Catheter ablation has become the standard of care for the management of antiarrhythmic drug-refractory atrial fibrillation (AF) in many patients. The cornerstone of AF ablation includes pulmonary vein isolation (PVI) and energy delivery can sometimes extend beyond the atrial myocardium and result in collateral damage to adjacent structures, include the esophagus.[1] While atrial esophageal fistula (AEF) is a generally a rare complication, there have been continued efforts aimed to reduce esophageal thermal injury during AF ablation. While emerging energy sources such as irreversible electroporation show exciting promise for selective, non-thermal targeting of myocardial tissue, safety and efficacy clinical trial evaluation is on-going.[2] Therefore, strategies that can prevent esophageal thermal injury without adversely impacting lesion formation using conventional ablation technologies are still needed.

Background: The presence of an epicardial connection (EC) decreases the success rate of pulmonary vein isolation (PVI); however, the effect of designing isolation lines has not been evaluated. Objective: We sought to clarify the effects of designing an anterior line for right-sided PVI considering the presence and location of the EC. Methods: Seventy-four consecutive patients who underwent initial catheter ablation for atrial fibrillation were retrospectively included in this study. The presence of the EC was determined by the left atrial (LA) activation map during right atrial pacing, and patients were divided into EC-positive (n=23, 31%) and EC-negative (n=51, 69%) groups. EC-positive patients were further subdivided based on the EC location: on-the-line group, (EC on the PVI line, n=11); inside-line group (EC on the pulmonary vein [PV] side, n=10); and outside-line group (EC on the LA side, n=2). The PVI parameters were compared among the three groups. Results: The success rates of the first-pass isolation were comparable between the EC-negative and EC-positive groups (70.6% vs. 60.9%, ns), but the success rate was significantly higher in the on-the-line group than in the inside-line group (91% vs. 20%, p=0.002). First-pass isolation was successful in both patients in the outside-line group. Additional carina ablation was required only in the inside-line group. Conclusions: The association between the EC site and the right-sided PV anterior isolation line affected the success rate of first-pass isolation. For successful right-sided PVI, it is important to consider the EC site when designing the PVI line.

Introduction Post ablation of the accessory pathway (AP), the patient is observed in the catheterization laboratory for a variable period for resumption of pathway conduction. Aim of the study was to determine whether the administration of intravenous adenosine at 10 minutes after ablation of accessory pathway (AP) would have the same diagnostic accuracy as waiting for 30 minutes in predicting the resumption of AP conduction. Methods: This was a prospective interventional study conducted in two centers. Post ablation of the AP, intravenous adenosine was administered at 10 minutes to look for dormant pathway conduction. The response was recorded as positive (presence of pathway conduction), negative (absence), or indeterminate (not able to demonstrate AV and VA block and inability to ascertain AP conduction). Results: The study included 110 procedures performed in 109 patients. Adenosine administration at 10 minutes showed positive result in 3 cases (2.7%), negative result in 99 cases (90%) and indeterminate result in 8 cases (7.3%). Reconnection of accessory pathway at 30 minutes post ablation was seen in 8 cases (7.3%). Of these 8 cases, 10minutes adenosine administration showed positive test in 3 patients and negative test in 5 patients. Adenosine test at 10 minutes has a sensitivity, specificity, positive predictive value, and negative predictive value of 37.5%, 100%, 100% and 94.9% in identifying the recurrence of accessory pathway conduction at 30 minutes, respectively. Conclusion: Absence of pathway conduction on administration of adenosine 10 minutes post ablation does not help predict the absence of resumption of conduction thereafter.

The preprocedural imaging before the left atrial appendage closure device is critical for selecting the appropriate device for the appropriate patient. CT scans and TEE have been used in the past for preprocedural imaging. In this report, the authors used cardiac MRI as a pre procedural planning tool in the wake of scarcity of contrast availability.

Left atrial field isolation with pulsed field ablation:

Introduction Vascular access is required for most cardiac electrophysiology procedures. Over the past two decades, ultrasound guidance has increased in utilization as the primary method for assisting operators in gaining access for cardiac implantable electronic device (CIED) implantation. Methods Ultrasound guidance using a technique that includes both short-axis and long-axis views combined with a twisting needle motion after maximal tenting provides an extremely safe and reproducible technique for vascular access for all CIED procedures. Results and Conclusions In this manuscript and accompanying videos, the author will provide a step-by-step guide for optimal ultrasound guided visualization and needle maneuver technique to maximize safety and efficiency for vascular access in all CIED procedures.

Background: Contact force has been used to titrate lesion formation for radiofrequency ablation. Pulsed Field Ablation (PFA) is a field-based ablation technology for which limited evidence on the impact of contact force on lesion size is available. Methods: Porcine hearts (n=6) were perfused using a modified Langendorff set-up. A prototype focal PFA catheter attached to a force gauge was held perpendicular to the epicardium and lowered until contact was made. Contact force was recorded during each PFA delivery. Matured lesions were cross-sectioned, stained, and the lesion dimensions were measured. Numerical modeling of the catheter-tissue interface under different contact forces was performed to aid in the interpretation of our results and isolate effects of biomechanical tissue displacement. Results: A total of 82 lesions were evaluated with contact forces between 1.3 g and 48.6 g. Mean lesion depth was 4.8 ± 0.9 mm (standard deviation), mean lesion width was 9.1 ± 1.3 mm and mean lesion volume was 217.0. ± 96.6 mm 3. Linear regression curves showed an increase of only 0.01 mm in depth (Depth = 0.01*Contact Force + 4.37, R 2 = 0.06), 0.03 mm in width (Width = 0.03*Contact Force + 8.32, R 2 = 0.12) for each additional gram of contact force, and 2.20 mm 3 in volume (Volume = 2.20*Contact Force + 163, R 2 = 0.11). Numerical modeling found consistent trends with experimental mean values and shows tissue displacement alone is likely not a significant factor to formation of lesion depth. Conclusions: Increasing contact force using a bipolar, biphasic focal PFA system has minor effects on acute lesion dimensions in an isolated porcine heart model.

A 72-year-old female with frequent palpitation was referred for radiofrequency ablation. The baseline 12-lead electrocardiogram and echocardiography results were normal. At baseline, the atrio-His (AH) and His-ventricular (HV) intervals were 90 and 41 ms, respectively. Dual atrioventricular (AV) nodal physiology or ventriculoatrial (VA) conduction was not observed during programmed atrial and ventricular stimulation. After isoproterenol infusion, VA conduction became decremental and concentric, with the earliest atrial activation seen at the His bundle (HB) region during ventricular pacing. A supraventricular tachycardia with a long RP interval (SVT) was induced by atrial extra-stimulation, without any jump-up in the AH interval. During the SVT, the AH and HV intervals were 180 and 180 ms, respectively, and the earliest atrial activation was recorded in the HB region (Figure 1A). During the SVT, transient 2:1AV conduction was observed (Figure 1B). Ventricular overdrive pacing at a pacing cycle length (CL) of 360 ms was performed during the SVT with a CL of 390ms (Figures 2A and B). Based on these observations, what is the mechanism of this tachycardia?

Introduction: The risk of typical atrial flutter (AFL) is increased proportionately to right atrial (RA) size or right atrial scarring that results in reduced conduction velocity. These characteristics result in propagation of a flutter wave by ensuring the macro re-entrant wave front does not meet its refractory tail. The time taken to traverse the circuit would take account of both of these characteristics and may provide a novel marker of propensity to develop AFL. Our goal was to investigate right atrial collision time (RACT) as a marker of existing or future typical AFL. Methods: This single centre, prospective study recruited consecutive typical AFL ablation patients that were in sinus rhythm. Controls were consecutive electrophysiology study patients >18 years of age. While pacing the coronary sinus (CS) ostium at 600 ms, a local activation time map was created to locate the latest collision point on the anterolateral right atrial wall. This RACT is a measure of conduction velocity and distance from CS to a collision point on the lateral right atrial wall. Results: 98 patients were included in the analysis, 41 with atrial flutter and 57 controls. Patients with atrial flutter were older, 64.7 ± 9.7 vs 52.4 ± 16.8 years (<0.001) and more often male (34/41vs 31/57 (0.003)). The AFL group mean RACT (132.6±17.3 ms) was significantly longer than that of controls (99.1±11.6 ms) (p<0.001). A RACT cut-off of 115.5 ms had a sensitivity and specificity of 92.7% and 93.0% respectively for diagnosis of atrial flutter. An ROC curve indicated an AUC of 0.96 (95% CI: 0.93-1.0, p<0.01). Conclusion: RACT is a novel and promising marker of propensity for typical AFL. This data will inform larger prospective studies. The ability to predict AFL would be of significant clinical value to guide anticoagulation and ablation decisions.

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

Background: Catheter ablation for atrial fibrillation (AF) is a common therapeutic strategy for patients with either paroxysmal or persistent AF, but long-term ablation success rates are imperfect. Maintenance of sinus rhythm immediately prior to ablation with anti-arrhythmic drug (AAD) therapy has been associated with improved outcomes in patients undergoing ablation. Amiodarone has superior efficacy relative to other AADs. Whether failure of amiodarone to maintain sinus rhythm prior to ablation for either paroxysmal or persistent AF is associated with poor outcomes is unknown. Methods: A total of 307 patients who received amiodarone in a one-year window before undergoing catheter ablation for AF were included. Patients were divided into amiodarone success (n=183) and amiodarone failure (n=124) groups based on the response to pre-ablation amiodarone treatment. Analysis of procedural outcomes as a function of response to amiodarone therapy was performed. Patients were followed for at least 12 months post-ablation to assess outcomes (adverse events and arrhythmia recurrence). Procedural success was defined by the absence of documented arrhythmia (>30s) without any anti-arrhythmic agents beyond a 90d blanking period. Results: Following ablation for either paroxysmal or persistent AF, freedom from any recurrent atrial arrhythmia at 1y was 57.7% for the entire cohort. One-year freedom from recurrent arrhythmia in the amiodarone success group was comparable to that in the amiodarone failure group (55.7% vs 60.5%; p=0.54). Success rates following ablation did not vary by the response to amiodarone when analyzed for paroxysmal or persistent AF subgroups. Conclusion: Failure to restore and maintain sinus rhythm with amiodarone prior to ablation for either paroxysmal or persistent AF is not a predictor of ablation procedural failure. Amiodarone failure alone should not deter practitioners from considering ablation therapy for patients with AF.

Introduction Oral sotalol initiation requires a multiple-day, inpatient admission to monitor for QT prolongation during loading. A one-day intravenous (IV) sotalol loading protocol was approved by the FDA in March 2020, but limited data on clinical use and administration currently exists. This study describes implementation of an IV sotalol protocol within an integrated health system, provides initial efficacy and safety outcomes, and examines length of stay compared to oral sotalol initiation. Methods IV sotalol was administered according to a pre-specified initiation protocol to adult patients with refractory atrial or ventricular arrhythmias. Baseline characteristics, safety and feasibility outcomes, and length of stay (LOS) were compared to patients receiving oral sotalol over a similar time period. Results From January 2021 to June 2022, a total of 29 patients (average age 66.0 ± 8.6 years, 27.6% women) underwent IV sotalol load and 20 patients (average age 60.4 ± 13.9 years, 65.0% women) underwent PO sotalol load. The load was successfully completed in 22/29 (75.9%) patients receiving IV sotalol and 20/20 (100%) of patients receiving oral sotalol, although 7/20 of the oral sotalol patients (35.0%) required dose reduction. Adverse events interrupting IV sotalol infusion included bradycardia (7 patients, 24.1%) and QT prolongation (3 patients, 10.3%). No patients receiving IV or oral sotalol developed sustained ventricular arrhythmias prior to discharge. LOS for patients completing IV load was 2.6 days shorter (mean 1.0 vs 3.6, p < 0.001) compared to LOS with oral load. Conclusion Intravenous sotalol loading has a safety profile that is similar to oral sotalol. It significantly shortens hospital LOS, potentially leading to large cost savings.

A 52-year-old woman presented with malignant ventricular arrthythmogenesis intraoperatively during kyphoplasty for an osteoporotic fracture of a lumbar vertebra. No previous cardiovascular condition was known. Causes of arrhythmogenesis associated with the procedure were excluded. Due to her positive family history for dilated cardiomyopathy, upcoming thoughts were made for unmasking a previous asymptomatic cardiomyopathy. Nevertheless, an intracardiac cement embolism was diagnosed and, finally, the patient underwent an open heart surgery with successful removal of the cardiac cement while no new arrhythmogenic episode was recorded during follow up.

Background Optimal occlusion of pulmonary vein (PV) is essential for atrial fibrillation (AF) cryoballoon ablation (CBA). The aim of the study was to investigate the performance of two different tools for the assessment of PV occlusion with a novel navigation system in CBA procedure. Methods In consecutive patients with paroxysmal AF who underwent CBA procedure with the guidance of the novel 3-dimentional mapping system, the baseline tool, injection tool and pulmonary venography were all employed to assess the degree of PV occlusion, and the corresponding cryoablation parameters were recorded. Results In 23 patients (mean age 60.0 + 13.9 years, 56.5% male), a total of 149 attempts of occlusion and 122 cryoablations in 92 PVs were performed. Using pulmonary venography as the gold standard, the overall sensitivity, specificity of the baseline tool was 96.7% (95% CI 90.0% - 99.1%), and 40.5% (95% CI 26.0% - 56.7%), respectively, while the corresponding value of the injection tool was 69.6% (95% CI 59.7% - 78.1%), and 100.0% (95% CI 90.6% - 100.0%), respectively. Cryoablation with optimal occlusion showed lower nadir temperature (baseline tool: -44.3 + 8.4 ℃ vs -35.1 + 6.5 ℃, p < 0.001; injection tool: -46.7 + 6.4 ℃ vs -38.3 + 9.2 ℃, p < 0.001) and longer total thaw time (baseline tool: 53.3 + 17.0 s vs 38.2 + 14.9 s, p = 0.003; injection tool: 58.5 + 15.5 s vs 41.7 + 15.2 s, p < 0.001) compared with those without. Conclusions Both tools were able to accurately assess the degree of PV occlusion and predict the acute cryoablation effect, with the baseline tool being more sensitive and the injection tool more specific.

Introduction: Contact force-sensing catheters are widely used for ablation of cardiac arrhythmias. They allow quantification of catheter-to-tissue contact, which is an important determinant for lesion formation and may reduce the risk of complications. The accuracy of these sensors may vary across the measurement range, catheter-to-tissue angle, and amongst manufacturers and we aim to compare the accuracy and reproducibility of four different force sensing ablation catheters. Methods: A measurement setup containing a heated saline water bath with an integrated force measurement unit was constructed and validated. Subsequently, we investigated four different catheter models, each equipped with a unique measurement technology: Tacticath Quartz (Abbott), AcQBlate Force (Biotronik/Acutus), Stablepoint (Boston Scientific), and Smarttouch SF (Biosense Webster). For each model, the accuracy of three different catheters was measured within the range of 0-60 grams and at contact angles of 0°, 30°, 45°, 60°, and 90°. Results: In total, 6685 measurements were performed using 4x3 catheters (median of 568, IQR 511-606 measurements per catheter). Over the entire measurement-range, the force measured by the catheters deviated from the real force by the following absolute mean values: Tacticath 1.29g ±0.99g, AcQBlate Force 2.87g ±2.37g, Stablepoint 1.38g ±1.29g, and Smarttouch 2.26g ±2.70g. For some models, significant under- and overestimation of >10g were observed at higher forces. Mean absolute errors of all models across the range of 10-40g were <3g. Conclusion: Contact measured by force-sensing catheters is accurate with 1-3g deviation within the range of 10g to 40g. Significant errors can occur at higher forces with potential clinical consequences.

Mitigating Esophageal Injury after Atrial Fibrillation Ablation Guided by Ablation Index; CLOSEr to goalJason S. Chinitz, MD1 and Eli Q. Harris, MD21.South Shore University HospitalNorthwell HealthBay Shore, NY2. Nassau University Medical CenterEast Meadow, NYFinancial support : none.Disclosures : Dr. Chinitz serves on the scientific advisory board for Biosense Webster and has received consulting fees

Abstract: After several years with sobering experiences with electrogram-based AF ablation approaches, Seitz et al present with the VX1 software a reliable tool to map and ablate spatio-temporal dispersion. The presented multicenter study in persistent AF patients was conducted in 1 expert and 7 satellite centers with a total of 17 operators, using the VX1 software to detect and subsequently ablate spatiotemporal dispersion. While the AF termination rate (88%) and the freedom from AF in 12 months FU (82%) was very encouraging, the VX1 software, using AI enhanced electrogram adjudication, achieved very similar results in all centers, regardless of the centre’s or the operator’s experience. Thus, the biggest criticism of electrogram-based ablation strategies, i.e. the lack of reproducibility in “non-expert” centers, seems to be finally addressed.

A 30-year-old man with a structurally normal heart was referred to us with a 2-year history of recurrent episodes of rapid paroxysmal palpitations. A few episodes required hospitalization and were terminated with intravenous diltiazem. During electrophysiology (EP) study done twice before in other hospitals, the patient was diagnosed as typical atrioventricular nodal reentrant tachycardia (AVNRT) and underwent radiofrequency ablation of the slow pathway. However, the episodes recurred.  Because of the patient’s persistent symptoms, an EP study was performed again. Tachycardia was easily induced using atrial extrastimuli, ventricular extrastimuli and with rapid atrial pacing.