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Aims: Arrhythmogenic right ventricular (RV) cardiomyopathy (ARVC) is associated with ventricular arrhythmias, even without RV structural disease. We aimed to characterize the RV substrate using electroanatomical mapping and to define outcomes following ventricular tachycardia (VT) ablation in patients with and without RV structural abnormalities., Methods and Results: Twenty-nine patients with definite or suspected ARVC undergoing VT ablation were classified as 'electrical' and 'structural' cardiomyopathy based on the absence or presence of major structural criteria. Right ventricular (RV) endocardial and epicardial mapping with assessment of bipolar and unipolar voltages, distribution of late potentials (LPs), and inducible VT morphologies were performed. The endpoints for VT ablation were VT non-inducibility and LP abolition. Fourteen patients were categorized as electrical RV cardiomyopathy and 15 were categorized as structural RV cardiomyopathy. In patients with electrical cardiomyopathy, scar was limited to the epicardial surface (epicardium 13 cm2vs. endocardium 1 cm2, P < 0.05), primarily in the outflow tract, whereas patients with structural disease had greater involvement of the endocardium. During a mean follow-up of 22 ± 11 months, the VT recurrence rate was 27%, with LP abolition being a predictor of VT-free survival (HR 0.075 (0.008-0.661), P = 0.020). There was a trend towards higher recurrence rates in structural RV cardiomyopathy (40%) compared with the electrical cardiomyopathy (15%, P = 0.17)., Conclusion: The development of RV structural disease in patients with ARVC is associated with extensive epicardial and endocardial scar. Conversely those patients without RV structural disease have identifiable epicardial scar limited to the RV outflow tract. Ventricular tachycardia (VT) ablation in both groups targeting LP abolition is effective in preventing VT recurrence., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions please email: journals.permissions@oup.com.)

Aims: Patients with non-ischaemic cardiomyopathy (NICM) and ventricular tachycardia can be categorized as anteroseptal (AS) or inferolateral (IL) scar sub-types based on imaging and voltage mapping studies. The aim of this study was to correlate the baseline electrocardiogram (ECG) with endo-epicardial voltage maps created during ablation procedures and identify the ECG characteristics that may help to distinguish the scar as AS or IL., Methods and Results: We assessed 108 baseline ECGs; 72 patients fulfilled criteria for dilated cardiomyopathy whereas 36 showed minimal structural abnormalities. Based on the unipolar low-voltage distribution, the scar pattern was classified as predominantly AS (n = 59) or IL (n = 49). Three ECG criteria (PR interval < 170 ms or QRS voltage in inferior leads <0.6 mV or a lateral q wave) resulted in 92% sensitivity and 90% specificity for predicting an IL pattern in patients with preserved ejection fraction (EF). The four-step algorithm for dilated cardiomyopathy included a paced ventricular rhythm or PR > 230 ms or QRS > 170 ms or an r ≤ 0.3 mV in V3 having 92 and 81% of sensitivity and specificity, respectively, in predicting AS scar pattern. A significant negative correlation was found between the extension of the endocardial unipolar low voltage area and left ventricular EF (r s = -0.719, P < 0.001). The extent of endocardial AS unipolar low voltage was correlated with PR interval and QRS duration (r s = 0.583 and r s = 0.680, P < 0.001, respectively) and the IL epicardial unipolar low voltage with the mean voltage of the limb leads (r s = -0.639, P < 0.001)., Conclusion: Baseline ECG features are well correlated with the distribution of unipolar voltage abnormalities in NICM and may help to predict the location of scar in this population., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.)

Objectives: This study sought to compare myocardial scars depicted by computed tomography (CT) with electrical features from electro-anatomic mapping (EAM), assessing the potential role of CT integration in ventricular tachycardia (VT) and radiofrequency catheter ablation (RFCA) procedures., Background: Imaging-based characterization of VT myocardial substrate is required to plan EAM and, potentially, to guide RFCA., Methods: Forty-two consecutive patients, 35 of whom had implantable cardioverter-defibrillator, all referred for VT RFCA, underwent pre-procedural CT including an angiographic and a 10-min delayed-enhancement scan. Segmental comparison between scars segmented from CT and low voltages (bipolar voltages <1.5 mV; unipolar voltages <8 mV), late potentials, and RF ablation points on EAM, was carried out. In a subset of 16 consecutive patients, a further point-by-point analysis was performed: a CT-derived 3-dimensional structure including heart anatomy and myocardial scars was integrated with EAM for quantitative comparison., Results: CT scans identified scars in 39 patients and defined left ventricular wall involvement and mural distribution. Overall segmental concordance between CT and EAM was good (κ = 0.536) despite the presence of implantable cardioverter-defibrillator, scar etiologies, and mural distribution. CT identified segments characterized by low voltages with good sensitivity (76%), good specificity (86%), and very high negative predictive value (95%). Late potentials and RF ablation points fell on scarred segments identified from CT in 79% and 81% of cases, respectively. Point-by-point quantitative comparison revealed good correlation between the average area of scar detected at CT and at bipolar mapping (CT = 4,901 mm(2), bipolar voltages-EAM = 4,070 mm(2); R = 0.78; p < 0.0001). In this study, 70% and 84% of low-amplitude bipolar points were mapped at a maximum distance of 5 mm and 10 mm from CT-segmented scar, respectively., Conclusions: CT with delayed-enhancement provides a 3-dimensional characterization of VT scar substrate together with a detailed anatomic model of the heart. This information may offer assistance to plan EAM and RFCA procedures and is potentially suitable for EAM-imaging integration., (Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Catheter ablation is an important therapeutic option in postmyocardial infarction patients with ventricular tachycardia (VT). We analyzed the endo-epicardial electroanatomical mapping (EAM) voltage and morphology characteristics, their association with clinical data and their prognostic value in a large cohort of postmyocardial infarction patients., Methods and Results: We performed total and segmental analysis of voltage (bipolar dense scar [DS] and low voltage areas, unipolar low voltage and penumbra areas) and morphology characteristics (presence of abnormal late potentials [LPs] and early potentials [EPs]) in 100 postmyocardial infarction patients undergoing electroanatomical mapping-based VT ablation (26 endo-epicardial procedures) from 2010-2012. All patients had unipolar low voltage areas, whereas 18% had no identifiable endocardial bipolar DS areas. Endocardial bipolar DS area >22.5 cm(2) best predicted scar transmurality. Endo-epicardial LPs were recorded in 2/3 patients, more frequently in nonseptal myocardial segments and were abolished in 51%. Endocardial bipolar DS area >7 cm(2) and endocardial bipolar scar density >0.35 predicted epicardial LPs. Isolated LPs are located mainly epicardially and EPs endocardially. As a primary strategy, LPs and VT-mapping ablation occurred in 48%, only VT-mapping ablation in 27%, only LPs ablation in 17%, and EPs ablation in 6%. Endocardial LP abolition was associated with reduced VT recurrence and increased unipolar penumbra area predicted cardiac death., Conclusions: Endocardial scar extension and density predict scar transmurality and endo-epicardial presence of LPs, although DS is not always identified in postmyocardial infarction patients. LPs, most frequently located in nonseptal myocardial segments, were abolished in 51% resulting in improved outcome., (© 2015 American Heart Association, Inc.)

Introduction: In patients with a prior myocardial infarction (MI), angiographic predictors of ventricular tachycardia (VT) recurrence after ablation are lacking. Recently, a proarrhythmic effect of a chronic total occlusion (CTO) in a coronary artery has been suggested., Methods and Results: A total of 191 patients with prior MI were referred to our Hospital between 2010 and June 2013 for a first ablation of VT. Of these, 84 patients (44%) with stable coronary artery disease that underwent a coronary angiography during the index hospitalization were included in this study. A CTO in an infarct-related artery (IRA-CTO) was present in 47 patients (56%). Patients with and without IRA-CTO did not differ in terms of comorbidities, severity of heart failure, presentation of VT or acute outcome of ablation, that was completely successful in 93% of cases. At electroanatomic mapping, IRA-CTO was associated with greater scar and especially with greater area of border zone (34 cm(2) vs. 19 cm(2) , P = 0.001). Median follow-up was 19 months (IQR 18). At follow-up, patients with IRA-CTO had a significantly higher rate of VT recurrence (47% vs. 16%, P = 0.003). At multivariate analysis, IRA-CTO resulted to be an independent predictor of VT recurrence after ablation (HR 4.05, P = 0.004)., Conclusions: IRA-CTO is an independent predictor of VT recurrence after ablation and identifies a subgroup of patients with high recurrence rate despite a successful procedure. IRA-CTO is associated with greater scars and border zone area; however, this association does not completely justify its proarrhythmic effect., (© 2015 Wiley Periodicals, Inc.)

Background: The mechanism of cardiac resynchronization therapy (CRT)-induced proarrhythmia remains unknown. We postulated that pacing from a left ventricular (LV) lead positioned on epicardial scar can facilitate re-entrant ventricular tachycardia. The aim of this study was to investigate the relationship between CRT-induced proarrhythmia and LV lead location within scar., Methods and Results: Twenty-eight epicardial and 63 endocardial maps, obtained from 64 CRT patients undergoing ventricular tachycardia ablation, were analyzed. A positive LV lead/scar relationship, defined as a lead tip positioned on scar/border zone, was determined by overlaying fluoroscopic projections with LV electroanatomical maps. CRT-induced proarrhythmia occurred in 8 patients (12.5%). They all presented early with electrical storm (100% versus 39% of patients with no proarrhythmia; P<0.01), requiring temporary biventricular pacing discontinuation in half of cases. They more frequently presented with heart failure/cardiogenic shock (50% versus 7%; P<0.01), requiring intensive care management. Ventricular tachycardia was re-entrant in all. The LV lead location within epicardial scar was significantly more frequent in the proarrhythmia group (60% versus 9% P=0.03 on epicardial bipolar scar, 80% versus 17% P=0.02 on epicardial unipolar scar, and 80% versus 17% P=0.02 on any-epicardial scar). Ablation was performed within epicardial scar, close to the LV lead, and allowed CRT reactivation in all patients., Conclusions: CRT-induced proarrhythmia presented early with electrical storm and was associated with an LV lead positioning within epicardial scar. Catheter ablation allowed for resumption of biventricular stimulation in all patients., (© 2014 American Heart Association, Inc.)

Aims: We present clinical, electroanatomical mapping (EAM), imaging, and catheter ablation (CA) strategies in patients with myocarditis-related ventricular tachycardia (VT)., Methods and Results: Between January 2010 and July 2012, 26 consecutive patients underwent imaging-guided CA of myocarditis-related ventricular arrhythmias, 23 of 26 using a combined endo-epicardial approach. Segment per segment correspondence of late enhanced (LE) scar localization with EAM scar was assessed in all patients with available uni/bipolar maps (n = 19). Induced VTs were targeted prior to substrate modification. Late potentials (LPs) abolition constituted a procedural endpoint independently from VT inducibility. Clinical monomorphic VT was induced in 15 of 26 patients (57.7%) and was associated with epicardial LPs in 10 of 15, completely abolished in 7 of 10 patients. Of the 10 patients rendered non-inducible VTs were ablated epicardially in 7. Late potentials were also detected in 7 of 11 initially non-inducible patients and completely abolished in 4. After a median follow-up of 23 (15-31) months, 20 of 26 patients (76.9%) remained free from VT recurrence. Bipolar mapping revealed low-voltage scar (<1.5 mV) in 1 patient endocardially and in 14 of 19 epicardially. Unipolar mapping revealed low-voltage scar (<8 mV) in 12 of 19 patients endocardially and in 18 of 19 epicardially. Correspondence of LE scar localization with endocardial bipolar scar was 1%, with endocardial unipolar scar 23.7%, with epicardial bipolar scar 39.8%, and with epicardial unipolar scar 66.2%., Conclusion: Pre-procedural scar imaging and EAM findings support the necessity of an epicardial approach in patients with prior myocarditis. Epicardial unipolar mapping (<8 mV) is superior in scar identification and CA based on substrate modification is safe and effective in this setting., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.)

Aims: Patients with well-tolerated sustained monomorphic ventricular tachycardia (SMVT) and left ventricular ejection fraction (LVEF) over 30% may benefit from a primary strategy of VT ablation without immediate need for a 'back-up' implantable cardioverter-defibrillator (ICD)., Methods and Results: One hundred and sixty-six patients with structural heart disease (SHD), LVEF over 30%, and well-tolerated SMVT (no syncope) underwent primary radiofrequency ablation without ICD implantation at eight European centres. There were 139 men (84%) with mean age 62 ± 15 years and mean LVEF of 50 ± 10%. Fifty-five percent had ischaemic heart disease, 19% non-ischaemic cardiomyopathy, and 12% arrhythmogenic right ventricular cardiomyopathy. Three hundred seventy-eight similar patients were implanted with an ICD during the same period and serve as a control group. All-cause mortality was 12% (20 patients) over a mean follow-up of 32 ± 27 months. Eight patients (40%) died from non-cardiovascular causes, 8 (40%) died from non-arrhythmic cardiovascular causes, and 4 (20%) died suddenly (SD) (2.4% of the population). All-cause mortality in the control group was 12%. Twenty-seven patients (16%) had a non-fatal recurrence at a median time of 5 months, while 20 patients (12%) required an ICD, of whom 4 died (20%)., Conclusion: Patients with well-tolerated SMVT, SHD, and LVEF > 30% undergoing primary VT ablation without a back-up ICD had a very low rate of arrhythmic death and recurrences were generally non-fatal. These data would support a randomized clinical trial comparing this approach with others incorporating implantation of an ICD as a primary strategy., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.)

Background: The aim was to relate distinct scar distributions found in nonischemic cardiomyopathy with ventricular tachycardia (VT) morphology, late potential distribution, ablation strategy, and outcome., Methods and Results: Eighty-seven patients underwent catheter ablation for drug-refractory VT. Based on endocardial unipolar voltage, 44 were classified as predominantly anteroseptal and 43 as inferolateral. Anteroseptal patients more frequently fulfilled diagnostic criteria for dilated cardiomyopathy (64% versus 36%), associated with more extensive endocardial unipolar scar (41 [22-83] versus 9 [1-29] cm(2); P<0.001). Left inferior VT axis was predictive of anteroseptal scar (positive predictive value, 100%) and right superior axis for inferolateral (positive predictive value, 89%). Late potentials were infrequent in the anteroseptal group (11% versus 74%; P<0.001). Epicardial late potentials were common in the inferolateral group (81% versus 4%; P<0.001) and correlated with VT termination sites (κ=0.667; P=0.014), whereas no anteroseptal patient had an epicardial VT termination (P<0.001). VT recurred in 44 patients (51%) during a median follow-up of 1.5 years. Anteroseptal scar was associated with higher VT recurrence (74% versus 25%; log-rank P<0.001) and redo procedure rates (59% versus 7%; log-rank P<0.001). After multivariable analysis, clinical predictors of VT recurrence were electrical storm (hazard ratio, 3.211; P=0.001) and New York Heart Association class (hazard ratio, 1.608; P=0.018); the only procedural predictor of VT recurrence was anteroseptal scar pattern (hazard ratio, 5.547; P<0.001)., Conclusions: Unipolar low-voltage distribution in nonischemic cardiomyopathy allows categorization of scar pattern as inferolateral, often requiring epicardial ablation mainly based on late potentials, and anteroseptal, which frequently involves an intramural septal substrate, leading to a higher VT recurrence., (© 2014 American Heart Association, Inc.)

Background: Successful late potential (LP) abolition and postprocedural ventricular tachycardia (VT) noninducibility constitute significant end points after catheter ablation for VT. We investigated the prognostic impact of a combined procedural end point of VT noninducibility and LP abolition in a large series of post-myocardial infarction patients with VT., Methods and Results: A total of 160 (154 men, 94% with implantable cardioverter defibrillators) consecutive post-myocardial infarction patients undergoing first-time ablation procedures from 2010 to 2012 were included. Of the 159 patients surviving the procedure, 137 (86%) were either inducible or in VT at baseline and 103 (65%) had baseline LP presence, of which 79 (77%) underwent successful LP abolition. The combined end point was assessable in 155 (97%) patients. There were 50 (32%) patients with VT recurrences and 17 (11%) cardiac deaths during follow-up. Patients who fulfilled the combined end point of VT noninducibility and LP abolition compared with inducible patients exhibited a significantly lower incidence of VT recurrence (16.4% versus 47.4%; log-rank P<0.001) and cardiac death (4.1% versus 42.1%; log-rank P<0.001). Among noninducible patients, those with additional LP abolition also had a lower incidence of VT recurrence (16.4% versus 46.0%; log-rank P<0.001). After multivariate analysis, the combined end point of VT noninducibility and LP abolition (hazard ratio, 0.205, P<0.001) was independently associated with VT recurrence and cardiac death (hazard ratio, 0.106; P=0.001)., Conclusions: Achieving a combined catheter ablation procedural end point of VT noninducibility and LP abolition reduces VT recurrence rates to low levels (16%). The overall strategy was associated with a significant impact on cardiac survival., (© 2014 American Heart Association, Inc.)

Background: Although the importance of contact force monitoring during mapping and ablation procedures is widely recognized, only indirect measurements have been validated., Methods: Real-time force values were measured using the force-sensing catheter and electroanatomical mapping system from 27 chambers (13 LVs, 6 RVs, and 8 epicardial space) in 17 patients affected by ventricular tachycardia. Left ventricular mapping was performed by the transaortic approach in all patients and in 5 patients also by a transseptal approach with the aid of a deflectable sheath. All points were divided into 2 groups according to the presence of positive contact force during diastole: good and poor contact. The frequency of good contact and its impact on electrophysiological parameters such as signal amplitude, local impedance, and frequency of late potentials was evaluated. The best cut-off value to discriminate the 2 groups was calculated by a generalized linear mixed-effects model., Results: Among all 5,926 points, 1,566 (26%) points were taken with poor contact. In healthy tissue, categorical increase of contact force caused the increase of unipolar and bipolar signal potential amplitude followed by plateau. The frequency of late potentials in the poor contact group was significantly lower when compared to the good contact group (11.9 vs 23.2%; P < 0.0001). The best cut-off force value to predict good contact during left ventricular endocardial and epicardial mappings was 9 g., Conclusions: A combined transaortic and transseptal approach allows better endocardial contact during left ventricular mapping. Ventricular mapping with sufficient contact force produces better substrate characterization within pathological areas., (© 2012 Wiley Periodicals, Inc.)

Background: We investigated the impact of catheter ablation on ventricular tachycardia (VT) recurrence and survival in a large number of patients with structural heart disease treated in the setting of a dedicated multiskilled unit., Methods and Results: Since January 2007, we have implemented a multidisciplinary model, aiming for a comprehensive management of VT patients. Programmed ventricular stimulation was used to assess acute outcome. Primary end points were VT recurrence and the occurrence of cardiac and sudden cardiac death. Overall, 528 patients were treated by ablation (634 procedures; 1-4 procedures per patient). Among 482 tested with programmed ventricular stimulation after the last procedure, a class A result (noninducibility of any VT) was obtained in 371 patients (77%), class B (inducibility of nondocumented VT) in 12.4%, and class C (inducibility of index VT) in 10.6%. After a median follow-up time of 26 months, VT recurred in 164 (34.1%) of 472 patients. VT recurrence was documented in 28.6% of patients with a class A result versus 39.6% of patients with class B and 66.7% with class C result (log-rank P<0.001). The incidence of cardiac mortality was lower in class A patients than in those with class B and class C (8.4% versus 18.5% versus 22%, respectively; log-rank P=0.002). On the basis of multivariate analysis, postprocedural inducibility of index VT was independently associated both with VT recurrence (hazard ratio, 4.030; P<0.001) and with cardiac mortality (hazard ratio, 2.099; P=0.04)., Conclusions: Within a dedicated VT unit, catheter ablation prevents long-term VT recurrences, which may favorably affect survival in a large number of patients who have VT.

Aims: The aim of this study is to evaluate the benefit of manually controlled steerable sheath, which provides greater flexibility and stability, in mapping and ablation procedure of ventricular tachycardia., Methods and Results: We retrospectively reviewed 40 patients who underwent epicardial mapping and conclusive ablation. The first attempt to reach the primary endpoint defined as successful creation of detailed map of entire epicardial space and was achieved in 16 patients. Among the remaining 24 patients, we used the steerable sheath and achieved further success to create an entire map in all patients. After the delivery of RF energy, final procedural success was defined as complete abolishment of late potential and no more induction of any VT, and that was obtained in 10 out of 16 patients mapped with conventional sheath and 21 out of 24 patients with steerable sheath. The advantage of the steerable sheath seemed to be consistent, regardless of the site of ablation. There was no procedure-related adverse event., Conclusions: The manually controlled steerable sheath was safe and effective to achieve procedural success in patients with epicardial VT.

Rationale: To evaluate the efficacy of radiofrequency ventricular tachycardia (VT) ablation targeting complete late potential (LP) activity., Methods and Results: Sixty-four consecutive patients (pts) with recurrent VTs and coronary artery disease or idiopathic dilated cardiomyopathy were evaluated. Fifty patients (47 male; 66.2 ± 10.1 years) had LPs at electroanatomical mapping; 35 patients had at least 1 VT inducible at basal programmed stimulation. After substrate mapping, radiofrequency ablation was performed with the endpoint of all LPs abolition. LPs could not be abolished in 5 patients despite extensive ablation, in 1 patient because of localization near an apical thrombus, and in 2 patients because of possible phrenic nerve injury. At the end of procedure, prevention of VT inducibility was achieved in 25 of 35 patients (71.4%) with previously inducible VT; VT was still inducible in 5 of 8 patients with incomplete LP abolition; and in 5 of 42 patients (16.1%) with complete LP abolition (P < 0.01). After a follow-up of 13.4 ± 4.0 months, 10 patients (20.0%) had VT recurrences and one of them died after surgical VT ablation; VT recurrence was 9.5% in patients with LPs abolition (4/42 pts) and 75.0% (6/8 pts) in those with incomplete abolition [positive predictive value (PPV): 75%, negative predictive value (NPV): 90.4%, sensibility: 60.0%, and specificity: 95.0%, P < 0.0001); although it was 12.5% (5/40 pts) in patients without inducibility VT after the ablation, and 50% (5/10 pts) in those with inducible VT (PPV: 50%, NPV: 87.5%, sensitivity: 50.0%, and specificity: 87.5%, P = 0.008)., Conclusions: LP abolition is an effective endpoint of VT ablation and its prognostic value compares favorably to that achieved by programmed electrical stimulation., (© 2012 Wiley Periodicals, Inc.)

Background: The purpose of this study was to describe the epicardial percutaneous ablation experience of 6 European high-volume ventricular tachycardia (VT) ablation centers., Methods and Results: Data from 218 patients with coronary artery disease (CAD, n=85 [39.0%]), idiopathic dilated of patients with idiopathic VT cardiomyopathy (IDCM, n=67 [30.7%]), arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARCD/C, n=13 [6%]), hypertrophic cardiomyopathy (HCM, n=5 [2.3%]), and absence of structural heart disease (n=48 [22%]) undergoing epicardial subxyphoid access for VT ablation were collected. The epicardial approach was attempted as first-line treatment in 78 patients (35.8%). Acute prevention of VT inducibility was obtained in 156 patients (71.6%). There were no procedure-related deaths. Cardiac tamponade occurred in 8 patients, and abdominal hemorrhage in 1 patient. Six patients died of electrical storm recurrence within 48 hours from the procedure. After a mean follow-up of 17.3±18.2 months, 60 patients (31.4%) presented with VT recurrence (39.3% of IDCM patients; 34.7% of CAD patients; 30.8% of ARVD/C patients; 25% of HCM patients; 17.1% of patients with idiopathic VT). Twenty patients (10.4%) died during follow-up (12 of heart failure, 2 of cardiac arrest, and 6 of extracardiac causes)., Conclusions: In experienced centers, epicardial ablation of VT has an acceptable risk and favorable outcome. In selected patients, it is reasonable to consider as a first-line ablation approach.

Unlabelled: Ultra High-Density Multipolar Mapping With Double Ventricular Access. , Background: Analogous to the use of circular loop catheters to guide ablation around the pulmonary veins, it may be advantageous to use a multipolar catheter in the ventricle for rapid mapping and to guide ablation. We describe a technique using double access into the left ventricle for multipolar electroanatomic mapping and ablation of scar-mediated ventricular tachycardia (VT)., Methods: Double access into the left ventricle was obtained via transseptal technique. Endocardial mapping was performed via the first transseptal sheath using a steerable duodecapolar catheter. Higher density mapping was performed in areas of dense scar (<0.5 mV) and border zone (0.5-1.5 mV). All late potentials (LPs) observed on the 20 poles were tagged and pacemapping was performed at these sites for comparison with the clinical or induced VT 12-lead template. If VT was hemodynamically tolerated, entrainment mapping was attempted at sites demonstrating diastolic activity. Ablation was performed through the second transseptal sheath with an open-irrigated catheter at target sites identified by LPs, pacemapping, and/or entrainment on the duodecapolar catheter., Results: Seventeen patients (88% ischemic cardiomyopathy) underwent electroanatomic mapping and ablation with double transseptal access. The mean number of endocardial mapping points was 819 ± 357 with an average mapping time of 31 ± 7 minutes. The mean number of VTs induced was 2.8 ± 1.6, mean cycle length 418 ms ± 101. LPs were seen in all patients during endocardial mapping with the duodecapolar catheter. Good (56%) and perfect (44%) pacemaps were seen in all patients when performed. Concealed entrainment, guided by the earliest diastolic activity seen on the duodecapolar catheter, was demonstrated in 4 patients (24%). Acute success was achieved in 94% of patients with complete success in 47% and partial success in 47%. The intermediate success rate (free of VT recurrence) was 69%, with an average follow-up of 8 ± 3 months., Conclusion: Mapping and ablation of scar-mediated VT using a multipolar catheter results in ultra high-density delineation of the left ventricular substrate. A novel double ventricular access strategy has the potential to facilitate identification of LPs, pacemapping, and entrainment mapping., (© 2010 Wiley Periodicals, Inc.)

Background: Electrical storm (ES) caused by recurrent episodes of ventricular tachycardia (VT) can cause sudden death in patients with implantable cardioverter-defibrillators and adversely affects prognosis in survivors. Catheter ablation has been proposed for treating ES, but its long-term effect in a large population has never been verified., Methods and Results: Ninety-five consecutive patients with coronary artery disease (72 patients), idiopathic dilated cardiomyopathy (10 patients), and arrhythmogenic right ventricular dysplasia/cardiomyopathy (13 patients) undergoing catheter ablation for drug-refractory ES were prospectively evaluated. Short-term efficacy was defined by a complete protocol of programmed electric stimulation and by in-hospital outcome; long-term analysis addressed ES recurrence, cardiac mortality, and VT recurrence. Pleomorphic/nontolerated VTs required electroanatomic and noncontact mapping in 48 and 22 patients, respectively, and percutaneous cardiopulmonary support in 10 patients. An epicardial approach was used in 10 patients. After 1 to 3 procedures, induction of any clinical VT(s) by programmed electrical stimulation was prevented in 85 patients (89%). ES was acutely suppressed in all patients; a minimum period of 7 days with stable rhythm was required before hospital discharge. At a median follow-up of 22 months (range, 1 to 43 months), 87 patients (92%) were free of ES and 63 patients (66%) were free of VT recurrence. Eight of 10 patients with persistent inducibility of clinical VT(s) had ES recurrence; 4 of them died suddenly despite appropriate implantable cardioverter-defibrillator intervention. All together, 11 of 95 patients (12%) died of cardiac-related reasons. In the group of patients presenting with all clinical VTs acutely abolished, no ES recurrence was documented, and cardiac mortality was significantly lower compared with the group of patients showing > or = 1 clinical VT still inducible after catheter ablation., Conclusions: Advanced strategies of catheter ablation applied to a large population of patients are effective in the short-term treatment of ES. By preventing ES recurrence, catheter ablation may play a protective role over the long term and, together with long-term pharmacological therapy, may favorably affect cardiac mortality.