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Background: Electrical posterior wall isolation (PWI) is increasingly being used for the treatment of patients with atrial fibrillation (AF). Few data exist on the durability of PWI using current technology., Objective: The purpose of this study was to characterize the frequency and location of posterior wall reconnection at the time of repeat catheter ablation for AF., Methods: We performed a single-center retrospective cohort study of 50 patients undergoing repeat AF ablation after previous PWI. Durability of PWI was assessed at the time of repeat ablation based on posterior wall entrance and exit block. Sites of posterior wall reconnection were characterized based on review of recorded electrical signals and electroanatomic maps., Results: At the time of repeat ablation, mean age was 67 ± 10 years, 31 of 50 patients had persistent AF, and mean CHA 2 DS 2 -VASc score was 3.0 ± 1.8. Of the 50 patients, 30 had durable PWI at repeat ablation, 1.4 ± 1.6 years after the index procedure. Patients with posterior wall reconnection required repeat ablation earlier (0.9 ± 0.6 years vs1.8 ± 1.9 years from index PWI; P = .048) and were more likely to have atypical atrial flutter (55% vs 27%; P = .043). Among patients with posterior wall reconnection, the roof was the most common site of reconnection (14/20), and 12 patients had multiple regions of reconnection noted., Conclusion: Posterior wall reconnection is noted in 40% of patients undergoing repeat ablation after an index PWI. The roof of the left atrium is the most common site of posterior wall reconnection., (Copyright © 2020 Heart Rhythm Society. All rights reserved.)

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., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: There has been increasing awareness of the 3-dimensional nature of ventricular tachycardia (VT) circuits. VT circuits in patients with ischemic cardiomyopathies (ICM) and non-ICM (NICM) may differ in this regard., Methods: Among patients with structural heart disease and at least 1 hemodynamically tolerated VT undergoing ablation, we retrospectively analyzed responses to all entrainment maneuvers., Results: Of 445 patients (ICM 228, NICM 217) undergoing VT ablation, detailed entrainment mapping of at least 1 tolerated VT was performed in 111 patients (ICM 71, NICM 40). Of 89 ICM VTs, the isthmus could be identified by endocardial entrainment in 55 (62%), compared with only 8 of 47 (17%) NICM VTs ( P<0.01). With combined endocardial and epicardial mapping, the isthmus could be identified in 56 (63%) ICM VTs and 12 (26%) NICM VTs ( P<0.01), whereas any critical component (defined as entrance, isthmus or exit) could be identified in 76 (85%) ICM VTs and 37 (79%) NICM VTs ( P=0.3). Complete success (no inducible VT at the end of ablation, 82% versus 65%, P=0.04) and 1-year, single-procedure VT-free survival (82% versus 55%, P<0.01) were both higher among patients with ICM., Conclusions: Among mappable ICM VTs, critical circuit components can usually be identified on the endocardium. In contrast, among mappable NICM VTs, although some critical component can typically be identified with the addition of epicardial mapping, the isthmus is less commonly identified, possibly due to midmyocardial location.

Introduction: In patients with monomorphic idiopathic outflow tract ventricular arrhythmias (OT-VAs), catheter ablation (CA) at the earliest activation site can result in a shift in QRS morphology indicating a change in the activation patterns. This study aimed to investigate the prevalence, mapping features, and ablation outcomes of OT-VAs displaying a QRS morphology shift following CA., Methods and Results: We retrospectively analyzed 446 patients with monomorphic OT-VAs. A QRS morphology shift following CA was observed in 17 (4%) patients. Initially, the earliest activation site was within the right ventricular outflow tract (RVOT) in one (6%) patient, the left ventricular outflow tract (LVOT) in 10 (59%) patients (left coronary cusp/right coronary cusp junction in seven patients and LVOT endocardium in three patients), and within the distal coronary venous system in six (35%) patients. The VA was suppressed in all 17 patients, but VA recurrence with a different QRS morphology was observed after a waiting period. The recurrent VA was remapped in all patients and was eliminated targeting the new earliest site in 15 (88%) cases. In 11 of 15 successful cases, the ablation site for the recurrent VA shifted to an anatomical structure distinct from but adjacent to the initial site. In the remaining four patients, the recurrent VA was eliminated within the same anatomical structure., Conclusions: In patients with idiopathic OT-VAs, a QRS morphology shift following CA can be observed in 4% of the cases. In these cases, detailed remapping is necessary since the successful ablation site for the VAs with altered QRS morphology shifts to different anatomical structures in most patients., (© 2018 Wiley Periodicals, Inc.)

Background: Previous studies have suggested a role of atrial arrhythmia inducibility as an endpoint of catheter ablation of atrial fibrillation (AF). The prognostic value of noninducibility after ablation and of a change in inducibility status has not been investigated in large studies., Objective: The purpose of this study was to evaluate the prognostic role of noninducibility and of a change in inducibility status after ablation of AF., Methods: We studied 305 consecutive patients with AF (66% paroxysmal) undergoing antral pulmonary vein (PV) isolation plus non-PV triggers ablation. All patients underwent a standardized induction protocol before and after ablation from the coronary sinus and right atrium: 15-beat burst pacing at 250 ms and decrementing to 180 ms (up to 20 μg/min isoproterenol). Inducibility was defined as any sustained AF or organized atrial tachycardia (AT) lasting >2 minutes., Results: A total of 197 patients (65%) had inducible AF/AT at baseline compared to 118 (39%) after ablation. One hundred seven patients (57%) changed their inducibility status from inducible preablation to noninducible postablation. After 19 ± 7 months of follow-up, 212 patients (70%) remained free from any recurrent AF/AT. Noninducibility of AF/AT postablation (log-rank P = .236) or change in inducibility status (log-rank P = .429) was not associated with reduced risk of recurrent AF/AT. Results were consistent across the paroxysmal and nonparoxysmal subgroups., Conclusion: Noninducibility of atrial arrhythmia or change in inducibility status after PV isolation and non-PV trigger ablation is not associated with long-term freedom from recurrent arrhythmia and should not be used as an ablation endpoint or to support the appropriateness of additional ablation lesion sets., (Copyright © 2017. Published by Elsevier Inc.)

Background: Repolarization abnormalities in arrhythmogenic right ventricular (RV) cardiomyopathy and their relationship to ventricular tachycardia substrate are incompletely understood., Methods and Results: In 40 patients (29 men, mean age 38 years) with arrhythmogenic RV cardiomyopathy, we compared the extent and location of abnormal T (NegT) waves ≥1 mm in depth (n=32) and downsloping elevated ST segment (n=13), in ≥2 adjacent leads, to area and location of endocardial bipolar (<1.5 mV) and unipolar (<5.5 mV) and epicardial bipolar (<1.0 mV) voltage abnormalities. Abnormal unipolar RV endocardial area of 33.4±19.3% was present in 8 patients without NegT waves. Patients with NegT waves extending beyond lead V 3 (n=20) had larger low bipolar (31.4±18.9% versus 16.5±14.6%; P =0.008) and unipolar endocardial areas (66.0±19.6% versus 47.4±25.1%; P =0.013) and larger epicardial low bipolar area (56.0±19.3% versus 40.1±24.9%; P =0.030) compared with those with NegT waves limited to leads V 1 through V 3 (n=20). ECG location of NegT waves regionalized to location of substrate. Patients with downsloping elevated ST segment, all localized to leads V 1 and V 2 , had more unipolar endocardial abnormalities (71.8±18.1% versus 49.4±23.5%; P =0.005) involving outflow and mid-RV, compared with patients without downsloping elevated ST segment., Conclusions: In arrhythmogenic RV cardiomyopathy, abnormal electroanatomic mapping areas are proportional to extent of T-wave inversion on 12-lead ECG. Marked voltage abnormalities can exist without repolarization change. Downsloping elevated ST-segment pattern in V 1 and V 2 occurs with more unipolar endocardial voltage abnormality, consistent with more advanced transmural disease., (© 2018 American Heart Association, Inc.)

Background: Contemporary techniques to enhance anatomical detail and catheter contact during atrial fibrillation (AF) ablation include (1) the integration of preacquired tomographic reconstructions with electroanatomical mapping (3-dimensional image integration [I-EAM]), (2) the use of steerable introducers (SIs), and (3) high-frequency jet ventilation (HFJV)., Objective: To prove that using these stabilizing techniques during AF ablation improves 1-year procedural outcome., Methods: We studied 300 patients undergoing AF ablation at our institution. Patients were divided into 3 equal treatment groups (100 patients each) on the basis of the tools utilized: (1) group 1: AF ablation performed without I-EAM, SI, or HFJV; (2) group 2: AF ablation performed using I-EAM and SI, but without HFJV; and (3) group 3: AF ablation performed with I-EAM, SI, and HFJV. The primary outcome was freedom from AF 1 year after a single ablation procedure. The burden of both acute and chronic pulmonary vein reconnection was also assessed., Results: Patients from groups 2 and 3 had significantly more nonparoxysmal AF (17% vs 30% vs 39%; P = .002), larger left atria (4.2 ± 0.8 cm vs 4.4 ± 0.7 cm vs 4.5 ± 0.8 cm; P<.001), and higher body mass index (BMI; 28.5 ± 5.8 kg/m² vs 29.1 ± 4.8 kg/m² vs 31.2 ± 5.4 kg/m²; P<.001). Despite these differences, with adoption of I-EAM, SI, and HFJV we noted a significant improvement in 1-year freedom from AF (52% vs 66% vs 74%; P = .006) as well as fewer acute (1.1 ± 1.2 vs 0.9 ± 1.1 vs 0.6 ± 0.9; P = .03) and chronic (3.5 ± 0.9 vs 3.2 ± 0.9 vs 2.4 ± 1.0; P = .02) pulmonary vein reconnections., Conclusions: The incorporation of contemporary tools to enhance anatomical detail and ablation catheter stability significantly improved 1-year freedom from AF after ablation., (Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Differentiation of right versus left ventricular outflow tract (RVOT vs. LVOT) arrhythmia origin with left bundle branch block right inferior axis (LBRI) morphology is relevant to ablation planning and risk discussion. Our aim was to determine if lead I R‐wave amplitude is useful for differentiation of RVOT from LVOT arrhythmias with LBRI morphology. Methods: The R‐wave amplitude in lead I was measured in a retrospective cohort of 75 consecutive patients with LBRI pattern ventricular arrhythmias (VAs) successfully ablated from the RVOT (n = 54), LVOT (n = 16), or the anterior interventricular vein (AIV; n = 5). The optimal R‐wave threshold was identified and diagnostic indices were compared with the previously reported transitional zone (TZ) index and V2S/V3R index. Results: An R‐wave amplitude greater than or equal to 0.1 mV predicted LVOT origin with 75% sensitivity and 98.2% specificity. In comparison, the TZ and V2S/V3R indices had 50% and 68.8% sensitivity, and 75.9% and 88.9% specificity, respectively, for predicting LVOT origin. The area under the curve (AUC) was 0.85 for lead I R‐wave amplitude, 0.87 for V2S/V3R, and 0.72 for the TZ index. Of 36 cases with QS in lead I, 30 (83.3%) were from the anterior RVOT, three (8.3%) from the LVOT, and three (8.3%) from the AIV. Conclusion: The presence of R‐wave amplitude in lead I (≥0.1 mV) is a simple and useful criterion to identify LVOT cusp or endocardium focus in LBRI arrhythmias. A QS pattern in lead I suggests an origin in the anterior RVOT, or less commonly the adjacent LV summit. [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]

Unipolar Voltage Mapping in ICM Introduction Following myocardial infarction (MI), left ventricular function is determined by cardiac remodeling occurring in both infarcted and noninfarcted myocardium (NIM). Unipolar voltage mapping may detect remodeling changes in NIM that are associated with the left ventricular ejection fraction (LVEF). We aimed to identify (1) unipolar voltage characteristics in patients with chronic MI, and (2) association of voltage abnormalities with degree of left ventricular dysfunction (LVD). Methods and Results Two groups of patients with ischemic cardiomyopathy (ICM) who underwent LV endocardial mapping during catheter ablation for ventricular tachycardia (VT) between January 2010 and December 2012 were studied. The first group (19 males) had mild to moderate LVD (M-LVD, LVEF >35%) and was matched for age, sex, infarction size, and infarction location with 10 males who had severe LVD (S-LVD, LVEF <35%). Both bipolar and unipolar endocardial abnormal voltage areas were measured and compared between groups. Abnormal bipolar area was comparable in both groups (30 ± 8% in the S-LVD group vs 28 ± 8% in the M-LVD group; P = 0.5). Total abnormal unipolar voltage area was significantly larger in the S-LVD group (57 ± 14% vs 43 ± 13%; P = 0.02). The abnormal unipolar voltage area within the normal bipolar voltage area was greater in the S-LVD group (26 ± 11% vs 15 ± 16%; P = 0.03). In receiver operating characteristic curve analysis, an 18.0% cut-off value for abnormal unipolar area within NIM identified severe LVD, with 90% sensitivity and 79% specificity (area under the curve 0.821). Conclusions Patients with ICM and severe LVD have larger areas of unipolar voltage abnormality in the noninfarcted tissue than patients with M-LVD. [ABSTRACT FROM AUTHOR]