist device (LVAD), intra-aortic balloon pump (IABP), and venoarterial extra-corpeal membrane oxygenation (VA ECMO), or any combination of these were included. Results: A total of 7 patients of average age 56 ± 10 years, predominantly male (85.7%), with cardiomyopathy of mean EF 18.6% +/- 8.5 (ischemic 71.4%) underwent MCS supported VT ablation. One patient had 2 separate VT ablation procedures for refractory VT. Of these 8 procedures, 4 utilized a single type of MCS (2 impella, 2 LVAD) while 4 used a second type of MCS in combination with an Impella (2 impella RP, 1 VA ECMO, 1 IABP). Success at time of ablation was present in 75% of cases. Average time of outpatient follow up was 82 ± 31 days. At time of follow up, 50% of patients remained free of VT or with a single VT episode not requiring implantable cardioverter-defibrillator (ICD) shock. One patient had gone on to undergo successful heart transplantation. Procedural complications were noted in one patient, who suffered cardioembolic cerebrovascular accident (CVA) 2 days post-op. Transthoracic echo (TTE) 5 days post-op revealed LV mural thrombus as likely etiology of CVA. Conclusion: While there are no clear guidelines directing the use of MCS during VT ablation, our single academic institution experience suggests safety and feasibility of its use to support select, high risk cases.

Abstract 4135425: Add-on Therapy with Dantrolene, a RyR2 Stabilizer, Terminates Ventricular Tachycardia Storm refractory to Intravenous Amiodarone in Heart Failure.

Background: Aberrant diastolic Ca 2+ leak through the cardiac ryanodine receptor (RyR2) is an important cause of heart failure (HF) and lethal arrhythmia. Dantrolene (DAN) specifically binds to the Leu 601- Cys 620 of N terminal domain in RyR2 and stabilizes the tetrameric structure of RyR2, preventing the Ca 2+ leak through RyR2. Our previous study as a proof-of-concept showed that intravenous injection (i.v.) of DAN was effective in termination and prevention of refractory ventricular tachycardia (VT) storm in HF. Research Question: How much is loading dose of DAN i.v. to terminate VT storm in HF? We hypothesized that the optimal dose was within 3mg/kg from our previous study. Aim: This study aimed to verify that 3mg/kg DAN i.v. was optimal for the termination of amiodarone-resistant VT storm in HF. Methods: This was an open-label, uncontrolled, single-center study. The detail in the study design and methods is shown in Fig.1 . We studied patients with episodes of VT storm regardless of medications, such as amiodarone and beta-blockers, recommended by HF guidelines. DAN(3mg/kg) was intravenously added on the above guideline treatment. The acute anti-arrhythmic efficacy of DAN was assessed as follows: 1) proportion of patients whose VT storm was terminated by 3mg/kg DAN i.v., 2) incidence rate of VT storm within 24 hours before and after DAN i.v.. Results: The consecutive 7 patients with refractory VT storm were enrolled in this study (median age:72 years old, male/female: 4/3, median LVEF29%). Underlying heart disease included 3 ischemic cardiomyopathy, 3 acute myocardial infarction after successful percutaneous coronary intervention and 1 tachycardia-induced cardiomyopathy. 2 of 7 patients underwent mechanical circulatory support before DAN i.v. because of pulseless VT. All patients were classified as NYHA class III/IV. 3 mg/kg of DAN i.v. ceased VT storm within 60 min in 7/7 (100%) (Fig.2, left). The number of sustained VT within 24 h after DAN i.v. were significantly lower than those within 24 h prior to DAN administration (Fig 2, right) . A representative case is shown in Fig.3 The VT storms refractory to amiodarone and landiolol (beta-blocker) as well as sedation showed complete response to 3mg/kg DAN i.v.. Conclusions: DAN, a RyR2 stabilizer, was effective in the termination of VT storm in HF resistant to guideline directed medical treatment. This is the first study to evaluate the optimal dose of DAN i.v. against the refractory VT storm in HF.

Abstract 4138424: Ring of Power: Unraveling a Rare Diagnosis in a Young Male with Palpitations

Case Description: A 36-year-old male presented for an outpatient treadmill ECG stress test for further evaluation of palpitations exacerbated by exercise. He had no ischemic ECG changes, but developed a sustained episode of polymorphic VT at 13 minutes (Figure 1a). The test was stopped and the VT self-terminated after 43 seconds. The patient was admitted for further workup. Lab workup was unremarkable; baseline ECG demonstrated no ST-T wave changes and displayed normal QT and QRS duration. TTE showed mild biventricular dysfunction. Coronary CT angiogram showed type 3 subtype of Vieussens’ arterial ring (VAR), with an absent left main and super-dominant RCA supplying both LAD and LCx. FFR-CT showed non-hemodynamically significant stenosis in the mid-distal LAD (Figure 1b). Left heart catheterization confirmed presence of VAR and mild diffuse disease in a small-caliber mid-distal LAD (Figures 1c&amp;d). No malignant course or dynamic coronary compression was present. Cardiac MRI revealed normal biventricular function and the absence of late gadolinium enhancement. An exercise stress test, now with myocardial perfusion, was performed and was entirely normal without evidence of myocardial ischemia. Genetic testing for catecholaminergic polymorphic VT was negative. After a multidisciplinary discussion, it was decided not to pursue CABG in the absence of demonstrable ischemia at peak exercise. He underwent an ICD placement for secondary prevention and was discharged on beta blockers. Discussion: Three distinct subtypes of VAR have been described, with type 3 being the rarest. The coronary anomaly was first described by Raymond de Vieussens in 1706, and represents an embryologic remnant of the conotruncal circle. It may be diagnosed incidentally in asymptomatic patients or present with angina especially if underlying CAD, aneurysms or fistulae are present. We report the first case of exercise-induced polymorphic VT in a type 3 VAR patient, theorizing that intermittent myocardial ischemia at peak exercise may induce VT in these patients. Surgical revascularization may be considered if myocardial ischemia is demonstrated on stress testing, although its benefit in patients without such evidence of ischemia is unknown.

Risk stratification for ventricular tachyarrhythmia in patients with nonischemic cardiomyopathy.

The implantable cardioverter defibrillator reduces mortality among patients with heart failure (HF) due to ischemic heart disease. Clinical trial data have called into question the benefit of an ICD in patients with HF due to nonischemic cardiomyopathy (NICM). We developed a risk stratification score for ventricular tachyarrhythmia (VTA) among patients with NICM receiving a primary prevention ICD. The study population comprised 1515 patients with NICM who were enrolled in the landmark MADIT trials. Fine and Gray analysis was used to develop a model to predict the occurrence of VTAs and ICD therapies while accounting for the competing risk of non-arrhythmic mortality. External validation was carried out in the RAID Trial population. Four risk factors associated with increased risk for VTA were identified: male sex, left ventricular ejection fraction ≤25%, no indication for cardiac resynchronization therapy with a defibrillator (CRT-D), and Black race. A score was generated based on this model, and patients were stratified into low (N = 390), intermediate (N = 728), and high-risk (N = 387) groups. The 5-year cumulative incidences of VTA were 15%, 24%, and 42%, respectively. Application of score groups for the secondary endpoints of Fast VT or VF and Appropriate ICD Shock revealed similar findings. Recurrent event analysis yielded consistent results. The AUC in the validation cohort for the endpoint of Appropriate ICD Shock was 69.3. Our study shows that patients with NICM can be risk stratified using demographic and clinical variables and may be used when evaluating such patients for a primary prevention ICD.

Abstract 4137919: Electrical Storm Caused by Chagasic Cardiomyopathy Successfully Treated with Ventricular Aneurysmectomy

Introduction: Chronic Chagasic cardiomyopathy (CCC) is a serious complication of Chagas disease that can manifest as LV dysfunction, ventricular aneurysms, and ventricular arrhythmias. Management of the electrical storm in CCC is challenging, especially when it is refractory to catheter ablation. Case Presentation: A 59-year-old woman from southern Peru presented to the ED with palpitations and dyspnea for 1 week. Physical exam was normal. ECG showed Q waves in III and AVF leads. TTE revealed an LVEF of 45% with an inferolateral LV aneurysm. Coronary angiography showed no lesions. CCC was suspected and serology was ordered, which was positive for T. cruzi . Cardiac MRI confirmed the presence of a 32x22mm basal inferolateral LV aneurysm. During hospitalization, she experienced 4 episodes of unstable monomorphic ventricular tachycardia (VT) within 24 hours, requiring defibrillation with 200J, vasopressor support, and invasive mechanical ventilation. The diagnosis of electrical storm secondary to CCC was proposed, for which amiodarone infusion was started until complete impregnation was achieved. Additionally, support was provided with IABP and specific antiparasitic treatment with benznidazole. Electrophysiology determined that the probable focus of the VT was situated at the level of the LV aneurysm. Therefore, ablation with endocardial-epicardial mapping was performed. However, the patient continued to experience recurrent episodes of VT. Consequently, in a multidisciplinary discussion, it was decided to perform a ventricular aneurysmectomy, which was successful. The patient's clinical progress was favorable, with initiation of GDMT and placement of a single-chamber ICD for secondary prevention. After one year of outpatient follow-up, the patient remains free of VT recurrences. Conclusion: Ventricular aneurysmectomy is a successful management approach for patients with CCC who present with electrical storm refractory to antiarrhythmic drugs and catheter ablation, and whose VT is believed to originate from the aneurysm. The diagnosis of CCC is highly arrhythmogenic and should be suspected at an early stage, given the patient's demographics and the presence of LV aneurysm in the absence of coronary artery disease.

Abstract 4124604: Finding the Right Course: Unknown Source of Hemorrhage Following Endocardial-Epicardial Ablation for Ventricular Tachycardia

Background: Epicardial radiofrequency ablation via percutaneous access is a common technique for ventricular tachycardia (VT) ablation. Rapid identification of and response to complications can reduce morbidity and mortality. Objective: We present a case of epicardial VT ablation complicated by a distal left internal mammary artery (LIMA) transection secondary to subxiphoid sheath insertion. Report: A 66-year-old man with hypertrophic cardiomyopathy was referred for endo-epicardial ablation of recurrent VT. Pericardial access was obtained using coronary vein exit and carbon dioxide insufflation technique. An 8.5F sheath was advanced over an indwelling pericardial wire, and ablation was performed. Following ablation, 400cc of blood was aspirated from the pericardial space after replacing the 8.5F sheath with a standard pericardial drain. Urgent angiography revealed intact coronary arteries, coronary sinus (CS) and LIMA. The 8.5F sheath was re-introduced and bleeding ceased. CT scan revealed no myocardial or great vessel damage. Mild pericardial drainage continued overnight. The next day, IR angiography demonstrated transection of the distal LIMA from the indwelling sheath. The patient underwent placement of a back-up pericardial drain, followed by coil embolization of the injured artery without complication (Fig). Conclusion: This case highlights the importance of maintaining a broad differential during apparent complications of epicardial access and the importance of staying close to midline for epicardial puncture given anatomic variability. The differential for acute blood loss and pericardial effusion following epicardial ablation includes 1) coronary artery damage, 2) CS damage, 3) extracardiac vascular injury, and 4) right ventricular injury. When extracardiac vascular injury is suspected, multidisciplinary collaboration is essential.

Abstract Su304: The Effect of Time to DC Shock on Return of Spontaneous Circulation in Out-of-Hospital Cardiac Arrest with Recurrent Shockable Rhythm

Objective: The optimal timing for defibrillation attempts in out-of-hospital cardiac arrest (OHCA) patients with recurrent shockable rhythms [ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT)] is uncertain. This study examined the association between "time to DC shock" and the return of spontaneous circulation (ROSC) in OHCA patients with recurrent shockable rhythms. Methods: This was a retrospective analysis of data from the Salt Lake City Fire Department (SLCFD) from 2012 to 2023. Rhythm-filtering technology, used since 2012, enabled real-time and accurate interpretation of cardiac rhythms during CPR, with local protocols allowing early defibrillation for recurrent VF/ pulseless VT cases. Patients who experienced four or five episodes of shockable rhythms and received defibrillation were included. Generalized estimating equation (GEE) analysis was used to evaluate the association between time to shock preceding recurrent defibrillation and ROSC. Results: A total of 142 patients were included, with a mean age of 59.7 ± 15 years; 105 (73.9%) were male, 63 (44.4%) arrested in public locations, and 101 (71.1%) had witnessed arrests. Adjusted GEE analysis revealed that longer time to shock was associated with lower odds of achieving ROSC (OR: 0.81, 95% CI: 0.72–0.93, p = 0.005). Every one-minute delay in defibrillation is predicted to decrease the likelihood of achieving ROSC by 19%. Conclusion: In patients with recurrent shockable rhythms, every one-minute delay in delivering a shock was associated with a statistically significant 19% reduction in the chance of achieving ROSC. This finding highlights the importance of reducing the time to defibrillation in managing recurrent shockable rhythms and suggests reevaluating the current recommendation of two-minute intervals for rhythm check and shock delivery.

Abstract 4122247: Impact of serum chloride levels for ventricular arrhythmias in patients with heart failure undergoing cardiac resynchronization therapy

Background: As previous reports of ventricular arrhythmia (VA) as a prognostic marker of mortality in heart failure (HF) patients included those with implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT) devices, little is known about the risk factors of VA among patients undergoing cardiac resynchronization therapy (CRT), especially those without previous VA. The prognostic role of electrolyte abnormalities has been highlighted in HF patients. This study evaluated the impact of serum chloride levels for VA and all-cause death in patients with HF who underwent CRT without VA before CRT implantation. Methods: From the retrospective cohort of 397 HF patients (age 63+/-13, male 74%) who undergoing CRT implantation between 2010 and 2020, this study enrolled 175 patients (82% implanted CRT with a defibrillator) without a previous history of VA (sustained ventricular tachycardia (VT) of ventricular fibrillation (VF)). We studied the impact of serum chloride levels before CRT implantation. The primary endpoint was defined as VA, VA with ICD therapy and sudden cardiac death. The secondary endpoint was all-cause mortality. Results: During median follow-up of 35 months, 53 patients (30%) experienced VA. Patients with VA had a tendency toward high LVESV (172ml vs. 150ml, p&lt;0.09) and low left ventricular ejection fraction (26 vs. 29, p&lt;0.09), and significantly reduced rate of angiotensin converting enzyme inhibitors or angiotensin receptor blockers (30% vs. 70%, p&lt;0.05) at the time of CRT implantation. The rate of CRT responders was significantly higher in patients without VA than with VA (59% vs. 40%, p&lt;0.05). The cut-off value of chloride for VA was determined to be 102mEq/l using receiver operating characteristic analysis. The patients with chloride ≤102mEq/l had significantly higher rates of VA (41% vs. 25%, log-rank p&lt;0.05) and mortality (33% vs. 18%, log-rank p&lt;0.05) (Figure). By multivariate cox analysis, the level of chloride had an independent predictive value of VA in patients with CRT (hazard ratio [HR] 1.08 per 1mEq/l decrease, 95% confidence interval [CI] 1.00-1.16, p&lt;0.05) (Table). Conclusions: The chloride level had a predictive value for VA after CRT implantation in HF patients without previous VA. The management of electrolytes, including chloride, might be important for preventing fatal arrhythmia in patients with HF undergoing CRT implantation.

Abstract 4137913: Role of serial evaluation of myocardial inflammatory activity and oxidative stress in determining the therapeutic efficacy of immunosuppression and clinical outcome in patients with cardiac sarcoidosis

Background: Cardiac sarcoidosis (CS) was characterized by formation of granulomas in the heart. Enhancement in myocardial inflammatory activity and oxidative stress is a crucial cause of major cardiovascular adverse events (MACE). Although immunosuppressive therapy is recommended for active CS, there is no established markers for treatment and prognosis. Hypothesis: We hypothesized that the inflammation and oxidative stress in heart were associated with MACE after steroid therapy. Aims: We identified prognostic markers for MACE in patients with CS after steroid therapy. Methods: This study was a prospective observational cohort study. Patients with CS diagnosed according to Japanese criteria were enrolled in this study. Patients with abnormal accumulation of 18 F-FDG in heart were treated with steroids with standard guideline-recommended protocol. 18 F-FDG PET were performed after more than 6 months of induction. Urinary 8-hydroxy-2'-deoxyguanosine (U-8-OHdG), a marker of oxidative DNA damage, and indices of cardiac and renal function were measured. The major outcome was a composite of the first sustained ventricular tachycardia (sVT) /sudden cardiac death (SCD), hospitalization for heart failure, and radiological relapse with exacerbation of clinical manifestation. Results: Fifty consecutive patients with CS underwent steroid therapy and followed up (median follow-up period of 58 months). 39 of 50 patients underwent 18F-FDG PET/CT more than 6 months after steroid therapy. During the follow-up period, 17 of 39 patients showed MACE, consisting of sVT/SCD (N= 11), hospitalization (N= 2) and radiological relapse (N= 4). A Cox proportional-hazard model showed that the U-8-OHdG and SUV max value of FDG-PET were independent predictors of MACE. ROC analysis revealed that the cut-off values of U-8-OHdG and SUV max for predicting the MACE were 11.6 ng/mg Cr (AUC 0.913, sensitivity 86.7%, specificity 90.0%) and 4.64 (AUC 0.878, sensitivity 76.5%, specificity 91.0%), respectively (Fig.1). Patients with a U-8-OHdG ≧11.6 ng/mg Cr or SUV max ≧4.64 had a significantly higher MACE risk (P values for U-8-OHdG and SUV max were both 0.001 by Log Rank analysis) (Fig.2). It is noted that U-8-OHdG &lt;11.6 ng/mg Cr and SUV max &lt;4.64 after steroid therapy indicate the good responses to the immunosuppressive therapy and better prognosis (Fig.3). Conclusion: U-8-OHdG and SUV max may be useful markers in determining the therapeutic efficacy and clinical outcome in patients with CS.