Search

Heart failure (HF) post-myocardial infarction (MI) presents with increased vulnerability to monomorphic ventricular tachycardia (mmVT). To appropriately evaluate new therapies for infarct-mediated reentrant arrhythmia in the preclinical setting, chronologic characterization of the preclinical animal model pathophysiology is critical. This study aimed to evaluate the rigor and reproducibility of mmVT incidence in a rodent model of HF. We hypothesize a progressive increase in the incidence of mmVT as the duration of HF increases. Adult male Sprague-Dawley rats underwent permanent left coronary artery ligation or SHAM surgery and were maintained for either 6 or 10 wk. At end point, SHAM and HF rats underwent echocardiographic and invasive hemodynamic evaluation. Finally, rats underwent electrophysiologic (EP) assessment to assess susceptibility to mmVT and define ventricular effective refractory period (ERP). In 6-wk HF rats ( n = 20), left ventricular (LV) ejection fraction (EF) decreased ( P < 0.05) and LV end-diastolic pressure (EDP) increased ( P < 0.05) compared with SHAM ( n = 10). Ten-week HF ( n = 12) revealed maintenance of LVEF and LVEDP ( P > 0.05), ( P > 0.05). Electrophysiology studies revealed an increase in incidence of mmVT between SHAM and 6-wk HF ( P = 0.0016) and ERP prolongation ( P = 0.0186). The incidence of mmVT and ventricular ERP did not differ between 6- and 10-wk HF ( P = 1.0000), ( P = 0.9831). Findings from this rodent model of HF suggest that once the ischemia-mediated infarct stabilizes, proarrhythmic deterioration ceases. Within the 6- and 10-wk period post-MI, no echocardiographic, invasive hemodynamic, or electrophysiologic changes were observed, suggesting stable HF. This is the necessary context for the evaluation of experimental therapies in rodent HF. NEW & NOTEWORTHY Rodent model of ischemic cardiomyopathy exhibits a plateau of inducible monomorphic ventricular tachycardia incidence between 6 and 10 wk postinfarction.

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., (© 2018 Wiley Periodicals, Inc.)

Objectives: This study sought to characterize septal substrate in patients with nonischemic left ventricular cardiomyopathy (NILVCM) undergoing ventricular tachycardia (VT) ablation., Background: The interventricular septum is an important site of VT substrate in NILVCM., Methods: The authors studied 95 patients with NILVCM and VT. Electroanatomic mapping using standard bipolar (<1.5 mV) and unipolar (<8.3 mV) low-voltage criteria identified septal scar location and size. Analysis of unipolar voltage was performed and scars quantified using graded unipolar cutoffs from 4 to 8.3 mV were correlated with delayed gadolinium-enhanced cardiac magnetic resonance (DE-CMR), performed in 57 patients., Results: Detailed LV endocardial mapping (mean 262 ± 138 points) showed septal bipolar and unipolar voltage abnormalities (VAs) in 44 (46%) and 79 (83%) patients, most commonly with basal anteroseptal involvement. Of the 59 patients in whom the septum was targeted, bipolar and unipolar septal VAs were seen in 36 (61%) and 54 (92%). Of the 35 with CMR-defined septal scar, bipolar and unipolar septal VAs were seen in 18 (51%) and 31 (89%). In 12 patients without CMR septal scar, 6 (50%) had isolated unipolar septal VAs on electroanatomic mapping, a subset of whom the septum was targeted for ablation (44%). In the graded unipolar analysis, the optimal cutoff associated with magnetic resonance imaging septal scar was 4.8 mV (sensitivity 75%, specificity 70%; area under the curve: 0.75; 95% confidence interval: 0.60 to 0.90)., Conclusions: Septal substrate by unipolar or bipolar voltage mapping in patients with NILVCM and VT is common. A unipolar voltage cutoff of 4.8 mV provides the best correlation with DE-CMR. A subset of patients with septal VT had normal DE-CMR or endocardial bipolar voltage with abnormal unipolar voltage., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

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., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.)

Objectives: This study sought to examine long-term outcomes in patients with structural heart disease in whom amiodarone was reduced/discontinued after ventricular tachycardia (VT) ablation., Background: VT in patients with structural heart disease increases morbidity and mortality. Amiodarone can decrease VT burden, but long-term use may result in organ toxicities and possibly increased mortality. Catheter ablation can also decrease VT burden. Whether amiodarone can be safely reduced/discontinued following ablation remains unknown., Methods: We studied consecutive patients undergoing VT ablation from 2008 to 2011, typically followed by noninvasive programmed stimulation several days later. Patients were divided into 3 groups by amiodarone use: group A-amiodarone reduced/discontinued following ablation; group B-amiodarone not reduced; group C-not on amiodarone at time of ablation. Baseline characteristics and outcomes were compared between groups., Results: Overall, 231 patients (90% male; mean age: 63.4 ± 12.9 years; 53.7% ischemic cardiomyopathy) were included (group A: 99 patients; group B: 29 patients; group C: 103 patients). Group B patients were older with more advanced heart failure. Group A patients less frequently had inducible VT at the end of ablation or noninvasive programmed stimulation. In follow-up, 1-year VT-free survival was similar between groups (p = 0.10). Mortality was highest in group B (p < 0.001). Higher amiodarone dose after ablation (hazard ratio: 1.23; 95% confidence interval: 1.03 to 1.47; p = 0.02) was independently associated with shorter time to death., Conclusions: After successful VT ablation, as confirmed by noninducibility at the end of ablation and noninvasive programmed stimulation, amiodarone may be safely reduced/discontinued without an unacceptable increase in VT recurrence. Reduction/discontinuation of amiodarone should be considered an important goal of VT ablation., (Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Catheter ablation (CA) of ventricular tachycardia (VT) in patients with nonischemic dilated cardiomyopathy can be challenging because of the complexity of underlying substrates. We sought to determine the long-term outcomes of endocardial and adjuvant epicardial CA in nonischemic dilated cardiomyopathy., Methods and Results: We examined 282 consecutive patients (aged 59±15 years, 80% males) with nonischemic dilated cardiomyopathy who underwent CA. Ablation was guided by activation/entrainment mapping for tolerated VT and pacemapping/targeting of abnormal electrograms for unmappable VT. Adjuvant epicardial ablation was performed for recurrent VT or persistent inducibility after endocardial-only ablation. Epicardial ablation was performed in 90 (32%) patients. Before ablation, patients failed a median of 2 antiarrhythmic drugs), including amiodarone, in 166 (59%) patients. The median follow-up after the last procedure was 48 (19-67) months. Overall, VT-free survival was 69% at 60-month follow-up. Transplant-free survival was 76% and 68% at 60- and 120-month follow-up, respectively. Among the 58 (21%) patients with VT recurrence, CA still resulted in a significant reduction of VT burden, with 31 (53%) patients having only isolated (1-3) VT episodes in 12 (4-35) months after the procedure. At the last follow-up, 128 (45%) patients were only on β-blockers or no treatment, 41 (15%) were on sotalol or class I antiarrhythmic drugs, and 62 (22%) were on amiodarone., Conclusions: In patients with nonischemic dilated cardiomyopathy and VT, endocardial and adjuvant epicardial CA is effective in achieving long-term VT freedom in 69% of cases, with a substantial improvement in VT burden in many of the remaining patients., (© 2016 American Heart Association, Inc.)

Background: Catheter ablation (CA) of ventricular tachycardia (VT) in patients with cardiac sarcoidosis can be challenging because of the complex underlying substrate. We sought to determine the long-term outcome of CA of VT in patients with cardiac sarcoidosis., Methods and Results: We enrolled 31 patients (age, 55±10 years) with diagnosis of cardiac sarcoidosis based on Heart Rhythm Society criteria and VT who underwent CA. In 23 (74%) patients, preprocedure cardiac magnetic resonance imaging and positron emission tomographic (PET) evaluation were performed. Preprocedure magnetic resonance imaging was positive for late gadolinium enhancement in 21 of 23 (91%) patients, whereas abnormal 18-fluorodeoxyglucose uptake was found in 15 of 23 (65%) cases. In 14 of 15 patients with positive PET at baseline, PET was repeated after 6.1±3.7-month follow-up. After a median follow-up of 2.5 (range, 0-10.5) years, 1 (3%) patient died and 4 (13%) underwent heart transplant. Overall VT-free survival was 55% at 2-year follow-up. Among the 16 (52%) patients with VT recurrences, CA resulted in a significant reduction of VT burden, with 8 (50%) having only isolated (1-3) VT episodes and only 1 patient with recurrent VT storm. The presence of late gadolinium enhancement at magnetic resonance imaging, a positive PET at baseline, and lack of PET improvement over follow-up were associated with increased risk of recurrent VT., Conclusions: In patients with cardiac sarcoidosis and VT, CA is effective in achieving long-term freedom from VT or improvement in VT burden in the majority of patients. The presence of late gadolinium enhancement at magnetic resonance imaging, a positive PET scan at baseline, or lack of improvement at repeat PET over follow-up predict worse arrhythmia-free survival., (© 2016 American Heart Association, Inc.)

Background: The posterior-superior process of the left ventricle (PSP-LV) is the most inferior and posterior aspect of the basal LV that extends posteriorly to the plane of the tricuspid valve. The PSP-LV is anatomically adjacent to the inferior and medial aspect of the right atrium (RA). We report a series of patients with ventricular arrhythmias (VAs) arising from the PSP-LV and describe a mapping and ablation approach from the RA guided by intracardiac echocardiography., Methods and Results: Mapping and ablation of the PSP-LV with an RA approach under intracardiac echocardiography guidance were performed in 5 patients with VAs (aged 44±14 years, 2 males) who had failed ablation attempts from multiple endocardial and epicardial (1 patient) sites. Mapping of the PSP-LV from the adjacent inferomedial RA was performed at sites anatomically opposite to the earliest endocardial site of activation under direct intracardiac echocardiography visualization. From the RA side of the PSP-LV, a small atrial signal and a larger ventricular signal were recorded in each case, with an activation time of 32±7 ms pre-QRS (versus 16±5 ms pre-QRS in the LV endocardium; P=0.068). We were able to capture the LV from these sites. Cryoablation was performed in 2 patients, and radiofrequency was used in the remaining 3 cases. In all patients, ablation from the RA eliminated the arrhythmia. All patients remained free of recurrent VAs after a mean follow-up of 12 (7-16) months. There were no immediate or long-term complications., Conclusions: The PSP-LV can be a site of origin of VAs, which can be successfully eliminated from the adjacent RA under direct intracardiac echocardiographic visualization., (© 2016 American Heart Association, Inc.)

Background: Catheter ablation of ventricular tachycardia (VT) in arrhythmogenic right ventricular cardiomyopathy improves short-term VT-free survival. We sought to determine the long-term outcomes of VT control and need for antiarrhythmic drug therapy after endocardial (ENDO) and adjuvant epicardial (EPI) substrate modification in patients with arrhythmogenic right ventricular cardiomyopathy., Methods and Results: We examined 62 consecutive patients with Task Force criteria for arrhythmogenic right ventricular cardiomyopathy referred for VT ablation with a minimum follow-up of 1 year. Catheter ablation was guided by activation/entrainment mapping for tolerated VT and pacemapping/targeting of abnormal substrate for unmappable VT. Adjuvant EPI ablation was performed when recurrent VT or persistent inducibility after ENDO-only ablation. Endocardial plus adjuvant EPI ablation was performed in 39 (63%) patients, including 13 who crossed over to ENDO-EPI after VT recurrence during follow-up, after ENDO-only ablation. Before ablation, 54 of 62 patients failed a mean of 2.4 antiarrhythmic drugs, including amiodarone in 29 (47%) patients. During follow-up of 56±44 months after the last ablation, VT-free survival was 71% with only a single VT episode in additional 9 patients (15%). At last follow-up, 39 (64%) patients were only on β-blockers or no treatment, 21 were on class 1 or 3 antiarrhythmic drugs (11 for atrial arrhythmias), and 2 were on amiodarone as a bridge to heart transplantation., Conclusions: The long-term outcome after ENDO and adjuvant EPI substrate ablation of VT in arrhythmogenic right ventricular cardiomyopathy is good. Most patients have complete VT control without amiodarone therapy and limited need for antiarrhythmic drugs., (© 2015 American Heart Association, Inc.)

Background: Percutaneous epicardial ablation of ventricular arrhythmias arising from the left ventricular summit is limited by the presence of major coronary vessels and epicardial fat. We report the outcomes of percutaneous epicardial mapping and ablation of ventricular arrhythmias arising from the left ventricular summit and the ECG features associated with successful ablation., Methods and Results: Between January 2003 and December 2012, a total of 23 consecutive patients (49 ± 14 years; 39% men) with ventricular arrhythmias arising from the left ventricular summit underwent percutaneous epicardial instrumentation for mapping and ablation because of unsuccessful ablation from the coronary venous system and multiple endocardial LV/right ventricular sites. Successful epicardial ablation was achieved in 5 (22%) patients. In the remaining 18 (78%) cases, ablation was aborted for either close proximity to major coronary arteries or poor energy delivery over epicardial fat. The Q-wave amplitude ratio in aVL/aVR was higher in the successful group, with a ratio of > 1.85 present in 4 (80%) patients in the successful group versus 2 (11%) in the unsuccessful group (P = 0.008). The ratio of R/S wave in V1 was greater in the successful group, with 4 (80%) patients in the successful group having a R/S ratio of > 2 in V1 versus 5 (28%) in the unsuccessful group (P = 0.056). None of the patients in the successful group had an initial q wave in lead V1, as opposed to 6 (33%) in the unsuccessful group. The presence of at least 2 of the 3 ECG criteria above predicted successful ablation with 100% sensitivity and 72% specificity., Conclusions: Epicardial instrumentation for mapping and ablation of ventricular arrhythmias arising from the left ventricular summit is successful only in a minority of patients because of close proximity to major coronary arteries and epicardial fat. A Q-wave ratio of > 1.85 in aVL/aVR, a R/S ratio of > 2 in V1, and absence of q waves in lead V1 help identify appropriate candidates for epicardial ablation., (© 2015 American Heart Association, Inc.)

Background: The occurrence of periprocedural acute hemodynamic decompensation (AHD) in patients undergoing radiofrequency catheter ablation of scar-related ventricular tachycardia (VT) has not been previously investigated., Methods and Results: We identified univariate predictors of periprocedural AHD in 193 consecutive patients undergoing radiofrequency catheter ablation of scar-related VT. AHD was defined as persistent hypotension despite vasopressors and requiring mechanical support or procedure discontinuation. AHD occurred in 22 (11%) patients. Compared with the rest of the population, patients with AHD were older (68.5±10.7 versus 61.6±15.0 years; P=0.037); had a higher prevalence of diabetes mellitus (36% versus 18%; P=0.045), ischemic cardiomyopathy (86% versus 52%; P=0.002), chronic obstructive pulmonary disease (41% versus 13%; P=0.001), and VT storm (77% versus 43%; P=0.002); had more severe heart failure (New York Heart Association class III/IV: 55% versus 15%, P<0.001; left ventricular ejection fraction: 26±10% versus 36±16%, P=0.003); and more often received periprocedural general anesthesia (59% versus 29%; P=0.004). At 21±7 months follow-up, the mortality rate was higher in the AHD group compared with the rest of the population (50% versus 11%, log-rank P<0.001)., Conclusions: AHD occurs in 11% of patients undergoing radiofrequency catheter ablation of scar-related VT and is associated with increased risk of mortality over follow-up. AHD may be predicted by clinical factors, including advanced age, ischemic cardiomyopathy, more severe heart failure status (New York Heart Association class III/IV, lower ejection fraction), associated comorbidities (diabetes mellitus and chronic obstructive pulmonary disease), presentation with VT storm, and use of general anesthesia., (© 2014 American Heart Association, Inc.)

Background: The moderator band (MB) can be a source of premature ventricular contractions (PVCs), monomorphic ventricular tachycardia (VT), and idiopathic ventricular fibrillation (IVF)., Objective: The purpose of this study was to define the electrocardiographic (ECG) characteristics and procedural techniques to successfully identify and ablate MB PVCs/VT., Methods: In 10 patients with left bundle branch block morphology PVCs/VT, electroanatomic mapping in conjunction with intracardiac echocardiography (ICE) localized the site of origin of the PVCs to the MB. Clinical characteristics of the patients, ECG features, and procedural data were collected and analyzed., Results: Seven patients presented with IVF and 3 presented with monomorphic VT. In all patients, the ventricular arrhythmias (VAs) had a left bundle branch block QRS with a late precordial transition (>V4), a rapid downstroke of the QRS in the precordial leads, and a left superior frontal plane axis. Mean QRS duration was 152.7 ± 15.2 ms. Six patients required a repeat procedure. After mean follow-up of 21.5 ± 11.6 months, all patients were free of sustained VAs, with only 1 patient requiring antiarrhythmic drug therapy and 1 patient having isolated PVCs no longer inducing VF. There were no procedural complications., Conclusion: VAs originating from the MB have a distinctive morphology and often are associated with PVC-induced ventricular fibrillation. Catheter ablation can be safely performed and is facilitated by ICE imaging., (Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

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 © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Identification of intramural basal-septal ventricular tachycardia (VT) substrate is challenging in nonischemic cardiomyopathy. We sought to (1) characterize normal/abnormal trans-septal right ventricular (RV) to left ventricular activation; (2) assess the effect of opposite RV pacing on left ventricular septal bipolar electrograms (EGMs); and (3) establish criteria for the identification of intramural septal VT substrate., Methods and Results: Endocardial activation mapping and local EGM assessment of the left interventricular septum was performed during RV basal septal pacing in 40 patients undergoing VT ablation with no evidence of septal scar (group 1, n=14) and with septal scar (group 2, n=26) defined by low septal unipolar voltage (<8.3 mV) and delayed enhancement on cardiac MRI with/without abnormal bipolar voltage (<1.5 mV) in sinus rhythm. Left ventricular trans-septal activation time was prolonged in Group 2 compared with Group 1 (55.3±33.0 versus 25.7±8.8 ms; P=0.003). In 6 group 2 patients, left ventricular septal breakthrough was displaced to the scar border. During RV pacing, group 2 had fractionated (8.8%), late (2.8%), and split (5.7%) EGMs not seen in group 1. Trans-septal activation >40 ms (sensitivity 60%, specificity 100%; P<0.001) and EGM duration >95 ms during pacing (sensitivity 22%, specificity 91%; P<0.001) identified septal scar (13/26 pts)., Conclusions: In patients with nonischemic cardiomyopathy, VT and septal scar, delayed transmural conduction time (>40 ms) and fractionated, late, split, and wide (>95 ms) bipolar EGMs during RV basal pacing identify intramural VT substrate. In select cases, the basal septum appears compartmentalized as the stimulated wavefront is rerouted to the scar border.

Background: Patients with coronary artery disease (CAD) may have ventricular tachycardia (VT) from a separate nonischemic process. Catheter ablation in these patients can be misguided by abnormalities of coronary arteries., Objective: To identify (1) the prevalence of unanticipated nonischemic VT in patients with known CAD presenting with VT and (2) the substrate and VT characteristics of this unique subset of patients., Methods: We examined consecutive patients referred for VT catheter ablation who had a history of myocardial infarction and angiography documented CAD with presumed ischemic VT. Patients with low-voltage zones and/or VT origin inconsistent with CAD distribution were included for further analysis., Results: Of 732 patients, 9 (1.2%) (7 men; median age 74 years; ejection fraction 30%) fulfilled inclusion criteria. Endocardial left ventricular scar inconsistent with CAD distribution was found in 8 patients. In 1 patient, only epicardial left ventricular scar was found. The distribution of low voltage (<1.5 mV) was predominantly around the aortic and mitral valves. Thirty-one VTs were induced in 8 patients. Most VTs had right bundle branch block (68%); of these VTs, 67% had an R/S transition zone later than lead V4 consistent with basal VT origin. Epicardial ablation was necessary in 2 patients. During follow-up (30 [25-39] months), 7 of 9 patients (78%) were free of recurrent VT., Conclusions: A small but important subgroup of patients with CAD and VT has a nonischemic substrate/etiology for VT. The presence of multiple VTs with basal origin suggests a potential nonischemic perivalvular substrate and possible need for epicardial VT ablation., (© 2013 Heart Rhythm Society. All rights reserved.)

The outflow tract (OT) regions of the right and left ventricles, common sites of origin for idiopathic ventricular arrhythmias (VA), have complex three-dimensional anatomical relationships. The understanding of in situ or "attitudinal" relationships not only informs the electrocardiographic interpretation of VA site of origin, but also facilitates their catheter-based mapping and ablation strategies. By viewing each patient as his or her own "control," the expected changes in ECG morphology (i.e., frontal plane QRS axis and precordial transition) between adjacent intracardiac structures (e.g., RVOT and aortic root) can be reliably predicted. Successful mapping of OT VAs involve a combination of activation and pacemapping guided by fluoroscopy, electroanatomical mapping, and intracardiac echocardiography. The purpose of this manuscript is to provide a simple, reliable strategy for catheter based mapping and ablation of OT VAs. We also discuss 2 specific challenges in OT VA mapping: (1) differentiating posterior RVOT from right coronary cusp VA origin; and (2) mapping VAs originating from the LV summit., (© 2013 Wiley Periodicals, Inc.)

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 cm(2)). 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 © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

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 © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Introduction: Patients with nonischemic cardiomyopathy (NICM) and ventricular tachycardia (VT) usually have basal-lateral scar in the left ventricle (LV). We sought to determine electrocardiogram (ECG) characteristics that may help identify NICM patients with basal-lateral scar and VT., Methods and Results: Phase I, study patients (n = 25) had NICM, VT, and endocardial/epicardial basal-lateral LV low voltage consistent with scar on detailed mapping. ECGs were compared to controls (n = 18) with NICM, and comparable age and gender without VT/known scar. All patients had either sinus or paced atrial rhythm ECGs without bundle-branch block or ventricular pacing. In phase II, criteria were evaluated prospectively, blinded to clinical data, using ECGs from 15 NICM patients, of which 7 patients had VT and endocardial/epicardial basal-lateral LV scar on detailed mapping. Of ECG characteristics studied, V1 R and R:S ratio, and V6 S and S:R ratio were univariately associated with basal-lateral-scar associated VT. Controlling for LVEF and multicollinearity in multivariate analyses, V1 R ≥ 0.15 mV (P = 0.001) and V6 S ≥ 0.15 mV (P < 0.001), or V6 S:R ≥ 0.2 mV (P < 0.001), best predicted presence of basal-lateral scar. In Phase II, the former criteria best identified those with NICM and VT because of basal-lateral scar, with sensitivity and specificity 0.86 and 0.88, respectively., Conclusions: Among patients with NICM, VT, and normal QRS duration, V1 R ≥ 0.15 mV and V6 S ≥ 0.15 mV predicted presence of basal-lateral LV areas of bipolar low voltage. This ECG information may have important value in defining presence of LV scar and possible risk for VT in NICM patients. , (© 2011 Wiley Periodicals, Inc.)

Background: Intracardiac echocardiography (ICE) has played a limited role in defining the substrate for ventricular tachycardia (VT). The purpose of this study was to assess whether ICE could identify abnormal epicardial substrate in patients with nonischemic cardiomyopathy (NICM) and VT., Methods and Results: We studied 18 patients with NICM and recurrent VT who had abnormal echogenicity identified on ICE imaging. Detailed left ventricular (LV) endocardial and epicardial electroanatomic mapping was performed in all patients. Low-voltage areas (<1.0 mV) in the epicardium were analyzed. ICE imaging in the NICM group was compared to a control group of 30 patients with structurally normal hearts who underwent ICE imaging for other ablation procedures. In 18 patients (age, 53±13 years; 17 men) with NICM (ejection fraction, 37±13%), increased echogenicity was identified in the lateral LV by ICE imaging. LV endocardial electroanatomic mapping identified normal voltage in 9 patients and at least 1 confluent low-voltage area (6.6 cm(2); minimum-maximum, 2.1-31.7 cm(2)) in 9 patients (5 posterolateral LV, 4 perivalvular LV). Detailed epicardial mapping revealed areas of low voltage (39 cm(2); minimum-maximum, 18.5-96.3 cm(2)) and abnormal, fractionated electrograms in all 18 patients (15 posterolateral LV, 3 lateral LV). In all patients, the epicardial scar identified by electroanatomic mapping correlated with the echogenic area identified on ICE imaging. ICE imaging identified no areas of increased echogenicity in the control group., Conclusions: ICE imaging identified increased echogenicity in the lateral wall of the LV that correlated to abnormal epicardial substrate. These findings suggest that ICE imaging may be useful to identify epicardial substrate in NICM.

Background: The substrate for ventricular tachycardia (VT) in nonischemic cardiomyopathy (NICM) has a predilection for the basolateral left ventricle with right bundle branch block VT morphology., Objective: The purpose of this study was to describe a unique group of NICM patients with septal VT substrate., Methods: Between 1999 and 2010, 31 (11.6%) of 266 patients with NICM undergoing VT ablation had septal substrate and no lateral involvement. Mean age was 59 ± 12 years, and ejection fraction was 30% ± 14%. Eight patients had heart block., Results: Cardiac magnetic resonance showed septal delayed enhancement in 8 of 9 patients. Electroanatomic mapping demonstrated bipolar low voltage (<1.5 mV) extending from the basal septum in 22 of 31 patients. The remaining 9 patients had normal endocardial bipolar voltage but abnormal unipolar septal voltage (<8.3 mV) consistent with intramural abnormalities. Epicardial mapping in 14 patients showed no scar in 9 and patchy basal left ventricular summit scar in 5. VTs were mapped to the septal substrate, with 62% having right bundle branch block morphology and V(2) precordial transition pattern break in 17% suggesting periseptal exit. After substrate and targeted VT ablation, no VT was inducible in 66% and no "clinical targeted" VT in 86%. Over a mean follow-up of 20 ± 28 months, VT recurred in 10 (32%) patients., Conclusion: Isolated septal VT substrate is uncommon in NICM. Biventricular low-voltage zones extending from the basal septum are characteristic, but septal scarring can be entirely intramural as evidenced by unipolar/bipolar electrograms and imaging. Multiple unmappable morphologies are the rule, often requiring several procedures aggressively targeting the septal substrate to achieve moderate long-term VT control., (Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The surgical approach for the treatment of ventricular tachycardia (VT) has been largely replaced by percutaneous, catheter-based techniques. However, some VT circuits, particularly in patients with nonischemic cardiomyopathy, remain inaccessible to percutaneous ablation. Surgical therapy of these VTs is an alternative approach; however, its methodology has not been well defined. The purpose of this study was to evaluate the efficacy of preoperative electroanatomic and electrophysiological characterization of the VT substrate and circuit to guide surgical ablation., Methods and Results: Eight patients with recurrent sustained VT refractory to antiarrhythmic drugs underwent endocardial and/or epicardial ablation procedures. Electroanatomic mapping was performed, and the VT substrate and circuit(s) were defined using voltage, activation, entrainment, and pace mapping. All 8 patients underwent detailed endocardial mapping; 6 patients also underwent epicardial mapping. Radiofrequency ablation was performed with the use of an open-irrigation catheter. After the unsuccessful percutaneous approach, surgical cryoablation was applied to the sites previously identified and targeted during the percutaneous procedure. There were no significant perioperative complications. During a mean follow-up period of 23 ± 6 months (range, 15 to 34 months), 6 patients had significant reduction in VT burden as evident by a reduced number of implantable cardioverter-defibrillator shocks after ablation (6.6 to 0.6 shocks per patient; P = 0.026). Two patients died, one of progressive heart failure and one of sepsis., Conclusions: VT circuits inaccessible to percutaneous ablation techniques are rare but can be encountered in patients with nonischemic cardiomyopathy. These VTs can be successfully targeted by surgical cryoablation guided by preoperative electroanatomic and electrophysiological mapping.

Background: Most idiopathic right ventricular (RV) ventricular tachycardias (VTs) originate from the outflow tract. Data on VT from the lower body of the RV are limited., Objective: The purpose of this study was to describe a large experience with idiopathic VT detailing the prevalence and characteristics of VT arising from the body of the RV., Methods: The distribution of mapping confirmed VTs within the RV body, ECG characteristics, and results of radiofrequency (RF) ablation were analyzed., Results: Among 278 patients who underwent ablation for idiopathic VT or ventricular premature depolarizations (VPDs) arising from the RV, 29 (10%) had VT/VPDs from the lower RV body. Fourteen (48%) patients had VT/VPDs within 2 cm of the tricuspid valve annulus (TVA), 8 (28%) from the basal and 7 (24%) from the apical RV segments. Among the VT/VPDs from the TVA, 8 (57%) originated from the free wall and 6 (43%) from the septum. All but one RV basal or apical VT/VPDs originated from the free wall. All VT/VPDs had a left bundle branch block pattern. VT/VPDs from the free wall had longer QRS duration (P = .0032) and deeper S wave in lead V(2) (P = .042) and V(3) (P = .046) than those from the septum. Apical VT/VPDs more often had precordial R wave transition ≥V(6) (P = .0001) and smaller R wave in lead II (P = .024) and S wave in lead aVR (P = .001) compared to VT/VPDs from basal RV or TVA. RF catheter ablation eliminated VT/VPDs in 96% of patients. No complications were observed. During median follow-up of 27 months (range 4-131 months), 81% of patients had elimination of all symptomatic VT/VPDs. Nineteen percent had rare symptoms (8% without medications, 11% on beta-blocker)., Conclusion: Idiopathic VT/VPDs from the body of RV comprise an important subgroup of idiopathic RV VTs. Although most VTs originate from the RV free wall and nearly 50% from the TVA region, septal and more apical VTs are common. ECG characteristics distinguish free-wall versus septal and more apical origin of VTs, and RF catheter ablation provides good long-term arrhythmia control., (Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Epicardial ablation of ventricular tachycardia (VT) presents multiple challenges for anesthetic management. General anesthesia lowers blood pressure, may interfere with arrhythmia mapping, and use of muscle relaxants precludes identification of the phrenic nerve. We describe a case in which remifentanil with minimal doses of midazolam was employed in a series of epicardial VT ablations and noninvasive programmed stimulations (NIPS), including 5 external cardioversions and discuss the advantages of this approach., (© 2010 Wiley Periodicals, Inc.)

Background: Patients with nonischemic left ventricular cardiomyopathy (LVCM) and ventricular tachycardia (Vt) have complex 3-dimensional substrate with variable involvement of the endocardium (ENDO) and epicardium (EPI). The purpose of this study was to determine whether ENDO unipolar (UNI) mapping with a larger electric field of view could identify EPI low bipolar (BIP) voltage regions in patients with LVCM undergoing Vt ablation., Methods and Results: The reference value for normal ENDO unipolar voltage was determined from 6 patients without structural heart disease. Consecutive patients undergoing Vt ablation over an 8-year period with detailed (>100 points) LV ENDO and EPI mapping and normal LV ENDO BIP voltage were identified. From this cohort, we compared patients with structurally normal hearts and normal EPI BIP voltage (EPI-, group 1) with patients with LVCM and low LV EPI BIP voltage regions present (EPI+, group 2). Confluent regions of ENDO UNI and EPI BIP low voltage (>2 cm(2)) were measured. The normal signal amplitude was >8.27 mV for LV ENDO UNI electrograms. Detailed LV ENDO-EPI maps in 5 EPI- patients were compared with 11 EPI+ patients. Confluent ENDO UNI low-voltage regions were seen in 9 of 11 (82%) of the EPI+ (group 2) patients compared with none of 5 EPI- (group 1) patients (P<0.001). In all 9 patients with ENDO UNI low voltage, the ENDO UNI low-voltage regions were directly opposite to an area of EPI BIP low voltage (61% ENDO UNI-EPI BIP low-voltage area overlap)., Conclusions: EPI arrhythmia substrate can be reliably identified in most patients with LVCM using ENDO UNI voltage mapping in the absence of ENDO BIP abnormalities.

Background: The endocardial substrate for ventricular arrhythmias in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is thought to be caused by a progressive degenerative process. Many clinical decisions and treatment plans are guided by this pathophysiologic assumption, but the extent of progression of macroscopic endocardial scar and right ventricular (RV) dilatation have not been assessed., Methods and Results: Eleven patients with ARVD/C and ventricular tachycardia had 2 detailed sinus rhythm electroanatomic endocardial voltage maps (average, 291+/-122 points per map; range, 114 to 558 points) performed a mean of 57 months apart (minimum, 9 months) as part of ventricular tachycardia ablation procedures. Voltage-defined scar (<1.5 mV) and RV volume were measured by area and volume measurement software and compared. Two of the 11 patients had a clear increase in scar area (47 cm(2); 32 cm(2)) confirmed by visual inspection. The remaining 9 (81%; 95% CI, 48% to 98%) patients had no increase (<10-cm(2) difference) in scar area between studies. In contrast, 10 of the 11 patients had a significant increase in RV volume, with an average increase of 24% (212+/-67 mL to 263+/-52 mL; P< or =0.01)., Conclusions: In patients with ARVD/C and ventricular tachycardia, progressive RV dilatation is the rule, and rapid progression of significant macroscopic endocardial scar occurs in only a subset of patients. These results have important management implications, suggesting that efforts to prevent RV dilatation in this population are needed and that an aggressive substrate-based ablation strategy offers the potential to provide long-term ventricular tachycardia control.

Background: Ventricular arrhythmias are known to originate from the aortic sinus of Valsalva., Objective: The purpose of this study was to identify the characteristics associated with ventricular arrhythmias originating from the right coronary cusp-left coronary cusp (RCC-LCC) commissure., Methods: Thirty-seven consecutive patients with ventricular arrhythmias originating from the aortic cusp region were studied. Intracardiac echocardiography and electroanatomic mapping were used to define coronary cusp anatomy and catheter position. Ventricular arrhythmias from the RCC-LCC commissure were compared with ventricular arrhythmias originating from other sites in the aortic cusp region., Results: Nineteen (51%) ventricular arrhythmias had an anatomic origin at the RCC-LCC commissure. Eighteen ventricular arrhythmias originated from other aortic cusp sites (4 right cusp, 7 left cusp, 3 left ventricular endocardium, 4 left ventricular epicardium anterior to aortic valve). A QS morphology in lead V(1) with notching on the downward deflection was present in 15 of 19 ventricular arrhythmias originating from the RCC-LCC commissure compared to 2 of 18 ventricular arrhythmias from other aortic cusp sites (P <.01). At the site of earliest activation, 13 of 19 patients with RCC-LCC ventricular arrhythmias had late potentials in sinus rhythm compared to 1 of 18 ventricular arrhythmias from other aortic cusp sites (P <.01). The site of successful ablation was confirmed to be above the aortic valve plane in 15 (79%) of 19 patients with RCC-LCC ventricular arrhythmias., Conclusion: RCC-LCC aortic cusp ventricular arrhythmias are common and have a QS morphology in lead V(1) with notching on the downward deflection with precordial transition at lead V(3). In the majority of cases, the site of successful ablation has late potentials in sinus rhythm., (Copyright 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)