Ischemic Ventricular Tachycardia Research Articles

Ischemic ventricular tachycardia from below the posteromedial papillary muscle, a particular entity: Substrate characterization and challenges for catheter ablation

In patients with ischemic ventricular tachycardia (VT), substrate may be "protected" by the posteromedial papillary muscle (PMPM), explaining failure of endocardial-only ablation. We sought to characterize the arrhythmogenic substrate and ablation approach in patients with ischemic VT mapped to the inferior left ventricle in which endocardial ablation failed because of inaccessible substrate underlying the PMPM. We included 10 patients with recurrent ischemic VT, evidence of inferior scar, and failed endocardial ablation. In all patients, epicardial mapping was performed via a percutaneous (n = 9) or surgical (n = 1) approach, and VT elimination was achieved by ablation opposite to the PMPM. Clinical characteristics, electrocardiographic characteristics, and procedural data were analyzed. In all patients, intracardiac echocardiography showed hyperechoic scar below the PMPM, and 5 exhibited a pattern characterized by subendocardial basal scar that became intramural and epicardial at distal segments. In 4 patients, VT remained inducible despite endocardial scar isolation, manifested by the absence of electrograms, dissociated potentials, and/or exit block. Eleven inducible VTs were mapped to the epicardium underlying the PMPM: 8 had a right bundle branch block configuration with variable transition, while 3 exhibited left bundle branch block with negative concordance. An inferior QS pattern was present in 10 of 11 VTs. Noninducibility was achieved in 8 patients, and 7 patients remained arrhythmia-free after a mean follow-up of 27 ± 23 months. In patients with inferior ischemic scar, VT may arise from the area underneath the PMPM, limiting endocardial ablation. Intracardiac echocardiography accurately defines the substrate distribution, and an epicardial approach may eliminate VT. A pattern of "basal-endocardial/apical-epicardial" ischemic involvement is described.

PCV66 BASELINE CHARACTERISTICS AMONG VENTRICULAR TACHYCARDIA ABLATION PATIENTS: A MULTI-HOSPITAL DATABASE ANALYSIS

Ablation is an effective treatment approach among patients with ventricular tachycardia (VT). Using a nationally representative hospital database, this study examined the baseline characteristics of patients undergoing VT ablation in the United States (US). A cross-sectional study design was used. Patients (aged ≥18 years) with a primary diagnosis of VT who underwent catheter ablation (first procedure) in an inpatient or outpatient setting between 2011-2018 were identified using the Premier Healthcare database. Demographic and clinical characteristics of patients and hospital characteristics were examined. Patients were classified into ischemic VT and non-ischemic VT for the assessment of baseline characteristics. A total of 11,390 patients met the study criteria, with 4,703 having ischemic VT and 6,687 having non-ischemic VT. A third of patients were aged ≥70 years (48% for ischemic VT and 22% for non-ischemic VT), with 70% being male (88% for ischemic VT and 57% for non-ischemic VT), and 78% being white (83% for ischemic VT and 78% for non-ischemic VT). Almost 60% of ablation occurred in an inpatient setting (74% for ischemic VT and 49% for non-ischemic VT). In terms of hospital characteristics, 54% of VT ablations occurred in hospitals with bed size 500+, and 58% were classified as teaching hospital. Almost 45% of patients had CHADS2VASc score of ≥3 (67% for ischemic VT and 31% for non-ischemic VT). As per comorbidity status, 61% of patients had hypertension (77% for ischemic VT and 49% for non-ischemic VT), 23% had diabetes (33% for ischemic VT and 16% for non-ischemic VT), and 48% had heart failure (72% for ischemic VT and 31% for non-ischemic VT). Variation in demographic and clinical characteristics was observed among ischemic VT and non-ischemic VT patients, with the former group having considerable comorbidity burden.

Paced Electrogram Feature Analysis (PEFA) for Ablation Targeting in Ischaemic Ventricular Tachycardia

Paced Electrogram Feature Analysis (PEFA) for Ablation Targeting in Ischaemic Ventricular Tachycardia

Long-term outcome of catheter ablation in post-infarction recurrent ventricular tachycardia

Objectives. Severe LV dysfunction and advanced age are associated with VT recurrence after catheter ablation in patients with post-infarction drug-refractory VT. We present retrospective analysis of long-term outcome after single and repeat VT ablation procedures in patients with ischemic heart disease. Design. Patients with recurrent VT post infarction who underwent catheter ablation between 2006 and 2017 in Isala Heart Centre were retrospectively analyzed. Univariate and multivariate analysis were used to identify predictors of arrhythmia recurrence post ablation. Patients were allocated to subgroups based on LVEF: severe (<30%), moderate (30–40%) and mild LV dysfunction (41–51%) and analyzed with log rank test. Results. A total of 144 patients were included. Two years VT free survival after a single procedure was 56.6% with median follow-up 46 [17–78] months. Recurrence of VT postablation wash high among patients with an old anteroseptal MI and LVEF < 30% with multiple morphologies of inducible VTs, indicating an extensive and complex substrate. Patients who underwent repeat ablations (27.1%) had significant more often LV aneurysms (20.5% vs. 7.6%, p = .03) and electrical storms (38.5% vs. 21.9%, p = .04). VT free survival was higher in patients with LVEF 41–51% compared to LVEF < 30% (71.4% vs. 47.8%, p = .01). In multivariate analysis, LVEF < 30% (vs 41–51%) was an independent predictor of arrhythmia recurrence (HR = 2.16, CI 1.15–4.06, p = .02). Conclusions. In patients with ischemic VT, success rate of ablation was highest among patients with preserved LV function and recurrent VT and ES was highest among patients with severe LV dysfunction after single and multiple ablation procedures.

Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction

Ventricular tachycardia (VT) in patients with ischemic cardiomyopathy mainly results from endocardial scars after myocardial infarction; those scars represent zones of slow conduction that allow the occurrence and maintenance of reentrant circuits. Catheter ablation enables substrate modification of those low voltage areas and thus can help to alter the scar tissue in such a way that arrhythmias cannot appear anymore. Hospitalizations of concerned patients decrease, quality of life and outcome rise. Consequently, VT ablation represents a growing field in electrophysiology, especially for patients with endocardial scars in ischemic heart disease after myocardial infarction. However, ablation of ventricular tachycardia remains one of the most challenging procedures in the electrophysiology lab. Precise scar definition and localization of abnormal potentials are critical for ablation success. The following manuscript describes the use of a multipolar mapping catheter and 3-dimensional (3D) mapping system to create a high density electro-anatomical map of the left ventricle including a precise scar representation as well as mapping of fractionated and late potentials in order to allow a highly accurate substrate modification.

Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction

Ventricular tachycardia (VT) in patients with ischemic cardiomyopathy mainly results from endocardial scars after myocardial infarction; those scars represent zones of slow conduction that allow the occurrence and maintenance of reentrant circuits. Catheter ablation enables substrate modification of those low voltage areas and thus can help to alter the scar tissue in such a way that arrhythmias cannot appear anymore. Hospitalizations of concerned patients decrease, quality of life and outcome rise. Consequently, VT ablation represents a growing field in electrophysiology, especially for patients with endocardial scars in ischemic heart disease after myocardial infarction. However, ablation of ventricular tachycardia remains one of the most challenging procedures in the electrophysiology lab. Precise scar definition and localization of abnormal potentials are critical for ablation success. The following manuscript describes the use of a multipolar mapping catheter and 3-dimensional (3D) mapping system to create a high density electro-anatomical map of the left ventricle including a precise scar representation as well as mapping of fractionated and late potentials in order to allow a highly accurate substrate modification.

Exit sites on the epicardium rarely subtend critical diastolic path of ischemic VT on the endocardium: Implications for noninvasive ablation.

Noninvasive electrocardiographic mapping of ventricular tachycardia (VT) and ablation using stereotactic radiotherapy was recently reported. This strategy does not directly evaluate the critical diastolic components and assumes that the epicardial exit site of VT subtends closely over the endocardial mid-diastolic isthmus. To determine if the epicardial exit site of VT spatially corresponds to the critical diastolic components of ischemic scar-related VT. Intraoperative simultaneous endocardial and epicardial mapping were performed during VT using a 112-bipole endocardial balloon and 112-bipole epicardial sock array. In eight patients, nine VTs having entire diastolic circuit mapped were included in the study. The diastolic path and VT-exit sites (epicardial and endocardial) were determined. The diastolic path was mapped in the endocardium for all nine VTs (median length, 50; interquartile range [IQR], 28 mm). The tachycardia cycle length ranged from 210-500 ms. The VT-exit site was early in the endocardium for six VTs and on the epicardium for three VTs. The mid-diastolic isthmus and endocardial exit site of the six endocardial VTs were spatially distant from their epicardial exit site by a median distance of 32 and 27 mm, respectively. For the three VTs with an early epicardial exit, the isthmus and endocardial exit sites were distant from the epicardial exit site by a median distance of 34 and 38 mm, respectively. The epicardial exit site and the mid-diastolic isthmus sites were spatially distant and discrepant. Surface electrocardiography (ECG)-derived strategy in identifying epicardial exit site to select noninvasive ablation targets is prone to identify epicardial exit sites and may not identify critical targets in ischemic scar VT.

Is it feasible to offer ‘targeted ablation’ of ventricular tachycardia circuits with better understanding of isthmus anatomy and conduction characteristics?

Successful mapping and ablation of ventricular tachycardias remains a challenging clinical task. Whereas conventional entrainment and activation mapping was for many years the gold standard to identify reentrant circuits in ischaemic ventricular tachycardia ablation procedures, substrate mapping has become the cornerstone of ventricular tachycardia ablation. In the last decade, technology has dramatically improved. In parallel to high-density automated mapping, cardiac imaging and image integration tools are increasingly used to assess the structural ventricular tachycardia substrate. The aim of this review is to describe the technologies underlying these new mapping systems and to discuss their possible role in providing new insights into identification and visualization of reentrant tachycardia mechanisms.

Ventricular substrate identification using close-coupled paced electrogram feature analysis.

Substrate based catheter ablation strategies are widely employed for treatment of scar-related ventricular tachycardia (VT). We analysed intracardiac electrograms (EGMs) from close-coupled paced extrastimuli extracted from the EnSite Precision mapping system. We sought to characterize EGM responses of ventricular myocardium to varying coupling intervals from the right ventricular apex (RVA) in both healthy individuals and patients presenting with VT for catheter ablation. Extrastimuli were delivered from the RVA after estimation of the ventricular effective refractory period. Electrograms were recorded from high-density mapping catheters in the left ventricle and exported for analysis to MATLAB. Observational data were collected from 14 patients with ischaemic VT (mean age 72.4 ± 6.3 years, one female) and five controls (mean age 59.4 ± 7.4 years, one female). These derived data were used to inform an interventional strategy on a further 10 patients (mean age 64.7 ± 10.0 years; two female). Significant differences were observed in EGM duration (ED) and latency (LT) at all coupling intervals between VT patients and controls. Significant increases in ED and LT with decreased RVA coupling interval were observed at VT isthmuses. Abnormal responses derived from control subject data were used to classify four types of ventricular EGM response. Targeting sites with abnormal LT and ED significantly reduced VT inducibility (5/14 derivation patients to 0/10 intervention patients; P = 0.03). Paced electrogram feature analysis is a novel tool to characterize the ischaemic substrate. Association with VT isthmuses and early ablation results suggest a possible role in substrate ablation for ischaemic VT.

VENTRICULAR SUBSTRATE IDENTIFICATION USING CLOSE COUPLED PACED ELECTROGRAM FEATURE ANALYSIS (PEFA)

Substrate based catheter ablation strategies are widely employed for treatment of scar related ventricular tachycardia (VT). We analysed intracardiac electrograms (EGM) from close coupled paced extrastimuli extracted from the EnSite Precision mapping system. We sought to characterize EGM responses of ventricular myocardium to varying degrees of coupling interval from the right ventricular apex (RVA), in both healthy individuals and patients presenting with VT for catheter ablation. Extrastimuli were delivered from the RVA after estimation of the ventricular effective refractory period. EGMs were recorded from high-density mapping catheters in the left ventricle and exported for analysis to MATLAB. Data derived were used to inform a validation study. Fourteen patients with ischaemic VT (mean age 72.4±6.3 years, one female), five controls (mean age 59.4±7.4yrs, one female) and 10 patients for validation (age 64.7±10.0 years; 2 female) were included. Mean electrogram features (latency or duration) ± standard deviation in response to coupling interval in milliseconds for control and VT patients are shown in the table. Value at the 95th percentile considered for upper limit of normal shown in milliseconds (ms). Significant differences were observed in EGM duration (ED) and latency (LT) at all coupling intervals between VT patients and controls. Significant increases in ED and LT with decreased coupling interval were observed at VT isthmuses. Abnormal responses derived from control subject data and were used to classify four types of ventricular EGM response. Representative examples of each type for S2: VERP+50msec coupling intervals is shown in the figure. Targeting Type I sites with abnormal LT and ED significantly reduced VT inducibility (5/14 derivation patients to 0/10 validation patients; p=0.03). Paced electrogram feature analysis (PEFA) is a novel tool to characterize the ischaemic substrate. Association with VT isthmuses and early ablation results suggest a role in substrate ablation for ischaemic VT.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

10-YEAR TRENDS IN CATHETER ABLATION OF ISCHEMIC AND NON-ISCHEMIC VENTRICULAR TACHYCARDIA

Catheter ablation for ventricular tachycardia (VT) is now commonplace for patients with both ischemic and non-ischemic VT substrates. We sought to describe 10-year trends in patient characteristics, procedure-related complications and in-hospital mortality in patients undergoing VT ablation,

Effect of Baseline Antiarrhythmic Drug on Outcomes With Ablation in Ischemic Ventricular Tachycardia: A VANISH Substudy (Ventricular Tachycardia Ablation Versus Escalated Antiarrhythmic Drug Therapy in Ischemic Heart Disease).

The VANISH trial (Ventricular Tachycardia Ablation Versus Escalated Antiarrhythmic Drug Therapy in Ischemic Heart Disease) compared the effectiveness of escalated antiarrhythmic drug therapy to catheter ablation in patients with prior myocardial infarction, an implanted defibrillator, and ventricular tachycardia (VT). The effectiveness of these interventions in patients on sotalol versus amiodarone was compared. Analysis was conducted based on whether patients had recurrent VT, despite amiodarone (amio-refractory) or nonamiodarone drugs (sotalol-refractory). Outcomes included death, VT storm, appropriate implantable cardioverter defibrillator shock, and any ventricular arrhythmia. At baseline, 169 (65.2%) were amio-refractory, and 90 (34.7%) were sotalol-refractory (1 patient on procainamide rather than sotalol). Amio-refractory patients had more renal insufficiency (23.7% versus 10%; P=0.0008), worse New York Heart Association class (82.3% II/III versus 65.5%; P=0.0003), and lower ejection fraction (29±9.7% versus 35.2±11%; P<0.0001). Within the amio-refractory group, ablation resulted in reduction of any ventricular arrhythmia compared with escalated drug therapy (hazard ratio, 0.53; 95% confidence interval, 0.31-0.9), P=0.020). Sotalol-refractory patients had trends toward higher mortality and VT storm with ablation, with no effect on implantable cardioverter defibrillator shocks. Within the escalated drug therapy arm, amio-refractory patients had a higher rate of the composite outcome (hazard ratio, 1.94; 95% confidence interval, 1.14-3.29; P=0.0144) and a trend to higher mortality (hazard ratio, 2.40; 95% confidence interval, 0.93-6.22; P=0.07), whereas mortality was not different between amio- and sotalol-refractory patients within the ablation treatment group. Patients with amio-refractory VT have a higher rate of ventricular arrhythmia and mortality than those with sotalol-refractory VT and derive greater benefit of catheter ablation than for patients with sotalol-refractory VT who are switched to amiodarone. URL: https://clinicaltrials.gov. Unique identifier: NCT00905853.

Ventricular Tachycardia Ablation in the Elderly

Successful ventricular tachycardia (VT) ablation is associated with improved survival in patients with heart failure. However, the safety and efficacy of VT ablation in the elderly, a population with higher competing nonsudden death risk and comorbidities, have not been well defined. The International Ventricular Tachycardia Center Collaborative Study Group registry of 2061 patients who underwent VT ablation at 12 international centers was analyzed. Kaplan-Meier analysis was used to estimate survival of patients ≥70 years with and without VT recurrence. Of the 2049 patients who met inclusion criteria, 681 (33%) patients were ≥70 years of age (mean age, 75±4 years). Among these, 92% were men, 71% had ischemic VT, and 42% had VT storm at presentation. Mean (±SD) left ventricular ejection fraction was 30±11%. Compared with patients <70 years, patients ≥70 years had higher in-hospital (4.4% versus 2.3%; P=0.01) and 1-year mortality (15% versus 11%; P=0.002) but a similar incidence of VT recurrence at 1 year (26% versus 25%; P=0.74) and time to VT recurrence (280 versus 289 days; P=0.20). Absence of VT recurrence during follow-up was strongly associated with improved survival in patients ≥70 years. VT ablation in the elderly is feasible and reasonably safe with a modestly higher in-hospital and 1-year mortality, with similar rates of VT recurrence at 1 year compared with younger patients. Successful VT ablation, that is, lack of VT recurrence, is strongly associated with improved survival even in this elderly subgroup.

Abstract 21033: Effect of Baseline Antiarrhythmic Drug on Outcomes With Ablation in Ischemic Ventricular Tachycardia: A Vanish Substudy

Introduction: The VANISH trial enrolled patients with prior myocardial infarction, an implanted defibrillator and ventricular tachycardia (VT) despite antiarrhythmic (AAD) drugs and compared the effectiveness of escalated AAD therapy to catheter ablation. We sought to compare the effectiveness of these interventions in patients with sotalol-refractory VT versus amiodarone-refractory VT. Methods: All patients enrolled in the VANISH study were included (n=259). VT recurrence was compared in patients despite amiodarone (amio-refractory) as compared to non-amiodarone drugs (sotalol-refractory). Outcomes were a composite of death, VT storm, appropriate ICD shock, each of these components and any ventricular arrhythmia. Results: At baseline, 169 (65.2%) were amio-refractory and 90 (34.7%) were sotalol-refractory (1 patient was enrolled with VT despite procainamide). Amio-refractory patients had more renal insufficiency (23.7% vs 10%, p=0.0008), worse NYHA class (82.3% II/III vs 65.5%, p=0.0003), and lower ejection fraction (29 ± 9.7% vs 35.2 ± 11%, p&lt;0.0001). After adjusting for these baseline differences, there was no difference in mortality between the two groups. When examined within the escalated drug therapy arm, amio-refractory patients had a higher incidence of the composite outcome (HR 1.94, 95%CI (1.14, 3.29), p=0.0144), and a trend to higher mortality (HR 2.40, 95%CI (0.93, 6.22), p=0.07), while no difference in outcomes were observed within the ablation treatment group. Within the amio-refractory group, ablation resulted in significant reduction of any ventricular arrhythmia (HR 0.53, 95%CI (0.31, 0.9), p=0.020). Sotalol-refractory patients had trends towards higher mortality and VT storm with ablation, with no effect on ICD shocks. Conclusions: The benefit of catheter ablation is greater for patients with amio-refractory VT than for patients with sotalol-refractory VT who are then switched to amiodarone.

PROGNOSTIC VALUE OF NON-INDUCIBILITY ON OUTCOMES OF VENTRICULAR TACHYCARDIA ABLATION: A VENTRICULAR TACHYCARDIA ABLATION VS. ENHANCED DRUG THERAPY IN STRUCTURAL HEART DISEASE (VANISH) SUBSTUDY

The traditional endpoint of VT ablation is non-inducibility of VT by programmed electrical stimulation (PES); however, the definition of inducibility remains variable and its prognostic value has been muddied by alterations in peri-ablation antiarrhythmic drug (AAD) therapy or non-standardized ICD programming in prior observational studies. The VANISH trial randomized ischemic VT patients to VT ablation (with endpoint of non-inducibility of VT >=300ms after ablation) vs. AAD escalation. We proposed to determine the predictive value of non-inducibility on long-term clinical outcomes, adjusting for other clinical and procedural characteristics. The relationship of inducibility on the primary composite endpoint of death, VT storm > 30 days, or appropriate ICD shock > 30 days, was assessed using a time-to-event analysis. Survival rates were summarized between inducibility groups using Kaplan-Meier product-limit estimates. Results were analyzed according to presence of inducible VT (defined as inducibility post ablation of any VT – including those < 300ms) vs. non-inducible or inducibility not performed. Polymorphic VT or VF were not considered to be inducible. 129 patients from the ablation arm were included in the primary analysis of which 51 were non-inducible post ablation as compared to 78 who were inducible or where inducibility was not performed. At baseline, there was no significant characteristic or procedural differences between the non-inducible vs inducible/not performed cohorts except for an increased number of ICD shocks within 3 months observed in the latter group. There were no baseline characteristics that were shown to be significantly predictive of inducibility. In multivariate analysis, inducibility was associated with an increase in the primary endpoint of death, appropriate shock or VT storm after 30 days (HR 1.87, 95% CI 1.12, 3.11, P = 0.017). Inducibility of any VT post ablation was associated with an increased risk of the composite outcome in the VANISH Trial. No patient or procedural characteristics were shown to be significantly predictive of inducibility. A randomized trial targeting faster induced VTs may determine whether a more aggressive strategy can improve outcomes.

The electrical circuit of a hemodynamically unstable and recurrent ventricular tachycardia diagnosed in 35 s with the Rhythmia mapping system

Herein, we report a 47-year-old woman with ischemic cardiomyopathy who underwent ablation therapy due to an electrical storm without any triggers. The voltage mapping in sinus rhythm with the Rhythmia system and Orion catheter displayed several LAVAs in and around the anteroapical scar area. Although the patient did not tolerate the induced clinical ventricular tachycardia, which was reproductively induced, 35-second-mapping in the scar zone with the Orion catheter demonstrated the VT circuit with the critical isthmus. This report shows the possibility of the new ultra-high density mapping system in a specific ischemic VT patient.

P1056Contact force as a predictor of complete lesion formation in patients with ischemic scar-related ventricular tachycardia

P1056Contact force as a predictor of complete lesion formation in patients with ischemic scar-related ventricular tachycardia

Aneurysm-related ischemic ventricular tachycardia: safety and efficacy of catheter ablation.

Left ventricular aneurysm (LVA) postmyocardial infarction (MI) might be an arrhythmogenic substrate. We examined the safety and efficacy of catheter ablation of LVA-related ventricular tachycardia (VT).Thirty-three consecutive patients who underwent primary catheter ablation of ischemic VT were divided into LVA group (11 patients, mean age 61.9 years, 10 men) and none LVA group. Acute procedural outcomes, complications, and long-term outcomes were assessed.In LVA group, average number of induced VTs were 3.2 ± 2.6 (range 1–7), clinical VTs were located in the ventricular septum scar zone in 4 (36.4%) patients, acute success was achieved in 7 (63.6%) patients, partial success in 3 (27.3%) and failure in 1 patient, while none LVA group showing a statistically similar distribution of acute procedural outcomes (P = 0.52). There were no major or life-threatening complications. VT-free survival rate at median 19 (1–44) months follow-up was numerically but not significantly lower in LVA versus none LVA group (48.5% vs 62.8%, log-rank P = 0.40).Catheter ablation of ischemic VT in the presence of LVA appears feasible and effective, with about one-third of cases having septal ablation targets. Further studies are warranted.

Catheter ablation of ventricular extrasystoles and ventricular tachycardia in the elderly

The prevalence of structural heart disease increases with higher age, and thereby the basis for ventricular arrhythmias is created. Catheter ablation has been shown to be an effective therapy option that is very safe and achieves good long-term results in patients with recurrent ventricular tachycardia (VT). Data regarding ablation in patients older than 75 years is sparse, although this patient group was included as a minority in most published VT ablation studies. Data from younger patient collectives may not be transferable to older patient cohorts due to differences in patient comorbidities and baseline characteristics. Studies with patient collectives ≥75 years or even ≥80 years show comparable efficacy of catheter ablation for VT; however, the complication rate is higher, mainly due to groin complications, increases. Catheter ablation of ischemic VT appears effective and safe even in ≥75 year olds; however, extensive data for other structural heart diseases are lacking. Epicardial procedures are also possible and safe in older patients (≥80years). Due to the significant challenges of VT ablation in older patients, including the consideration of complex comorbidities, these should be performed in specialized centers with high expertise. The aim of catheter ablation in older patients is, above all, to improve quality of life and morbidity. Long-term survival is significantly lower due to the "near end of life" situation than in younger patients. Careful consideration of alternative therapy options, chances for success of the catheter ablation, and their risks, taking into account specific patient conditions and symptoms, is crucial in these patients.

MAGNETIC VT study: a prospective, multicenter, post-market randomized controlled trial comparing VT ablation outcomes using remote magnetic navigation-guided substrate mapping and ablation versus manual approach in a low LVEF population.

Patients with ischemic cardiomyopathy (ICM) are prone to scar-related ventricular tachycardia (VT). The success of VT ablation depends on accurate arrhythmogenic substrate localization, followed by optimal delivery of energy provided by constant electrode-tissue contact. Current manual and remote magnetic navigation (RMN)-guided ablation strategies aim to identify a reentry circuit and to target a critical isthmus through activation and entrainment mapping during ongoing tachycardia. The MAGNETIC VT trial will assess if VT ablation using the Niobe™ ES magnetic navigation system results in superior outcomes compared to a manual approach in subjects with ischemic scar VT and low ejection fraction. This is a randomized, single-blind, prospective, multicenter post-market study. A total of 386 subjects (193 per group) will be enrolled and randomized 1:1 between treatment with the Niobe ES system and treatment via a manual procedure at up to 20 sites. The study population will consist of patients with ischemic cardiomyopathy with left ventricular ejection fraction (LVEF) of ≤35% and implantable cardioverter defibrillator (ICD) who have sustained monomorphic VT. The primary study endpoint is freedom from any recurrence of VT through 12months. The secondary endpoints are acute success; freedom from any VT at 1year in a large-scar subpopulation; procedure-related major adverse events; and mortality rate through 12-month follow-up. Follow-up will consist of visits at 3, 6, 9, and 12months, all of which will include ICD interrogation. The MAGNETIC VT trial will help determine whether substrate-based ablation of VT with RMN has clinical advantages over manual catheter manipulation. Clinicaltrials.gov identifier: NCT02637947.