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Introduction: Radiofrequency ablation (RFA) slow pathway modification for catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed using a 4‐mm nonirrigated (NI) RF ablation catheter. Slow pathway modification using irrigated, contact‐force sensing (ICFS) RFA catheters has been described in case reports, but the outcomes have not been systematically evaluated. Methods: Acute procedural outcomes of 200 consecutive patients undergoing slow pathway modification for AVNRT were analyzed. A 3.5‐mm ICFS RFA catheter (ThermoCool SmartTouch STSF, Biosense Webster, Inc.) was utilized in 134 patients, and a 4‐mm NI RFA catheter (EZ Steer, Biosense Webster, Inc.) was utilized in 66 patients. Electroanatomic maps were retrospectively analyzed in a blinded fashion to determine the proximity of ablation lesions to the His region. Results: The baseline characteristics of patients in both groups were similar. Total RF time was significantly lower in the ICFS group compared to the NI group (5.53 ± 4.6 vs. 6.24 ± 4.9 min, p = 0.03). Median procedure time was similar in both groups (ICFS, 108.0 (87.5–131.5) min vs. NI, 100.0 (85.0–125.0) min; p = 0.2). Ablation was required in closer proximity to the His region in the NI group compared to the ICFS group (14.4 ± 5.9 vs. 16.7 ± 6.4 mm, respectively, p = 0.01). AVNRT was rendered noninducible in all patients, and there was no arrhythmia recurrence during follow‐up in both groups. Catheter ablation was complicated by AV block in one patient in the NI group. Conclusion: Slow pathway modification for catheter ablation of AVNRT using an ICFS RFA catheter is feasible, safe, and may facilitate shorter duration ablation while avoiding ablation in close proximity to the His region. [ABSTRACT FROM AUTHOR]

Introduction: Patients with HIV infection have increased risk of atrial fibrillation, but the pathophysiologic mechanisms and the utility of catheter ablation in this population are not well‐studied. We aimed to characterize outcomes of atrial fibrillation ablation and left atrial substrate in patients with HIV. Methods: The study was a retrospective propensity score‐matched analysis of patients with and without HIV undergoing atrial fibrillation ablation. A search was performed in the electronic medical record for all patients with HIV who received initial atrial fibrillation ablation from 2011 to 2020. After calculating propensity scores for HIV, matching was performed with patients without HIV by using nearest‐neighbor matching without replacement in a 1:2 ratio. The primary outcome was freedom from atrial arrhythmia and secondary outcomes were freedom from atrial fibrillation, freedom from atrial tachycardia, and freedom from repeat ablation, compared by log‐rank analysis. The procedures of patients with HIV who underwent repeat ablation at our institution were further analyzed for etiology of recurrence. To further characterize the left atrial substrate, a subsequent case‐control analysis was then performed for a set of randomly chosen 10 patients with HIV matched with 10 without HIV to compare minimum and maximum voltage at nine pre‐specified regions of the left atrium. Results: Twenty‐seven patients with HIV were identified. All were prescribed antiretroviral therapy at time of ablation. These patients were matched with 54 patients without HIV by propensity score. 86.4% of patients with HIV and 76.9% of controls were free of atrial fibrillation or atrial tachycardia at 1 year (p =.509). Log‐rank analysis showed no difference in freedom from atrial arrhythmia (p value.971), atrial fibrillation (p‐value.346), atrial tachycardia (p value.306), or repeat ablation (p value.401) after initial atrial fibrillation ablation in patients with HIV compared to patients without HIV. In patients with HIV with recurrent atrial fibrillation, the majority had pulmonary vein reconnection (67%). There were no significant differences in minimum or maximum voltage at any of the nine left atrial regions between the matched patients with and without HIV. Conclusions: Ablation to treat atrial fibrillation in patients with HIV, but without overt AIDS is frequently successful therapy. The majority of patients with recurrence of atrial fibrillation had pulmonary vein reconnection, suggesting infrequent nonpulmonary vein substrate. In this population, the left atrial voltage in patients with HIV is similar to that of patients without HIV. These findings suggest that the pulmonary veins remain a critical component to the initiation and maintenance of atrial fibrillation in patients with HIV. [ABSTRACT FROM AUTHOR]

Introduction: Micra atrioventricular (AV) provides leadless atrioventricular synchronous pacing by sensing atrial contraction (A4 signal). Real‐world operation and reliability of AV synchrony (AVS) assessment using device data have not been described. The purposes of this study were to (1) assess the correlation between AVS and atrial mechanical sensed‐ventricular pacing (AM‐VP) percentages in patients with permanent high‐degree AV block and (2) report on the real‐world effectiveness of Micra AV. Methods: The correlation between ECG‐determined AVS in‐clinic and device‐collected %AM‐VP was assessed using data from 40 patients with high‐degree AV block enrolled in the Micra Atrial tRacking using a Ventricular AccELerometer (MARVEL) 2 study. A retrospective analysis to assess continuously‐sampled %AM‐VP since last session, device programming, and electrical parameters was performed using Micra AV transmissions from the Medtronic CareLink database. Patients with transmissions ≥180 days postimplant were included. Results: Among the 40 MARVEL 2 AV block patients with a median %VP of 99.7%, AVS was highly correlated with AM‐VP (median AVS 87.1%, median AM‐VP 79.1%; R2 = 0.764, p <.001). The CareLink cohort included 4384 patients programmed to VDD mode. The mean A4 amplitude was 2.3 ± 1.8 m/s2 at implant and 2.3 ± 1.6 m/s2 at 28 weeks. In patients with %VP >90% (n = 1662), the median %AM‐VP was 74.7%. For the full cohort, median %VP was 65.6% and median projected battery longevity was 10.5 years. Conclusion: In patients with a high pacing burden, %AM‐VP provides a reasonable estimation of AVS. The first large real‐world analysis of Micra AV patients with >90% VP showed stable atrial sensing over time with a median %AM‐VP, a correlate of AVS, of 74.7%. [ABSTRACT FROM AUTHOR]

Aims: There is limited information on what clinical factors are associated with the development of pericardial effusion after leadless pacemaker implantation. We sought to determine predictors of and to develop a risk score for pericardial effusion in patients undergoing Micra leadless pacemaker implantation attempt.Methods and Results: Patients (n = 2817) undergoing implant attempt from the Micra global trials were analysed. Characteristics were compared between patients with and without pericardial effusion (including cardiac perforation and tamponade). A risk score for pericardial effusion was developed from 18 pre-procedural clinical variables using lasso logistic regression. Internal validation and future prediction performance were estimated using bootstrap resampling. The scoring system was also externally validated using data from the Micra Acute Performance European and Middle East (MAP EMEA) registry. There were 32 patients with a pericardial effusion [1.1%, 95% confidence interval (CI): 0.8-1.6%]. Following lasso logistic regression, 11 of 18 variables remained in the model from which point values were assigned. The C-index was 0.79 (95% CI: 0.71-0.88). Patient risk score profile ranged from -4 (lowest risk) to 5 (highest risk) with 71.8% patients considered low risk (risk score ≤0), 16.6% considered medium risk (risk score = 1), and 11.7% considered high risk (risk score ≥2) for effusion. The median C-index following bootstrap validation was 0.73 (interquartile range: 0.70-0.75). The C-index based on 9 pericardial effusions from the 928 patients in the MAP EMEA registry was 0.68 (95% CI: 0.52-0.83). The pericardial effusion rate increased significantly with additional Micra deployments in medium-risk (P = 0.034) and high-risk (P < 0.001) patients.Conclusion: The overall rate of pericardial effusion following Micra implantation attempt is 1.1% and has decreased over time. The risk of pericardial effusion after Micra implant attempt can be predicted using pre-procedural clinical characteristics with reasonable discrimination.Clinical Trial Registration: The Micra Post-Approval Registry (ClinicalTrials.gov identifier: NCT02536118), Micra Continued Access Study (ClinicalTrials.gov identifier: NCT02488681), and Micra Transcatheter Pacing Study (ClinicalTrials.gov identifier: NCT02004873). [ABSTRACT FROM AUTHOR]

Introduction: Prior studies have shown that addition of posterior wall isolation (PWI) may reduce atrial fibrillation recurrence in patients with persistent atrial fibrillation. No data on PWI in paroxysmal AF (pAF) patients with normal left atrial voltage is available, to date. Objective: This study sought to evaluate the efficacy of PWI in addition to pulmonary vein isolation (PVI) in patients presenting with pAF and normal left atrial voltage. Methods: Consecutive patient registry analysis was performed on all patients with pAF and normal left atrial voltage undergoing initial radiofrequency ablation from November 1, 2018 to November 15, 2019. Primary endpoint was recurrence of atrial arrhythmia including AF, atrial tachycardia (AT), or atrial flutter (AFL). Results: A total of 321 patients were studied, 214 in the PVI group and 107 in the PWI + PVI group. Recurrence of any atrial arrhythmia occurred in 18.2% of patients in the PVI group and 16.8% in the PVI + PWI cohort (p = 0.58). At 1 year, recurrence was 14.0% in the PVI group and 15.0% in the PWI + PVI group (p = 0.96). There was a lower AT/AFL recurrence in the PVI + PWI group, not reaching significance (3.7% in the PWI + PVI group vs. 7.9% in PVI group, p = 0.31). Need for carina lesions predicted recurrence in the PVI‐only group. Conclusions: Addition of PWI to PVI in pAF patients undergoing their first ablation did not reduce the frequency of atrial arrhythmia recurrence. This warrants further study in a prospective trial. [ABSTRACT FROM AUTHOR]

Objective: To compare multiple‐procedure catheter ablation outcomes of a stepwise approach versus left atrial posterior wall isolation (LA PWI) in patients undergoing nonparoxysmal atrial fibrillation (NPAF) ablation. Background: Unfavorable outcomes for stepwise ablation of NPAF in large clinical trials may be attributable to proarrhythmic effects of incomplete ablation lines. It is unknown if a more extensive initial ablation strategy results in improved outcomes following multiple ablation procedures. Methods: Two hundred twenty two consecutive patients with NPAF underwent first‐time ablation using a contact‐force sensing ablation catheter utilizing either a stepwise (Group 1, n = 111) or LA PWI (Group 2, n = 111) approach. The duration of follow‐up was 36 months. The primary endpoint was freedom from atrial arrhythmia >30 s. Secondary endpoints were freedom from persistent arrhythmia, repeat ablation, and recurrent arrhythmia after repeat ablation. Results: There was similar freedom from atrial arrhythmias after index ablation for both stepwise and LA PWI groups at 36 months (60% vs. 69%, p =.1). The stepwise group was more likely to present with persistent recurrent arrhythmia (29% vs. 14%, p =.005) and more likely to undergo second catheter ablation (32% vs. 12%, p <.001) compared to LA PWI patients. Recurrent arrhythmia after repeat ablation was more likely in the stepwise group compared to the LA PWI group (15% vs. 4%, p =.003). Conclusions: Compared to a stepwise approach, LA PWI for patients with NPAF resulted in a similar incidence of any atrial arrhythmia, lower incidence of persistent arrhythmia, and fewer repeat ablations. Results for repeat ablation were not improved with a more extensive initial approach. [ABSTRACT FROM AUTHOR]

Introduction: Implantable cardioverter defibrillators (ICDs) are proven to prevent sudden death in patients at elevated risk for sustained ventricular tachycardia or fibrillation. Complications related to ICD failure can stem from lead dysfunction, manufacturing defects, patient characteristics, or implantation technique. We conducted a review of all ICD leads implanted at our center from 2011 to 2017 to determine risk factors for premature lead failure. Methods: We conducted a retrospective review of patients of all ICD leads implanted from December 2011 to June 2017 at our institution. A total of 660 patients (Biotronik Linox S/SD, n = 281; Sprint Quatro, n = 207; Durata, n = 121; Endotak, n = 51) underwent ICD implantations. Patient and lead characteristics, procedural outcomes and complications were recorded. Lead failure was defined per Heart Rhythm Society lead‐management consensus as a lack of procedural or clinical success, thus requiring an extraction of the lead. Patient and lead outcomes were recorded and variables associated with lead failure were assessed by the Kaplan‐Meier method. Results: Overall failure rate was similar for all leads: Linox S/SD—0.29%/year; Sprint Quattro—0.21%/year, Durata—0.39%/year and Endotak Reliance—0.0% (P =.769). No difference was found in overall survival when comparing all ICD manufacturers during the study period. Subgroup analysis revealed the risk of premature lead failure was particularly pronounced in multi‐lead ICD systems implanted via cephalic access (P <.001). The estimated failure rate of Linox leads implanted via cephalic access in multi‐lead systems was 19%/year. The estimated failure rate of non‐Linox leads implanted via cephalic access in multi‐lead systems was 11%/year. Neither age, nor gender were risk factors for lead failure in the Linox, or non‐Linox cohorts. Conclusion: All analyzed ICD leads were found to have a similar overall risk of premature failure. ICD lead implantation via cephalic access in multilead ICD systems may be a previously unidentified risk factor for premature ICD lead failure, although these findings require further validation. [ABSTRACT FROM AUTHOR]

Introduction: Acute hemopericardium during cardiac electrophysiology (EP) procedures may result in significant blood loss and is the most common cause of procedure‐related death. Matched allogeneic blood is often not immediately available. The feasibility and safety of direct autotransfusion in cardiac electrophysiology patients requiring emergency pericardiocentesis is unknown. Methods: We retrospectively analyzed records of patients undergoing EP procedures at a single, tertiary care medical center who had procedure‐related acute hemopericardium requiring emergency pericardiocentesis during a 3‐year period. Procedure details, transfusion volumes, and clinical outcomes of patients who received direct autotransfusion of aspirated pericardial blood via a femoral venous sheath were compared to those of patients who did not receive direct autotransfusion. Results: During the study period, 10 patients received direct autotransfusion (group 1) and outcomes were compared with those of 14 control patients who did not receive direct autotransfusion (group 2). The volume of aspirated pericardial blood was similar in groups 1 and 2 (1.6 ± 0.7 L vs 1.3 ± 1.0 L, respectively; P =.52). Amongst patients with aspirated volumes <1 L, group 1 patients (n = 4) were less likely than group 2 patients (n = 8) to require allotransfusion (0% vs 75%, P =.02). Amongst patients with aspirated volume ≥1 L, group 1 patients (n = 6) required fewer units of red cell allotransfusion than group 2 patients (n = 6) (1.5 ± 0.8 units vs 4.3 ± 2.0 units, P =.01). No procedural complications related to direct autotransfusion occurred. Conclusions: Direct autotransfusion following emergency pericardiocentesis during electrophysiology procedures requiring systemic anticoagulation is feasible and safe. The utilization of direct autotransfusion may eliminate or reduce the need for allotransfusion. [ABSTRACT FROM AUTHOR]

Background Venous occlusion is not uncommon and total venous obstruction with more proximal patency may occur in as many as 10% of previous implants. Many techniques are available to obtain ipsilateral access; however, most require special equipment or skills. We describe a technique of infraclavicular cannulation of the brachiocephalic vein ipsilateral to the occlusion that is safe and feasible for most implanters. Methods Fourteen patients with subclavian/axillary occlusions ipsilateral to the implanted device and requiring revision or upgrade of their system or venous occlusion with contraindication to implant on the contralateral side underwent lead addition/placement via a brachiocephalic approach. Following venography, an 18-gauge needle was used to gain brachiocephalic access. The needle was initially positioned in a lateral infraclavicular location. The needle was then advanced under the clavicle in a horizontal plane and advanced toward the sternal notch under fluoroscopic guidance. Results Fourteen patients underwent an attempt at brachiocephalic access. Cannulation of the brachiocephalic was possible in all 14 and lead(s) were successfully implanted in all. There were no complications with the procedure, specifically no pneumothoraces. In follow-up (mean 36 months, range 1-86 months), all implanted leads function well, with no evidence of lead failure or impedance changes. Conclusion A lateral infraclavicular approach is a safe and effective technique for obtaining brachiocephalic access when the subclavian/axillary vein is occluded. This technique is easy to learn and may be useful for implanters without the equipment or skills needed for lead extraction or microdissection or in cases where patients refuse these procedures. [ABSTRACT FROM AUTHOR]

RF Ablation of VT in Chronic Cocaine Users Background Cocaine use is a known but rare cause of cardiac arrhythmias. Ventricular arrhythmias related to cocaine may not respond to antiarrhythmic drugs and may need treatment with radiofrequency ablation. Objectives We describe the clinical and electrophysiological characteristics of cocaine-related ventricular tachycardia (VT) from a multicenter registry. Methods Subjects presenting with VT related to cocaine use and being considered for radiofrequency ablation have been included in the study. Patients who were refractory to maximal medical therapy underwent radiofrequency ablation of the VT. Clinical, procedural variables, efficacy, and safety outcomes were assessed. Results A total of 14 subjects met study criteria (age 44 ± 13, range 18- to 68-year-old with 79% male, 71% Caucasian). MRI showed evidence of scar only in 43% of patients (6/14). The mechanism of VT was focal in 50% (n = 7) and scar related reentry in 50% (n = 7) based on 3D mapping. The mean VT cycle length was 429 ± 96 milliseconds. The site of origin was epicardial in 16% (3/18) of VTs. Most clinical VTs were hemodynamically stable (75%). Mean ejection fraction at the time of admission was 44 ± 14%. Duration of procedure was 289 ± 50 minutes. One subject developed pericardial tamponade requiring drainage. At 18 ± 11 months follow-up, freedom from arrhythmia was seen in 86% (1 case lost to follow-up and 2 died). Conclusion Radiofrequency ablation is not only feasible but also safe and effective in patients who have drug refractory VT related to chronic cocaine use. [ABSTRACT FROM AUTHOR]

Background: The Medtronic Sprint Fidelis (Medtronic Inc., Minneapolis, MN, USA) lead family is associated with an unacceptable incidence of premature lead failure. There are limited data on risk factors for lead fracture. We hypothesized that factors leading to potential increased forces on the lead related to device implantation or technique may be associated with premature lead failure. Methods: We reviewed the implant data from our group and identified 176 patients who received active fixation Medtronic Fidelis (Model 6931, single coil and Model 6949, dual coil) leads. Implant data, including age, sex, venous access site, implant side, implant location, and number of venous leads were reviewed. Hospital, pacemaker clinic, and Medtronic registration databases were reviewed for evidence of lead failure, replacement, or abandonment. Data was evaluated in univariate and multivariate regression analyses. Results: Of the 176 leads implanted, 10 (5.7%) were noted to develop malfunction. This presented as inappropriate shocks from sensed noise or elevated impedance measurements. Of the above noted implant features, only right-sided (vs left-sided) implant (hazard ratio [HR] 18.8, 95% confidence intervals [CI] 3.8, 93.3), and subpectoral implant (vs prepectoral; HR 14.31, 95% CI 3.2, 64.0) were predictive of lead failure in maximally adjusted models. Conclusions: We have identified both right-sided implantation and subpectoral generator positioning as factors associated with premature lead malfunction in Fidelis active fixation leads. Clinical decisions regarding patient management should incorporate these findings in regard to lead replacement in high-risk patients. (PACE 2012; 35:659-664) [ABSTRACT FROM AUTHOR]

. Transmural lesions are essential for efficacious ablation. There are, however, no accurate means to estimate lesion depth. Explore use of the electrical coupling index (ECI) from the EnSite Contact™ System as a potential variable for lesion depth estimation. Radiofrequency (RF) ablation lesions were created in atria and the thighs of swine using an irrigated RF catheter. Power was 30 W for 20 or 30 seconds intracardiac and 30-50 W for 10-60 seconds for the thigh. Intracardiac, the percentage change in ECI during ablation was compared with transmurality and collateral damage occurrence. For the thigh model, an algorithm estimating lesion depth was derived. Factors included: power, duration, and change in the ECI subcomponents (ΔECI+) during ablation. The ΔECI+ algorithm was compared to one using power and duration (PD) alone. Intracardiac, lesions with ≥12% reduction in ECI were more likely to be transmural (92.3% vs. 59.4%, P < 0.001). Twenty-second lesions were less likely to cause collateral damage compared to 30 seconds (33% vs. 70%, P = 0.003), while transmurality was similar. With the thigh model, ΔECI+ had a better correlation than the PD algorithm (P < 0.01). Accuracy of the ΔECI+ algorithm was unimproved with inclusion of tip orientation, while PD improved (R= 0.64). Change in ECI provides evidence of transmural versus nontransmural swine intracardiac atrial lesions. A lesion depth estimation algorithm using ECI subcomponents is unaffected by tip orientation and is more accurate than using PD alone. Use of ECI as a factor in a lesion depth algorithm may provide clinically valuable information regarding the efficacy of intracardiac RF ablation lesions. (J Cardiovasc Electrophysiol, Vol. 22, pp. 684-690, June 2011) [ABSTRACT FROM AUTHOR]

There are little data on the appropriate endpoint for slow pathway ablation that balances acceptable procedural times, recurrence rates, and complication rates. This study compared recurrence rates of three commonly utilized endpoints of slow pathway ablation for atrioventricular nodal reentrant tachycardia (AVNRT). We performed a meta-analysis of AVNRT slow pathway ablation cohorts by searching electronic databases, the Internet, and conference proceedings. Inclusion criteria were age >18 years, >20 human subjects per study, primary AVNRT ablation, English language publication, and >1 month of follow-up. Data were analyzed with a fixed-effects model using Comprehensive Meta-Analysis software version 2.2.046 (Biostat, Englewood, NJ, USA). We included 10 studies encompassing 1,204 patients with a mean age of 41-53 years. Endpoints were complete slow pathway ablation, residual jump only, and single remaining echo beat. Pooled estimates revealed 28 of 641 patients (4.4%) with complete slow pathway ablation, 13 of 192 patients (6.8%) with a residual jump only, and 24 of 371 patients (6.5%) with one echo had recurrences. With uniform isoproterenol use after ablation, there was no significant difference in recurrence rates among the endpoints. However, when isoproterenol was utilized after ablation only if needed to induce AVNRT before ablation, a significantly higher recurrence rate occurred in patients with a residual jump (P = 0.002), a single echo (P = 0.003), or the combined group of a residual jump and/or one echo (P = 0.001). Isoproterenol should be used routinely after slow pathway modification, when a residual jump and/or single echo remain. (PACE 2011; 34:269-277) [ABSTRACT FROM AUTHOR]

Background: Typical atrial flutter (AFL) is a macroreentrant arrhythmia characterized by a counterclockwise circuit that passes through the cavotricuspid isthmus with passive depolarization of the left atrium. These electrical events are thought to be responsible for the classic "sawtooth" wave of atrial flutter seen on the surface electrocardiogram characterized by a gradual downward deflection followed by a sharp negative deflection. It has been suggested that the negative flutter wave is a result of passive depolarization of the left atrium. We hypothesized that interruption of the circuit within the isthmus would prevent the reentrant wave from depolarizing the left atrium thus eliminating the component of the electrocardiogram reflecting left atrial depolarization.Methods: We examined 100 cases of atrial flutter with the typical "sawtooth" pattern referred for radiofrequency ablation. Ninety-seven of the 100 were successfully ablated. All cases were reviewed for termination of atrial flutter with the last intracardiac electrogram just lateral to the site of linear ablation and surface flutter wave at the moment of termination not obscured by the QRS segment or the T-wave. Seventeen of the 97 met these criteria.Results: Seventeen of the 17 cases demonstrated a gradual negative deflection as the last discernible wave of atrial activity followed by an isoelectric period and resumption of normal sinus rhythm. The last generated wave lacked the sharp negative downstroke.Conclusion: These results suggest that the sharp negative deflection of flutter waves likely correlates with the wavefront's penetration of the interatrial septum and passive depolarization of the left atrium. [ABSTRACT FROM AUTHOR]