Utilizing median and maximum QTc values improves prediction of breakthrough cardiac events in pediatric long QT syndrome.

INTRODUCTION: Although prior studies indicate that a QTc > 500 ms on a single baseline 12-lead electrocardiogram (ECG) is associated with significantly increased risk of arrhythmic events in long QT syndrome (LQTS), less is known about the risk of persistent QT prolongation. We sought to determine QTc persistence and its prognostic effect on breakthrough cardiac events (BCEs) among pediatric patients treated for LQTS. METHODS: We performed a retrospective analysis of 433 patients with LQTS evaluated, risk-stratified, and undergoing active guideline-based LQTS treatment between 1999 and 2019. BCEs were defined as arrhythmogenic syncope/seizure, sudden cardiac arrest (SCA), appropriate VF-terminating ICD shock, and sudden cardiac death (SCD). RESULTS: During the median follow-up of 5.5 years (interquartile range [IQR] = 3-9), 32 (7%) patients experienced a total of 129 BCEs. A maximum QTc threshold of 520 ms and median QTc threshold of 490 ms were determined to be strong predictors for BCEs. A landmark analysis controlling for age, sex, genotype, and symptomatic status demonstrated models utilizing both the median QTc and maximum QTc demonstrated the highest discriminatory value (c-statistic = 0.93-0.95). Patients in the high-risk group (median QTc > 490 ms and maximum QTc > 520 ms) had a significantly lower BCE free survival (70%-81%) when compared to patients in both medium-risk (93%-97%) and low-risk (98%-99%) groups. CONCLUSIONS: The risk of BCE among patients treated for LQTS increases not only based upon their maximum QTc, but also their median QTc (persistence of QTc prolongation). Patients with a maximum QTc > 520 ms and median QTc > 490 ms over serial 12-lead ECGs are at the highest risk of BCE while on guideline-directed medical therapy.

Endoscopic Ultrasound for the Evaluation of Esophageal Injury After Catheter Ablation for Atrial Fibrillation.

BACKGROUND & AIM: Atrial fibrillation (AF) ablation is an increasingly utilized rhythm control strategy that can damage adjacent structures in the mediastinum including the esophagus. Atrioesophageal fistulas and esophagopericardial fistulas are life-threatening complications that are thought to progress from early esophageal mucosal injury (EI). Endoscopic ultrasound (EUS) has been proposed as a superior method than EGD to survey EI and damage to deeper structures. We aim to evaluate the safety of EUS in categorizing post-ablation EI and quantify EUS-detected lesions and their correlation with injury severity and clinical course. METHODS: 234 consecutive patients between 2006-2020 who underwent AF ablation followed by EUS for the purpose of EI screening were retrospectively reviewed. Kansas City Classification (KCC) was used to classify EI (Type 1, Type 2a/b, Type 3a/b). RESULTS: EUS identified pleural effusions (31.6%) of patients, mediastinal adventitia changes (22.2%), mediastinal lymphadenopathy (14.1%), pulmonary vein changes (10.6%), and esophageal wall changes (7.7%). EGD revealed 175 (75%) patients without and 59 (25%) with EI. Patients with Type 2a/b EI and no EI were compared with multivariate logistic regression, and the presence of esophageal wall abnormality on EUS with OR 72.85 (95% CI 13.9-380.7), female sex with OR 3.97 (95% CI 1.3-12.3), and number of energy deliveries with OR 1.01 (95% CI 1.003-1.03), were associated with the presence EI type 2a or 2b. Pre-ablation PPI use was not associated with decreased risk of EI. CONCLUSIONS: EUS safely assesses mediastinal damage after ablation for atrial fibrillation and may excel over EGD in evaluating mucosal lesions of uncertain significance, with reduced risk of gas embolization in the setting of a full thickness injury (entero-vascular fistula). We propose an EUS-first guided approach to post-AF ablation examination, followed by EGD if it is safe to do so.

Leak closure following left atrial appendage exclusion procedures: A multicenter registry.

BACKGROUND: Though infrequent, incomplete left atrial appendage closure (LAAC) may result from residual leaks. Percutaneous closure has been described though data is limited. METHODS: We compiled a registry from four centers of patients undergoing percutaneous closure of residual leaks following LAAC via surgical means or with the Watchman device. Leak severity was classified as none (no leak), mild (1-2 mm), moderate (3-4 mm), or severe (≥5 mm). Procedural and clinical success was defined as the elimination of leak or mild residual leak at the conclusion of the procedure or follow-up, respectively. RESULTS: Of 72 (age 72.2 ± 9.2 years; 67% male) patients, 53 had undergone prior LAAC using the Watchman device and 19 patients surgical LAAC. Mean CHADS2 -VA2 Sc score was 4.0 ± 1.8. The median leak size was 5 mm, range: 2-13). A total of 13 received Amplatzer Vascular Plug-II, 18 received Amplatzer Duct Occluder-II and 40 patients received coils. One underwent closure using a 21 mm-Watchman. Procedural success was 94%. Zero surgical and nine Watchman patients (13%) had a residual leak at procedural-end (five mild, three moderate, and one severe)-only one patient had no reduction in leak size. Overall leak size reduction was 94%. Two (3%) had intraoperative pericardial effusion. There were no device embolizations, device-related thrombi, or procedural deaths. Clinical success was maintained at 94%. Two had cerebrovascular accidents-at 2 days (transient ischemic attack) and 10 months postprocedure. Two had major bleeding outside the 30-day periprocedural window. CONCLUSION: Percutaneous closure of residual leaks following left atrial appendage closure is feasible and associated with good outcomes. The procedural risk appears to be satisfactory.

Cardiac ablation with pulsed electric fields: principles and biophysics.

Pulsed electric fields (PEFs) have emerged as an ideal cardiac ablation modality. At present numerous clinical trials in humans are exploring PEF as an ablation strategy for both atrial and ventricular arrhythmias, with early data showing significant promise. As this is a relatively new technology there is limited understanding of its principles and biophysics. Importantly, PEF biophysics and principles are starkly different to current energy modalities (radiofrequency and cryoballoon). Given the relatively novel nature of PEFs, this review aims to provide an understanding of the principles and biophysics of PEF ablation. The goal is to enhance academic research and ultimately enable optimization of ablation parameters to maximize procedure success and minimize risk.

Incremental benefit of a novel signal recording system during mapping and ablation.

AIMS: Current electrophysiology signal recording and mapping systems have limited dynamic range (DR) and bandwidth, which causes loss of valuable information during acquisition of cardiac signals. We evaluated a novel advanced signal processing platform with the objective to obtain and assess additional information of clinical importance. METHODS AND RESULTS: Over 10 canines, we compared intracardiac recordings within all cardiac chambers, in various rhythms, in pacing and during radiofrequency (RF) ablation across two platforms; a conventional system and the PURE EP™ [(PEP); Bio Sig Technologies, Inc., Los Angeles, CA, USA]. Recording cardiac signals with varying amplitudes were consistently and reproducibly observed, without loss of detail or introduction of artefact. Further the amplitude of current of injury (COI) on the unipolar signals correlated with the instantaneous contact force (CF) recorded on the sensing catheter in all the animals (r2 = 0.94 in ventricle). The maximum change in the unipolar COI correlated with the change in local electrogram amplitude during non-irrigated RF ablation (r2 = 0.61 in atrium). Reduction in artefact attributable to pacing (20 sites) and noise during ablation (48 sites) was present on the PEP system. Within the PEP system, simultaneous display of identical signals, filtered differently, aided the visualization of discrete conduction tissue signals. CONCLUSION: Compared to current system, the PEP system provided incremental information including identifying conduction tissue signals, estimates of CF and a surrogate for lesion formation. This novel signal processing platform with increased DR and minimal front-end filtering may be useful in clinical practice.

Sinus rhythm heart rate increase after atrial fibrillation ablation is associated with lower risk of arrhythmia recurrence.

BACKGROUND: Pulmonary vein isolation (PVI) with autonomic modulation may be more successful than PVI alone for atrial fibrillation (AF) ablation and may be signaled by changes in sinus rhythm heart rate (HR) post ablation. We sought to determine if a change in sinus rhythm HR predicted AF recurrence post PVI. METHODS: Patients who underwent AF ablation from 2000 to 2011 were included if sinus rhythm was noted on ECG within 90 days pre and 7 days post ablation. Basic ECG interval and HR changes were analyzed and outcomes determined. RESULTS: A total of 1152 patients were identified (74.3% male, mean age 57 ± 11 years). Mean AF duration was 5.2 ± 5.3 years. Paroxysmal AF was noted in 712 (61.8%) of the patients. Mean EF was 61% ± 6%. Sinus rhythm HR was 61 ± 11 pre-ablation and 76 ± 13 bpm post-ablation (27% ± 24% increase, p < .001). The ability of relative HR change post-ablation to predict AF recurrence was borderline (hazard ratio 0.65 [0.41-1.01], p = .067). With patients separated into quartiles based on the relative HR change, the upper quartile with the largest relative increase in HR had a significantly lower rate of AF recurrence compared to the lowest quartile following multi variable modeling (p = .038). There were significant changes in PR (171 ± 28 to 167 ± 30 ms) and QTc (424 ± 25 to 434 ± 29 ms) intervals (both p < .001) but these were not predictive of outcome. CONCLUSION: Relative changes in HR post AF ablation correlates with AF recurrence. Further prospective studies are needed to confirm this relationship.

Injectable conductive hydrogel restores conduction through ablated myocardium.

INTRODUCTION: Therapies for substrate-related arrhythmias include ablation or drugs targeted at altering conductive properties or disruption of slow zones in heterogeneous myocardium. Conductive compounds such as carbon nanotubes may provide a novel personalizable therapy for arrhythmia treatment by allowing tissue homogenization. METHODS: A nanocellulose carbon nanotube-conductive hydrogel was developed to have conduction properties similar to normal myocardium. Ex vivo perfused canine hearts were studied. Electroanatomic activation mapping of the epicardial surface was performed at baseline, after radiofrequency ablation, and after uniform needle injections of the conductive hydrogel through the injured tissue. Gross histology was used to assess distribution of conductive hydrogel in the tissue. RESULTS: The conductive hydrogel viscosity was optimized to decrease with increasing shear rate to allow expression through a syringe. The direct current conductivity under aqueous conduction was 4.3 × 10-1 S/cm. In four canine hearts, when compared with the homogeneous baseline conduction, isochronal maps demonstrated sequential myocardial activation with a shift in direction of activation to surround the edges of the ablated region. After injection of the conductive hydrogel, isochrones demonstrated conduction through the ablated tissue with activation restored through the ablated tissue. Gross specimen examination demonstrated retention of the hydrogel within the tissue. CONCLUSIONS: This proof-of-concept study demonstrates that conductive hydrogel can be injected into acutely disrupted myocardium to restore conduction. Future experiments should focus on evaluating long-term retention and biocompatibility of the hydrogel through in vivo experimentation.

Electroporation of epicardial autonomic ganglia: Safety and efficacy in medium-term canine models.

BACKGROUND: Endocardial radiofrequency ablation of epicardial ganglionic plexus (GP) for atrial fibrillation (AF) is complicated by myocardial damage. OBJECTIVES: We hypothesized that an epicardial approach with a novel nitinol catheter system capable of causing irreversible electroporation (IRE) with direct current (DC) could selectively and permanently destroy GP without collateral myocardial injury. METHODS: Acute studies and medium-term terminal studies (mean survival, 1137 days) were performed with seven dogs. In the acute studies, DC was used to target epicardial GP within the transverse sinus, oblique sinus, vein of Marshall, and right periaortic space. Successful electroporation was defined as the presence of ablative lesions in the GP without collateral myocardial damage. A four-point integer system was used to classify histologic changes in tissue harvested from the ablation sites. Atrial effective refractory period (AERP) was measured during the acute and medium-term studies. RESULTS: For six dogs in the medium-term studies, the postablation period was uneventful without complications. Lesions were successfully created at 20 of 21 sites (95.2%) with more than minimal myocardial damage in one dog. An increase in AERP occurred in both atria during the acute studies but was maintained only in the right atrium at medium-term follow-up (5032 milliseconds). No dog had damage to the esophagus, adjacent great arteries, or pulmonary veins. CONCLUSIONS: This proof-of-concept study suggests that safe, effective, and selective epicardial ablation of GP can be performed with DC by IRE with minimal collateral myocardial damage.

Comparing the incidence of ventricular arrhythmias during epicardial ablation in swine versus canine models.

BACKGROUND: Choosing the appropriate animal model for development of novel technologies requires an understanding of anatomy and physiology of these different models. There are little data about the characteristics of different animal models for the study of technologies used for epicardial ablation. We aimed to compare the incidence of ventricular arrhythmias during epicardial radiofrequency ablation between swine and canine models using novel epicardial ablation catheters. METHODS: We conducted a retrospective study using data obtained from epicardial ablation experiments performed on swine (Sus Scrofa) and canine (Canis familiaris) models. We compared the incidence of ventricular arrhythmias during ablation between swine and canine using multivariate regression analysis. Six swine and six canine animals underwent successful epicardial radiofrequency ablation. A total of 103 ablation applications were recorded. RESULTS: Ventricular arrhythmias requiring cardioversion occurred in 13.11% of radiofrequency ablation applications in swine and 9.75% in canine (relative risk: 117.6%, 95% confidence interval [CI]: 83.97-164.69, animal-based odds ratio [OR]: .55, 95% CI: .23-61.33; P = .184). When adjusting for application position, duration of ablation and power, the odds of developing potentially lethal ventricular arrhythmia in swine increased significantly compared to canine (OR: 3.60, 95% CI: 1.35-9.55; P = .010). CONCLUSIONS: The swine myocardium is more susceptible to developing ventricular arrhythmias compared to canine model during epicardial ablation. This issue should be carefully considered in future studies.

Percutaneous epicardial pacing using a novel transverse sinus device.

BACKGROUND: Transvenous lead implantation has multiple drawbacks and complications that can be overcome by epicardial lead placement. We aimed to design percutaneously implanted epicardial leads that are anchored through the transverse sinus (TS). METHODS AND RESULTS: We designed a novel multielectrode pacing device with four bipole electrode pairs. The device is advanced through the TS, with both ends externalized out of the pericardium. We tested the prototype in one proof-of-concept and 5 additional acute canine experiments. The TS device recorded ventricular and atrial electrograms. The median amplitude of near-field ventricular electrograms was 3.3 mA (IQR 2.0-4.3) and of near-field atrial electrograms was 2.1 mA (IQR 1.3-2.2). The median ventricular threshold (N  =  30) was 1.1 mA (IQR 0.7-3.1) at a median pulse width of 0.5 ms (IQR 0.5-0.5). The median atrial threshold (N  =  10) was 2.4 mA (IQR 1.1-7.8) at a median pulse width of 0.5 ms (IQR 0.5-0.9). Right and left ventricular and atrial pacing morphologies were noted while pacing electrodes adjacent to these chambers. Simultaneous left (LV) and right ventricular (RV) pacing showed reduction in QRS duration from 116 ms (RV) and 105 ms (LV) to 91 ms. On necropsy, the device was located in the TS in all animals. There were TS abrasions in one animal, and no other acute complications. CONCLUSIONS: This study highlights a novel approach to epicardial pacing harnessing the unique anatomy of the transverse sinus as an anchoring point. Placement of this novel transverse sinus device was safe and feasible, with acceptable atrial and ventricular thresholds.

Impact of sedation vs. general anaesthesia on percutaneous epicardial access safety and procedural outcomes.

Aims: Patient movement while under moderate/deep sedation may complicate percutaneous epicardial access (EpiAcc), mapping and ablation. We sought to compare procedural outcomes in patients undergoing EpiAcc under sedation vs. general anaesthesia (GA) for ablation. Methods and results: Patients undergoing EpiAcc between January 2004 and July 2014 were included. Safety, procedural, and clinical outcomes were compared between patients undergoing EpiAcc under sedation or GA for ventricular tachycardia or premature ventricular complex ablation. Between January 2004 and July 2014, 170 patients underwent EpiAcc (mean age, 53.2 ± 15.8 years; average ejection fraction, 44.3 ± 15.3%). The majority (122 [72%] patients) were male. GA was used in 69 (40.6%). There was no difference in route of access (more often anterior, 53.0%) or the rate of successful access (96% overall) between groups. Similarly, the site of ablation (endocardial vs. epicardial vs. combined endocardial/epicardial) was similar between groups. Complications were equally seen between groups-the most frequent event/complication was pericardial effusion, occurring in 10.6% of patients. Finally, procedural and clinical success rates between GA and sedation groups were comparable (93 vs. 91% and 44 vs. 51%, respectively, P > 0.05). Conclusions: Choice of anaesthesia for EpiAcc does not appear to significantly affect safety and procedural or clinical outcomes. For patients in whom anaesthesia may pose increased risk, it is reasonable to obtain epicardial access under sedation.

QT Prolongation, Torsades de Pointes, and Psychotropic Medications: A 5-Year Update.

BACKGROUND: Some psychotropic medications have been associated with prolongation of the QT interval and QT prolongation, especially in those with medical illness, and are linked to lethal ventricular arrhythmias, such as Torsades de Pointes (TdP). In 2013, we published a review of QT prolongation, TdP, and psychotropic medications. OBJECTIVE: We provide an update over the past 5 years on the specific concerns most relevant to clinicians who see medically ill patients. METHODS: In this nonsystematic review, we aimed to carefully and intensively identify new articles by utilizing a structured PubMed search from 2012-present. RESULTS: QT prolongation remains an imperfect, though well-established marker of risk for TdP. Among antidepressant medications, citalopram does appear to prolong the QT interval more than other selective serotonin reuptake inhibitors, though the clinical significance of this prolongation remains unclear. Escitalopram appears to prolong the QT interval to a lesser extent. Haloperidol carries a risk for QT prolongation, but the assertion that intravenous haloperidol is inherently riskier may be confounded by its primary use in medically ill populations. Among atypical antipsychotic agents, ziprasidone-and possibly iloperidone-is associated with the greatest QT prolongation, whereas aripiprazole appears safest from this standpoint. CONCLUSIONS: The evidence for clinically meaningful QT prolongation with most classes of psychiatric agents remains minimal. The most important risk-reducing intervention clinicians can make is undertaking a careful analysis of other QT risk factors when prescribing psychiatric medications.

Intramural conduction system gradients and electrogram regularity during ventricular fibrillation.

INTRODUCTION: The His-Purkinje system has been shown to harbor triggers for ventricular fibrillation (VF) initiation. However, the substrate responsible for VF maintenance remains elusive. We hypothesized that standard, electrode-based, point-to-point mapping would yield meaningful insight into site-specific patterns and organization which may shed light on the critical substrate for maintenance of VF. METHODS: VF was induced under general anesthesia by direct current (DC) application to the right ventricle in 7 acute canines. A standard EPT Blazer mapping catheter (Boston Scientific, Natuck, MA) was used for mapping in conjunction with a Prucka recording system. We collected 30 consecutive electrograms at 24 distinct sites, confirmed by fluoroscopy and intracardiac echo. These sites included both endocardial and epicardial locations throughout the ventricles and conduction system. RESULTS: A total of 5040 individual data points were collected in 7 separate canine studies. During VF mapping, a transmural disparity was found between the epicardium (average cycle length [CL] of 1136 m s) and the endocardium (average CL of 123 m s) with a p value of <0.01. An additional, intramural gradient was found when comparing the proximal, insulated conduction system to the distal, non-insulated conduction system (average CL 218 versus 111 m s [p = 0.03]). CONCLUSION: Our data are supportive of a novel observation of intramural difference between insulated and non-insulated regions of the His-Purkinje network in canines. In addition, certain areas exhibited periods of regular electrogram characteristics; this was despite the heart remaining in terminal VF. These early canine data merit further study to investigate if specific ablation of the distal conduction system can perturb or extinguish VF.

Automated T-wave analysis can differentiate acquired QT prolongation from congenital long QT syndrome.

BACKGROUND: Prolongation of the QT on the surface electrocardiogram can be due to either genetic or acquired causes. Distinguishing congenital long QT syndrome (LQTS) from acquired QT prolongation has important prognostic and management implications. We aimed to investigate if quantitative T-wave analysis could provide a tool for the physician to differentiate between congenital and acquired QT prolongation. METHODS: Patients were identified through an institution-wide computer-based QT screening system which alerts the physician if the QTc ≥ 500 ms. ECGs were retrospectively analyzed with an automated T-wave analysis program. Congenital LQTS was compared in a 1:3 ratio to those with an identified acquired etiology for QT prolongation (electrolyte abnormality and/or prescription of known QT prolongation medications). Linear discriminant analysis was performed using 10-fold cross-validation to statistically test the selected features. RESULTS: The 12-lead ECG of 38 patients with congenital LQTS and 114 patients with drug-induced and/or electrolyte-mediated QT prolongation were analyzed. In lead V5 , patients with acquired QT prolongation had a shallower T wave right slope (-2,322 vs. -3,593 mV/s), greater T-peak-Tend interval (109 vs. 92 ms), and smaller T wave center of gravity on the x axis (290 ms vs. 310 ms; p < .001). These features could distinguish congenital from acquired causes in 77% of cases (sensitivity 90%, specificity 58%). CONCLUSION: T-wave morphological analysis on lead V5 of the surface ECG could successfully differentiate congenital from acquired causes of QT prolongation.

Electrocardiographic Predictors of Torsadogenic Risk During Dofetilide or Sotalol Initiation: Utility of a Novel T Wave Analysis Program.

INTRODUCTION: Initiation of class III anti-arrhythmic medications requires telemetric monitoring for ventricular arrhythmias and QT prolongation to reduce the risk of torsades de pointes (TdP). Heart rate-corrected QT interval (QTc) is an indicator of risk, however it is imperfect, and subtle abnormalities of repolarization have been linked with arrhythmogenesis. PURPOSE: Identification of electrocardiographic predictors of torsadogenic risk through the application of a novel T wave analysis tool. METHODS: Among all patients admitted to Mayo Clinic for initiation of dofetilide or sotalol, we identified 13 cases who developed drug-induced TdP and 26 age and sex matched controls that did not develop TdP. The immediate pre-TdP ECG of those with TdP was compared to the last ECG performed prior to hospital discharge in controls using a novel T wave program that quantified subtle changes in T wave morphology. RESULTS: The QTc and 12 T wave parameters successfully distinguished TdP cases from controls. The top performing parameters were the QTc in lead V3 (mean case vs control 480 vs 420 msec, p < 0.001, r = 0.72) and T wave right slope in lead I (mean case vs control -840.29 vs -1668.71 mV/s, p = 0.002, r = 0.45). The addition of T wave right slope to QTc improved prediction accuracy from 79 to 88 %. CONCLUSION: Our data demonstrate that, in addition to QTc, the T wave right slope is correlated strongly with TdP risk. This suggests that a computer-based repolarization measurement tool that integrates additional data beyond the QTc may identify patients with the greatest torsadogenic potential.

Atrial Fibrillation Substrate and Catheter Ablation Outcomes in MYBPC3- and MYH7-Mediated Hypertrophic Cardiomyopathy.

BACKGROUND: The effects of disease-causing MYBPC3 or MYH7 genetic variants on atrial myopathy, atrial fibrillation (AF) clinical course, and catheter ablation efficacy remain unclear. OBJECTIVES: The aim of this study was to characterize the atrial substrate of patients with MYBPC3- or MYH7-mediated hypertrophic cardiomyopathy (HCM) and its impact on catheter ablation outcomes. METHODS: A retrospective single-center study of patients with HCM who underwent genetic testing and catheter ablation for AF was performed. Patients with MYBPC3- or MYH7-mediated HCM formed the gene-positive cohort; those without disease-causative genetic variants formed the control cohort. High-density electroanatomical mapping was performed using a 3-dimensional mapping system, followed by radiofrequency ablation. RESULTS: Twelve patients were included in the gene-positive cohort (mean age 55.6 ± 9.9 years, 83% men, 50% MYBPC3, 50% MYH7, mean ejection fraction 59.3% ± 13.7%, mean left atrial [LA] volume index 51.7 ± 13.1 mL/m2, mean LA pressure 20.2 ± 5.4 mm Hg) and 15 patients in the control arm (mean age 61.5 ± 12.6 years, 60% men, mean ejection fraction 64.9% ± 5.1%, mean LA volume index 54.1 ± 12.8 mL/m2, mean LA pressure 19.6 ± 5.41 mm Hg). Electroanatomical mapping demonstrated normal voltage in 87.7% ± 5.03% of the LA in the gene-positive cohort and 94.3% ± 3.58% of the LA in the control cohort (P < 0.001). Of the abnormal regions, intermediate scar (0.1-0.5 mV) accounted for 6.33% ± 1.97% in the gene-positive cohort and 3.07% ± 2.46% in the control cohort (P < 0.01). Dense scar (<0.1 mV) accounted for 5.93% ± 3.20% in the gene-positive cohort and 2.61% ± 2.19% in the control cohort (P < 0.01). Freedom from AF at 12 months was similar between the gene-positive (75%) and control (73%) cohorts (P = 0.92), though a greater number of procedures were required in the gene-positive cohort. CONCLUSIONS: Patients with MYBPC3- or MYH7-mediated HCM undergoing AF ablation have appreciably more low-amplitude LA signals, suggestive of fibrosis. However, catheter ablation remains an effective rhythm-control strategy.

Arrhythmic Prognosis According to Left Ventricular Systolic Dysfunction Severity in Cardiac Sarcoidosis.

BACKGROUND: Current guidelines present varying classes of recommendations for implantable cardioverter-defibrillator (ICD) utilization in patients with cardiac sarcoidosis (CS) and left ventricular ejection fraction (LVEF) <50%. OBJECTIVE: To investigate the ventricular arrhythmia risk in CS patients with ICDs and varying degrees of LV systolic dysfunction. METHODS: We included CS patients with an ICD and LVEF <50% at index evaluation. The primary outcome was survival free of sustained ventricular tachycardia/fibrillation (VT/VF) after ICD implantation and was assessed comparatively for LVEF ≤35 vs 36-49% and for primary vs secondary prevention ICD indication. RESULTS: We included 61 patients (median age 57 years, 61% male) with LVEF 36-49% (n=23) or LVEF ≤35% (n=38). An ICD was implanted for secondary prevention in 24% and 44% of the LVEF ≤35% and 36-49% groups, respectively (p=0.11). The primary outcome did not differ between the two groups in univariable analysis (LVEF ≤35% vs 36-49% HR 0.85 [95% CI 0.39, 1.82], p=0.67). In multivariable analysis, secondary prevention ICD indication was the only significant predictor of incident sustained VT/VF (HR 2.86 [95% CI 1.23, 6.67], p=0.015). The mean sustained VT/VF event burden was higher in the secondary as compared with the primary prevention ICD patients (0.47 vs 0.11 events/patient-year, p=0.005) but did not differ significantly between LVEF ≤35% and 36-49% patients. CONCLUSIONS: CS patients with ICD indications and LVEF 36-49% carry similarly high arrhythmic risk as those with LVEF ≤35%. Patients with secondary prevention ICDs have the highest overall risk.

Arrhythmic manifestations and outcomes of definite and probable cardiac sarcoidosis.

BACKGROUND: The 2014 Heart Rhythm Society consensus statement defines histological (definite) and clinical (probable) diagnostic categories of cardiac sarcoidosis (CS), but few studies have compared their arrhythmic phenotypes and outcomes. OBJECTIVE: The purpose of this study was to evaluate the electrophysiological/arrhythmic phenotype and outcomes of patients with definite and probable CS. METHODS: We analyzed the arrhythmic/electrophysiological phenotype in a single-center North American cohort of 388 patients (median age 56 years; 39% female, n = 151) diagnosed with definite (n = 58) or probable (n = 330) CS (2000-2022). The primary composite outcome was survival to first ventricular tachycardia/fibrillation (VT/VF) event or sudden cardiac death. Key secondary outcomes were also assessed. RESULTS: At index evaluation, in situ cardiac implantable electronic devices and antiarrhythmic drug use were more common in definite CS. At a median follow-up of 3.1 years, the primary outcome occurred in 22 patients with definite CS (38%) and 127 patients with probable CS (38%) (log-rank, P = .55). In multivariable analysis, only a higher ratio of the 18F-fluorodeoxyglucose maximum standardized uptake value of the myocardium to the maximum standardized uptake value of the blood pool (hazard ratio 1.09; 95% confidence interval 1.03-1.15; P = .003, per 1 unit increase) was associated with the primary outcome. During follow-up, patients with definite CS had a higher burden of device-treated VT/VF events (mean 2.86 events per patient-year vs 1.56 events per patient-year) and a higher rate of progression to heart transplant/left ventricular assist device implantation but no difference in all-cause mortality compared with patients with probable CS. CONCLUSION: Patients with definite and probable CS had similarly high risks of first sustained VT/VF/sudden cardiac death and all-cause mortality, though patients with definite CS had a higher overall arrhythmia burden. Both CS diagnostic groups as defined by the 2014 Heart Rhythm Society criteria require an aggressive approach to prevent arrhythmic complications.

Intraoperative Pectoral Nerve Blocks During Cardiac Implantable Electronic Device Procedures.

BACKGROUND: Cardiac implantable electronic device (CIED) procedures can cause significant post-operative pain. Opioid use for post-operative pain is associated with risk of persistent use. The benefits of pectoral nerve blocks (PECs) have been established for other chest wall surgeries but adoption in electrophysiology has been limited. OBJECTIVES: To evaluate the efficacy of intraoperative ultrasound guided PECs performed at the time of CIED procedures by the implanting physician from within the device pocket. METHODS: Patients undergoing a pectoral CIED procedure at 7 centers from 2022-2023 were included. Patients underwent intraoperative PECs and subcutaneous local anesthetic vs subcutaneous local anesthetic only at the discretion of the operator. Patients were prospectively evaluated for post-operative pain. RESULTS: 610 patients (67±15 years old, 63% male) were enrolled and half (n=305) underwent PECs. Patients who underwent PECs were more likely to have a history of chronic pain (32 vs 11%, p<0.001). PECs was associated with lower pain scores in the 4 hours after the procedure (1.5±2.1 vs 4.5±2.5, p<0.001). Pain scores were not different after 24-hours (2.8±1.7 vs 3.1±2.2) and 2-weeks (0.9±1.4 vs 0.9±1.2). PECs patients were less likely to receive inpatient opioids (10 vs 48%, p<0.001) and to be discharged with an opioid prescription (15 vs 59%, p<0.001). In multivariable linear regression, PECs (p<0.001), age (p=0.002) and absence of chronic pain (p=0.009) were associated with lower acute post-operative pain. CONCLUSIONS: Intraoperative PECs can reduce post operative pain and opioid use. This procedure can be readily performed by the implanting physician from within the device pocket.