Search

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]

Background: Polymorphic ventricular tachycardia (PMVT) is a rare genetic disease associated with structurally normal hearts which in 8% of cases can lead to sudden cardiac death, typically exercise-induced. We previously showed a link between the RyR2-H29D mutation and a clinical phenotype of short-coupled PMVT at rest using patient-specific hiPSC-derived cardiomyocytes (hiPSC-CMs). In the present study, we evaluated the effects of clinical and experimental anti-arrhythmic drugs on the intracellular Ca2+ handling, contractile and molecular properties in PMVT hiPSC-CMs in order to model a personalized medicine approach in vitro. Methods: Previously, a blood sample from a patient carrying the RyR2-H29D mutation was collected and reprogrammed into several clones of RyR2-H29D hiPSCs, and in addition we generated an isogenic control by reverting the RyR2-H29D mutation using CRIPSR/Cas9 technology. Here, we tested 4 drugs with anti-arrhythmic properties: propranolol, verapamil, flecainide, and the Rycal S107. We performed fluorescence confocal microscopy, video-image-based analyses and biochemical analyses to investigate the impact of these drugs on the functional and molecular features of the PMVT RyR2-H29D hiPSC-CMs. Results: The voltage-dependent Ca2+ channel inhibitor verapamil did not prevent the aberrant release of sarcoplasmic reticulum (SR) Ca2+ in the RyR2-H29D hiPSC-CMs, whereas it was prevented by S107, flecainide or propranolol. Cardiac tissue comprised of RyR2-H29D hiPSC-CMs exhibited aberrant contractile properties that were largely prevented by S107, flecainide and propranolol. These 3 drugs also recovered synchronous contraction in RyR2-H29D cardiac tissue, while verapamil did not. At the biochemical level, S107 was the only drug able to restore calstabin2 binding to RyR2 as observed in the isogenic control. Conclusions: By testing 4 drugs on patient-specific PMVT hiPSC-CMs, we concluded that S107 and flecainide are the most potent molecules in terms of preventing the abnormal SR Ca2+ release and contractile properties in RyR2-H29D hiPSC-CMs, whereas the effect of propranolol is partial, and verapamil appears ineffective. In contrast with the 3 other drugs, S107 was able to prevent a major post-translational modification of RyR2-H29D mutant channels, the loss of calstabin2 binding to RyR2. Using patient-specific hiPSC and CRISPR/Cas9 technologies, we showed that S107 is the most efficient in vitro candidate for treating the short-coupled PMVT at rest. [ABSTRACT FROM AUTHOR]

Introduction: Frequent right ventricular (RV) pacing is associated with cardiomyopathy. The impact of RV pacing on left ventricular (LV) global longitudinal strain (GLS) and clinical outcomes is unclear. Methods: We analyzed GLS via two‐dimensional speckle tracking and LV ejection fraction (EF) on pre‐ and post‐implantation transthoracic echocardiograms of patients undergoing dual chamber pacemaker implantation. We collected long‐term data on strain, LVEF, and clinical outcomes. Results: One hundred and ten patients (mean age 76 ± 12 years; 59 [54%] female) were followed for mean 23 ± 17 months. Mean baseline LVEF was 58 ± 11% and mean GLS was −17 ± 4%. Twenty‐four (22%) patients had an absolute decrease in LVEF > 10% and 43 (39%) patients had a relative reduction of GLS > 15%. Among patients with a reduction of GLS, a larger proportion of patients had RV pacing burden ≥20% (67% vs. 46%; p =.048). Compared to patients without GLS reduction, more patients with a reduction in GLS reached a composite endpoint of HF hospitalization, CRT upgrade or death (47% vs. 16%; p =.001). Conclusion: Reduction in LV GLS was seen in nearly four in 10 patients undergoing pacemaker implantation and was significantly associated with increased RV pacing burden. LV GLS reduction was associated with increased risk of adverse outcomes. LV GLS may have utility in predicting outcomes among patients with RV pacing. [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]

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]

Purpose of review: In this review, we provide a practical approach to the catheter ablation of idiopathic focal ventricular arrhythmias (VAs) by summarizing the electrocardiographic (ECG) characteristics, mapping strategies, and ablation techniques for each of the major types of idiopathic VAs. We identify special considerations to be taken when treating specific forms of idiopathic VAs with catheter ablation that can increase success rates and reduce complications. Recent findings: Insights on ECG morphologies of VAs have led to novel criteria that can aid in accurate identification and localization of VA sites of origin. Advancements in mapping catheters and software as well as the use of intracardiac echocardiography have allowed for more precise mapping and ablation of arrhythmias arising from complex cardiac structures. Summary: Idiopathic VAs occurring in patients without overt structural heart disease can be categorized into four groups on the basis of anatomic location: (1) outflow tract VAs (which include the right ventricular outflow tract, left ventricular outflow tract, and left ventricular summit; (2) fascicular VAs; (3) papillary muscle VAs; and (4) annular VAs. Knowledge of the ECG characteristics of idiopathic VAs and the three-dimensional anatomy surrounding their sites of origin can guide pre-procedure planning, prioritization of cardiac regions for mapping, and approach for ablation. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

In delaying transmission of the cardiac impulse from the atria to the ventricles, the atrioventricular (AV) node serves a critical function in augmenting ventricular filling during diastole and limiting the ventricular response during atrial tachyarrhythmias. The complex structure of the nodal region, however, also provides the substrate for reentrant rhythms. Recent discoveries have elucidated the cellular basis and anatomical determinants of slow conduction in the node. Based on analysis of gap junction proteins, distinct structural components of the AV node have been defined, including the compact node, right and left inferior nodal extensions, the lower nodal bundle, and transitional tissue. Emerging evidence supports the role of the inferior nodal extensions in mediating slow pathway conduction. The most common form of reentry involving the node, slow-fast AV nodal reentrant tachycardia (AVNRT), utilizes the inferior nodal extensions for anterograde slow pathway conduction; the structures responsible for retrograde fast pathway activation in the superior septum are less well defined and likely heterogeneous. Atypical forms of AVNRT arise from circuits that activate at least one of the inferior extensions in the retrograde direction. [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]

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.

The authors discuss the article on the relevance of computed tomographic datasets (CTD) for demonstrating the anatomy of pulmonary artery root, by X. Dong, M. Tang, Q. Sun, and S. Xhang which appeared within the issue. Topics mentioned include the characterization of the valvar sinuses and valvar leaflets through catheter ablation (CA), and the use of CTD for showing the extent of the myocardium, and the potential application of intracardiac echocardiography during CA.

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]

Background Although ECG left ventricular hypertrophy (LVH) by Cornell product (CP) predicts increased mortality in patients with ischemic cardiomyopathy (ICM), those without CP LVH remain at relatively high risk. We examined whether T-wave alternans (TWA) testing and ST depression can improve risk stratification in these patients. Methods and Results This study examined 317 patients with ICM, nonsustained ventricular tachycardia, and a resting ECG in sinus rhythm, who presented for electrophysiology and TWA testing, and potential implantable cardioverter defibrillator (ICD) implantation. LVH was defined by CP :[(RaVL + SV3) +6 mm in women] × QRS duration > 2440 mm * msec. ST depression was examined as a categorical variable using an established threshold of depression of ≥50 μV in V5 or V6. In Cox multivariate models, abnormal TWA testing and ST depression were independent predictors of mortality in patients without CP LVH (HR 2.52, CI 1.09-5.80, P = 0.030 and HR 2.87, CI 1.41-5.81, P = 0.004, respectively). Individuals with no LVH by CP, normal TWA, and no significant ST depression, comprised 23% of the study population and had a 5.6% 3-year mortality, compared to an overall 20% mortality. Conclusions TWA and ST depression testing are strong predictors of mortality among ICM patients without CP LVH, with normal testing conversely predicting low 3-year mortality. Thus, risk assessment with TWA testing and a resting ECG can identify ICM patients at low risk who may be less likely to benefit from ICD implantation. [ABSTRACT FROM AUTHOR]

Background Electrical isolation of pulmonary vein (PV) conduction from the left atrium (LA) is the cornerstone of successful atrial fibrillation (AF) ablation. Exit block is confirmed by the absence of LA capture during pacing from a circular mapping catheter positioned in the PV; however, far-field capture of the left atrial appendage (LAA) (pseudo-pulmonary vein exit conduction) can occur. In this study, we evaluated a methodology for identifying pseudo-exit conduction. Methods and Results A total of 135 consecutive AF patients undergoing PV isolation were studied. After circumferential ablation established PV entrance block, circumferential pacing (10 mA at 2.0 msec) was performed to assess exit block. In 16 (11.9%) patients, pacing the anterior poles of the left superior PV (LSPV) captured the LA. To differentiate true PV exit conduction from pseudo-exit conduction, the ablation catheter was positioned within the LAA during PV pacing. LAA activation preceding PV capture was consistent with far-field capture and this was confirmed by demonstrating local capture and exit block with decreasing pacing output. Using this approach, 14 patients (10.4%) were identified with pseudo-exit conduction. Conclusions Due to the close proximity between the LSPV and LAA, pseudo-exit conduction is not uncommon and may lead to the erroneous conclusion that the LSPV is not isolated. Using this method to differentiate pseudo-exit conduction from true exit conduction should prevent unnecessary ablation after achievement of complete PV isolation. [ABSTRACT FROM AUTHOR]

Spontaneous junctional ectopic tachycardia (JET) in adults is rare, and the electrophysiologic mechanism has not been definitively established. Two patients who presented with JET, not associated with cardiac surgery, were evaluated and studied in the electrophysiology laboratory, and electrophysiologic and pharmacologic maneuvers were performed to assess the mechanisms of tachycardia. The junctional tachycardia in Patient 1 manifested characteristics consistent with a triggered mechanism, and was sensitive to adenosine. The junctional tachycardia in Patient 2 manifested characteristics consistent with abnormal automaticity, and was insensitive to adenosine. This is a rare clinical example of abnormal automaticity. These two cases demonstrate that JET may be due to multiple mechanisms, with data consistent with triggered activity and abnormal automaticity. (PACE 2013; 36:e7-e10) [ABSTRACT FROM AUTHOR]

Background: Adenosine (ADO) has been proposed to reconnect isolated pulmonary veins (PVs) postablation through hyperpolarization of damaged myocytes in an animal model. However, PV reconnection can occur via ADO-mediated sympathetic activation. We sought to determine the mechanism of ADO-induced PV reconnection in the clinical setting by characterizing its time course and location in patients undergoing PV isolation. Methods: Seventy-four patients (61 male; age 61 ± 10 years) undergoing PV isolation for atrial fibrillation (54 [73%] paroxysmal and 19 [27%] persistent) were studied. After each PV was isolated, a 12-mg intravenous bolus of ADO was administered and onset, offset, and location of ADO-induced PV reconnection and onset and offset of bradycardia were analyzed. Results: In 22 (30%) patients, ADO-induced PV reconnection occurred in 34 of 270 (13%) PVs. In 24 (71%) PVs, the duration of ADO-induced reconnection exceeded that of bradycardia. The onset of ADO-induced reconnection occurred before the onset of bradycardia in 10 (30%) PVs and during bradycardia in 23 (70%) PVs. No PVs exhibited onset of reconnection after resolution of bradycardia. Common sites of PV reconnection included the carinal region (41% of right PVs and 29% of left PVs) and left PV-atrial appendageal ridge region (35% of left PVs). Conclusions: ADO-induced PV reconnection occurs during the bradycardic phase of the ADO bolus response and not during the late tachycardic phase. ADO-induced PV dormant conduction is closely associated with the negative dromotropic effects of ADO and suggests that hyperpolarization of the resting membrane is the unifying mechanism. (PACE 2012;XX:1-8) [ABSTRACT FROM AUTHOR]