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Background: Several studies have demonstrated that females have a higher risk of arrhythmia recurrence after pulmonary vein (PV) isolation for atrial fibrillation (AF). There are limited data on sex‐based differences in PV reconnection rates at repeat ablation. We aimed to investigate sex‐based differences in electrophysiological findings and atrial arrhythmia recurrence after repeat AF ablation Methods: We conducted a retrospective study of 161 consecutive patients (32% female, age 65 ± 10 years) who underwent repeat AF ablation after index PV isolation between 2010 and 2022. Demographics, procedural characteristics and follow‐up data were collected. Recurrent atrial tachycardia (AT)/AF was defined as any atrial arrhythmia ≥30 s in duration. Results: Compared to males, females tended to be older and had a significantly higher prevalence of prior valve surgery (10 vs. 2%; P =.03). At repeat ablation, PV reconnection was found in 119 (74%) patients. Males were more likely to have PV reconnection at repeat ablation compared to females (81 vs. 59%; P =.004). Excluding repeat PV isolation, there were no significant differences in adjunctive ablation strategies performed at repeat ablation between females and males. During follow‐up, there were no significant differences in freedom from AT/AF recurrence between females and males after repeat ablation (63 vs. 59% at 2 years, respectively; P =.48). Conclusions: After initial PV isolation, significantly fewer females have evidence of PV reconnection at the time of repeat ablation for recurrent AF. Despite this difference, long‐term freedom from AT/AF was similar between females and males after repeat ablation. [ABSTRACT FROM AUTHOR]

Etripamil, a fast‐acting nondihydropyridine L‐type calcium channel blocker, is under investigation for potential self‐administration for the acute treatment of supraventricular tachyarrhythmias in a medically unsupervised setting. We report detailed pharmacokinetics and pharmacodynamics of intranasally administered etripamil in healthy adults from 2 Phase 1, randomized, double‐blind studies: Study MSP‐2017‐1096 (sequential dose‐escalation, crossover study design, n = 64) and NODE‐102 (single dose, 4‐way crossover study, n = 24). Validated bioanalytical assays determined plasma concentrations of etripamil and its inactive metabolite. Noncompartmental pharmacokinetic parameters were calculated. Pharmacodynamic parameters were determined for PR interval, blood pressure, and heart rate. Etripamil was rapidly absorbed intranasally, with time to maximal plasma concentration of 5‐8.5 minutes, corresponding to a rapid greater than 10% increase in mean maximum PR interval from baseline within 4‐7 minutes of doses of 60 mg or greater. Following peak plasma concentrations, systemic etripamil levels declined rapidly within the first 15 minutes following dosing and decreased more gradually thereafter. PR interval prolongation greater than 10% from baseline was generally sustained for about 45 minutes at doses of 60 mg or greater. The mean terminal half‐life ranged from about 1.5 hours with 60 mg to about 2.5‐3 hours for the 70‐ and 105‐mg doses. Etripamil was generally well tolerated without symptomatic hypotension. Adverse events were primarily mild to moderate and related to the administration site; no serious adverse events or episodes of atrioventricular block occurred. Intranasal etripamil administration, at doses of 60 mg or greater, produced rapidly occurring slowing of atrioventricular nodal conduction with a limited duration of effect without hemodynamic or electrocardiographic safety signals in healthy volunteers. [ABSTRACT FROM AUTHOR]

Paroxysmal supraventricular tachycardia (PSVT) is commonly seen in clinical practice and represents a significant burden to the healthcare system and to patients. First-line treatments include calcium channel blockers (CCB), although they are intravenous and require medical supervision. Etripamil is an investigational self-administered intranasal L-type CCB for unsupervised treatment of PSVT. In this podcast, we discuss the RAPID trial (NCT03464019), which was a phase 3 study that evaluated the safety and efficacy of etripamil in terminating PSVT episodes using a repeat-dosing regimen. RAPID was a multicenter, randomized trial that enrolled adults with electrocardiograph (ECG)-documented PSVT episodes lasting ≥ 20 min. Patients who tolerated test doses of etripamil were randomized 1:1 to receive either etripamil or placebo. Upon perceiving PSVT symptoms, patients began ECG monitoring and performed a vagal maneuver. If arrhythmia termination was unsuccessful, they self-administered 70 mg of etripamil or placebo, followed by an optional second dose after 10 min. The primary endpoint was time to conversion of PSVT to sinus rhythm within 30 min of the initial dose and sustained for ≥ 30 s. The safety group included all patients who self-administered the study treatment. Of 692 enrollees, 184 self-administered the study drug (99 etripamil, 85 placebo) for ECG-confirmed PSVT. Conversion of PSVT to sinus rhythm within 30 min was achieved in 64.3% of etripamil-treated subjects versus 31.2% of placebo-treated subjects. A significant threefold reduction in the median time to conversion of 17.2 min was observed in the etripamil group versus 53.5 min in the placebo group. Treatment-emergent adverse events were mild or moderate and primarily included transient nasal discomfort, nasal congestion, and rhinorrhea. If etripamil is approved by the US FDA, it can potentially address a significant unmet need for PSVT treatment outside a clinical setting, reducing the need for intravenous treatments that require medical supervision. Podcast available for this article. 1VEqT_HzS7TNge6AVaxeS- [ABSTRACT FROM AUTHOR]

The article describes the case of a 63-year-old woman with no previous cardiac history who developed occasional dyspnea on exertion. Topics include findings on her electrocardiogram, her worsening exertional dyspnea two years after she had complete resolution of her symptoms, and potential consequences of enabling the automatic postventricular atrial refractory period (PVARP) algorithm.

The article describes the case of a 54-year-old man who underwent dual chamber pacemaker eight years ago because of symptomatic, high-grade atrioventricular block. Topics discussed include his electrocardiogram (EEG) during a routine visit to his cardiologist seven months later and algorithms designed to promote delivery of biventricular pacing during atrial tachycardia (AT/AF) in Medtronic cardiac resynchronization therapy (CRT) devices.

Introduction: Leadless cardiac pacemakers (LCPs) are becoming more commonly utilized because of their potential advantages (i.e., reduced short and long‐term complications, improved patient comfort) and may be the preferred option for patients with venous access problems, high‐risk for infection, previous lead fractures, or skin erosion. There are currently two types of LCP fixation mechanisms that have been FDA approved—Medtronic's Micra system has a tine‐based fixation and Abbott's Aveir system has a helix‐fixation design. This article highlights important tips and tricks for a successful implant of a helix‐fixation LCP, particularly when difficulties are encountered, and provides precautions to avoid potential complications. Methods: Cases of single chamber Aveir LCP implantation were reviewed to highlight examples of procedural pitfalls and suggested methods to circumnavigate them. Results: There are unique procedural considerations regarding the Aveir LCP implant as well as challenges that that may be occasionally encountered. Techniques to address these—such as avoiding air embolism, maneuvering difficult entry into the right ventricle, handling complicated positioning/repositioning, evaluating proper fixation, and releasing difficult tethers—are illustrated in detail. Advice to reduce risks of perforation and to position optimally for potential retrieval and communication for dual chamber pacing are also described. Conclusions: The advanced teaching concepts described and emphasized in this article may help improve success and prevent procedural complications, especially when physicians are learning how implant these novel helix‐fixation LCPs. [ABSTRACT FROM AUTHOR]

Introduction: Left bundle branch area pacing (LBBP) has emerged as an alternative method for conduction system pacing. While initial experience with delivery systems for stylet‐driven and lumenless lead implantation for LBBP has been described, data comparing outcomes of stylet‐driven versus lumenless lead implantation for LBBP are limited. In this study, we compare success rates and outcomes of LBBP with stylet‐driven versus lumenless lead delivery systems. Methods: Eighty‐three consecutive patients (mean age 74.1 ± 11.2 years; 56 [68%] male) undergoing attempted LBBP at a single institution were identified. Cases were grouped by lead delivery systems used: stylet‐driven (n = 53) or lumenless (n = 30). Baseline characteristics and procedural findings were recorded and compared between the cohorts. Intermediate term follow‐up data on ventricular lead parameters were also compared. Results: Baseline characteristics were similar between groups. Successful LBBP was achieved in 77% of patients, with similar success rates between groups (76% in stylet‐driven, 80% in lumenless, p = 0.79), and rates of adjudicated LBB capture and other paced QRS parameters were also similar. Compared with the lumenless group, the stylet‐driven group had significantly shorter procedure times (90 ± 4 vs. 112 ± 31 min, p = 0.004) and fluoroscopy times (10 ± 5 vs. 15 ± 6 min, p = 0.003). Ventricular lead parameters at follow‐up were similar, and rates of procedural complications and need for lead revision were low in both groups. Conclusion: Delivery systems for stylet‐driven and for lumenless leads for LBBP have comparable acute success rates. Long‐term follow‐up of lead performance following use of the various delivery systems is warranted. [ABSTRACT FROM AUTHOR]

The author reflects on the potential long-term effects of catheter ablation as a treatment for atrioventricular nodal re-entrant tachycardia (AVNRT), which is a form of paroxysmal supraventricular tachycardia (PSVT). Also cited are the effectiveness of ablation as an alternative to chronic pharmacologic therapy in treating AVNRT, and how to minimize the risk of acute atrioventricular block (AVB) during AVNRT ablation.

Introduction: Cardiac implantable electronic device (CIED) pocket related problems such as infection, hematoma, and device erosion cause significant morbidity and the clinical consequences are substantial. Bioabsorbable materials have been developed to assist in the prevention of these complications but there has not been any direct comparison of these adjunctive devices to reduce these complications. We sought to directly compare the TYRX absorbable antibacterial and CanGaroo extracellular matrix (ECM) envelopes in an animal model susceptible to these specific CIED‐related complications (i.e., skin erosion and infection). Methods and Results: Sixteen mice undergoing implantation with biopotential transmitters were divided into three groups (no envelope = 4, TYRX = 5, and CanGaroo = 7) and monitored for device‐related complications. Following 12 weeks of implantation, gross and histological analysis of the remaining capsules was performed. Three animals in the CanGaroo group (43%) had device erosion compared to none in the TYRX group. The remaining capsules excised at 12 weeks were qualitatively thicker following CanGaroo compared to TYRX and no envelope and histological evaluation demonstrated increased connective tissue with CanGaroo. Conclusion: CanGaroo ECM envelopes did not reduce the incidence of device erosion and were associated with qualitatively thicker capsules and connective tissue staining at 12 weeks compared to no envelope or TYRX. Further studies regarding the use of these envelopes to prevent device erosion and their subsequent impact on capsule formation are warranted. [ABSTRACT FROM AUTHOR]

The article describes the case of a 58-year-old man with a history of pancreatic cancer status post-Whipple surgery and chemotherapy, noischemic cardiomyopathy, bacteremia, and deep vein thrombosis who underwent subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation for primary prevention of sudden cardiac death. Topics include findings on a posteroanterior (PA) and lateral chest X-ray and steps in evaluating and managing elevated S-ICD defibrillation threshold.

Introduction: The impact of atrial arrhythmias on coronavirus disease 2019 (COVID‐19)‐associated outcomes are unclear. We sought to identify prevalence, risk factors and outcomes associated with atrial arrhythmias among patients hospitalized with COVID‐19. Methods: An observational cohort study of 1053 patients with severe acute respiratory syndrome coronavirus 2 infection admitted to a quaternary care hospital and a community hospital was conducted. Data from electrocardiographic and telemetry were collected to identify atrial fibrillation (AF) or atrial flutter/tachycardia (AFL). The association between atrial arrhythmias and 30‐day mortality was assessed with multivariable analysis. Results: Mean age of patients was 62 ± 17 years and 62% were men. Atrial arrhythmias were identified in 166 (15.8%) patients, with AF in 154 (14.6%) patients and AFL in 40 (3.8%) patients. Newly detected atrial arrhythmias occurred in 101 (9.6%) patients. Age, male sex, prior AF, renal disease, and hypoxia on presentation were independently associated with AF/AFL occurrence. Compared with patients without AF/AFL, patients with AF/AFL had significantly higher levels of troponin, B‐type natriuretic peptide, C‐reactive protein, ferritin and d‐dimer. Mortality was significantly higher among patients with AF/AFL (39.2%) compared to patients without (13.4%; p <.001). After adjustment for age and co‐morbidities, AF/AFL (adjusted odds ratio [OR]: 1.93; p =.007) and newly detected AF/AFL (adjusted OR: 2.87; p <.001) were independently associated with 30‐day mortality. Conclusion: Atrial arrhythmias are common among patients hospitalized with COVID‐19. The presence of AF/AFL tracked with markers of inflammation and cardiac injury. Atrial arrhythmias were independently associated with increased mortality. [ABSTRACT FROM AUTHOR]

Introduction: The real‐world distribution of hospital atrial fibrillation (AF) ablation volume and its impact on outcomes are not well‐established. We sought to examine patient characteristics, complications, and readmissions after AF ablation stratified by hospital procedural volume. Methods and Results: Using the nationally representative inpatient Nationwide Readmissions Database, we evaluated 54 597 admissions for AF ablation between 2010 and 2014. Hospitals were categorized according to tertiles of annual AF ablation volume. Index complications, 30‐day readmissions, and early mortality were examined. Multivariable logistic regression was performed to assess the predictors of adverse outcomes. Between 2010 and 2014, low volume tertile hospitals accounted for 79.3% of hospitals performing AF ablations. When stratified by first, second, and third volume tertiles, complication and early mortality rates were higher in low volume centers (8.9% and 0.67% vs 6.1% and 0.33%, vs 4.5% and 0.16%, respectively; P <.001). Patients undergoing AF ablation at low volume centers were older and had a higher prevalence of congestive heart failure, coronary artery disease, and other comorbidities. Low volume hospitals were associated with increased cardiac perforation (adjusted odds ratio [aOR], 4.79; P <.001), vascular complications (aOR 1.49; P <.001), and any complication (aOR 2.06; P <.001) during index admission as well as increased early mortality (aOR 2.43; P =.039). Conclusions: Among patients hospitalized for AF ablation, low inpatient AF ablation hospital volume was associated with worse outcomes following ablation, which was exacerbated by a greater comorbidity burden among patients at these centers. [ABSTRACT FROM AUTHOR]

Robotic technology has emerged as an important tool to facilitate catheter ablation of arrhythmias. Robotic cardiac electrophysiology technology includes remote magnetic navigation and manual robotic navigation. Robotics can confer advantages with respect to ease of catheter manipulation in anatomically challenging spaces, minimization of fluoroscopic exposure to both patients and operators, and reduction in operator fatigue. This review provides a comprehensive summary of robotic electrophysiology technology, its practical applications and its safety and efficacy for targeting cardiac arrhythmias. [ABSTRACT FROM AUTHOR]

Introduction: The role of focal impulse and rotor modulation (FIRM)‐guided ablation for the treatment of atrial fibrillation (AF) remains unclear. Previous studies on the FIRM‐guided ablation outcomes have been limited by a focus on AF termination as an endpoint and by patient population heterogeneity. We sought to determine differences in rates of AF termination, inducibility, and recurrence in patients with persistent AF undergoing first‐time ablation with a FIRM‐guided approach compared with patients undergoing conventional ablation. Methods and Results: Eight‐five consecutive patients (38 FIRM, 47 conventional) with persistent AF undergoing first‐time ablation were retrospectively analyzed. There were no significant differences in the rates of AF termination in the FIRM group compared to the conventional group (26% vs 15%; P = .15). Rates of inducible AF after ablation were 37% in the FIRM group and 30% in the conventional group (P = .32). Over a median follow‐up of 2.4 years, the rates of freedom from AF were similar between the FIRM and conventional groups (1‐year freedom from AF 65% vs 50%, respectively; P = .18). Procedural termination of AF with either FIRM ablation or conventional ablation was not associated with any significant reduction in AF recurrence. Conclusion: A FIRM‐guided approach was not associated with a significant difference in freedom from AF when compared to conventional ablation. Termination of AF with ablation was not associated with increased freedom from AF. While AF termination using substrate‐based ablation may have mechanistic implications for understanding AF rotor physiology, its impact on clinical outcomes remains unclear. [ABSTRACT FROM AUTHOR]

Left atrial tachycardias (ATs) most commonly occur after catheter or surgical ablation of atrial fibrillation and in patients with atrial myopathies. Pre‐existing scar in the left atrium (LA) can result in complex circuits, sometimes with narrow channels that can be detected with high‐resolution mapping. The most common forms of macroreentrant AT from the LA are variants of peri‐mitral and roof‐dependent reentry. Localized reentrant rhythms occur in the setting of fibrosis that gives rise to slow conduction and may occur adjacent to areas of prior ablation. The approach to treating these ATs involves first identifying the left atrial origin, defining the tachycardia circuit – which can be facilitated by ultrahigh density mapping and entrainment – and selecting a suitable isthmus to target for ablation. An important endpoint in ablating left atrial flutters is to establish and confirm bidirectional line of the block. Challenges in ablating these ATs include the presence of multiple tachycardias, defining circuits with complex activation patterns and achieving durable lines of block, particularly in the lateral mitral isthmus. Progress in treating these arrhythmias has come from new mapping technologies and the recognition of epicardial connections that allow for persistent conduction across ablation lesions. Also, advances in delivering energy to obtain complete transmural lesions promise to improve the long‐term success of ablating ATs from the LA. [ABSTRACT FROM AUTHOR]

This is a plain language summary of a clinical research study called RAPID. The study looked at the potential for how safe and effective etripamil was at stopping an episode of rapid heartbeats in people with atrioventricularnodal-dependent supraventricular tachycardia (AV-node-dependent SVT). An episode is used to describe the period of time when a person experiences an abnormally very fast heartbeat. This was done by comparing an investigational drug called etripamil with a placebo, each administered via a rapidly acting nasal spray. AV-node-dependent SVT affects the rhythm of the heart, causing it to suddenly beat rapidly. The condition often requires medical treatment to help return the heart to its normal, healthy heartbeat pattern and speed, called 'sinus rhythm'. Researchers are looking at ways of improving the management of supraventricular tachycardias (SVT) by reducing the need for patients to attend an urgent care clinic, emergency ward or hospital for treatment. In the RAPID study, participants used a nasal spray containing either 70 mg etripamil or a placebo solution when they experienced an episode of SVT. The researchers wanted to know how long it took for each participant's rapid heartbeat to return to sinus rhythm after administering the etripamil or placebo nasal spray. Participants in the study were considered successfully treated if their heartbeats returned to sinus rhythm for at least 30 seconds within 30 minutes of using the nasal spray. Although 30 seconds may seem brief, it's medically important because it shows that a person's heartbeat has been temporarily stabilized and returned to normal functioning. Out of 99 people who used etripamil during an SVT episode, 63 participants (64%) experienced a return to sinus rhythm for at least 30 seconds within 30 minutes after using the nasal spray. In contrast, 26 out of 85 participants (31%) who used the placebo nasal spray experienced a return to sinus rhythm for at least 30 seconds within 30 minutes after use. Furthermore, the average time taken for the return to sinus rhythm was 17 minutes for the etripamil group which was 3-times faster than the placebo group at 53 minutes. Also, in the study no serious side effects occurred that were related to etripamil. The RAPID study supports the potential that etripamil may be safe and well tolerated by participants as a treatment for episodes of rapid heartbeat in people with AV-node-dependent SVT. The results also showed a significant improvement in symptoms following treatment with etripamil. [ABSTRACT FROM AUTHOR]

Background: Ablation of atrial tachycardia (AT) that occurs after cardiac surgery or prior ablation often requires complex lesion sets. In combination with the pre‐existing atrial scar, these lesion sets may result in inadvertent intra‐atrial conduction block. This study reports the phenomenon of incidental isolation of right atrial (RA) regions that occurs secondary to AT ablation, which in some cases results in profound bradycardia due to sinus exit block. Methods and Results: Intracardiac electrograms were examined in consecutive patients who underwent AT ablation in the RA. Cases of localized isolation of the RA were defined as areas that developed electrical dissociation during ablation. Of 132 patients having ablation in both the RA free wall and the cavotricuspid isthmus (CTI), 10 (7.6%) developed unintentional isolation of the lateral RA. Five of these patients had prior mitral valve surgery, comprising 12.2% of all 41 patients with mitral surgery who underwent ablation in the CTI and the RA free wall. All patients with regional isolation had a pre‐existing scar in the lateral wall of the RA. In six patients, isolation of the lateral RA resulted in profound bradycardia due to exit block from the peri‐sinus node myocardium. Conclusions: Complex ablation lesions in patients with prior valve surgery, prior ablation, or atrial myopathy may result in unintended localized conduction block in the RA. In some cases, isolation of the lateral RA can result in complete sinus exit block with profound bradycardia requiring pacemaker implantation. [ABSTRACT FROM AUTHOR]

Aims Although catheter ablation has emerged as an important therapy for patients with symptomatic atrial fibrillation (AF), there are limited data on sex-based differences in outcomes. We sought to compare in-hospital outcomes and 30-day readmissions of women and men undergoing AF ablation. Methods and results Using the United States Nationwide Readmissions Database, we analysed patients undergoing AF ablation between 2010 and 2014. Based on ICD-9-CM codes, we identified co-morbidities and outcomes. Multivariable logistic regression and inverse probability-weighting analysis were performed to assess female sex as a predictor of endpoints. Of 54 597 study patients, 20 623 (37.7%) were female. After adjustment for age, co-morbidities, and hospital factors, women had higher rates of any complication [adjusted odds ratio (aOR) 1.39; P  < 0.0001], cardiac perforation (aOR 1.39; P  = 0.006), and bleeding/vascular complications (aOR 1.49; P  < 0.0001). Thirty-day all-cause readmission rates were higher for women compared to men (13.4% vs. 9.4%; P  < 0.0001). Female sex was independently associated with readmission for AF/atrial tachycardia (aOR 1.48; P  < 0.0001), cardiac causes (aOR 1.40; P  < 0.0001), and all causes (aOR 1.25; P  < 0.0001). Similar findings were confirmed with inverse probability-weighting analysis. Despite increased complications and readmissions, total costs for AF ablation were lower for women than men due to decreased resource utilization. Conclusions Independent of age, co-morbidities, and hospital factors, women have higher rates of complications and readmissions following AF ablation. Sex-based differences and disparities in the management of AF need to be explored to address these gaps in outcomes. Open in new tab Download slide Open in new tab Download slide [ABSTRACT FROM AUTHOR]

The EMBLEM subcutaneous implantable cardioverter defibrillator (S‐ICD) has an expected longevity of 7 years. In August 2019, Boston Scientific released an advisory regarding a limited subset of ~400 S‐ICDs that exhibited an increased likelihood of an electrical component malfunction causing accelerated battery depletion. We observed several cases of nonadvisory S‐ICD early battery depletion and sought to systematically evaluate the cohort of EMBLEM devices implanted and followed in our medical center. Out of 118 nonadvisory EMBLEM S‐ICDs with a median time to most recent follow‐up after implant of 735 days (interquartile range 375–1219 days), there were four premature battery failures identified. Serial device interrogations showed a sudden reduction in battery life at 1 195, 1 205, 1 300, and 678 days after implant. The number of shocks delivered during the lifetime of the devices did not explain the premature depletion. There was a sudden departure from the gradual linear decrease in battery longevity observed over time. We are the first to report a signal of premature battery depletion among S‐ICD EMBLEM devices that were not among the initial advisory devices. The prevalence of premature battery failure in our cohort was 3.4%, occurring at an average of 1 095 days. Following these reports, Boston Scientific issued an advisory on EMBLEM devices in December 2020 extending beyond the initial advisory subset. The current projected occurrence rate for hydrogen‐induced accelerated battery depletion is 3.7% at 5 years. Increased surveillance of this potential device issue and mitigation to identify patients at risk for this is warranted. [ABSTRACT FROM AUTHOR]

The development of pacing and defibrillator systems that do not involve hardware traversing the tricuspid annulus can be desirable in order to minimize lead‐related complications such as tricuspid regurgitation. Occasionally, primary tricuspid valve pathology (ie, infectious endocarditis, nonbacterial thrombotic endocarditis, and carcinoid disease) or congenital heart disease prohibits use of transvenous leads and alternative strategies are required to provide pacing or defibrillation. We describe such a case in which a biventricular implantable cardioverter defibrillator was implanted using a hybrid system involving endocardial and epicardial components. [ABSTRACT FROM AUTHOR]

The use of insertable cardiac monitors (ICM) has been increasing because of their ability to provide long-term electrocardiographic monitoring and symptom correlation. Indications for implantation include evaluation of cryptogenic stroke, unexplained syncope, intermittent palpitations, and atrial fibrillation. When the ICM needs to be removed because of battery depletion and/or diagnostic revelation, its removal can be challenging because of its small size and the capsule that forms around the proximal end of the device. A simple technique is described that takes advantage of the ICM design to facilitate its successful extraction. [ABSTRACT FROM AUTHOR]

Purpose: Left atrial thrombus (LAT) may be detected by transesophageal echocardiography (TEE) in patients with atrial fibrillation (AF) or flutter (AFL) despite continuous anticoagulation therapy. We sought to examine the rates and timing of LAT resolution in response to changes in anticoagulation regimen.Methods: A retrospective study of 1517 consecutive patients on ≥ 4 weeks continuous oral anticoagulation (OAC) undergoing TEE prior to either direct current cardioversion or catheter ablation for AF or AFL was performed. Patients who had LAT on index TEE imaging and had follow-up TEEs were analyzed.Results: Despite ≥ 4 weeks of continuous anticoagulation therapy, 63 (4.2%) patients had LAT. Forty-four patients (median age 67 [IQR 58, 74]; 33 [75%] male; 25 [57%] on direct oral anticoagulant [DOAC]) had follow-up TEEs performed. Upon detection of LAT on index TEE, 8 patients switched from warfarin to a DOAC, 21 patients switched from a DOAC to warfarin or another DOAC, and 15 patients remained on the same OAC. Over median 4.2 months (IQR 2.9, 6.6), LAT resolution was seen in 25 (57%) patients. Of the 25 patients who had LAT resolution, 7 (28%) required TEE imaging > 6 months after index TEE to show clearance of thrombus. Rates of LAT resolution were similar between patients who had alterations in OAC and those who did not (52 vs. 60%; P = 0.601).Conclusions: After initial detection of left atrial thrombus despite uninterrupted anticoagulation for atrial fibrillation or flutter, > 40% patients have persistent clot despite additional extended anticoagulation. [ABSTRACT FROM AUTHOR]

Abstract: Idiopathic sustained focal right ventricular tachycardia (VT) is most frequently due to outflow tract (OT) tachycardia. This arrhythmia is recognized by its characteristic ECG pattern and sensitivity to adenosine. However, there are other forms of idiopathic, focal sustained VT that originate from the right ventricle (RV), which are less well appreciated and easily overlooked. This review will identify the characteristic features and electrophysiologic properties of these forms of RV VT, including those originating from the tricuspid annulus, right ventricular papillary muscles, and moderator band as well as variants of classic RVOT tachycardia and those due to microreentry in the presence of preclinical disease. Recognition of these subtypes of focal RV tachycardia should facilitate targeted therapy. [ABSTRACT FROM AUTHOR]

Aims: Due to the complex anatomy of the left ventricular (LV) and right ventricular (RV) papillary muscles (PMs), PM ventricular arrhythmias (VAs) can be challenging to target with ablation. We sought to compare the outcomes of robotic magnetic navigation-guided (RMN) ablation and manual ablation of VAs arising from the LV and RV PMs.Methods and results: We evaluated 35 consecutive patients (mean age 65 ± 12 years, 69% male) who underwent catheter ablation of 38 VAs originating from the LV and RV PMs as confirmed by intracardiac echocardiography. Catheter ablation was initially performed using RMN-guidance in 24 (69%) patients and manual guidance in 11 (31%) patients. Demographic and procedural data were recorded and compared between the two groups. The VA sites of origin were mapped to 20 (53%) anterolateral LV PMs, 14 (37%) posteromedial LV PMs, and 4 (11%) RV PMs Acute successful ablation was achieved for 20 (74%) VAs using RMN-guided ablation and 8 (73%) VAs using manual ablation (P = 1.000). Fluoroscopy times were significantly lower among patients undergoing RMN ablation compared to patients undergoing manual ablation [median 7.3, interquartile range (IQR) 3.9-18 vs. 24 (16-44) min; P = 0.005]. Retrograde transaortic approach was used in 1 (4%) RMN patients and 5 (46%) manual patients (P = 0.005). No procedural complications were seen in study patients.Conclusion: Use of an RMN-guided approach to target PM VAs results in comparable success rates seen with manual ablation but with lower fluoroscopy times and decreased use of transaortic retrograde access. [ABSTRACT FROM AUTHOR]

Pacemakermagnet application during surgery for patients who are pacemaker-dependent is often utilized to avoid perioperative inhibition from electromagnetic interference. We present a case during which such routine magnet use resulted in an unexpected response and discuss the limitations and nuances of this common practice. [ABSTRACT FROM AUTHOR]

Introduction Recovery of conduction has been demonstrated in >50% of patients who receive pacemakers (PPMs) for high-degree atrioventricular block (HD-AVB) after transcatheter aortic valve replacement (TAVR). Little information is available about the time course of conduction recovery in these patients and if any features predict early recovery of conduction. Methods A retrospective review was performed of patients who underwent TAVR with balloon and self-expanding valves who required PPMs for HD-AVB. Serial PPM interrogations were analyzed to detect recovery of AV conduction. Analysis was performed to identify predictors and timing of conduction recovery. Results Of a total population of 578 patients, 54 (9%) received PPMs for HD-AVB. In multivariate analysis, predictors of HD-AVB requiring a PPM included age (P = 0.014), right bundle branch block (OR 7.33 [3.64-14.8], P < 0.0001), atrial fibrillation (OR 2.16 [1.16-4.05], P = 0.016), and self-expanding valves (OR 4.19 [2.20-7.97], P < 0.0001). Of the 54 patients who received PPMs, 38 had follow-up sufficient to evaluate AV conduction recovery. Of these, 23 (61%) showed recovery of AV nodal conduction; 20 had already recovered by their first interrogation, a median of 22 days (IQR 14-31) post-PPM placement. There were no statistically significant predictors of AV nodal conduction recovery, including type of valve implanted. Conclusions A majority of patients who receive PPMs for HD-AVB after TAVR recover AV conduction during follow­up, and in most patients conduction recovery occurs within weeks. These findings imply that programming to minimize ventricular pacing may be beneficial in a majority of these patients. [ABSTRACT FROM AUTHOR]

S-ICD Candidacy Among Ventricularly Paced Patients Introduction The subcutaneous implantable cardioverter defibrillator (ICD) has emerged as a viable therapeutic option for patients who are deemed high risk for sudden cardiac death. Previous studies have shown that 7-15% of patients are not candidates for the S-ICD based on their intrinsic QRS/T-wave morphology. Presently, it is not known if the S-ICD can be considered as supplementary therapy in patients who are ventricularly paced. We sought to determine the proportion of ventricularly paced patients who would qualify for an S-ICD. Methods and Results We evaluated 100 patients with transvenous pacemakers/ICDs, including 25 biventricular devices to determine S-ICD candidacy during right ventricular (RV) pacing and biventricular pacing based on the recommended QRS:T-wave ratio screening template. Fifty-eight percent of patients qualified for an S-ICD based on their QRS morphology during ventricular pacing. More patients during biventricular pacing met criteria compared to during RV pacing alone (80% vs. 46%, P <0.01). Patients that were paced from the RV septum were more likely to qualify compared to those paced from the RV apex (67% vs. 37%, respectively, P <0.01). Conclusion While S-ICD implantation may be considered as supplemental therapy in select patients with preexisting transvenous devices, relatively fewer candidates who are paced from the RV apex qualify. QRS morphologies generated from biventricular pacing as well as from septal RV pacing are more likely to screen in based on the recommended S-ICD template. [ABSTRACT FROM AUTHOR]

There are no established methods for subcutaneous implantable cardioverter‐defibrillator (S‐ICD) extraction other than simple manual traction for devices with short dwell time. However, as more chronic indwelling S‐ICDs need removal for various reasons, understanding the S‐ICD lead design and methods for its removal are essential. A case of a chronic indwelling S‐ICD extraction is described, and a technique utilizing a modified mechanical polypropylene sheath to safely remove the lead is outlined in detail. [ABSTRACT FROM AUTHOR]

In some elderly patients with atrial fibrillation, especially in combination with heart failure, a rate control strategy may be preferred. When pharmacological therapy is ineffective or not tolerated, it is reasonable to perform atrioventricular (AV) node ablation with ventricular pacing. We describe a case in which this approach was necessary for management. However, the presence of periprocedural, drug-induced AV block just before ablation provided a unique and challenging circumstance. We discuss the steps taken to ensure a successful procedure. [ABSTRACT FROM AUTHOR]

The article describes the case of a-70-year old woman with nonischemic cardiomyopathy and left bundle branch block (LBBB) with biventricular implantable cardioverter/defibrillator implanted five years earlier. Her suboptimal percentage of biventricular pacing needed investigation despite improvement in ventricular function with cardiac resynchronization therapy. When T-wave oversensing (TWO) is suspected, changing generator with different signal filtering may reportedly be a potential solution.

A case study is presented of a 32-year-old man with coincident proximal and distal retrograde left atrial activation. Topics discussed include use of ablation for blocking activation and ventriculoatrial dissociation; sequence of coronary sinus activation after ablation; and aborization at the atrial insertion site.

Background Adenosine (ADO) can uncover dormant conduction following pulmonary vein (PV) isolation. We sought to identify the value of dormant conduction for predicting atrial fibrillation (AF) recurrence and chronic PV reconnection. Methods One hundred fifty-two patients (80 male; age 60 ± 11 years) undergoing PV isolation for AF were studied. After PV isolation, sites of ADO-induced PV reconnection were recorded and targeted with additional ablation. In patients undergoing repeat ablation for recurrent AF, chronic PV reconnection was assessed. Results Forty-five (30%) patients had ADO-induced PV reconnection following PV isolation. Dormant conduction was successfully eliminated with additional ablation in 41 (91%) of these patients. After follow-up of 598 ± 270 days, 60 (39%) patients had recurrent AF. Dormant PV conduction was not a significant predictor of AF recurrence (hazard ratio 1.51; 95% confidence interval: 0.89-2.56; P = 0.12) although three of four (75%) patients with residual dormant conduction following initial ablation developed recurrent AF. Twenty-six patients with recurrent AF underwent repeat ablation with 52 of 99 (53%) PVs found to have chronic reconnection. Nine of 11 (82%) PVs with dormant conduction and 43 of 88 (49%) PVs without dormant conduction at initial procedure had chronic reconnection at repeat ablation. Conclusions When additional ablation is performed to eliminate ADO-induced PV reconnection after PV isolation, dormant conduction is not a significant predictor of recurrent AF. Although PVs with dormant conduction at initial procedure may develop chronic reconnection, the majority of PVs that show conduction recovery at repeat ablation occur in nondormant PVs. [ABSTRACT FROM AUTHOR]

Introduction: Because of prognostic and therapeutic implications, the distinction between idiopathic right ventricular (RV) outflow tract (iRVOT) and arrhythmogenic RV cardiomyopathy (ARVC) is clinically important. Over the last 2 decades multiple reports have identified RV abnormalities using CMR in patients with idiopathic VT, suggesting a link between these arrhythmias and ARVC. The purpose of this study was to assess for structural abnormalities in patients with iRVOT tachycardia using contemporary cardiac magnetic resonance (CMR) imaging. Methods and Results:CMRwas performed in 46 patients with iRVOTtachycardia and 16 normal controls, with quantitative evaluation of RV and left ventricular volumes and function, as well as assessment of myocardial fat and scar. iRVOT patients were similar to controls with respect to RV end-diastolic volumes (81 ± 19 mL/m2 vs. 79 ± 18 mL/m2, P = 0.77) and RV ejection fraction (57 ± 8% vs. 59 ± 7%, P = 0.31). The prevalence of RV chamber dilation, defined using ARVC major task force criteria, was uncommon among iRVOT patients (9%) and controls (7%; P = 1.0). Regional RV wall motion abnormalities were present in 2 iRVOT patients who had concomitant RV dilation or dysfunction. CMR tissue characterization demonstrated absence of both myocardial scar and fat infiltration in all patients and controls. Conclusions: In patients with the clinical diagnosis of iRVOT tachycardia, CMR reveals RV structure, function, and myocardial tissue characteristics similar to normal controls. These findings suggest that the vast majority of patients with RVOT arrhythmias have a primary electrical disorder that is not a forme-fruste of ARVC. [ABSTRACT FROM AUTHOR]

Introduction: There is no universally accepted method by which to diagnose clinical ventricular tachycardia (VT) due to cAMP-mediated triggered activity. Based on cellular and clinical data, adenosine termination of VT is thought to be consistent with a diagnosis of triggered activity. However, a major gap in evidence mitigates the validity of this proposal, namely, defining the specificity of adenosine response in well-delineated reentrant VT circuits. To this end, we systematically studied the effects of adenosine in a model of canine reentrant VT and in human reentrant VT, confirmed by 3-dimensional, pace- and substrate mapping. Methods and Results: Adenosine (12 mg [IQR 12-24]) failed to terminate VT in 31 of 31 patients with reentrant VT due to structural heart disease, and had no effect on VT cycle length (age, 67 years [IQR 53-74]); ejection fraction, 35% [IQR 20-55]). In contrast, adenosine terminated VT in 45 of 50 (90%) patients with sustained focal right or left outflow tract tachycardia. The sensitivity of adenosine for identifying VT due to triggered activity was 90% (95% CI, 0.78-0.97) and its specificity was 100% (95% CI, 0.89-1.0). Additionally, reentrant circuits were mapped in the epicardial border zone of 4-day-old infarcts in mongrel dogs. Adenosine (300-400 μg/kg) did not terminate sustained VT or have any effect on VT cycle length. Conclusion: These data support the concept that adenosine's effects on ventricular myocardium are mechanism specific, such that termination of VT in response to adenosine is diagnostic of cAMP-mediated triggered activity. [ABSTRACT FROM AUTHOR]

Recovery of AV Conduction After Valve Surgery Background Atrioventricular block (AVB) occurs commonly after valve surgery, and permanent pacemaker (PPM) implantation is often required. However, the rate and time course of spontaneous recovery of AV conduction in these patients is not known. The goal of this study was to define the rate and risk factors for late high-grade AVB in patients who have PPM implantation for this indication. Methods Serial PPM or defibrillator interrogation data as well as demographic and operative data were reviewed from consecutive patients who had device implantation for AVB following valve surgery. Predictors of late AVB were identified with multiple regression models, and recovery of AV conduction was determined with Kaplan-Meier analyses. Results Among 98 patients included in the analysis, 58% (57/98) had evidence of late high-grade AVB, with a mean follow-up of 3.6 years. Of the 57 patients with late AVB after PPM implantation, 44 (77%) displayed pacing dependency. In multivariate analyses, persistent AVB in the immediate postoperative period was the only variable associated with late AVB (odds ratio 5.3, 95% confidence interval [2.1, 13.5], P = 0.0006). Among patients who recovered AV conduction within 1 month of surgery, 26% developed AVB during extended follow-up. Conclusions Approximately 40% of patients who received a PPM for AVB after valve surgery displayed no evidence of high-grade AVB during serial device interrogations. However, simple baseline demographic, operative, and postoperative variables are not sufficiently robust for discriminating those patients with early postoperative AVB who will not need long-term pacing following valve surgery. [ABSTRACT FROM AUTHOR]