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BackgroundSeveral distinct risk factors for arrhythmia recurrence and mortality following ventricular tachycardia (VT) ablation have been described. The effect of concurrent risk factors has not been assessed so far; thus, it is not yet possible to estimate these risks for a patient with several comorbidities. The aim of the study was to identify specific risk groups for mortality and VT recurrence using the Survival Tree (ST) analysis method.MethodsIn 1251 patients 16 demographic, clinical and procedure-related variables were evaluated as potential prognostic factors using ST analysis using a recursive partitioning algorithm that searches for relationships among variables. Survival time and time to VT recurrence in groups derived from ST analysis were compared by a log-rank test. A random forest analysis was then run to extract a variable importance index and internally validate the ST models.ResultsLeft ventricular ejection fraction, implantable cardioverter defibrillator/cardiac resynchronization device, previous ablation were, in hierarchical order, identified by ST analysis as best predictors of VT recurrence, while left ventricular ejection fraction, previous ablation, Electrical storm were identified as best predictors of mortality. Three groups with significantly different survival rates were identified. Among the high-risk group, 65.0% patients were survived and 52.1% patients were free from VT recurrence; within the medium- and low-risk groups, 84.0% and 97.2% patients survived, 72.4% and 88.4% were free from VT recurrence, respectively.ConclusionsOur study is the first to derive and validate a decisional model that provides estimates of VT recurrence and mortality with an effective classification tree. Preprocedure risk stratification could help optimize periprocedural and postprocedural care.

ObjectivesThis study sought to characterize ventricular tachycardia (VT) ablation outcomes across nonischemic cardiomyopathy (NICM) etiologies and adjust these outcomes by patient-related comorbidities that could explain differences in arrhythmia recurrence rates.BackgroundOutcomes of catheter ablation of VT in patients with NICM could be related to etiology of NICM.MethodsData from 2,075 patients with structural heart disease referred for catheter ablation of VT from 12 international centers was retrospectively analyzed. Patient characteristics and outcomes were noted for the 6 most common NICM etiologies. Multivariable Cox proportional hazards modeling was used to adjust for potential confounders.ResultsOf 780 NICM patients (57 ± 14 years of age, 18% women, left ventricular ejection fraction 37 ± 13%), underlying prevalence was 66% for dilated idiopathic cardiomyopathy (DICM), 13% for arrhythmogenic right ventricular cardiomyopathy (ARVC), 6% for valvular cardiomyopathy, 6% for myocarditis, 4% for hypertrophic cardiomyopathy, and 3% for sarcoidosis. One-year freedom from VT was 69%, and freedom from VT, heart transplantation, and death was 62%. On unadjusted competing risk analysis, VT ablation in ARVC demonstrated superior VT-free survival (82%) versus DICM (p ≤ 0.01). Valvular cardiomyopathy had the poorest unadjusted VT-free survival, at 47% (p < 0.01). After adjusting for comorbidities, including age, heart failure severity, ejection fraction, prior ablation, and antiarrhythmic medication use, myocarditis, ARVC, and DICM demonstrated similar outcomes, whereas hypertrophic cardiomyopathy, valvular cardiomyopathy, and sarcoidosis had the highest risk of VT recurrence.ConclusionsCatheter ablation of VT in NICM is effective. Etiology of NICM is a significant predictor of outcomes, with ARVC, myocarditis, and DICM having similar but superior outcomes to hypertrophic cardiomyopathy, valvular cardiomyopathy, and sarcoidosis, after adjusting for potential covariates.

BackgroundThe impact of catheter ablation of ventricular tachycardia (VT) on all-cause mortality remains unknown.ObjectiveThe purpose of this study was to examine the association between VT recurrence after ablation and survival in patients with scar-related VT.MethodsAnalysis of 2061 patients with structural heart disease referred for catheter ablation of scar-related VT from 12 international centers was performed. Data on clinical and procedural variables, VT recurrence, and mortality were analyzed. Kaplan-Meier analysis was used to estimate freedom from recurrent VT, transplant, and death. Cox proportional hazards frailty models were used to analyze the effect of risk factors on VT recurrence and mortality.ResultsOne-year freedom from VT recurrence was 70% (72% in ischemic and 68% in nonischemic cardiomyopathy). Fifty-seven patients (3%) underwent cardiac transplantation, and 216 (10%) died during follow-up. At 1 year, the estimated rate of transplant and/or mortality was 15% (same for ischemic and nonischemic cardiomyopathy). Transplant-free survival was significantly higher in patients without VT recurrence than in those with recurrence (90% vs 71%, P

Cardiac stereotactic body radiotherapy (SBRT) has emerged as a promising noninvasive treatment for refractory ventricular tachycardia (VT). The purpose of this study was to describe the safety and effectiveness of SBRT for VT in refractory to extensive ablation. After maximal medical and ablation therapy, patients were enrolled in a prospective registry. Available electrophysiological and imaging data were integrated to generate a plan target volume. All SBRTs were planned with a single 25 Gy fraction using respiratory motion mitigation strategies. Clinical outcomes at 6 weeks, 6 months, and 12 months were analyzed and compared with the 6 months prior to treatment. VT burden (implantable cardioverter-defibrillator [ICD] shocks and antitachycardia pacing sequences) as well as clinical and safety outcomes were the main outcomes. Fifteen patients were enrolled and underwent planning. Fourteen (93%) underwent treatment, with 12 (80%) surviving to the end of the 6-week period and 10 (67%) surviving to 12 months. From 6 week to 12 months, there was recurrence of VT, which resulted in either appropriate antitachycardia pacing or ICD shocks in 33% (4 of 12). There were significant reductions in treated VT at 6 weeks to 6 months (98%) and at 12 months (99%) compared to the 6 months before treatment. There was a nonsignificant trend toward lower amiodarone dose at 12 months. Four deaths occurred after treatment, with no changes in ventricular function. For a select group of high-risk patients with VT refractory to standard therapy, SBRT is associated with a reduction in VT and appropriate ICD therapies over 1 year. [ABSTRACT FROM AUTHOR]

Background: The right ventricle (RV) is uncommonly implicated in postinfarction ventricular tachycardia (VT). The prevalence and features of the RV substrate participating in postinfarction VT are undefined.Objectives: The purpose of this study was to characterize critical right ventricular substrate (CRVS) involvement in patients with postinfarction VT.Methods: We retrospectively reviewed 1279 patients with postinfarction VT undergoing catheter ablation at our center from January 2000 through May 2020. Cases with CRVS defined by conclusive demonstration of participation in VT with activation, entrainment, and/or pacemapping during sinus rhythm were identified.Results: CRVS was identified in 27 of 1279 patients (2.1%): age 65 ± 13 years, 96% male, median left ventricular (LV) ejection fraction 25%, and 93% with left bundle branch block (LBBB) morphology VT. CRVS was identified by RV activation and/or entrainment mapping (n = 19) or by the presence of low-voltage abnormal electrograms with excellent pacemap for the targeted VT and noninducibility after ablation (n = 8). VT termination during RV ablation occurred in 15 patients. After median follow-up of 20 months (interquartile range 9-53 months) and median of 2 procedures (interquartile range 1-3), 22 of 27 patients (80%) had no VT recurrence and 11 (41%) died.Conclusion: The RV contains critical substrate elements of postinfarction VT in at least 2.1% of cases. RV mapping should be considered in cases in which LV mapping fails to demonstrate adequate targets, particularly in patients with LBBB morphology VT. [ABSTRACT FROM AUTHOR]

Background: Ventricular tachycardia (VT) substrate in left ventricular (LV) nonischemic cardiomyopathy (NICM) consists of fibrosis with surviving myocardium.Objective: The purpose of this study was to determine whether, in patients with LV NICM and sustained VT, reduced QRS amplitude and QRSf during sinus rhythm can identify the presence and location of abnormal septal (S-NICM) and/or free-wall (FW-NICM) VT substrate.Methods: We compared patients with NICM and VT (group 1) with electroanatomic mapping septal (S-NICM; n = 21) or free-wall (FW-NICM; n = 20) VT substrate to a 38-patient reference cohort (group 2) with cardiac magnetic resonance imaging (cMRI) and NICM but no VT referred for primary prevention implantable cardioverter-defibrillator (26 [68.4%] with late gadolinium enhancement).Results: Group 1 had lower QRS amplitude in leads II (0.60 ± 0.22 vs 0.86 ± 0.35, P <.001), aVR (0.60 ± 0.24 vs 0.75 ± 0.31, P = .002), aVF (0.48 ± 0.20 vs 0.70 ± 0.28, P <.001), and V2 (1.09 ± 0.52 vs 1.38 ± 0.55, P = .001) than group 2. QRS <0.55 mV in lead aVF identified VT and accompanying substrate with sensitivity 70% and specificity 71%. Most group 1 and group 2 patients had 12-lead ECG QRS fractionation (QRSf) in ≥2 contiguous leads (78% vs 63.2%, P = .14). Sensitivity and specificity for ≥2 QRSf leads identifying respective regional electroanatomic or cMRI abnormalities were 76% and 50% for inferior, 44% and 87% for lateral, and 21% and 89% for anterior leads.Conclusion: In LV NICM, low frontal plane QRS (<0.55 mV in aVF) is associated with VT substrate. Although multilead QRS fractionation is associated with the presence and location of VT substrate, it is frequently identified in patients without VT with cMRI abnormalities. [ABSTRACT FROM AUTHOR]

Introduction: Patients with prior cardiac surgery may represent a subgroup of patients with ventricular tachycardia (VT) that may be more difficult to control with catheter ablation. Methods: We evaluated 1901 patients with ischemic and nonischemic cardiomyopathy who underwent VT ablation at 12 centers. Clinical characteristics and VT radiofrequency ablation procedural outcomes were assessed and compared between those with and without prior cardiac surgery. Kaplan–Meier analysis was used to estimate freedom from recurrent VT and survival. Results: There were 578 subjects (30.4%) with prior cardiac surgery identified in the cohort. Those with prior cardiac surgery were older (66.4 ± 11.0 years vs. 60.5 ± 13.9 years, p <.01), with lower left ventricular ejection fraction (30.2 ± 11.5% vs. 34.8 ± 13.6%, p <.01) and more ischemic heart disease (82.5% vs. 39.3%, p <.01) but less likely to undergo epicardial mapping or ablation (9.0% vs. 38.1%, p<.01) compared to those without prior surgery. When epicardial mapping was performed, a significantly greater proportion required surgical intervention for access (19/52 [36.5%] vs. 14/504 [2.8%]; p <.01). Procedural complications, including epicardial access‐related complications, were lower (5.7% vs. 7.0%, p <.01) in patients with versus without prior cardiac surgery. VT‐free survival (75.1% vs. 74.1%, p =.805) and survival (86.5% vs. 87.9%, p =.397) were not different between those with and without prior heart surgery, regardless of etiology of cardiomyopathy. VT recurrence was associated with increased mortality in patients with and without prior cardiac surgery. Conclusion: Despite different clinical characteristics and fewer epicardial procedures, the safety and efficacy of VT ablation in patients with prior cardiac surgery is similar to others in this cohort. The incremental yield of epicardial mapping in predominant ischemic cardiomyopathy population prior heart surgery may be low but appears safe in experienced centers. [ABSTRACT FROM AUTHOR]

Background: Ablation of septal substrate‐associated ventricular tachycardia (VT) in patients with nonischemic cardiomyopathy (NICM) is challenging. We sought to standardize the characterization of septal substrates on late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) and to examine the association of that substrate with VT exit and isthmus sites on invasive mapping. Methods: LGE‐CMR was performed before electroanatomic mapping and ablation for VT in 20 NICM patients. LGE extent and distribution were quantified using myocardial signal‐intensity Z scores (SI‐Z). The SI‐Z thresholds correlating to previously validated voltage thresholds, for abnormal tissue and dense scar were defined. Results: Bipolar and unipolar (electrogram) voltage amplitude measurements from the LV and RV were negatively associated with SI‐Z from LGE‐CMR imaging (p <.05). SI‐Z thresholds for appropriate CMR identification of septal substrates were determined to be greater than −.15 for border zone and greater than.03 for a dense scar. Among all patients, 34 critical VT sites were identified with SI‐Z distribution in the range of −.97 to.06. Thirty (88.2%) critical sites were located in the dense LGE, 1 (2.9%) in the border zone, and 3 (8.9%) in healthy tissue but within 7 mm of LGE. Of note, critical VT sites were all located at the basal septum close to valves (distance to aortic valve: 17.5 ± 31.2 mm, mitral valve: 21.2 ± 8.7 mm) in nonsarcoidosis cases. Conclusions: Critical sites of septal VT in NICM patients are predominantly in the CMR defined dense scar when using standardized signal‐intensity thresholds. [ABSTRACT FROM AUTHOR]

Introduction: The association of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) with epicardial and surface ventricular tachycardia (VT) electrogram features, in nonischemic cardiomyopathy (NICM), is unknown. We sought to define the association of LGE and viable wall thickness with epicardial electrogram features and exit site paced QRS duration in patients with NICM. Methods: A total of 19 patients (age 53.5 ± 11.5 years) with NICM (ejection fraction 40.2 ± 13.2%) underwent CMR before VT ablation. LGE transmurality was quantified on CMR and coregistered with 2294 endocardial and 2724 epicardial map points. Results: Both bipolar and unipolar voltage were associated with transmural signal intensity on CMR. Longer electrogram duration and fractionated potentials were associated with increased LGE transmurality, but late potentials or local abnormal ventricular activity were more prevalent in nontransmural versus transmural LGE regions (p <.05). Of all critical VT sites, 19% were located adjacent to regions with LGE but normal bipolar and unipolar voltage. Exit site QRS duration was affected by LGE transmurality and intramural scar location, but not by wall thickness, at the impulse origin. Conclusions: In patients with NICM and VT, LGE is associated with epicardial electrogram features and may predict critical VT sites. Additionally, exit site QRS duration is affected by LGE transmurality and intramural location at the impulse origin or exit. [ABSTRACT FROM AUTHOR]

Introduction: In patients with nonischemic cardiomyopathy (NICM) little is known about the clinical impact of catheter ablation (CA) of septal ventricular tachycardia (VT) resulting in the collateral injury of the conduction system (CICS). Methods and Results: Ninety‐five consecutive patients with NICM underwent CA of septal VT. Outcomes in patients with no baseline conduction abnormalities who developed CICS (group 1, n = 28 [29%]) were compared to patients with no CICS (group 2, n = 17 [18%]) and to patients with preexisting conduction abnormalities or biventricular pacing (group 3, n = 50 [53%]). Group‐1 patients were younger, had a higher left ventricular ejection fraction and a lower prevalence of New York Heart Association III/IV class compared to group 3 while no significant differences were observed with group 2. After a median follow‐up of 15 months, VT recurred in 14% of patients in group 1, 12% in group 2 (P =.94) and 32% in group 3 (P =.08) while death/transplant occurred in 14% of patients in group 1, 18% in group 2 (P =.69) and 28% in group 3 (P =.15). A worsening of left ventricular ejection fraction (LVEF) (median LVEF variation, −5%) was observed in group 1 compared to group 2 (median LVEF variation, 0%; P <.01) but not group‐3 patients (median LVEF variation, −4%; P =.08) with a consequent higher need for new biventricular pacing in group 1 (43%) compared to group 2 (12%; P =.03) and group 3 (16%; P <.01). Conclusions: In patients with NICM and septal substrate, sparing the abnormal substrate harboring the conduction system provides acceptable VT control while preventing a worsening of the systolic function. [ABSTRACT FROM AUTHOR]

Background: Outcomes of ventricular tachycardia (VT) ablation in structural heart disease have been reported to differ by sex. Whether this is due to differences in the underlying arrhythmogenic substrates among patients with nonischemic cardiomyopathy (NICM) remains unclear.Objective: The purpose of this study was to compare the characteristics of arrhythmogenic substrates between women and men with NICM.Methods: We analyzed 160 consecutive patients (26 women) with NICM who were undergoing VT ablation at the Hospital of the University of Pennsylvania. Of these 160 patients, 59 (13 women) underwent cardiac magnetic resonance (CMR) before the ablation procedure. The arrhythmogenic substrate was analyzed qualitatively and quantitatively by CMR and/or detailed electroanatomic mapping.Results: There were no significant differences in left ventricular scar percentage as defined by CMR (9.5% ± 7.8% in women vs 11.2% ± 8.6% in men; P = .5), endocardial bipolar voltage (<1.5 mV; 11.3% ± 19.3% in women vs 11.5% ± 16.3% in men; P = .4), endocardial unipolar voltage (<8.3 mV; 38.0% ± 30.8% in women vs 45.6% ± 30.9% in men; P = .2), or epicardial bipolar voltage (<1.0 mV; 21.5% ± 38.9% in women vs 10.7% ± 13.9% in men; P = .6). There were no significant differences in scar transmurality as defined by CMR (5 categories: endocardial, midwall, epicardial, transmural, and right ventricular endocardial). Similarly, there were no significant differences in scar distribution as defined by CMR or electroanatomic mapping (anteroseptal vs inferolateral).Conclusion: Scar percentage, transmurality, and distribution are similar between women and men with NICM. [ABSTRACT FROM AUTHOR]

Background: Ventricular tachycardia (VT) is frequently encountered in patients with repaired and unrepaired congenital heart disease (CHD), causing significant morbidity and sudden cardiac death. Data regarding underlying VT mechanisms and optimal ablation strategies in these patients remain limited. Objective: To describe the electrophysiologic mechanisms, ablation strategies, and long‐term outcomes in patients with CHD undergoing VT ablation. Methods: Forty‐eight patients (mean age 41.3 ± 13.3 years, 77.1% male) with CHD underwent a total of 57 VT ablation procedures at two centers from 2000 to 2017. Electrophysiologic and follow‐up data were analyzed. Results: Of the 77 different VTs induced at initial or repeat ablation, the underlying mechanism in 62 (81.0%) was due to scar‐related re‐entry; the remaining included four His‐Purkinje system–related macrore‐entry VTs and focal VTs mainly originating from the outflow tract region (8 of 11, 72.7%). VT‐free survival after a single procedure was 72.9% (35 of 48) at a median follow‐up of 53 months. VT‐free survival after multiple procedures was 85.4% (41 of 48) at a median follow‐up of 52 months. There were no major complications. Three patients died during the follow‐up period from nonarrhythmic causes, including heart failure and cardiac surgery complication. Conclusion: While scar‐related re‐entry is the most common VT mechanism in patients with CHD, importantly, nonscar‐related VT may also be present. In experienced tertiary care centers, ablation of both scar‐related and nonscar‐related VT in patients with CHD is safe, feasible, and effective over long‐term follow‐up. [ABSTRACT FROM AUTHOR]

Background: In patients with ischemic ventricular tachycardia (VT), substrate may be "protected" by the posteromedial papillary muscle (PMPM), explaining failure of endocardial-only ablation.Objective: 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.Methods: 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.Results: 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.Conclusion: 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. [ABSTRACT FROM AUTHOR]

Epicardial ablation may be required to eliminate ventricular tachycardia (VT) in patients with underlying structural heart disease. The decision to gain epicardial access is frequently based on the suspicion of an epicardial origin for the VT and/or presence of an arrhythmogenic substrate. Epicardial pathology and VT is frequently present in patients with nonischemic right and/or left cardiomyopathies even in the setting of modest or no endocardial bipolar voltage substrate. In this setting, unipolar voltage mapping from the endocardium serves to help identify midmyocardial and/or epicardial VT substrate. The additional value of endocardial unipolar mapping includes its usefulness to predict the clinical outcome after VT ablation, to determine the irreversibility of myocardial disease, and to guide endomyocardial biopsy procedures to specific areas of intramural scarring. In this review, we aim to provide a guide to the use of endocardial unipolar mapping and its appropriate interpretation in a variety of clinical situations. [ABSTRACT FROM AUTHOR]

Background: Ripple mapping displays every deflection of a bipolar electrogram and enables the visualization of conduction channels (RMCC) within postinfarction ventricular scar to guide ventricular tachycardia (VT) ablation. The utility of RMCC identification for facilitation of VT ablation in the setting of arrhythmogenic right ventricular cardiomyopathy (ARVC) has not been described. Objective: We sought to (a) identify the slow conduction channels in the endocardial/epicardial scar by ripple mapping and (b) retrospectively analyze whether the elimination of RMCC is associated with improved VT‐free survival, in ARVC patients. Methods: High‐density right ventricular endocardial and epicardial electrograms were collected using the CARTO 3 system in sinus rhythm or ventricular pacing and reviewed for RMCC. Low‐voltage zones and abnormal myocardium in the epicardium were identified by using standardized late‐gadolinium–enhanced (LGE) magnetic resonance imaging (MRI) signal intensity (SI) z‐scores. Results: A cohort of 20 ARVC patients that had undergone simultaneous high‐density right ventricular endocardial and epicardial electrogram mapping was identified (age 44 ± 13 years). Epicardial scar, defined as bipolar voltage less than 1.0 mV, occupied 47.6% (interquartile range [IQR], 30.9‐63.7) of the total epicardial surface area and was larger than endocardial scar, defined as bipolar voltage less than 1.5 mV, which occupied 11.2% (IQR, 4.2 ± 17.8) of the endocardium (P < 0.01). A median 1.5 RMCC, defined as continuous corridors of sequential late activation within scar, were identified per patient (IQR, 1‐3), most of which were epicardial. The median ratio of RMCC ablated was 1 (IQR, 0.6‐1). During a median follow‐up of 44 months (IQR, 11‐49), the ratio of RMCC ablated was associated with freedom from recurrent VT (hazard ratio, 0.01; P = 0.049). Among nine patients with adequate MRI, 73% of RMCC were localized in LGE regions, 24% were adjacent to an area with LGE, and 3% were in regions without LGE. Conclusion: Slow conduction channels within endocardial or epicardial ARVC scar were delineated clearly by ripple mapping and corresponded to critical isthmus sites during entrainment. Complete elimination of RMCC was associated with freedom from VT. [ABSTRACT FROM AUTHOR]

Background: Noninducibility of ventricular tachycardia (VT) at noninvasive programmed stimulation performed shortly following ablation (negative NIPS) predicts low risk of the medium‐term recurrence. This study aimed to evaluate long‐term rate and mode of recurrence following negative NIPS. Methods: We extended follow‐up on patients in whom no VT could be induced at NIPS following ablation between 2008 and 2010. Recurrent VTs were categorized as "Original clinical" if they matched VT that had occurred spontaneously prior to the index ablation; "Original nonclinical" if they matched VT that was induced during the index ablation but had not occurred spontaneously; or "New." Among those undergoing repeat ablation, the area ablated to treat the recurrent VT was categorized as "Targeted initial scar" if it was targeted during the index procedure; "Untargeted initial scar" if it was present but not targeted during the index procedure; or "New scar" if it was not present during the index procedure. Results: Of 60 patients with negative NIPS, 18 (30%) had recurrent VT and nine underwent repeat ablation over (4.1 ± 3.2) years follow‐up. Of 23 recurrent VTs, 18 (78%) were "New." During repeat ablations, six (46%) of the 13 recurrent VTs were ablated in "untargeted initial scar" and four (31%) in "new scar." Conclusions: When spontaneous or inducible VTs are eliminated with ablation and no longer inducible during NIPS, these VTs are unlikely to recur during long‐term follow‐up. More commonly, new VTs occur, which are either associated with areas of scar not present or not targeted during the initial ablation. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation of ventricular arrhythmias (VA) from the papillary muscles (PM) is challenging due to limited catheter stability and contact on the PMs with their anatomic complexity and mobility. Objective: This study aimed to evaluate the effectiveness of cryoablation as an adjunctive therapy for PM VAs when radiofrequency (RF) ablation has failed. Methods: We evaluated a retrospective series of patients who underwent cryoablation for PM VAs when RF ablation had failed. The decision to switch to cryoablation was at the operator's discretion when intracardiac echocardiography (ICE) suggested that cryoablation might be more effective in achieving catheter stability and energy delivery. Results: Sixteen patients underwent cryoablation of PM VAs between 2014 and 2016 after RF ablation was unsuccessful. VAs originated from the anterolateral left ventricle (LV) PM (six patients), posterolateral LV PM (six patients), and right ventricle PM (four patients). VAs were predominantly frequent premature ventricular complexes (PVCs); however, patients with sustained ventricular tachycardia and PVC‐triggered VF were also represented. Fifteen of the 16 patients were treated with cryoablation; in one patient, a procedural complication with retrograde aortic access precluded treatment. In all patients treated with cryoablation, contact and stability was confirmed with ICE to be superior to the RF catheter, and there was acute and long‐term elimination of VAs. Conclusion: Cryoablation is a useful adjunctive therapy in ablation of PM VAs, providing excellent procedural outcomes even when RF ablation has failed. Cryoablation catheters are less maneuverable than RF ablation catheters and care is required to avoid complications. [ABSTRACT FROM AUTHOR]

Introduction: The characteristics of the epicardial (EPI) substrate responsible for ventricular tachycardia (VT) in ischemic cardiomyopathy (ICM) are undefined, and data on the long‐term outcomes of EPI catheter ablation limited. We evaluated the prevalence, electrophysiologic features, and outcomes of catheter ablation of EPI VT in ICM. Methods and Results: From December 2010 to June 2013, a total of 13 of 93 (14%) patients with ICM underwent catheter ablation at our institution and had conclusive evidence of critical EPI substrate demonstrated to participate in VT with activation, entrainment and/or pace mapping during sinus rhythm (two other patients underwent EPI mapping but had no optimal ablation targets). The electrophysiologic substrate characteristics and activation/entrainment mapping data were compared with a reference group of ICM patients without evidence of critical EPI substrate (N = 44), defined as a complete procedural success (noninducibility of any VT at programmed stimulation) after endocardial (ENDO)‐only ablation. Patients with failed EPI access (N = 2) or history of cardiac surgery (N = 92) were excluded from the study. All 13 patients had evidence of abnormal EPI substrate with fractionated/late/split electrograms and low‐bipolar voltage areas. The critical VT ablation sites were all located within the EPI bipolar "dense" scar (<1.0 mV) opposite the ENDO bipolar scar in 77% of cases and extending beyond the ENDO bipolar scar (within the ENDO unipolar low‐voltage area) in the remaining patients. Compared with the reference ENDO‐only group, patients with EPI VT had a smaller ENDO bipolar scar area, 54.0 (37.1‐84) vs 86.7 (55.6‐112) cm2; P = 0.0159, with a similar extent of ENDO unipolar low voltage. No other substrate characteristics or location differed between the two groups. After 35.2 ± 24.2 months of follow‐up, VT‐free survival was 73% in patients with EPI VT compared with 66% in the ENDO‐only group (log‐rank P = 0.56). Conclusions: The presence of the critical EPI substrate responsible for VT can be demonstrated in at least 14% of patients with ICM. The majority of EPI critical ablation sites are distributed opposite the ENDO bipolar scar area and catheter ablation is effective in achieving long‐term arrhythmia control. [ABSTRACT FROM AUTHOR]

Background: The PAINESD score predicts the risk of periprocedural acute hemodynamic decompensation (AHD) and postprocedural mortality in patients undergoing catheter ablation (CA) of scar-related ventricular tachycardia (VT). The role of prophylactic placement of percutaneous left ventricular assist devices (pLVADs) in high-risk patients is unknown.Objective: The purpose of this study was to evaluate the outcomes of prophylactic use of pLVAD in high-risk patients undergoing CA of scar-related VT.Methods: We included 75 patients undergoing CA of scar-related VT in whom a prophylactic pLVAD was implanted because of perceived high risk. The control population was a propensity-matched group of 75 patients who did not undergo prophylactic pLVAD placement. The PAINESD score was used for propensity matching.Results: The median PAINESD score was 13 (41% with score ≥15) in the prophylactic pLVAD group and 12 (40% with score ≥15) in the control group. Periprocedural AHD occurred in 5 patients (7%) in the prophylactic pLVAD group and in 17 patients (23%) in the control group (P < .01). The 12-month cumulative incidence of VT was 40% in the prophylactic pLVAD group vs 41% in the control group (P = .97), while the 12-month incidence of death/transplant was 33% vs 66%, respectively (P < .01). In multivariable analysis, left ventricular ejection fraction (HR 0.97, 95% CI 0.95-0.99, P = .03), chronic kidney disease (HR 2.24, 95% CI 1.35-3.72, P < .01), VT recurrence (HR 2.33, 95% CI 1.31-4.14, P < .01), and prophylactic pLVAD (HR 0.28, 95% CI 0.16-0.49, P < .01) were all independently associated with death/transplant.Conclusion: Prophylactic pLVAD placement in high-risk patients undergoing CA of scar-related VT is associated with a reduced risk of AHD and death/transplant during follow-up without affecting VT-free survival. [ABSTRACT FROM AUTHOR]

Aims: Limited data exist on the long-term outcome of patients (pts) with non-ischemic cardiomyopathy (NICM) and ventricular tachycardia (VT) refractory to conventional therapies undergoing surgical ablation (SA). We aimed to investigate the long-term survival and VT recurrence in NICM pts with VT refractory to radiofrequency catheter ablation (RFCA) who underwent SA.Methods and results: Consecutive pts with NICM and VT refractory to RFCA who underwent SA were included. VT substrate was characterized in the electrophysiology lab and targeted by RFCA. During SA, previous RFCA lesions/scars were identified and targeted with cryoablation (CA; 3 min/lesion; target -150 °C). Follow-up comprised office visits, ICD interrogations and the social security death index. Twenty consecutive patients with NICM who underwent SA (age 53 ± 16 years, 18 males, LVEF 41 ± 20%; dilated CM = 9, arrhythmogenic right ventricular CM = 3, hypertrophic CM = 2, valvular CM = 4, and mixed CM = 2) were studied. Percutaneous mapping/ablation in the electrophysiology lab was performed in 18 and 2 pts had primary SA. During surgery, 4.9 ± 4.0 CA lesions/pt were delivered to the endocardium (2) and epicardium (11) or both (7). VT-free survival was 72.5% at 1 year and over 43 ± 31 months (mos) (range 1-83mos), there was only one arrhythmia-related death. There was a significant reduction in ICD shocks in the 3-mos preceding SA vs. the entire follow-up period (6.6 ± 4.9 vs. 2.3 ± 4.3 shocks/pt, P = 0.001).Conclusion: In select pts with NICM and VT refractory to RFCA, SA guided by pre-operative electrophysiological mapping and ablation may be a therapeutic option. [ABSTRACT FROM AUTHOR]

Background: In patients with ventricular tachycardia or ventricular fibrillation (VT/VF) electrical storm (ES) undergoing catheter ablation (CA), hypotension due to refractory VT/VF, use of anesthesia, and cardiac stunning due to repeated implantable cardioverter-defibrillator shocks might precipitate acute hemodynamic decompensation (AHD).Objective: We evaluated the outcomes of emergent cardiopulmonary support with extracorporeal membrane oxygenation (ECMO) to rescue AHD in patients undergoing CA of ES.Methods: Between January 1, 2010 and December 31, 2016, 21 patients with ES (VT in 11 and premature ventricular complex-triggered VF in 10) were referred for CA and had periprocedural AHD requiring emergent ECMO support.Results: In 14 patients, AHD occurred a mean of 1.5 ± 1.7 days before the procedure. In the remaining 7 patients, AHD occurred during or shortly after the procedure. ECMO was started successfully in all patients. Ablation was performed in 18 patients (9 with VF and 9 with VT). In patients with VF, premature ventricular complex suppression was achieved in 8 of 9 (89%). In those with VT, noninducibility was achieved in 7 of 9 (78%). After a median follow-up of 10 days, 16 patients died (13 during the index admission). Death was due to refractory VT/VF in 4 patients, heart failure in 11, and noncardiac cause in 1 patient. Seven patients survived beyond 6 months postablation; 5 remained free of VT/VF and 3 ultimately received a destination therapy (heart transplantation in 2 and left ventricular [LV] assist device in 1).Conclusion: In patients with ES undergoing CA, the outcomes of ECMO support as rescue intervention for AHD are poor. The majority of these patients die of refractory heart failure in the short-term. Strategies to prevent AHD including preemptive use of hemodynamic support may improve survival. [ABSTRACT FROM AUTHOR]

Background Most idiopathic ventricular arrhythmias (VAs) originate from the outflow tracts and are characterized by an inferior axis on the 12-lead ECG. A group of patients will exhibit inferior lead discordance (ILD), demonstrating a positive QRS in lead II with negative QRS in III or the opposite finding. Methods and results We identified patients undergoing ablation of idiopathic premature ventricular contractions (PVCs) or ventricular tachycardia (VT) between 2013 and 2015. The site of earliest activation was determined using electroanatomic mapping and intracardiac echocardiography. Out of 281 patients, 25 (8.9%) exhibited ILD. In patients with positive/negative discordance (n = 18), the source was mapped to the parahisian region in 14 cases and to the right ventricular (RV) moderator band (MB) or papillary muscles (PMs) in 4, while all those with negative/positive discordance (n = 7) were mapped to the anterolateral PM (ALPM). In the group with positive/negative discordance, a later precordial transition (>V4), wider QRS duration, and the presence of notch in the inferior leads pointed toward a RV MB/PM origin. Complete PVC/VT suppression was achieved in 72%. In 2 patients with parahisian PVCs, ablation was not attempted due to risk of heart block. Conclusions The presence of ILD is associated with particular anatomical locations, namely, the parahisian region, RV MB/PM, and ALPM. The outcomes of ablation are more modest compared to other idiopathic VAs, reflecting the technical difficulties associated with these anatomical locations, such as the proximity to the conduction system in parahisian VAs or stability issues when ablating the PMs or MB. [ABSTRACT FROM AUTHOR]

Background: Data evaluating repeat radiofrequency ablation (>1RFA) of ventricular tachycardia (VT) are limited.Objective: The purpose of this study was to determine the safety and outcomes of VT >1RFA in patients with structural heart disease.Methods: Patients with structural heart disease undergoing VT RFA at 12 centers with data on prior RFA history were included. Characteristics and outcomes were compared between first-time (1RFA) and >1RFA patients.Results: Of 1990 patients, 740 had >1RFA (mean 1.4 ± 0.9, range 1-10). >1RFA vs 1RFA patients did not differ with regard to age (62 ± 13 years vs 62 ± 13 years), left ventricular ejection fraction (33% ± 13% vs 34% ± 13%), or sex (88% vs 87% men), but they more often were nonischemic (53% vs 41%), had implantable cardioverter-defibrillator shocks (70% vs 63%) or VT storm (38% vs 33%), and had been treated with amiodarone (55% vs 48%) or ≥2 antiarrhythmic drugs (22% vs 14%). >1RFA procedures were longer (300 ± 122 minutes vs 266 ± 110 minutes), involved more epicardial access (41% vs 21%), induced VTs (2.4 ± 2.2 vs 1.9 ± 1.6) and only unmappable VTs (15% vs 9%), and VT was more often inducible after RFA (42% vs 33%, all P <.03). Total complications were higher for >1RFA vs 1RFA (8% vs 5%, P <.01), mostly related to pericardial effusion (2.4% vs 1.3%, P = .07) and venous thrombosis (0.8% vs 0.2%, P = .06). VT recurrence was higher for >1RFA vs 1RFA (29% vs 24%, P <.001). Survival was worse for >1RFA vs 1RFA if VT recurred (67% vs 78%, P = .003) but was equivalent if successful (93% vs 92%, P = .96).Conclusion: Patients requiring repeat VT ablation differ significantly from those undergoing first-time ablation. Despite more challenging ablation characteristics, VT-free survival after repeat ablations is encouraging. Mortality is comparable if VT does not recur after RFA at specialized centers. [ABSTRACT FROM AUTHOR]

Background: In patients referred for radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in the setting of structural heart disease, early post-procedural mortality (EM) has not been previously investigated.Objectives: The purpose of this study was to evaluate EM after catheter ablation of scar-related VT.Methods: Associations between clinical and procedural variables and EM (within 31 days of the procedure) were tested in patients with structural heart disease undergoing RFCA of VT at 12 international centers.Results: Of 2,061 patients (mean age 62 ± 13 years; left ventricular ejection fraction [LVEF] 34 ± 13%; 53% ischemic etiology), EM occurred in 100 (5%; 95% confidence interval [CI]: 4% to 6%). A total of 54 (3%) patients died before hospital discharge (median 9 days after the procedure; 25% for refractory VT), including 12 (0.6%) after a major procedure-related complication. In multivariable analysis, the following factors were found to be significantly associated with EM: LVEF (odds ratio [OR] per percent decrease: 1.12; 95% CI: 1.05 to 1.20; p < 0.001), chronic kidney disease (OR: 2.73; 95% CI: 1.10 to 6.80; p = 0.030), presentation with VT storm (OR: 3.61; 95% CI: 1.37 to 9.48; p = 0.009), and presence of unmappable VTs (OR: 5.69; 95% CI: 1.37 to 23.69; p = 0.017). Recurrent VT was also associated with an increased risk of subsequent death (hazard ratio: 7.19; 95% CI: 5.57 to 9.28; p < 0.001) and EM (hazard ratio: 11.45; 95% CI: 7.47 to 17.59; p < 0.001).Conclusions: In a contemporary cohort of patients with scar-related VT undergoing RFCA, EM occurred in 5% of cases. Clinical and procedural variables indicating poorer clinical status (low LVEF, chronic kidney disease, VT storm, and unmappable VTs) and post-procedural VT recurrence may predict EM. Identification of such features may prompt early consideration for hemodynamic support or other care to help mitigate later potential complications. [ABSTRACT FROM AUTHOR]

Outflow Tract VT With Pattern Break in Lead V2 Introduction In outflow tract ventricular arrhythmias (OT-VAs), an abrupt loss of the R wave in lead V2 compared to V1 and V3 (pattern break in V2-PBV2) suggests an origin close to the anterior interventricular sulcus (anatomically opposite to lead V2) and adjacent to proximal coronaries. We studied the outcome of catheter ablation of OT-VAs with a PBV2. Methods and Results Of 130 consecutive patients with idiopathic left bundle block morphology OT-VAs and transition ≤V4, 12 (9%) had PBV2. Outcomes in this group were compared to the remaining 118 patients. Patients with PBV2 were more likely to be younger (41 ± 18 vs. 50 ± 14 years, P = 0.0384) and women (11 [92%] vs. 70 [59%], P = 0.0302). The earliest activation was at the RVOT in seven, left coronary cusp (LCC) in one, anterior interventricular vein (AIV) in two and the epicardium in two. In five (42%) cases (earliest activation in the AIV in two, epicardium in two, and RVOT below the valve level in one), ablation was aborted due to proximity to the left anterior descending (LAD) coronary artery. After 36 ± 17 months and 1.3 ± 0.5 procedures, VAs elimination was achieved in 58% of patients with PBV2 compared to 89% of the reference population (P = 0.0125) with effective site in five of seven at the most anterior and leftward RVOT adjacent to the pulmonic valve (PV). Conclusions OT-VAs with PBV2 demonstrate a unique ECG pattern and challenging catheter ablation. Proximity to LAD precludes ablation in about half. Long-term VA suppression could be achieved in only 58% of cases most commonly when the earliest site is at the anterior and leftward RVOT just under the PV. [ABSTRACT FROM AUTHOR]

Background: Left ventricular noncompaction (LVNC) is a primary cardiomyopathy that can present with recurrent ventricular arrhythmias (VAs). Data on the benefit of catheter ablation of VAs in LVNC are lacking.Objective: The purpose of this study was to describe the electrophysiologic features and outcomes of catheter ablation of VAs in LVNC.Methods: The cohort consisted of 9 patients (age 42 ± 15 years) with diagnosis of LVNC based on established criteria and VA (ventricular tachycardia [VT] in 3 and frequent premature ventricular contractions (PVCs) in 6) despite treatment with a mean of 2 ± 1 antiarrhythmic drugs. Ablation sites were identified using a combination of entrainment, activation, late/fractionated potential ablation, and pace-mapping.Results: A total of 8 patients (89%) had left ventricular (LV) systolic dysfunction (mean ejection fraction 40% ± 13%). Patients who presented with VT had evidence of abnormal electroanatomic substrate involving the mid- to apical segments of the LV, which matched the noncompacted myocardial segments identified by preprocedural magnetic resonance imaging or echocardiography. In patients presenting with frequent PVCs, the site of origin was identified at the papillary muscles (50%) and/or basal septal regions (67%). After median follow-up of 4 years (range 1-11) and a mean of 1.8 ± 1.1 procedures, VAs recurred in 1 patient (11%). Significant improvement in LV function occurred in 4 of 8 cases (50%). No patients died or underwent heart transplantation.Conclusion: The VA substrate in patients with LVNC and VT typically involves the mid-apical LV segments, whereas focal PVCs often arise from LV basal-septal regions and/or papillary muscles. Catheter ablation is safe and effective in achieving good VA control over long-term follow-up in most patients. [ABSTRACT FROM AUTHOR]

Background: Ventricular tachycardia (VT) radiofrequency ablation has been associated with reduced VT recurrence and mortality, although it is typically not considered among New York Heart Association class IV (NYHA IV) heart failure patients. We compared characteristics and VT radiofrequency ablation outcomes of those with and without NYHA IV in the International VT Ablation Center Collaboration.Methods and Results: NYHA II-IV patients undergoing VT radiofrequency ablation at 12 international centers were included. Clinical variables, VT recurrence, and mortality were analyzed by NYHA IV status using Kaplan-Meier analysis and Cox proportional hazard models. There were significant differences between NYHA IV (n=111) and NYHA II and III (n=1254) patients: NYHA IV had lower left ventricular ejection fraction; more had diabetes mellitus, kidney disease, cardiac resynchronization implantable cardioverter-defibrillator, and VT storm despite greater antiarrhythmic drug use (P<0.01). NYHA IV subjects required more hemodynamic support, were inducible for more and slower VTs, and were less likely to undergo final programmed stimulation. There was no significant difference in acute complications. In-hospital deaths, recurrent VT, and 1-year mortality were higher in the NYHA IV group, in the context of greater baseline comorbidities. Importantly, NYHA IV patients without recurrent VT had similar survival compared with NYHA II and III patients with recurrent VT (68% versus 73%). Early VT recurrence (≤30 days) was significantly associated with mortality, especially in NYHA IV patients.Conclusions: Despite greater baseline comorbidities, VT radiofrequency ablation can be safely performed among NYHA IV patients. Early VT recurrence is significantly associated with subsequent mortality regardless of NYHA status. Elimination of recurrent VT in NYHA IV patients may reduce mortality to a level comparable to NYHA II and III with arrhythmia recurrence. [ABSTRACT FROM AUTHOR]

Background: Treatment strategies to prevent ventricular tachycardia (VT) in patients with an implantable cardioverter-defibrillator (ICD) include antiarrhythmic drugs (AADs) and catheter ablation (CA).Objective: The purpose of this study was to systematically compare the efficacy of AADs and CA for the prevention of VT in patients with ICDs.Methods: Major databases were searched (October 2015) for randomized trials evaluating AADs or CA vs standard medical therapy to prevent VT in ICD patients. Primary outcome was the number of VT episodes leading to appropriate ICD interventions.Results: Eight trials (n = 2268, follow-up 15 ± 6 months) evaluated AADs, and 6 trials (n = 427, follow-up 14 ± 8 months) evaluated CA. A significant reduction in appropriate ICD interventions was found with both CA (odds ratio [OR] 0.45, 95% confidence interval [CI] 0.28-0.71, P = .001) and AADs (OR 0.66, 95% CI 0.44-0.97, P = .037), with no significant difference between the 2 treatment strategies. The benefit of AADs was driven by amiodarone and not confirmed with other AADs. A reduction of inappropriate ICD interventions was found with AADs (OR 0.30, P = .001) but not with CA. Both CA and AADs were not associated with decreased mortality over follow-up. Amiodarone appeared to increase the risk of death (OR 3.36, 95% CI 1.36-8.30, P = .009).Conclusion: In patients with an ICD, both AADs (amiodarone) and CA reduce the risk of recurrent VT compared to control medical therapy, with no significant difference between the 2 treatments. AADs are also associated with a reduction of inappropriate ICD therapies. The significant reduction of recurrent VT episodes does not appear to result in a mortality benefit, with a potential for increased mortality with amiodarone. [ABSTRACT FROM AUTHOR]

Background The coronary venous system (CVS) is linked to the origin of idiopathic epicardial ventricular arrhythmias (VAs). Objective The purpose of this study was to identify the prevalence and effective mapping/ablation strategies for idiopathic VAs mapped to the CVS. Methods Detailed activation and pace-mapping of the right ventricle (RV), left ventricle (LV), CVS, and aortic cusps was performed, followed by attempted catheter ablation. Results Forty-seven of 511 patients with non–scar-related VAs (21 males, age 55 ± 15) had earliest activation in the CVS, 39 ± 18 ms before QRS. Twenty-five (53%) were in the great cardiac vein, 19 (40%) in the anterior interventricular vein, and 3 (7%) in the middle cardiac vein. We ablated inside CVS in 32 patients (68%) at the earliest activation site, in 18 patients at an adjacent CVS site, and in 14 patients because of an inability to advance the catheter in 4, inadequate power delivery in 2, and for safer distance from the coronary artery in 8. Proximity to coronaries precluded ablation inside the CVS in the remaining 15 patients (32%), who underwent ablation from adjacent left sinus of Valsalva, RV or LV endocardium, or LV epicardium. Success was achieved in 17 of 18 (94%) ablated at the earliest CVS site and in 16 of 29 (55%) ablated at adjacent CVS or non-CVS sites. Conclusion Idiopathic VAs are occasionally (9%) linked to CVS. Although ablation at the earliest CVS site is effective, it is often (62%) precluded, mainly because of proximity to coronary arteries. Ablation at adjacent CVS and non-CVS sites can be successful in 55% of these anatomically challenging cases, for an overall ablation success rate of 70%. [ABSTRACT FROM AUTHOR]

Background: Disease progression in patients with nonischemic cardiomyopathy (NICM) is poorly understood. Objective: To assess left ventricular (LV) scar progression and dilatation by using endocardial electroanatomic mapping. Methods: We studied 13 patients with NICM and recurrent ventricular tachycardia. Two detailed sinus rhythm endocardial voltage maps (265 ± 122 points/map) were obtained after a mean of 32 months (range 9–77 months). The scar area, defined by low bipolar (BI; <1.5 mV) and unipolar (UNI; <8.3 mV) endocardial voltage, and the LV volume were measured and compared. A scar difference of >6% of the LV surface and an increase in LV volume of ≥20 mL were considered beyond measurement error. Results: Six (46%) patients had an increase in scar area beyond boundaries of prior ablation. Five patients had an increase in UNI and 1 patient had an increase in both BI and UNI areas. The increase in BI area represented 16% and the increase in UNI area represented 6.5%–46.2% of the LV surface. A significant decrease in LV ejection fraction was found only in patients with scar progression (from 39% ± 8% to 32% ± 8%; P = .003). LV dilation (LV volume increase ranging between 9% and 23%) was noted in 3 patients, all of whom had scar progression. Conclusions: Progressive scarring with an increase in the area of UNI and less commonly BI electrogram abnormality is seen in 46% of the patients with NICM and ventricular tachycardia and is associated with LV dilatation and decrease in LV ejection fraction. The prominent UNI abnormality suggests predominantly midmyocardial or epicardial scarring. [Copyright &y& Elsevier]

Background: The scar of patients with left ventricular (LV) nonischemic cardiomyopathy (NICM) and ventricular tachycardia (VT) typically originates at or near the mitral annulus and extends a variable distance toward the apex. Objective: To determine whether electrocardiograms of VT with LV apical exit sites would identify patients with larger scars extending a greater distance from the base toward the apex and decreased heart transplant/left ventricular assist device (LVAD)-free survival. Methods: Consecutive patients with LV NICM undergoing VT ablation between May 2008 and April 2011 were studied. All electrocardiograms of spontaneous and induced VT were analyzed. Apical VT was defined as left bundle branch morphology with precordial transition≥V5 or right bundle branch morphology with precordial transition≤V3. Scar percentage was defined as the area of low voltage divided by the total surface area. Results: Thirty-two of 76 patients had 1 or more apical VTs. Those with apical VTs had larger percentage of endocardial and epicardial bipolar scars (14.9% vs 8.1%, P = .01, and 15.5% vs 5.5%, P = .03, respectively), scar that, although originating from the periannular region (94.7% of the patients), was more likely to extend apically beyond the basal half (48.3% vs 24.4%, P = .05 endocardial, and 85.7% vs 25.9%, P = .07 epicardial), and worse transplant/LVAD-free survival during a mean follow-up of 332 days (P = .006). Conclusions: Patients with NICM and apical VTs have larger voltage abnormality extending as contiguous or patchy “scar” from the base further toward the apex and worse transplant/LVAD-free survival. Particular attention should be paid to optimal heart failure management in these patients, with more guarded prognosis. [Copyright &y& Elsevier]

Objectives: The goal of this study was to evaluate the ability of noninvasive programmed stimulation (NIPS) after ventricular tachycardia (VT) ablation to identify patients at high risk of recurrence. Background: Optimal endpoints for VT ablation are not well defined. Methods: Of 200 consecutive patients with VT and structural heart disease undergoing ablation, 11 had clinical VT inducible at the end of ablation and 11 recurred spontaneously. Of the remaining 178 patients, 132 underwent NIPS through their implantable cardioverter-defibrillator 3.1 ± 2.1 days after ablation. At 2 drive cycle lengths, single, double, and triple right ventricular extrastimuli were delivered to refractoriness. Clinical VT was defined by comparison with 12-lead electrocardiograms and stored implantable cardioverter-defibrillator electrograms from spontaneous VT episodes. Patients were followed for 1 year. Results: Fifty-nine patients (44.7%) had no VT inducible at NIPS; 49 (37.1%) had inducible nonclinical VT only; and 24 (18.2%) had inducible clinical VT. Patients with inducible clinical VT at NIPS had markedly decreased 1-year VT-free survival compared to those in whom no VT was inducible (<30% vs. >80%; p = 0.001), including 33% recurring with VT storm. Patients with inducible nonclinical VT only, had intermediate 1-year VT-free survival (65%). Conclusions: When patients with VT and structural heart disease have no VT or nonclinical VT only inducible at the end of ablation or their condition is too unstable to undergo final programmed stimulation, NIPS should be considered in the following days to further define risk of recurrence. If clinical VT is inducible at NIPS, repeat ablation may be considered because recurrence over the following year is high. [Copyright &y& Elsevier]

VT Ablation Treatment of Last Resort. Introduction: Despite advances in ablation of ventricular tachycardia (VT), recognized toxicity of amiodarone, and potential harm of implantable cardioverter defibrillator (ICD) shocks, there appears to be reluctance to pursue catheter ablation. Methods and Results: We tested the hypothesis that patients with structural heart disease and VT are referred late for ablation and may have worse outcomes as a result. Consecutive patients with VT and structural heart disease referred to a single center, between January 2008 and April 2009 were studied. Patients with prior VT ablations were excluded. Late referrals were defined as those with 2 or more episodes of VT, separated by at least 1 month. Ninety-eight consecutive patients were analyzed. Ninety-six percent of patients had an ICD implanted prior to ablation, 58% were in VT storm and 67% taking ≥400 mg daily of amiodarone or amiodarone intolerant (10%). Thirty-six patients fit the definition of early referral and 62 late. Overall acute procedural success was achieved in 89%. Amiodarone dose decreased from a mean and median of 559 and 400 mg daily preablation to 98 and 0 postablation (P < 0.01). Mean and median VT episodes decreased from 17 and 6 in the month preceding ablation to 1 and 0 in the 6 months following ablation (P < 0.01). In Kaplan-Meier analysis, the early referral group had superior 1-year VT free survival (P = 0.01). Conclusions: VT ablation is frequently reserved for patients receiving recurrent ICD shocks despite high dose amiodarone. Stronger consideration should be given to earlier referral for VT ablation in patients with structural heart disease. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1123-1128, October 2011) [ABSTRACT FROM AUTHOR]

Background: The substrate for ventricular tachycardia (VT) in left ventricular (LV) nonischemic cardiomyopathy may be epicardial. We assessed the prevalence, location, endocardial electrograms, and VT ablation outcomes in LV nonischemic cardiomyopathy with isolated epicardial substrate.Methods: Forty-seven of 531 (9%) patients with LV nonischemic cardiomyopathy and VT demonstrated normal endocardial (>1.5 mV)/abnormal epicardial bipolar low-voltage area (LVA, <1.0 mV and signal abnormality). Abnormal endocardial unipolar LVA (≤8.3 mV) and endocardial bipolar split electrograms and predictors of ablation success were assessed.Results: Epicardial bipolar LVA (27.3 cm2 [interquartile range, 15.8-50.0]) localized to basal (40), mid (8), and apical (3) LV with basal inferolateral LV most common (28/47, 60%). Of 44 endocardial maps available, 40 (91%) had endocardial unipolar LVA (24.5 cm2 [interquartile range, 9.4-68.5]) and 29 (67%) had characteristic normal amplitude endocardial split electrograms opposite the epicardial LVA. At mean of 34 months, the VT-free survival was 55% after one and 72% after multiple procedures. Greater endocardial unipolar LVA than epicardial bipolar LVA (hazard ratio, 10.66 [CI, 2.63-43.12], P=0.001) and number of inducible VTs (hazard ratio, 1.96 [CI, 1.27-3.00], P=0.002) were associated with VT recurrence.Conclusions: In patients with LV nonischemic cardiomyopathy and VT, the substrate may be confined to epicardial and commonly basal inferolateral. LV endocardial unipolar LVA and normal amplitude bipolar split electrograms identify epicardial LVA. Ablation targeting epicardial VT and substrate achieves good long-term VT-free survival. Greater endocardial unipolar than epicardial bipolar LVA and more inducible VTs predict VT recurrence. [ABSTRACT FROM AUTHOR]

Keywords: Editorials; catheter ablation; tachycardia, ventricular EN Editorials catheter ablation tachycardia, ventricular 1068 1070 3 04/20/20 20200331 NES 200331 B Article, see p 1057 b In this issue of I Circulation i , Willems et al[1] report on the BERLIN VT trial (Preventive Ablation of Ventricular Tachycardia in Patients with Myocardial Infarction), comparing the outcomes of ventricular tachycardia (VT) ablation at the time of implanted cardioverter-defibrillators (ICD) implant for documented VT, "preventive ablation", versus, at the time of shocks for recurrent VT, "deferred ablation." VTACH study group Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial. 2006, 295, 165-171, doi: 10.1001/jama.295.2.165 7 Marchlinski FE, Haffajee CI, Beshai JF, Dickfeld TL, Gonzalez MD, Hsia HH, Schuger CD, Beckman KJ, Bogun FM, Pollak SJ, Long-term success of irrigated radiofrequency catheter ablation of sustained ventricular tachycardia: post-approval THERMOCOOL VT trial. [Extracted from the article]

Objectives: The goal of this study was to determine the relationship of the ventricular tachycardia (VT) isthmus to channels of preserved voltage on an electroanatomic voltage map in postinfarction cardiomyopathy. Background: Substrate mapping in patients with postinfarction cardiomyopathy and VT may involve lowering the voltage cutoff that defines the scar (<1.5 mV) to identify “channels” of relative higher voltage within the scar. However, the prevalence of channels within the scar identified by using electroanatomic mapping and the relationship to the protected VT isthmus identified by entrainment mapping is unknown. Methods: Detailed bipolar endocardial voltage maps (398 ± 152 points) from 24 patients (mean age 69 ± 9 years) with postinfarction cardiomyopathy (ejection fraction 33 ± 9%) and tolerated VT were reviewed. Endocardial scar was defined according to voltage <1.5 mV. Isolated late potentials (ILPs) were identified and tagged on the electroanatomic voltage map. The baseline voltage cutoffs were then adjusted until all channels were identified. The VT isthmus was identified using entrainment mapping. Results: Inferior and anterior/lateral infarction was present by voltage mapping in 18 and 6 patients, respectively (scar area 44 ± 24 cm2). By adjusting voltage cutoffs, 37 channels were identified in 21 (88%) of 24 patients. The presence of ILPs within a channel was seen in 11 (46%) of 24 patients and 17 (46%) of 37 channels. A VT isthmus site was contained within a channel in only 11 of 24 patients or 11 of 37 channels. No difference in voltage characteristics was identified between clinical and nonclinical channels. Voltage channels with ILPs harbored the clinical isthmus with a sensitivity and specificity of 78% and 85%, respectively. Conclusions: Channels were identified in 88% of patients with VT by adjusting the voltage limits of bipolar maps; however, the specificity of those channels in predicting the location of VT isthmus sites was only 30%. The presence of ILPs inside the voltage channel significantly increases the specificity for identifying the clinical VT isthmus. [Copyright &y& Elsevier]

Keywords: antiarrhythmic drugs; arrhythmias; atrial fibrillation; supraventricular tachycardia; ventricular tachycardia EN antiarrhythmic drugs arrhythmias atrial fibrillation supraventricular tachycardia ventricular tachycardia 937 939 3 04/20/20 20200317 NES 200317 Antiarrhythmic drugs (AADs) are widely prescribed to treat both ventricular and supraventricular arrhythmias. Arrhythmia diagnoses were combined into meaningful categories including atrial fibrillation and flutter; ventricular tachycardia and fibrillation; and supraventricular tachycardia. Antiarrhythmic drugs, arrhythmias, atrial fibrillation, supraventricular tachycardia, supraventricular tachycardia, ventricular tachycardia. [Extracted from the article]