Artificial Intelligence-guided mapping of persistent atrial fibrillation:

Aggressive Treatment of Atrial Fibrillation in Hypertrophic Cardiomyopathy

Introduction: Pulsed electric field (PEF) ablation relies on the intersection of a critical voltage gradient with tissue to cause cell death. Field-based lesion formation with PEF technologies may still depend on catheter-tissue contact (CTC). The purpose of this study was to assess the impact of CTC on PEF lesion formation with an investigational large area focal (LAF) catheter in a preclinical model. Methods: PEF ablation via a 10-spline LAF catheter was used to create discrete RV lesions and atrial lesion sets in 10 swine (8 acute, 2 chronic). Local impedance (LI) was used to assess CTC. Lesions were assigned to 3 cohorts using LI above baseline: No Tissue Contact (NTC: ≤∆10Ω, close proximity to tissue), Low Tissue Contact (LTC: ∆11-29Ω), and High Tissue Contact (HTC: ≥∆30Ω). Acute animals were infused with triphenyl tetrazolium chloride (TTC) and sacrificed ≥2hrs post-treatment. Chronic animals were remapped 30 days post-index procedure and stained with infused TTC. Results: Mean (±SD) RV treatment sizes between LTC (n=14) and HTC (n=17) lesions were not significantly different (depth: 5.65±1.96mm vs 5.68±2.05mm, p=0.999; width: 15.68±5.22mm vs 16.98±4.45mm, p=0.737) while mean treatment size for NTC lesions (n=6) was significantly smaller (1.67±1.16mm depth, 5.97±4.48mm width, p<0.05). For atrial lesion sets, acute and chronic conduction block were achieved with both LTC (N=7) and HTC (N=6), and NTC resulted in gaps. Conclusions: PEF ablation with a specialized LAF catheter in a swine model is dependent on CTC. LI as an indicator of CTC may aid in the creation of consistent transmural lesions in PEF ablation.

1. Using the Farapulse pulse configuration and ablation procedure results in a significant esophageal temperature increase that is underestimated using the Circa probe and it is likely significantly higher temperature can be recorded at close proximity to the ablation electrodes. 2. A near-field tissue ablation is a mix of irreversible electroporation and thermal injury. 3. The bipolar energy delivery using the Farawave-catheter limits the field and thermal ablation to close proximity to the bipolar ablation electrodes limiting the impact on extracardiac tissues. 4. In the two published papers accompanying this editorial, the Farapulse PFA technology is shown to have no short or long-term adverse effect on the esophagus. However, reported phrenic nerve conduction stunning may occur (7,8). It is also noted that while Meininghaus et al. reported significant esophageal acute injuries using RF and Cryo no long-term data is provided that these findings resulted in long-term disabilities. 5. PFA is hampered by the inability to adequately assess irreversible lesion formation in real-time. 6. The advantage provided by using PFA ablation technology is added safety and faster procedure time. These conclusions need further affirmation when the technology is widely used.

Title: Leadless Pacemakers in Post Operative Patients: Is It Time For the New to Become the Normal?Invited Editorial: Manuscript ID JCE-23-0567.R2Tyler P. Rasmussen, MD, PhD and E. Michael Powers, MD, MBAUniversity of Iowa Carver College of MedicineDivision of Cariology, Clinical Cardiac Electrophysiology200 Hawkins Dr.Iowa City, IA [email protected] et al. describe a single center retrospective analysis of leadless pacemaker (LP) implant following cardiac surgery or transcatheter valvular procedures that highlights the performance of LPs when implanted in patients with atrioventricular block (AVB) and either high risk features for conventional transvenous pacing or permanent atrial fibrillation (1). LPs performed well with a limited number of patients (7%) requiring conversion to transvenous pacing and only a single procedural complication. However, there was a statistically significant decline in left ventricular ejection fraction (LVEF) in the overall cohort. When subgroup analysis was performed, LVEF decline was only seen in those implanted with VVI devices but not in patients with VDD devices. Here, we discuss implications of this study.Transcatheter aortic valve implantation (TAVI) is now more common than surgical AVR but carries a greater risk of high degree atrioventricular block (AVB) (~10%) (2,3). Cardiac surgery has been linked to a 1-3% risk of permanent pacemaker implantation with higher rates in patients undergoing valve replacement (4). Therefore, the number of patients at risk for AVB related to cardiac surgery and catheter-based valve interventions is increasing over time and warrants a critical evaluation of optimal pacing strategy.Longitudinal registry data show that Micra (Medtronic, Minneapolis, MN) LPs have fewer required reinterventions and chronic complications compared to conventional transvenous pacing systems (5). Furthermore, mortality is comparable despite being implanted in patients with higher rates of end stage renal disease (ESRD) and medical complexity (5). LPs greatly outperform transvenous systems with respect to device related infections, as the rate of infection in LPs is trivial both short and long term (5,6). The risk of pacing induced cardiomyopathy (LVEF drop ≥ 10%) in pacemaker dependent patients is suggested to be equivalent or lower in those implanted with an LP (3%) versus those with a transvenous system (~13%) (7). A major drawback to the use of LPs is their inability to provide atrial pacing, which typically limits their use to patients without sinus node dysfunction.The current paper demonstrates that the use of LPs is a viable strategy in post-operative patients. Their cohort included 50 patients having undergone cardiac surgery and 28 with a transcatheter valvular procedure (1). Of the 28 transcatheter procedures, 25 were TAVI. Factors prompting an LP implant versus transvenous were permanent AF, ESRD, tricuspid valve pathology, history of endovascular infection, and dermatological disease. Mean time from surgery to device implant was 7.3 ± 8.0 days, which suggests an adequate waiting period for AV conduction recovery in most circumstances. The only complication in the cohort (1.3%) was an access site hematoma requiring evacuation. Device parameters were stable at follow-up with a small but clinically insignificant decline in impedance and trivial rise in threshold, which is consistent with previously published data regarding Micra (6). The two major findings were that the pacing burden declined significantly in the follow-up period and that there was a significant reduction in the left ventricular ejection fraction (LVEF) in this cohort. Pacing percentages fell from mean 75% at implant to mean 48% at follow-up. The reduction in pacing burden suggests that many patients have late recovery in AV conduction post procedure. There was a drop in LVEF from baseline (55.0% ± 10.6%) versus follow-up (51.5% ± 11.2%, p =< 0.001), but this study is not designed to determine if the LVEF drop is because of the Micra or another unidentifiable factor. Importantly, the drop in LVEF was significant in the Micra VR group: baseline (54.1% ± 11.9%) versus follow-up (48.8% ± 11.9%, p = 0.003) but not in the Micra AV group: baseline (56.1 ± 9.0%) versus (54.6% ± 9.7%, p = 0.06). The only patient characteristic that was associated with a significant drop in LVEF (> 10%) versus those with stable EF was having a prior history of heart failure with a reduced ejection fraction. Taken together, this study showed that both Micra AV and VR can provide safe RV pacing in post-operative patients with a small, but significant risk for LVEF reduction that is likely linked to right ventricular pacing.

Background: Intracardiac echocardiography (ICE) is increasingly used during left atrial appendage occlusion (LAAO) as an alternative to transesophageal echocardiography (TEE) Aim: To evaluate the impact of ICE vs. TEE guidance during LAAO on procedural characteristics and acute outcomes, as well the presence of peri-device leaks and residual septal defects during follow-up. Methods: All studies comparing ICE-guided vs. TEE-guided LAAO were identified. The primary outcomes were procedural efficacy and occurrence of procedure-related complications. Secondary outcomes included lab efficiency (defined as a reduction in in-room time), procedural time, fluoroscopy time, and presence of peri-device leaks and residual interatrial septal defects (IASD) during follow-up. Results: Twelve studies (n=5637) were included. There were no differences in procedural success group (98.3% vs. 97.8%; OR 0.73, 95% CI 0.42-1.27, p=0.27; I2=0%) or adverse events (4.5% vs. 4.4%; OR 0.81 95% CI 0.56-1.16, p=0.25; I2=0%) between the ICE-guided and TEE-guided groups. ICE guidance reduced in in-room time (mean-weighted 28.6-minute reduction in in-room time) without differences in procedural time or fluoroscopy time. There were no differences in peri-device leak (OR 0.93, 95% CI 0.68-1.27, p=0.64); however, an increased prevalence of residual IASD was observed with ICE-guided vs. TEE-guided LAAO (46.3% vs. 34.2%; OR 2.23, 95% CI 1.05-4.75, p=0.04). Conclusion: ICE guidance is associated with similar procedural efficacy and safety, but could result in improved lab efficiency (as established by a significant reduction in in-room time). No differences in the rate of periprocedural leaks were found. A higher prevalence of residual interatrial septal defects was observed with ICE guidance.

In the last few years novel ablative technologies featuring several devices incorporating different energy sources and catheter design for ensuring an effective PVI have been proposed. In particular, two prominent technologies, such as the non-thermal ablation modality based on pulsed field ablation (also defined as “electroporation”) and radio frequency balloon-based catheter has been introduced in the clinical practice. The adoption of such technologies aims at simplifying PVI procedures, improving efficacy, and increasing safety. Furthermore, the evaluation of the extension of area of lesion promoted by the two technologies might affect the clinical outcome

Reply to: Two Ripples in a Pond: The Subtleties of Mapping Observations in Localizing

Case: A 41-year-old man with no prior cardiac history and a history of regular narrow QRS tachycardia, presenting with frequent paroxysmal palpitations, was referred to our institution. The tachycardia was adenosine-sensitive, leading to the acute termination of the tachycardia. The baseline electrocardiogram was unremarkable. During an electrophysiology study (EPS), supraventricular tachycardia (SVT) was easily induced by ventricular extrastimuli. Figure [1](#fig-cap-0003) shows a single ventricular extrastimulus applied from the right ventricular apex (RVa) during the tachycardia, and this finding was reproducible. Questions: What is the mechanism of the observed response? What are the clinical implications?

Reply by Casella et al to Letter Regarding Article,

A 70-year-old man revealed a rare type of atrioventricular nodal reentrant tachycardia (AVNRT) involving distinct retrograde pathways, Superior Slow Pathway (SSP) and Inferolateral Left Atrial Slow Pathway (ILA-SP). Radiofrequency ablation was successfully performed on the non-coronary cusp and in the left atrium, respectively, to eliminate the tachycardias. Due to the anomalous electrical conduction patterns, careful diagnosis and ablation strategies were necessary to avoid the risk of atrioventricular block. These findings underscore the diversity and complexity of AVNRT and highlight the importance of tailored therapeutic approaches.

Editorial

In figure 1, word Model was misspelled as Madel and the lead is Model 6937. The correct figure 1 is below:

Clinical Needs Should Drive InnovationJennifer N. Avari Silva, MD1, 2, 3, 4Affiliations: 1Division of Pediatric Cardiology, Washington University School of Medicine, St. Louis, MO;2Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO;3Sentiar, Inc, St. Louis, MO;4Excera, Inc, St. Louis, MOCorresponding Author:Jennifer N. Avari Silva, MD [email protected]: I am the co-founder and co-inventor of Sentiar and Excera, Inc. The technology has been licensed from Washington University to both Sentiar and Excera.Words:Conflicts: I have no relevant conflicts of disclosure.The tried-and-true methodology for designing medical devices starts with product ideation and rapid prototyping. But the most vital step starts prior to product ideation—that is, identifying the unmet clinical need. Starting with clear identification of clinical need may take time to fully elucidate and, importantly, may change over time as clinical practices, medical knowledge, and scientific discoveries change the field. Developing tools to address these unmet needs is the goal for medical device developers. When we start with developing tools that address unmet needs, the tools inherently provide added value. Conversely, tools are often developed to implement new technologies without a clear understanding of the need being addressed. Often, these technologies are in search of a clinically relevant use case—these tools become proverbial hammers in search of nails.In this study from Kumthekar et al1 in this month’s JCE, we learn the results of early feasibility testing of PeriScope in an animal (porcine) study. PeriScope is a novel percutaneous access tool for epicardial access developed to aid in the implantation of epicardial cardiac implantable electronic devices (CIEDs) in both pediatric and congenital patients who require systems at a young age. The clinical conundrum is that young patients who need CIEDs will often require lifelong devices, with transvenous systems often being delayed into adolescence (or later) due to small stature, linear growth, and concerns for causing venous stenosis or occlusion2, 3. Additionally, patients with congenital heart disease often have abnormal vasculature and anatomy which may prohibit transvenous CIED systems4, 5 This clinical problem has been debated rigorously in the pediatric EP community, with reports of transvenous systems placed in some of our youngest and smallest of patients6. This has been a longstanding need in the pediatric and congenital community which members of this investigative team have spent years working towards7-10.The authors set out to address this issue by creating a tool to ease epicardial device lead placement, and the first step in this multistep plan is epicardial access. The current data presented by Kumthekar et al1 demonstrate the use of this tool in an immature porcine model (Yorkshire piglets) to test the implant procedure characteristics and efficiencies. Early results are promising, showing the time from skin nick to sheath access in the pericardium was <10 minutes with a mean total procedure time of 16 minutes. Lead characteristics were acceptable, though not excellent, speaking to the need to develop additional new tools. To address the long-term goal of minimally invasive epicardial device implantation, adjunctive technologies will need to be developed, including leads designed for implantation via a minimally invasive approach and tools to simplify minimally invasive generator implantation. Given the breadth of tools that will be required to meet this need, an academic-industry partnership may emerge as a viable path for co-development.As with all novel tools and procedures, there is a learning curve and PeriScope is no different. Even within this small study with 6 piglets, there was a learning curve for the operator with piglet #1 having a longer procedure time than the rest of the cohort. Understanding learning curves, or assessments of performance over experience, for new technologies/tools and procedures is itself an entire field of study11 which over time has created standard learning curve models for guidance with certain types of procedures, including laparoscopic surgical procedures. With PeriScope, there appeared to be a steep learning curve with increased competency after a short experience (n=1). More experience with a varied user group will be invaluable to determining the true learning curve for the device.Finally, like many innovations developed to a specific clinical need, creative physicians will find novel, often off-label, use cases for technologies that address their own clinical needs. With the growing performance of epicardial ablation, accessing the epicardial space is no longer a need relegated to pediatric and congenital device implants, but is now an emerging need in adult, pediatric and congenital ablation. These changing needs over time are to be expected and reflect advances in medical knowledge and scientific discovery.By nature, cardiac electrophysiologists are innovators. We are fortunate to practice our field at a time when there is an abundance of devices being developed and engineered to address the unmet clinical needs emerging as we learn more about mechanisms of various substrates and develop best practices. Our mission is to ensure that these novel devices are practical, useful and of benefit to us and our patients.References:1. Kumthekar RN OJ, Mass P, M JC, Berul CI. Percutaneous Epicardial Pacing in Infants Using Direct VIsualization: A Feasibility Animal Study. Journal of Cardiovascular Electrophysiology . 2023.2. Berul CI, Triedman JK, Forbess J, Bevilacqua LM, Alexander ME, Dahlby D, Gilkerson JO and Walsh EP. Minimally invasive cardioverter defibrillator implantation for children: an animal model and pediatric case report. Pacing Clin Electrophysiol . 2001;24:1789-94.3. Kwak JG, Kim SJ, Song JY, Choi EY, Lee SY, Shim WS, Lee CH, Lee C and Park CS. Permanent epicardial pacing in pediatric patients: 12-year experience at a single center. Ann Thorac Surg . 2012;93:634-9.4. Maginot KR, Mathewson JW, Bichell DP and Perry JC. Applications of pacing strategies in neonates and infants. Prog Pediatr Cardiol . 2000;11:65-75.5. Rao V, Williams WG, Hamilton RH, Williams MG, Goldman BS and Gow RM. Trends in pediatric cardiac pacing. Can J Cardiol . 1995;11:993-9.6. Konta L, Chubb MH, Bostock J, Rogers J and Rosenthal E. Twenty-Seven Years Experience With Transvenous Pacemaker Implantation in Children Weighing <10 kg. Circ Arrhythm Electrophysiol . 2016;9:e003422.7. Clark BC, Kumthekar R, Mass P, Opfermann JD and Berul CI. Chronic performance of subxiphoid minimally invasive pericardial Model 20066 pacemaker lead insertion in an infant animal model. J Interv Card Electrophysiol . 2020;59:13-19.8. Clark BC, Opfermann JD, Davis TD, Krieger A and Berul CI. Single-incision percutaneous pericardial ICD lead placement in a piglet model. J Cardiovasc Electrophysiol . 2017;28:1098-1104.9. Kumthekar RN, Opfermann JD, Mass P, Clark BC, Moak JP, Sherwin ED, Whitman T, Marshall M and Berul CI. Minimally invasive percutaneous epicardial placement of a prototype miniature pacemaker with a leadlet under direct visualization: A feasibility study in an infant porcine model. Heart Rhythm . 2019;16:1261-1267.10. Kumthekar RN, Opfermann JD, Mass P, Clark BC, Moak JP, Sherwin ED, Whitman T, Marshall M and Berul CI. Percutaneous epicardial placement of a prototype miniature pacemaker under direct visualization: An infant porcine chronic survival study. Pacing Clin Electrophysiol . 2020;43:93-99.11. Hopper AN, Jamison MH and Lewis WG. Learning curves in surgical practice. Postgrad Med J . 2007;83:777-9.

The chance for the development of right AFL is strictly related to changes in functional conduction properties of the atrial myocardium which are greatly influenced by fibrotic/scar tissue and increased atrial volume. If these circumstances take place, reduction in conduction velocity can favor a macro-reentry circuit with the wavefront that does not meet its refractory tail and perpetuate the arrhythmia. Therefore, the time required to traverse the entire circuit is related to the circuit’s functional properties. With pacing from the coronary sinus os the right atrial collision time (RACT) of the two wavefronts traveling the circuit in counterclockwise and clockwise direction is calculated. in this prospective study, a cut-off of 115.5 ms of RACT showed a sensitivity and specificity of 92.7% and 93.0% respectively for diagnosis of AFL and an ROC curve indicated an AUC of 0.96 (95% CI: 0.93-1.0, p<0.01). Based on these premises, RACT could be utilized as new marker for the propensity of developing typical AFL.

Introduction: Wearable Cardioverter Defibrillator (WCD) is utilized in patients with assumed but not yet confirmed risk for sudden cardiac death (SCD). Many of these patients also present with atrial fibrillation (AF). However, the rate of WCD-detected ventricular or atrial arrhythmia events in this specific high-risk cohort is not well understood. Methods: In WEARIT-II, the cumulative probability of any sustained or non-sustained VT/VF (WCD-treated and non-treated), and atrial/supraventricular arrhythmias during WCD use was assessed using the Kaplan-Meier method by prior AF, with comparisons by the log-rank test. The incidence of ventricular and atrial arrhythmia events were expressed as events per 100 patient-years, and were analyzed by prior AF using negative binomial regression. Results: WEARIT-II enrolled 2000 patients, 557 (28%) of whom had AF prior to enrollment. Cumulative probability of any sustained or non-sustained WCD-detected VT/VF during WCD use was significantly higher among patients with a history of AF than without AF (6% vs. 3%, p=0.001). Similarly, the recurrent rate of any sustained or non-sustained VT/VF was significantly higher in patients with prior AF vs. no prior AF (131.5 events per 100 patient-years vs. 22.7 events per 100 patient-years, p=0.001). Patients with prior AF also had a significantly higher burden of any WCD-detected atrial arrhythmias/SVT/inappropriate therapy (183.2 events per 100 patient-years vs. 74.8 events per 100 patient-years, p<0.001). Conclusion: Our results demonstrate that patients with a history of AF wearing the WCD for risk assessment have a higher incidence of ventricular arrhythmias that may facilitate the decision making for ICD implantation.

Early product performance issues involving a new leadless pacemaker result in potentially harmful exchanges during device implantation.

This editorial reviews the data to guide the discussion on whether or not to replace implantable cardioverter-defibrillator generator when the left ventricular ejection fraction has improved.