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 52242Edward-powers@uiowa.eduMerchant 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.

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 jennifersilva@wustl.eduDisclosures: 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.

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.

Atrial fibrillation (AF) provides extremel rapid excitation frequency in both atria, and induces several pathophysiological mechanisms by influencing each other to promote AF. This auto-enhancing feature is often described by the well-known concept “AF begets AF”. The cure of AF by creating pulmonary vein (PV) isolation may be able to reverse the spiral and be able to achieve reverse remodeling. Because of the initial focus on PV in the pathogenesis of AF, the effects of reverse remodeling after catheter ablation (CA) have been investigated on improvement of the left-sided cardiac system. On the other hand, tricuspid regurgitation (TR), the most neglected of all valvular diseases, is increasingly recognized as an important prognostic condition in heart failure patients. Previous reports, which tested the role of CA for AF patients with TR, have demonstrated that maintenance of SR provides reverse remodeling of the right-sided cardiac system, but have yet to prove whether this leads to improvement in patient prognosis. What is new and noteworthy about the report by Ukita et al. in this issue is that they found that TR improvement itself improves major event-free survival rate (incidence of heart failure hospitalization and all-cause mortality). However, several issues remain unresolved in their report. They observed a low AF recurrence rate in the TR-improved group, but did not address the possibility that AF suppression itself contributed to improve event-free survival rate. Further investigation is required to clarify whether TR improvement or maintenance of SR is the greater contributor to improved prognosis in AF.

We introduce a fast and easy method of successfully grasping a lead without a free end called the “Wire ThRoUgh Snare Twice (Wire TRUST)” technique in a 49-year-old male patient who required transvenous lead extraction (TLE) and lead replacement due to lead malfunction. Our proposed technique is less difficult than using the Needle’s eye snare because the pigtail catheter is softer and has better operability. The Wire TRUST technique promptly allows a combined superior and femoral approach for TLE, even when the lead tip is difficult to free because of severe adhesion.

A document by Anindya Ghosh. Click on the document to view its contents.

Objective: To investigate the optimal range of quantitative ablation index (AI) value during superior vena cava (SVC) electrical isolation by radiofrequency catheter ablation (RFCA). Methods: First, in a development cohort of patients with atrial fibrillation (AF), the RFCA with 40W was performed to complete SVC isolation guided by the conduction breakthrough point from the right atrium to SVC. Then, the range of AI value was calculated by offline analysis on different segments of SVC. Lastly, for the validation of AF patients, the safety and effectiveness of SVC isolation with the optimized target range of AI value were evaluated with an additional adenosine test. Results: A total of 101 patients with AF were included in the study (44 patients in the development cohort / 57 in the validation cohort). The segmental ablation strategy was applied in 70% of the patients. According to the offline analysis of the AI values in the development cohort, the target AI value range was set as 350-400. The success rate of SVC isolation in the validation cohort was significantly higher than that in the exploration cohort (100% vs 90.9%, P = 0.02), and no complications occurred in the exploration cohort. During the adenosine test, the recovery rate of electrical conduction in SVC was significantly lower than that in the pulmonary vein (3.5% vs 17.5%). Conclusion: The target AI value with a range from 350 to 400 is safe and effective for high-power RFCA to complete SVC isolation.

Background: Studies have identified significant sex-based differences and disparities in the clinical presentation and treatment of atrial fibrillation (AF). Studies have shown women are less likely to be referred for catheter ablation, are older at the time of ablation, and are more likely to have recurrence after ablation. However, in most studies investigating AF ablation outcomes, the female cohorts were relatively small. The impact of gender on the outcome and safety of ablation procedures is still unclear. Objective: To investigate sex-based differences in outcomes and complications after AF catheter ablation, with a significant size female cohort Method: In this retrospective study, patients undergoing AF ablation from January 1, 2014, to March 31, 2021, were included. We investigated clinical characteristics, duration and progression of AF, number of EP appointments from diagnosis to ablation, procedural data, and procedure complications. Results: Total 1346 patients underwent first catheter ablation for AF during this period, including 896 (66.5%) male and 450 (33.4%) female patients. Female patients were older at the time of ablation (66.2y vs 62.4y; p<0.001). Women had higher CHA 2DS 2-VASc scores (3 vs 2; p<0.001) than men, expectedly, as the female sex warrants an additional point. 25.3% female patients had PersAF at the time of diagnosis vs 35.3% male patients (p<0.001). At the time of ablation, 31.8% female patients had PersAF as compared to 43.1% male patients (p<0.001), indicating progression of PAF to PersAF in both genders. Women tried more AADs than men before ablation (1.13 vs 0.98; p=0.002). Male and female patients had no statistically significant difference in (a) arrhythmia recurrence at 1-y post ablation (27.7% vs 30%; p=0.38) or (b) procedural complication rate (1.8% vs 3.1%; p=0.56). Conclusion: Female patients were older and had higher CHA 2DS 2-VASc scores compared to males at the time of AF ablation. Women tried more AADs than men prior to ablation. 1-y arrhythmia recurrence rates and procedural complications were similar in both genders. No sex- based differences were observed in safety and efficacy of ablation.

Introduction: The advancement of artificial intelligence (AI) has aided clinicians in the interpretation of electrocardiograms (ECGs) serving as an essential tool to provide rapid triage and care. However, in some cases, AI can misinterpret an ECG and may mislead the interpreting physician. Therefore, we aimed to describe the rate of ECG misinterpretation and its potential clinical impact in patient’s management. Methods: We performed a retrospective descriptive analysis of misinterpreted ECGs and its clinical impact from May 28, 2020 to May 9, 2021. An electrophysiologist screened ECGs with confirmed diagnosis of atrial fibrillation (AF), sinus tachycardia (ST), sinus bradycardia (SB), intraventricular conduction delay (IVCD), and premature atrial contraction (PAC) that were performed in the emergency department. We then classified the misinterpreted ECGs as pseudo-AF, ST, SB, IVCD, or PAC into the correct diagnosis and reviewed the misinterpreted ECGs and medical records to evaluate inappropriate use of antiarrhythmic drugs (AAD), beta-blockers (BB), calcium channel blockers (CCB), anticoagulation, or resource utilization of cardiology and/or electrophysiology (EP) consultation. Results: A total of 4,969 ECGs were screened with diagnoses of AF (2,282), IVCD (296), PAC (972), SB (895), and ST (638). Among these, 101 ECGs (2.0%) were misinterpreted. Pseudo-AF (58.4%) was the most common followed by pseudo-PAC (14.9%), pseudo-ST (12.9%), pseudo-IVCD (7.9%) and pseudo-SB (6.0%). Patients with misinterpreted ECGs were aged 76.6±11.6yr with male (52.5%) predominance and hypertension being the most prevalent (83.2%) comorbid condition. The misinterpretation of ECGs led to the inappropriate use of BB (19.8%), CCB (5.0%), AAD therapy (7.9%), anticoagulation (6.9%) in patients with pseudo-AF, as well as inappropriate resource utilization including cardiology (41.6%) and EP (8.9%) consultations. Conclusions: Misinterpretation of ECGs may lead to inappropriate medical therapies and increased resource utilization. Therefore, it is essential to encourage physicians to carefully examine AI interpreted ECG’s, especially those interpreted as having AF.