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Background: Following left atrial appendage (LAA) electrical isolation, the decision on whether to continue oral anticoagulation after successful atrial fibrillation ablation is based on the study of its mechanical function on transesophageal echocardiography (TEE). In this cohort, LAA contraction is absent and the incorrect interpretation of emptying flow velocities can lead to unwanted clinical sequelae.Methods: One hundred and sixty consecutive TEE exams performed to evaluate the LAA mechanical function following its electrical isolation were reviewed by an experienced operator blinded to the original diagnosis of LAA dysfunction. The rate of diagnostic discrepancy in the assessment LAA dysfunction and its clinical implications were evaluated.Results: Diagnostic discrepancy with misclassification of the LAA mechanical function occurred 36% (58/160) of TEE exams. In most cases (57/58), such discrepancy was observed in the setting of an incorrect original diagnosis of a normal LAA mechanical function despite absent/reduced or inconsistent LAA contraction. This main source of this wrong diagnosis was the wrong interpretation of passive LAA flows (34/57; 60%), followed by failure to identify dissociated firing (15/57; 26%). In rare cases (8/57; 14%), velocities of surrounding structures were interpreted as LAA flow due to misplacement of the pulsed-wave Doppler sample volume. Following LAA isolation, the proportion of patients who experienced a cerebrovascular event while off oral anticoagulation due to the misclassification of their LAA mechanical function was 70% (7/10 [95% CI, 40%-89%]).Conclusions: Underdiagnosis of LAA mechanical dysfunction is common in TEEs performed following LAA electrical isolation, and it is associated with an increased risk of cerebrovascular events owing to oral anticoagulation discontinuation despite absent/reduced LAA contraction. Careful review of the TEE exam by an operator with specific expertise in LAA imaging and familiar with the functional implications of LAA isolation is necessary before interrupting oral anticoagulation in this cohort. [ABSTRACT FROM AUTHOR]

Study Design of the Man and Machine Trial. Background: Pulmonary vein isolation (PVI) has become the cornerstone procedure for the treatment of symptomatic drug-resistant atrial fibrillation (AF). At the present time, circumferential PVI (CPVI) using irrigated radiofrequency (RF) is the mostly used ablation technique. However, for CPVI, precise catheter navigation and excellent catheter stability is crucial thereby requiring experienced operators. Robotic navigation systems have been introduced to facilitate catheter navigation and to improve catheter stability, therefore potentially increasing procedural success and making CPVI accessible to less experienced operators. To date, no prospective randomized trial has evaluated the efficacy and safety of CPVI using RNS compared to manually performed ablation. Methods: In this prospective international multicenter noninferiority trial, 258 patients with either paroxysmal or short-standing persistent AF will be randomized for comparison of PVI using either manual or robotic ablation. In all patients, CPVI will be performed using irrigated RF ablation in combination with a 3D mapping system. The primary endpoint of the trial is the absence of AF or atrial tachycardia without antiarrhythmic drug therapy during 12-month follow-up. Secondary endpoints will be evaluation of periprocedural complications and procedural data such as procedure time, fluoroscopy time, as well as the incidence of esophageal injury assessed by endoscopy within 48 hours after the procedure. Conclusion: The 'Man and Machine Trial' is the first prospective international randomized controlled multicenter noninferiority trial to compare manually performed CPVI with robotically navigated CPVI, evaluating both the safety and efficacy of the 2 techniques during a 12-month follow-up period. (J Cardiovasc Electrophysiol, Vol. 24, pp. 40-46, January 2013) [ABSTRACT FROM AUTHOR]

Worldwide Survey on Robotic AF Ablation. Introduction: The Hansen Robotic system has been utilized in ablation procedures for atrial fibrillation (AF). However, because of the lack of tactile feedback and the rigidity of the robotic sheath, this approach could result in higher risk of complications. This worldwide survey reports a multicenter experience on the methodology, efficacy, and safety of the Hansen system in AF ablations. Methods and Results: A questionnaire addressing questions on patient's demographics, procedural parameters, ablation success rate and safety information was sent to all centers where more than 50 robotic AF ablation cases have been performed. From June 2007 to December 2009, 1,728 procedures were performed at 12 centers utilizing the Hansen robotic navigation technology. The overall complication rate was 4.7% and the success rate was 67.1% after 18 ± 4 months of follow-up. In 5 low volume centers there appeared to be a learning curve of about 50 cases (complication rate 11.2% for the first 50 cases vs 3.7% for the 51-100 cases; P = 0.044) and a trend showing a decrease of complication rate with increasing case volume. However, in the remaining 7 centers no learning curve was present and the complication rate was stable over time (3.7% for the first 50 cases vs 3.6% for the 51st case thereafter; P = 0.942). Conclusion: The Hansen robotic system can be used for AF ablation safely. In low volume centers, there appeared to be a learning curve of the first 50 cases after which the complication rate decreased. With a higher case volume, the success rate increased. (J Cardiovasc Electrophysiol, Vol. 23, pp. 820-826, August 2012) [ABSTRACT FROM AUTHOR]

Incomplete LAA Occlusion by WATCHMAN Device. Introduction: Transcatheter left atrial appendage (LAA) closure with the WATCHMAN device has become one of the therapeutic options in atrial fibrillation (AF) patients who are at high risk for ischemic stroke. However, the incidence and evolution of incomplete occlusion of the LAA during and after placement of the WATCHMAN device has not been reported. Methods and Results: Fifty-eight consecutive patients who had undergone WATCHMAN device implant were included in the study. Intraprocedural, 45-day and 12-month transesophageal echocardiogram images were reviewed and analyzed. Peridevice gap was noted in 16 (27.6%), 17 (29.3%), and 20 (34.5%) patients across the 3 time points. Intraprocedural gaps are more likely to be persistent until 12 months and become larger in size over time. New gap also occurs during follow-up even if the LAA was completely sealed at implantation. One patient had an ischemic stroke 4.7 months after implant; another patient developed a left atrial thrombus over the device 21.6 months after implant. Both patients had intraprocedural gap and discontinued warfarin therapy after the 45-day evaluation. Conclusion: Incomplete LAA occlusion with a gap between the WATCHMAN device surface and the LAA wall is relatively common. Intraprocedural gaps are more likely to become bigger over time and persist, while new gaps also occur during follow-up. Further studies are warranted to verify whether the presence and persistence of a peridevice gap is associated with increased risk of thromboembolic event in AF patients implanted with a WATCHMAN device. (J Cardiovasc Electrophysiol, Vol. 23, pp. 455-461, May 2012) [ABSTRACT FROM AUTHOR]

MVI Block vs Trigger Ablation in PMFL. Introduction: Patients with previous ablation for atrial fibrillation (AF) may experience recurrence of perimitral flutter (PMFL). These arrhythmias are usually triggered from sources that may also induce AF. This study aims at determining whether ablation of triggers or completing mitral valve isthmus (MVI) block prevents more arrhythmia recurrences. Methods and Results: Sixty-five patients with recurrent PMFL after initial ablation of long standing persistent AF were included in this study. Thirty-two patients were randomized to MVI ablation only (Group 1) and 33 were randomized to cardioversion and repeat pulmonary vein (PV) isolation plus ablation of non-PV triggers (Group 2). MVI bidirectional block was achieved in all but 1 patient from Group 1. In Group 2, reconnection of 17 PVs was detected in 14 patients (42%). With isoproterenol challenge, 44 non-PV trigger sites were identified in 28 patients (85%, 1.57 sites per patient). At 18-month follow-up, 27 patients (84%) from Group 1 had recurrent atrial tachyarrhythmias, of whom 15 remained on antiarrhythmic drug (AAD); however, 28 patients from Group 2 (85%, P < 0.0001 vs Group 1) were free from arrhythmia off AAD. The ablation strategy used in Group 2 was associated with a lower risk of recurrence (hazard ratio = 0.10, 95% CI 0.04-0.28, P < 0.001) and an improved arrhythmia-free survival (log rank P < 0.0001). Conclusion: In patients presenting with PMFL after ablation for longstanding persistent AF, MVI block had limited impact on arrhythmia recurrence. On the other hand, elimination of all PV and non-PV triggers achieved higher freedom from atrial arrhythmias at follow-up. (J Cardiovasc Electrophysiol, Vol. 23, pp. 137-144, February 2012) [ABSTRACT FROM AUTHOR]

[Figure: see text]. [ABSTRACT FROM AUTHOR]

Introduction: Both atrial fibrillation (AF) and amyloidosis increase stroke risk. We evaluated the best anticoagulation strategy in AF patients with coexistent amyloidosis. Methods: Consecutive AF patients with concomitant amyloidosis were divided into two groups based on the postablation stroke‐prophylaxis approach; group 1: left atrial appendage occlusion (LAAO) in eligible patients and group 2: oral anticoagulation (OAC). Group 1 patients were further divided into Gr. 1A: LAAO + half‐does NOAC (HD‐NOAC) for 6 months followed by aspirin 81 mg/day and Gr. 1B: LAAO + HD‐NOAC. In group 1 patients, with complete occlusion at the 45‐day transesophageal echocardiogram, patients were switched to aspirin, 81 mg/day at 6 months. In case of leak, or dense "smoke" in the left atrium (LA) or enlarged LA, they were placed on long‐term half‐dose (HD) NOAC. Group 2 patients remained on full‐dose NOAC during the whole study period. Results: A total of 92 patients were included in the analysis; group 1: 56 and group 2: 36. After the 45‐day TEE, 31 patients from group 1 remained on baby‐aspirin and 25 on HD NOAC. At 1‐year follow‐up, four stroke, one TIA and six device‐thrombus were reported in group 1A, compared to none in patients in group 1B (5/31 vs. 0/25, p =.03). No bleeding events were reported in group 1, whereas group 2 had five bleeding events (one subdural hematoma, one retinal hemorrhage, and four GI bleedings). Additionally, one stroke was reported in group 2 that happened during brief discontinuation of OAC. Conclusion: In patients with coexistent AF and amyloidosis, half‐dose NOAC following LAAO was observed to be the safest stroke‐prophylaxis strategy. [ABSTRACT FROM AUTHOR]

Aims: Superior vena cava (SVC) isolation might be difficult to achieve because of the vicinity of the phrenic nerve (PN) and sinus node. Based on its embryogenesis, we hypothesized the presence of preferential conduction from the right atrial (RA) posterior wall, making it possible to isolate the SVC antrally, sparing its anterior and lateral aspect.Methods and results: This is a descriptive cohort study of 105 consecutive patients in which SVC isolation was obtained with radiofrequency ablation, starting in the septal aspect of the SVC-RA junction and continued posteriorly and inferiorly targeting sites of early activation until electrical isolation was obtained. Acute SVC isolation was achieved in 103 (98%) patients; the mean distance between the site of SVC isolation and the SVC-RA junction was 19.9 ± 5.3 (range 9.7-33.7) mm. During follow-up, 2 (2%) patients developed symptomatic diaphragmatic paralysis due to transient right PN injury; 13 patients underwent a repeat ablation: SVC reconnection was observed in 5 patients, and re-isolation was easily achieved by targeting the corresponding sites of early activation.Conclusion: Superior vena cava isolation can be completed by targeting its septal segment and sites of early activation in the posterior SVC-RA junction and RA posterior wall; this is a feasible alternative ablation strategy in patients in which SVC isolation cannot be completed with the standard approach. The risk of sinus node injury or SVC stenosis are eliminated; PN injury is still possible but can easily be prevented with high-output pacing to exclude a true posterior course of the PN. [ABSTRACT FROM AUTHOR]

Introduction: Diabetes mellitus (DM) is known to be an independent risk factor for atrial fibrillation (AF). This study investigates the impact of fasting blood glucose control on the long-term outcomes of radiofrequency catheter ablation for AF in patients with DM. Methods: Consecutive patients with DM and undergoing first-time AF radiofrequency catheter ablation in our center were included in this retrospective cohort study. Based on the pre-procedural fasting blood glucose (FBG) levels, participants were divided into two groups: i) normal FBG (≤110 mg/dl) and ii) high FBG (>110 mg/dl). Long-term (four years) outcomes of ablation (recurrence of AT/AF) were compared between these groups. Results: 412 patients were included in the study, 98 with normal FBG and 314 with high FBG. After four years of follow-up, 84/98 (87%) of the normal FBG group and 232/314 (74%) of the high FBG group remained arrhythmia-free (p-value = 0.008). The presence of high FBG significantly increased the risk of arrhythmia recurrence, with a hazard ratio of 1.82 (95% CI 1.05 to 3.15; p-value = 0.03). On multivariable regression analysis, high FBG was the most important clinical predictor of arrhythmia recurrence (odds ratio 1.78; 95% CI 1.02 to 3.13; p-value = 0.044). Conclusions: In patients with DM, high pre-procedural FBG is associated with a significant reduction in the long-term success rate of catheter ablation in patients with AF and can be used as a predictor of post-ablation arrhythmia recurrence in this cohort. [ABSTRACT FROM AUTHOR]

Background: Loss of contractility leading to stasis of blood flow following left atrial appendage electrical isolation (LAAEI) could lead to thrombus formation.Objectives: This study evaluated the incidence of thromboembolic events (TE) in post-LAAEI cases "on" and "off" oral anticoagulation (OAC).Methods: A total of 1,854 consecutive post-LAAEI patients with follow-up transesophageal echocardiography (TEE) performed in sinus rhythm at 6 months to assess left atrial appendage (LAA) function were included in this analysis.Results: The TEE at 6 months revealed preserved LAA velocity, contractility, and consistent A waves in 336 (18%) and abnormal parameters in the remaining 1,518 patients. In the post-ablation period, all 336 patients with preserved LAA function were off OAC. At long-term follow-up, patients with normal LAA function did not experience any stroke events. Of the 1,518 patients with abnormal LAA contractility, 1,086 remained on OAC, and the incidence of stroke/transient ischemic attack (TIA) in this population was 18 of 1,086 (1.7%), whereas the number of TE events in the off-OAC patients (n = 432) was 72 (16.7%); p < 0.001. Of the 90 patients with stroke, 84 received left atrial appendage occlusion (LAAO) devices. At median 12.4 months (interquartile range: 9.8 to 15.3 months) of device implantation, 2 (2.4%) patients were on OAC because of high stroke risk or personal preference, whereas 81 patients discontinued OAC after LAAO device implantation without any TE events.Conclusions: LAAEI is associated with a significant risk of stroke that can be effectively reduced by optimal uninterrupted OAC or LAAO devices. [ABSTRACT FROM AUTHOR]

Abstract: Aims: This study investigated the impact of weight loss in longstanding persistent (LSPAF) patients undergoing catheter ablation (CA). Methods: Ninety consecutive obese LSPAF patients were approached; 58 volunteered to try weight loss interventions for up to 1 year (group 1), while 32 patients declined weight loss interventions and were included as a control (group 2). Both groups remained on antiarrhythmic drugs. If they continued to experience AF, CA was performed. Body weight was measured at 6‐month intervals and arrhythmia status was assessed by event recorder, electrocardiogram (ECG), and Holter monitoring. Symptom severity and quality of life (QoL) were evaluated by AFSS and SF‐36 survey, respectively. A scoring algorithm with two summary measures, physical component score (PCS) and mental component score (MCS), was prepared for QoL analysis. Results: Significant reduction in body weight (median −24.9 (IQR −19.1 to −56.7) kg, P < 0.001) was observed in the group 1 patients, while no such change was seen in group 2. The PCS and MCS scores improved significantly in group 1 only, with a change from baseline of 8.4 ± 3 (P = 0.013) and 12.8 ± 8.2 (P < 0.02). However, AF symptom severity remained unchanged from baseline in both groups (P = 0.84). All 90 patients eventually underwent CA and received PVAI+ posterior wall+ non‐PV triggers ablation. At 1‐year follow‐up after single procedure, 37 (63.8%) in group 1 and 19 (59.3%) patients in group 2 remained arrhythmia‐free off AAD (P = 0.68). Conclusion: In this prospective analysis, in LSPAF patients weight loss improved QoL but had no impact on symptom severity and long‐term ablation outcome. [ABSTRACT FROM AUTHOR]

Introduction This study reports the procedural findings and ablation outcome in AF patients referred after ≥2 failed PV isolation (PVI). Methods Three hundred and five consecutive AF patients referred after ≥2 PVI were included in the analysis. High-dose isoproterenol challenge was used to identify PV reconnection and non-PV triggers; the latter were ablated based on the operator's discretion during the index procedure. At the repeat procedure, non-PV triggers were ablated in all. Empirical isolation of LA appendage (LAA) and coronary sinus (CS) was performed if the PVs were silent and no non-PV triggers were detected. Results PV reconnection was detected in 226 and non-PV triggers were identified or empirically isolated in 285 patients during the index procedure. At follow-up, 182 (60%) patients were recurrence-free off-AAD; the success rate with and without non-PV ablation was 81% vs. 8% (P < 0.0001). 104 patients underwent repeat procedure with non-PV trigger ablation in all. At 1 year, 90% were arrhythmia free off-AAD in non-PV ablation group, and 72% who did not receive non-PV triggers ablation at the index procedure (P = 0.035). The success rate of empirical LAA and CS isolation was 78.5% and 82% after the index and repeat procedure, respectively. Conclusion In patients experiencing AF recurrence after multiple failed PVI, despite PV reconnection, non-PV triggers were found to be responsible for AF maintenance in the majority and ablating those triggers increased ablation success. Additionally, in the presence of permanent PVI and no non-PV triggers on isoproterenol, empirical isolation of LAA and CS provided high rate of arrhythmia-free survival. [ABSTRACT FROM AUTHOR]

Background: Nonrandomized studies have reported focal impulse and rotor modulation (FIRM)-guided ablation to be superior to pulmonary vein antrum isolation (PVAI) for persistent atrial fibrillation and long-standing persistent atrial fibrillation.Objectives: This study sought to compare efficacy of FIRM ablation with or without PVAI versus PVAI plus non-PV trigger ablation in randomized persistent atrial fibrillation and long-standing persistent atrial fibrillation patients.Methods: Nonparoxysmal atrial fibrillation (AF) patients undergoing first ablation were randomized to FIRM only (group 1), FIRM + PVAI (group 2) or PVAI + posterior wall + non-PV trigger ablation (group 3). Primary endpoint was freedom from atrial tachycardia/AF. The secondary endpoint was acute procedural success, defined as AF termination, ≥10% slowing, or organization into atrial tachycardia.Results: A total of 113 patients were enrolled at 3 centers; 29 in group 1 and 42 each in groups 2 and 3. Group 1 enrollment was terminated early for futility. Focal drivers or rotors were detected in all group 1 and 2 patients. Procedure time was significantly shorter in group 3 versus groups 1 and 2 (p < 0.001). In groups 1 and 2, acute success after rotor-only ablation was achieved in 12 patients (41%) and 11 (26%), respectively. After 12 ± 7 months' follow-up, 4 patients (14%), 22 (52.4%), and 32 (76%) in groups 1, 2, and 3, respectively, were AF/atrial tachycardia-free while off antiarrhythmic drugs (log-rank p < 0.0001). Group 3 patients experienced higher success compared with groups 1 (p < 0.001) and 2 (p = 0.02).Conclusions: Outcomes were poor with rotor-only ablation. PVAI + rotor ablation had significantly longer procedure time and lower efficacy than PVAI + posterior wall + non-PV trigger-ablation. (Outcome of Different Ablation Strategies in Persistent and Long-Standing Persistent Atrial Fibrillation [OASIS]; NCT02533843). [ABSTRACT FROM AUTHOR]

Background: Purkinje fibers play an important role in initiation and maintenance of ventricular fibrillation (VF) and polymorphic ventricular tachycardia (PMVT). Fascicular substrate modification (FSM) approaches have been suggested to treat recurrent VF in case reports and small case series., Objectives: The aim of this study was to investigate outcomes of catheter-based FSM to treat VF and PMVT., Methods: Of 2,212 consecutive patients with ventricular arrhythmia undergoing catheter ablation, 18 (0.81%) underwent FSM of the Purkinje fibers as identified with high-density mapping during sinus rhythm. Fascicular substrate and VF initiation were mapped using a multipolar catheter. The endpoint of the ablation was noninducibility of VF and PMVT. In select patients, remapping revealed elimination of the targeted Purkinje potentials. Demographic, clinical, and follow-up characteristics were prospectively collected in our institutional database., Results: A total of 18 patients (mean age 56 ± 3.8 years, 22% women) were included in the study. Of those, 11 (61.1%) had idiopathic VF, 3 (16.7%) had nonischemic cardiomyopathy, and 4 (22.2%) had mixed cardiomyopathy. The average left ventricular ejection fraction was 42.5%. At least 2 antiarrhythmic drugs had failed preablation. At baseline, all patients had inducible VF or PMVT. At the end of the procedure, no patient demonstrated new evidence of fascicular block or bundle branch block. There were no procedure-related complications. After a median follow-up period of 24 months, 16 patients (88.9%) were arrhythmia free on or off drugs: 11 of 11 patients (100%) with idiopathic VF vs 5 of 7 patients (71.4%) with underlying cardiomyopathy (P = 0.06)., Conclusions: Catheter ablation of human VF and PMVT with FSM is feasible and safe and appears highly effective, with high rates of acute VF noninducibility and long-term freedom from recurrent VF., Competing Interests: Funding Support and Author Disclosures Dr Burkhardt is a consultant for Biosense Webster and Stereotaxis. Dr Di Biase is a consultant for Biosense Webster, Stereotaxis, and I-Rhythm; and has received speaker honoraria and travel expenses from Biosense Webster, Abbott Medical, Boston Scientific, Medtronic, Biotronik, and Zoll. Dr Santangeli is a consultant for Abbott, Biosense Webster, Boston Scientific, and Medtronic. Dr Natale is a consultant for Abbott, Baylis, Biotronik, Biosense Webster, Boston Scientific, and Medtronic. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Competing Interests: Disclosures Dr Di Biase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis, and St. Jude Medical; and has received speaker honoraria from Medtronic, AtriCure, EPiEP, and Biotronik. Dr Natale is a consultant for Biosense Webster, Stereotaxis, and Abbott Medical; and has received speaker honoraria/travel from Medtronic, AtriCure, Biotronik, and Janssen. All other authors have no conflicts of interest to disclose.

Background: High-voltage pulses can cause hemolysis., Objectives: The authors evaluated the occurrence of hemoglobinuria after pulsed-field ablation (PFA) and its impact on renal function in patients with atrial fibrillation (AF)., Methods: A consecutive series of patients with AF undergoing PFA were included in this analysis. The initial patients who did not receive postablation hydration immediately after the procedure were classified as group 1 (n = 28), and the rest of the study patients who received planned fluid infusion (0.9% sodium chloride ≥2 L) after the procedure were categorized as group 2 (n = 75)., Results: Of the 28 patients in group 1, 21 (75%) experienced hemoglobinuria during the 24 hours after catheter ablation. The mean postablation serum creatinine (S-Cr) was significantly higher than the baseline value in those 21 patients (1.46 ± 0.28 mg/dL vs 0.86 ± 0.24 mg/dL, P < 0.001). Of those 21 patients, 4 (19%) had S-Cr. >2.5 mg/dL (mean: 2.95 ± 0.21 mg/dL). The mean number of PF applications was significantly higher in those 4 patients than in the other 17 patients experiencing hemoglobinuria (94.63 ± 3.20 vs 46.75 ± 9.10, P < 0.001). In group 2 patients, no significant changes in S-Cr were noted. The group 2 patients received significantly higher amounts of fluid infusion after catheter ablation than did those in group 1 (2,082.50 ± 258.08 mL vs 494.01 ± 71.65 mL, P < 0.001). In multivariable analysis, both hydration (R 2  = 0.63, P < 0.01) and number of PFA applications (R 2  = 0.33, P < 0.01) were independent predictors of postprocedure acute kidney injury., Conclusions: On the basis of our findings, both the number of PFA applications and postablation hydration were independent predictors of renal insult that could be prevented using planned fluid infusion immediately after the procedure., Competing Interests: Funding Support and Author Disclosures Dr. Chierchia has received compensation for teaching purposes and proctoring from Medtronic, Abbott, Biotronik, Boston Scientific, and Acutus Medical. Dr. Burkhardt is a consultant for Biosense Webster and Stereotaxis. Dr. Di Biase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis, and St. Jude Medical and has received speaker honoraria from Medtronic, Atricure, EPiEP, and Biotronik. Dr. de Asmundis has received research grants on behalf of the center from Biotronik, Medtronic, Abbott, LivaNova, Boston Scientific, AtriCure, Philips, and Acutus and compensation for teaching purposes and proctoring from Medtronic, Abbott, Biotronik, Livanova, Boston Scientific, Atricure, Acutus Medical, and Daiichi Sankyo. Dr. Dello Russo is a consultant for Abbott Medical. Dr, Natale is a consultant for Abbott, Biosense Webster, Biotronik, Boston Scientific, and iRhythm. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Studies have reported development of pulmonary hypertension (PH) secondary to reduced LA compliance following AF ablation., Objectives: This study aimed to compare the risk of worsening of baseline PH between non-paroxysmal AF patients undergoing pulsed-field ablation (PFA) and standard radiofrequency ablation (RFA)., Methods: This multicenter study included 28 nonparoxysmal AF patients with PH undergoing a PFA-based ablation procedure after >1 failed RFA. A cohort of 28 AF patients with PH, scheduled for repeat RFA, 1:1 propensity-score matched using a multivariable logistic model, were used as the comparator group. Right heart catheterization and echocardiography were performed before and after the procedure to assess the pulmonary artery pressure (PAP). PH was defined as resting mean PAP of >20 mm Hg., Results: The baseline characteristics of the PFA and propensity-matched RFA groups were comparable. The mean PAP assessments at baseline, follow-up, and change from baseline were analyzed. The groups had comparable baseline mean pulmonary artery pressures (mPAP) (P = 0.177). After adjustment for baseline mPAP in an analysis of covariance model, the least-squares means change at 3 months after ablation was -1.71 ± 1.03 mm Hg and 19.67 ± 1.03 mm Hg in PFA and RFA, respectively (P <0.001)., Conclusions: In this propensity-matched population, no worsening of mPAP was detected following pulsed-field ablation in patients with pre-existing PH undergoing a repeat procedure for recurrence., Competing Interests: Funding Support and Author Disclosures Dr Chierchia has received compensation for teaching purposes and proctoring from Medtronic, Abbott, Biotronik, Boston Scientific, and Acutus Medical. Dr Dello Russo has served as a consultant for Abbott Medical. Dr Burkhardt is a consultant for Biosense Webster and Stereotaxis. Dr Di Biase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis, and St. Jude Medical; and has received speaker honoraria from Medtronic, Atricure, EPiEP, and Biotronik. Dr de Asmundis has received research grants on behalf of the center from Biotronik, Medtronic, Abbott, LivaNova, Boston Scientific, AtriCure, Philips, and Acutus; and compensation for teaching purposes and proctoring from Medtronic, Abbott, Biotronik, Livanova, Boston Scientific, Atricure, Acutus Medical, and Daiichi Sankyo. Dr Natale has been a consultant for Abbott, Biosense Webster, Biotronik, Boston Scientific, and iRhythm. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Acute pericarditis is a known complication of ablation procedures for atrial fibrillation (AF)., Objectives: This study aimed to evaluate the benefits of colchicine monotherapy in terms of reducing the risk of pericarditis and related hospitalization rate in AF patients undergoing catheter ablation., Methods: Consecutive AF patients undergoing first catheter ablation were classified into 3 groups based on their colchicine use: Group 1: no colchicine; group 2: colchicine from 7 days before to 1 month after ablation; and group 3: colchicine from the day of the procedure to 1 month after. Standard institutional protocol was used to follow all patients for 1 year., Results: A total of 1,075 patients were classified into groups 1 (n = 607), 2 (n = 213), and 3 (n = 255). Symptoms of acute pericarditis were reported in 129 patients (12%): group 1: n = 106 (17.5%); group 2: n = 4 (1.9%); and group 3: n = 19 (7.5%); P < 0.001. Rate of mild-moderate as well as severe pericarditis were significantly lower in group 2. In the multivariable regression analysis, pre- and post-ablation colchicine use was seen to be associated with significantly lower risk of acute pericarditis and related hospitalization compared with the other 2 groups. In addition, at 1-year follow-up, arrhythmia-free survival rate was significantly higher in paroxysmal AF patients receiving colchicine compared with the no-colchicine population., Conclusions: Colchicine therapy starting 7 days before to 1 month after the ablation procedure was associated with significantly lower risk of acute pericarditis and related hospitalization. In addition, paroxysmal AF patients receiving colchicine had a higher arrhythmia-free survival rate compared with those not receiving colchicine., Competing Interests: Funding Support and Author Disclosures Dr Natale is a consultant for Abbott, Baylis, Biosense Webster, Biotronik, Boston Scientific, and Medtronic. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

COVID-19 mainly affects the respiratory system but has been correlated with cardiovascular manifestations such as myocarditis, heart failure, acute coronary syndromes, and arrhythmias. Cardiac arrhythmias are the second most frequent complication affecting about 30% of patients. Several mechanisms may lead to an increased risk of cardiac arrhythmias during COVID-19 infection, ranging from direct myocardial damage to extracardiac involvement. The aim of this review is to describe the role of COVID-19 in the pathogenesis of cardiac arrhythmias and provide a comprehensive guidance for their monitoring and management., Competing Interests: Disclosure Dr J.D. Burkhardt is a consultant for Biosense Webster and Stereotaxis. Dr L. Di Biase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis, and St. Jude Medical; and has received speaker honoraria from Medtronic, Atricure, EPiEP, and Biotronik. Dr A. Natale has received speaker honoraria from Boston Scientific, Biosense Webster, St. Jude Medical, Biotronik, and Medtronic; and is a consultant for Biosense Webster, St. Jude Medical, and Janssen. All other authors have reported that they have no relationships relevant to the contents of this article to disclose., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objectives: This study sought to report the incidence of device-related thrombosis (DRT) and thromboembolic (TE) events when an alternative to clopidogrel is prescribed in loss-of-function (LOF) allele carriers of the cytochrome P450 2C19 (CYP2C19) gene., Background: LOF polymorphisms of the CYP2C19 gene are associated with reduced hepatic bioactivation of clopidogrel., Methods: A total of 1,002 Watchman patients were included. Six hundred forty-five patients underwent CYP2C19 genetic testing; among patients with clopidogrel resistance, clopidogrel was replaced by either prasugrel (pilot cohort) or half dose direct oral anticoagulant ([DOAC]/Group 1), both in combination with aspirin. We compared the incidence of DRT/TE events among genotyped patients and a control group which received standard dual antiplatelet therapy (DAPT) (Group 2; n = 357). All reported events occurred during a timeframe between 45- and 180-day follow-up transesophageal echocardiograms, when the 2 different antithrombotic strategies (genotype-guided vs standard DAPT) were adopted., Results: In the pilot cohort (n = 244), bleeding events occurred in 10.2% of patients who received aspirin plus prasugrel, leading to early discontinuation of the prasugrel-based protocol. DOAC Group 1 patients (n = 401), 25.7% were reduced metabolizers, and clopidogrel was replaced by half dose direct oral anticoagulant. DRT was documented in 1 (0.2%) patient of Group 1 and 7 (1.96%) patients of Group 2 (log-rank P = 0.021). The composite endpoint of DRT/TE events was significantly lower among patients receiving a genotype-guided antithrombotic strategy (0.75% vs 3.10%; log-rank P = 0.017)., Conclusions: In Watchman patients, a genotype-based antithrombotic strategy with aspirin plus half dose DOAC in reduced clopidogrel metabolizers was superior to standard DAPT with respect to DRT/TE events., Competing Interests: Funding Support and Author Disclosures The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021. Published by Elsevier Inc.)

Objectives: The aim of this study was to evaluate the efficacy of radiofrequency (RF) energy applications targeting the atrial side of a significant residual leak in patients with acute and chronic evidence of incomplete percutaneous left atrial appendage (LAA) occlusion., Background: RF applications have been proved to prevent recanalization of intracranial aneurysms after coil embolization, thereby favoring complete sealing. From a mechanistic standpoint, in vitro and in vivo experiments have demonstrated that RF promotes collagen deposition and tissue retraction., Methods: Forty-three patients (mean age 75 ± 7 years mean CHA 2 DS 2 -VASc score 4.6 ± 1.4, mean HAS-BLED score 4.0 ± 1.1) with residual leaks ≥4 mm after Watchman implantation were enrolled. Procedural success was defined as complete LAA occlusion or presence of a mild or minimal (1- to 2-mm) peridevice leak on follow-up transesophageal echocardiography (TEE), which was performed approximately 45 days after the procedure., Results: RF-based leak closure was performed acutely after Watchman implantation in 19 patients (44.2%) or scheduled after evidence of significant leaks on follow-up TEE in 24 others (55.8%). The median leak size was 5 mm (range: 4-7 mm). On average, 18 ± 7 RF applications per patient (mean maximum contact force 16 ± 3 g, mean power 44 ± 2 W, mean RF time 5.1 ± 2.5 minutes) were performed targeting the atrial edge of the leak. Post-RF median leak size was 0 mm (range: 0-1 mm). A very low rate (2.3% [n = 1]) of major periprocedural complications was observed. Follow-up TEE revealed complete LAA sealing in 23 patients (53.5%) and negligible residual leaks in 15 (34.9%)., Conclusions: RF applications targeting the atrial edge of a significant peri-Watchman leak may promote LAA sealing via tissue remodeling, without increasing complications. (RF Applications for Residual LAA Leaks [REACT]; NCT04726943)., Competing Interests: Funding Support and Author Disclosures Dr Burkhardt is a consultant for Biosense Webster and Stereotaxis. Dr Di Biase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis, and St. Jude Medical; and has received speaker honoraria from Medtronic, Atricure, EPiEP, and Biotronik. Dr Natale has received speaker honoraria from Abbott, Biosense Webster, Boston Scientific, Biotronik, Baylis, Medtronic; and is a consultant for Biosense Webster, St. Jude Medical, and Janssen. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021. Published by Elsevier Inc.)

Background: Direct oral anticoagulants (DOACs) are contraindicated in patients with atrial fibrillation (AF) and mechanical cardiac valves. However, safety and efficacy are controversial in patients with biological cardiac valves., Objective: We report the safety and feasibility of periprocedural and long-term treatment with DOACs in patients with biological valves undergoing ablation for AF., Methods: A total of 127 patients with AF and biological cardiac valve undergoing CA on uninterrupted DOAC were matched by gender and age with 127 patients with AF and biological cardiac valves undergoing CA on uninterrupted warfarin. All patients were anticoagulated for at least 3-4 weeks prior to ablation with either rivaroxaban (70%) or apixaban (30%), which were continued for at least 3 months and subsequently based on CHA 2 DS 2 -VASc score., Results: Mean age of the study population was 63.0 ± 10.9 with 66% being male. The majority of patients on NOACs had aortic valve replacement (59%), while mitral valve was replaced in 41% of patients, which did not differ from the matched cohort on coumadin (aortic valve 57% and mitral valve 43%, (p = 0.8) (p = 0.8), respectively). The CHADS 2 score was ≥ 2 in 90 patients (71.0%) on DOAC and 86 patients in (68%) the control (p = 0.6) group. Patients underwent ablation predominantly with uninterrupted rivaroxaban [89 (70%)], while the remaining 38 patients (30%) underwent ablation while on apixaban. Two groin hematomas were observed periprocedurally in both groups. No stroke/transient ischemic attack (TIA) was observed both periprocedurally and at long-term follow-up in either group., Conclusion: Periprocedural and long-term administration of DOACs in patients with biological cardiac valves undergoing AF ablation appears as safe as warfarin therapy., (© 2020. Springer Science+Business Media, LLC, part of Springer Nature.)

Objectives: This study evaluated the association of the post-ablation scar with stroke risk in patients undergoing atrial fibrillation (AF) ablation., Background: Late gadolinium enhancement-cardiac magnetic resonance studies have reported a direct association between pre-ablation left atrial scar and thromboembolic events in patients with AF., Methods: Consecutive patients with AF were classified into 2 groups based on the type of ablation performed at the first procedure. Group 1 involved limited ablation (isolation of pulmonary veins, left atrial posterior wall, and superior vena cava); and group 2 involved extensive ablation (limited ablation + ablation of nonpulmonary vein triggers from all sites except left atrial appendage). During the repeat procedure, post-ablation scar (region with bipolar voltage amplitude <0.5 mV) was identified by using 3-dimensional voltage mapping., Results: A total of 6,297 patients were included: group 1, n = 1,713; group 2, n = 4,584. Group 2 patients were significantly older and had more nonparoxysmal AF. Nineteen (0.3%) thromboembolic events were reported after the first ablation procedure: 9 (1.02%) in group 1 and 10 (0.61%) in group 2 (p = 0.26). At the time of the event, all 19 patients were experiencing arrhythmia. Median time to stroke was 14 (interquartile range: 9 to 20) months in group 1 and 14.5 (interquartile range: 8 to 18) months in group 2. Post-ablation scar data were derived from 2,414 patients undergoing repeat ablation. Mean scar area was detected as 67.1 ± 4.6% in group 2 and 34.9 ± 8.8% in group 1 at the redo procedure (p < 0.001)., Conclusions: Differently from the cardiac magnetic resonance-detected pre-ablation scar, scar resulting from extensive ablation was not associated with increased risk of stroke compared with that from the limited ablation., Competing Interests: FUNDING SUPPORT AND AUTHOR DISCLOSURES Dr. Burkhardt is a consultant for Biosense-Webster and Stereotaxis. Dr. Di Biase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis and St. Jude Medical; and has received speaker honoraria/travel support from Medtronic, Bristol Meyers Squibb, Pfizer and Biotronik. Dr. Natale is a consultant for Abbott, Biosense Webster, Boston Scientific, Biotronik, Baylis and Medtronic. All other authors have reported that they have no relationships relevant to the contents of this paper., (Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

A recent surveillance analysis indicates that cardiac arrest/death occurs in ≈1:50,000 professional or semi-professional athletes, and the most common cause is attributable to life-threatening ventricular arrhythmias (VAs). It is critically important to diagnose any inherited/acquired cardiac disease, including coronary artery disease, since it frequently represents the arrhythmogenic substrate in a substantial part of the athletes presenting with major VAs. New insights indicate that athletes develop a specific electro-anatomical remodeling, with peculiar anatomic distribution and VAs patterns. However, because of the scarcity of clinical data concerning the natural history of VAs in sports performers, there are no dedicated recommendations for VA ablation. The treatment remains at the mercy of several individual factors, including the type of VA, the athlete's age, and the operator's expertise. With the present review, we aimed to illustrate the prevalence, electrocardiographic (ECG) features, and imaging correlations of the most common VAs in athletes, focusing on etiology, outcomes, and sports eligibility after catheter ablation.

Objectives: This study sought to compare the effect of high-dose dobutamine (DBT) with that of high-dose isoproterenol (IPN) in eliciting triggers during atrial fibrillation (AF) ablation., Background: High-dose IPN is commonly used to elicit triggers during AF ablation. However, it is not available worldwide and, in the United States, its cost per dose has significantly increased. DBT is a similarly nonselective β-agonist and, as such, is a potential alternative., Methods: This was a prospective, randomized 2×2 crossover study of patients undergoing AF ablation. Patients were assigned to receive IPN (20 to 30 μg/min for 10 min) followed by DBT (40 to 50 μg/kg/min for 10 min) or vice versa in a 1:1 fashion. The type, number, and location of triggers as well as heart rate, blood pressure, and side effects were noted., Results: Fifty patients were included in the study. Both drugs caused a significant increase in heart rate, with a consistently lower peak for DBT. Blood pressure significantly increased with DBT, while there was a significant reduction with IPN, despite phenylephrine support. Atrial arrhythmias induced during DBT were comparable to that induced during IPN. In patients with IPN-inducible outflow tract premature ventricular contractions, a similar effect was noted with DBT. No major complications occurred during either drug challenge., Conclusions: High-dose DBT is safe and comparable to high-dose IPN in respect of eliciting AF triggers, with the advantage to maintain systemic pressure without the need of additional vasopressor support. This study supports the use of high-dose DBT in electrophysiology laboratories in which IPN is not readily available and for those patients in whom hypotension is a concern., Competing Interests: Author Disclosures The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2020 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

In the past decade, the use of interventional electrophysiological (EP) procedures for the diagnosis and treatment of cardiac arrhythmias has exponentially increased. These procedures usually require fluoroscopy to guide the advancement and frequent repositioning of intracardiac catheters, resulting in both the patient and the operator being subjected to a considerable degree of radiation exposure. Although shielding options such as lead gowns, glasses, and pull-down shields are useful for protecting the operator, they do not lessen the patient's level of exposure. Furthermore, the prolonged use of lead gowns can exponentiate the onset of orthopedic problems among operators. Recent advancements in three-dimensional cardiac mapping systems and the use of radiation-free imaging technologies such as magnetic resonance imaging and intracardiac ultrasound allow operators to perform EP procedures with minimal or even no fluoroscopy. In this review, we sought to describe the state of fluoroless procedures in EP practice., Competing Interests: Dr. Burkhardt is a consultant for Biosense Webster and Stereotaxis. Dr. Natale has received speaker honoraria from Boston Scientific, Biosense Webster, St. Jude Medical, Biotronik, and Medtronic and is a consultant for Biosense Webster, St. Jude Medical, and Janssen. All other authors no conflicts of interest for the published content., (Copyright: © 2020 Innovations in Cardiac Rhythm Management.)

Background: The electrocardiogram (ECG) is essential for the differential diagnosis of wide QRS complex tachycardia (WCT)., Objective: The purpose of this study was to evaluate the diagnostic value of a novel ECG algorithm on the basis of the morphological characteristics of the QRS on the limb leads., Methods: The limb lead algorithm (LLA) was evaluated by analyzing 528 monomorphic WCTs with electrophysiology-confirmed diagnoses. In the LLA, ventricular tachycardia (VT) is diagnosed in the presence of at least 1 of the following: (1) monophasic R wave in lead aVR; (2) predominantly negative QRS in leads I, II, and III; and (3) opposing QRS complex in the limb leads: concordant monophasic QRS in all 3 inferior leads and concordant monophasic QRS in 2 or 3 of the remaining limb leads with a polarity opposite to that of the inferior leads. The diagnostic performance of the LLA was compared with that of the Brugada, Vereckei, and R-wave peak time (RWPT) algorithms., Results: Of 528 WCT cases, 397 were VT and 131 supraventricular tachycardia. The interobserver agreement for the LLA was excellent (κ = 0.98), better than that for the other algorithms. The overall accuracy of the LLA (88.1%) was similar to that of Brugada (85.4%) and Vereckei (88.1%) algorithms but was higher than that of the RWPT algorithm (70.8%). The LLA had a lower sensitivity (87.2%) than did Brugada (94.0%) and Vereckei (92.4%) algorithms, but not the RWPT algorithm (67.8%). Furthermore, the LLA showed a higher specificity (90.8%) than did Brugada (59.5%), Vereckei (76.3%), and RWPT (80.2%) algorithms., Conclusion: The LLA is a simple yet accurate method to diagnose VT when approaching WCTs on the ECG., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objectives: The aim of this study was to assess the feasibility and efficacy of transcatheter leak closure with detachable coils in patients with incomplete left atrial appendage (LAA) closure., Background: Incomplete LAA closure is common after interventional therapies targeting the LAA, potentially hindering effective thromboembolic prevention. Detachable coils have found a wide range of applications for transcatheter vascular occlusion and embolization procedures., Methods: Thirty consecutive patients at high thromboembolic risk with clinically relevant residual leaks (mean age 72 ± 9 years, 73.3% men, mean CHA 2 DS 2 -VASc score 4.4 ± 1.4, mean HAS-BLED score 3.6 ± 0.8) underwent percutaneous closure of the LAA patency using embolization coils. Transesophageal echocardiography was performed at 60 ± 15 days post-procedure., Results: LAA closure had been previously attempted with the Watchman device in 25 patients, the Amulet device in 2 patients, and the LARIAT device in 3 patients. Baseline transesophageal echocardiography documented moderate and severe leaks in 20 (66.7%) and 10 (33.3%) patients, respectively. After a single procedure, 25 patients (83.3%) showed complete LAA sealing or minimal leaks. Five patients (16.7%) had moderate residual leaks; 3 patients of them were offered repeat procedures. Mean procedure and fluoroscopy times were 76 ± 41 min and 21 ± 14 min, respectively; the mean volume of iodinated contrast medium used was 80 ± 47 ml. Coil deployment was successful in all cases. The overall complication rate was 6.1%. After a median follow-up period of 54 days (range 43 to 265 days) and an average of 1.1 procedures/patient, transesophageal echocardiography revealed complete LAA sealing or negligible residual leaks in 28 patients (93.3%; 25 with no residual leak, 3 patients with minimal to mild residual leaks) and moderate residual leaks in 2 patients (6.7%)., Conclusions: Transcatheter LAA leak occlusion using endovascular coils appears to be a safe, effective, and promising approach in patients at high echo time risk with incomplete LAA closure. (Transcatheter Leak Closure With Detachable Coils Following Incomplete Left Atrial Appendage Closure Procedures [TREASURE]; NCT03503253)., (Copyright © 2020 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Fragmented QRS (fQRS) on 12-lead electrocardiography is a noninvasive marker of intramyocardial conduction delay due to ventricular scarring that has not previously been studied in atrial fibrillation., Objective: The purpose of this study was to assess the association of fQRS with left atrial (LA) scarring in patients with persistent atrial fibrillation (PsAF) undergoing first catheter ablation., Methods: A total of 376 patients with PsAF were enrolled. Severity of LA scarring was assessed using electroanatomic mapping. Narrow fQRS was defined by the presence of an additional R wave (R') or notching in the nadir of the S wave, or the presence of >1 R' in 2 contiguous leads corresponding to inferior, lateral, or anterior myocardial regions., Results: Both any degree (97.3% vs 63.3%) and severe (42.2% vs 6.3%) LA scarring were higher in patients with fQRS. Age and fQRS were found to be independent predictors of severe LA scarring. At multiple ventricular regions, fQRS had diagnostic accuracy of 79.8% for prediction of severe LA scarring. Nonpulmonary vein triggers were more often detected and ablated in patients with fQRS and severe LA scarring (84.4% vs 70%; P = .001). Atrial tachyarrhythmia recurrence was observed in 131 patients (34.8%) during 18.9 ± 7.7 months of follow-up, which was significantly higher in patients with fQRS (53.2% vs 16.8%). In multivariate analysis, fQRS was found to be a significant predictor of recurrence (hazard ratio 4.65; 95% interval confidence 2.91-7.42; P <.001)., Conclusion: The study results showed that fQRS is a simple, available, and noninvasive marker, and that fQRS at multiple ventricular regions is significantly associated with the severity of LA scarring in PsAF patients., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Atrial fibrillation (AF) triggers within the coronary sinus (CS)/great cardiac vein (GCV) and the left atrial appendage (LAA) have been recognized as nonpulmonary vein triggers of AF., Objective: The aim of this study was to describe an electrical connection between the LAA and CS/GCV and its importance in achieving LAA electrical isolation (LAAEI)., Methods: A total of 488 consecutive patients undergoing catheter ablation for persistent or long-standing persistent AF who showed firing from the LAA and/or from the CS/GCV were enrolled in this multicenter prospective study. In all patients, potential defragmentation of the CS/GCV to achieve isolation and LAAEI was attempted with both endocardial and epicardial ablation., Results: In 7% (n = 34) of these patients, after attempting endocardial LAAEI, the LAA was isolated during epicardial ablation in the GCV. In 8% (n = 39) of patients after attempting endocardial LAA isolation, the LAA was isolated during ablation along the endocardial aspect of the GCV. The presence of a venous branch connecting the GCV with the LAA was found in all these patients. In 23% (n = 112) of patients, the isolation of the LAA also isolated the GCV. In all these patients, LAA dissociated firing was present together with the CS/GCV recordings., Conclusion: These findings suggest the presence of a distinct electrical connection between the GCV and the LAA. The clinical relevance of our results requires further investigation. Ablation in the CS/GCV can result in inadvertent isolation of the LAA. Ablation of the GCV is relevant to achieve LAAEI. Considering the potential long-term implications, ablation in the distal CS/GCV should prompt assessment of LAA conduction., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)