McLeod, Christopher J.

ABSTRACT Background Pulsed field ablation (PFA) is an emerging non‐thermal ablation modality with proven safety in atrial arrhythmia ablation. However, data on its performance for ventricular arrhythmias (VA) remain limited. Objective To evaluate the feasibility, safety, and efficacy of PFA for complex VA in a multicenter real‐world US registry. Methods This retrospective study included consecutive patients undergoing PFA for ventricular tachycardia (VT) or premature ventricular contractions (PVCs) at three Mayo Clinic centers (April 2024 to July 2025). The primary feasibility outcome was the successful delivery of PFA lesions to the intended target substrate. Primary efficacy outcomes included acute procedural success; sustained VT recurrence requiring implantable cardioverter‐defibrillator (ICD) shocks or multiple antitachycardia pacing therapies; and ≥ 80% reduction in PVC burden. Safety outcomes included procedural complications, valvular function, thromboembolic events, renal function, and conduction disturbances. Results Twenty‐six patients were included (13 PVC, 13 VT). Acute success was achieved in all VT ablations (69.2% complete; 30.8% partial) and in 92.3% of PVC ablations. Complications occurred in 11.5% of patients (transient LBBB [ n = 1] and vascular complications [ n = 2]). No thromboembolic events, intracardiac thrombus, or acute kidney injury were observed. Lesions near the mitral valve apparatus did not worsen mitral regurgitation, including in patients with pre‐existing valve disease. After a median follow‐up of 365 days, one patient experienced VT recurrence requiring ICD shocks. Estimated recurrence‐free survival after VT ablation was 61.5% at 12 months; 58.3% of PVC patients achieved ≥ 80% burden reduction. Conclusion PFA for VA appears feasible and acutely effective, with a low rate of procedure‐related complications. While acute success was high, long‐term outcomes were acceptable for VT ablation and relatively modest for PVC ablation, highlighting the need for continued refinement of technology and energy‐delivery strategies. Larger prospective studies are warranted.

Abstract Objectives This study aimed to investigate the procedural characteristics, efficacy, and safety of atrioventricular junction (AVJ) ablation for atrial tachyarrythmia (AT) in patients with congenital heart disease (CHD). Background Although AVJ ablation is an established treatment option for intractable AT in the general population, there is no existing data on this treatment in patients with CHD. Methods Data were analyzed from an observational, retrospective, multicenter cohort, initiated jointly by the Pediatric and Congenital Electrophysiology Society and the International Society of Adult Congenital Heart Disease. Eleven centers contributed baseline, procedural and longitudinal data, including vital status, echocardiographic data, QRS duration, and NYHA class. Outcomes were assessed at early (3 months-1 year), and late follow-up (≥2 years) after AVJ ablation. Results A total of 66 patients (46.7 ± 20.2 years) underwent 71 AVJ ablations. In total, 58.5% had moderate or complex CHD, including 17.1% patients with a systemic RV or single ventricular circulation. The cumulative AVJ ablation success rate was 98.5%. An abnormal location of the atrioventricular conduction pathway was successfully targeted in 20.0% of the patients, which was significantly more common in patients with complex CHD compared to moderate or mild CHD (44.4%, 15.8%, and 3.6%, respectively; both P<0.05). Thirty-six patients (54.5%) underwent primary pacemaker implantation as part of the ‘pace and ablate’ strategy; final pacing modes were VVI pacing in 60.9%, and CRT/CSP in 39.1%. The transplant-free survival rates at 2, 5 and 10 years after AVJ ablation were 91.5%, 84.3%, and 69.0%, respectively. The acute and long-term complication rates were 3.0% and 13.6%, respectively. Conclusions AVJ ablation can be successfully performed in CHD patients with a high acute success rate and low complication rate. Anatomical challenges were common, which underscores the need for careful planning and operator experience. Given the acceptable long-term survival, these findings support the consideration of a ‘pace and ablate’ strategy in CHD patients with intractable AT.

Abstract Background Radiation-induced heart disease (RIHD) may develop months to years following radiation therapy for cancers near the heart such as lung or breast cancer. Several mouse models of RIHD exist to study the pathogenesis of disease, but to our knowledge no studies have examined whether sex differences exist in RIHD in mice. Methods Female and male BALB/cJ mice received one whole heart dose of 22 Gray (Gy) radiation via a C5 collimator vs. sham controls that received 0 Gy, anesthesia and were placed in the X-ray machine for the same length of time. Mechanisms of cardiotoxicity were examined at 24 h (innate cardiotoxicity), day 10 (acute cardiotoxicity) and day 35 (chronic cardiotoxicity) post irradiation. Results Females and males developed dsDNA breaks from radiation at day 10 but females had more damage than males ( p < 0.001). Vessel area and cardiac hypertrophy were increased by radiation at day 10 and 35 but were higher in males than females at day 35 ( p < 0.001, p = 0.001, respectively). Bulk RNA sequencing of the heart at day 10 revealed that females and males developed similar gene pathway responses to radiation by upregulating cellular repair pathways and downregulated mitochondrial function. However, females upregulated the master regulator of mitochondrial function, Pgc1α ( p = 0.0001), suggesting improved mitochondrial repair in females. By day 35, males developed heart failure with reduced ejection fraction (HFrEF), inflammatory dilated cardiomyopathy (iDCM) and fibrosis while females developed heart failure with preserved ejection fraction (HFpEF) without inflammation or fibrosis. Conclusions We observed sex differences in nearly every cardiac parameter that we examined following radiation exposure. BALB/c males exposed to 22 Gy radiation developed HFrEF and iDCM by day 35 while females developed HFpEF. Further research is needed to better understand mechanisms driving sex differences in RIHD using translational animal models.

Abstract Background: Specialised knowledge in adult congenital heart disease is crucial but often lacking, particularly in resource-limited settings. The Global Conversations in Adult Congenital Heart Disease webinar series was initiated to provide accessible, global education via virtual platforms. Objective: This study evaluates the attendance patterns, participant demographics, knowledge outcomes, and audience feedback of the Global Conversations in Adult Congenital Heart Disease webinar series , analysing 19 monthly sessions conducted from October 2023 to April 2025. Methods: Registration data, session viewership, and total series reach were recorded. Demographics were collected per session. Pre- and post-session quizzes were used to assess changes in knowledge; scores from these independent groups were compared using the Mann–Whitney U test. Post-webinar surveys collected improvement suggestions. Results: Out of 1,956 registrants from 89 countries, 54.6% attended the sessions, representing 1,068 participants from 64 nations: mainly Colombia (30.9%), Peru (18%), the USA (14.1%), and Mexico (9.9%). Median quiz scores improved from 50% pre-session ( n = 120) to 100% post-session ( n = 108), a statistically significant gain ( p = 0.035). Notably, 29% had no prior adult congenital heart disease education. Most post-webinar survey respondents rated case presentations and discussions as excellent (75.0%) or good (20.1%). Qualitative feedback suggested areas for improvement included audiovisual quality, audience engagement, content delivery, and language accessibility. Conclusion: The Global Conversations in Adult Congenital Heart Disease webinar series successfully engaged a diverse international audience and showed significant differences in quiz scores between pre- and post-session independent groups, demonstrating the potential benefit and feasibility of virtual education in bridging gaps in adult congenital heart disease training, particularly in resource-limited countries.

Abstract Aims The clinical significance of early recurrences during the blanking period following pulmonary vein isolation (PVI) remains uncertain, particularly after pulsed field ablation (PFA). This study aimed to evaluate the prognostic impact of early recurrences at 30-, 60-, and 90-day thresholds on outcomes following PFA for atrial fibrillation (AF). Methods and results Consecutive patients who underwent PFA for AF across multiple centres within the Mayo Clinic health system were included. The primary endpoint was AF-free survival. Kaplan–Meier and multivariate Cox regression analyses were performed to compare outcomes between patients with and without early recurrences using 30-, 60-, and 90-day thresholds. A total of 1162 patients were included. The estimated AF-free survival at 1 year was 70%. Early recurrences within 30-, 60-, and 90-days post-ablation were significantly associated with late recurrences beyond 90 days (hazard ratio [HR] 5.9, 95% confidence interval [CI] 4.4–7.9, P &lt; 0.01; HR 6.6, 95% CI: 5.0–8.6, P &lt; 0.01; and HR 9.1, 95% CI: 7.0–11.7, P &lt; 0.01, respectively). These findings remained significant among patients undergoing continuous rhythm monitoring. Early recurrences within 30 days in this subgroup were significantly associated with a 1-year AF burden &gt;1% or the need for repeat AF ablation (odds ratio 25.0, 95% CI: 6.6–126.8, P &lt; 0.01). Conclusion Early recurrences following PFA are strongly predictive of long-term arrhythmia recurrence and are unlikely to represent transient inflammatory phenomena. Accordingly, the applicability of the conventional blanking interval after PFA should be reconsidered.

Background: Subaortic membrane (SAM) is a fibromuscular ridge beneath the aortic valve that causes fixed left ventricular outflow tract (LVOT) obstruction. Surgical resection is the standard treatment for symptomatic patients or those with high gradients; however, recurrence occurs in up to 14% of adults within 5 years. While radiofrequency ablation (RFA) is well-established in arrhythmia management, its role in treating SAM has not been previously described. Case Information: 53-year-old man with HTN, BMI 51.7, and well-controlled OSA presented with worsening exertional dyspnea and fatigue in April 2024. He had prior surgical SAM resection in 2018, complicated by third-degree AV block requiring pacemaker implantation. Follow-up echocardiography revealed SAM recurrence with peak LVOT gradient of 52 mmHg. Given elevated surgical risk, a novel catheter-based RFA approach was pursued. In July 2024, the patient underwent catheter-based RFA under general anesthesia. A ThermoCool SmartTouch SF catheter was advanced retroaortically across the aortic valve toward the subaortic ridge, guided by CARTO 3 with CartoSound. A semi-circular lesion set was delivered to the septum inferior to the membrane. Two steam pops occurred during ablation in this area. Serial transthoracic echocardiograms at 3 and 8 months demonstrated sustained LVOT gradient reduction, from 52 mmHg pre-ablation to 49 mmHg and 38 mmHg, respectively. Left ventricular ejection fraction (EF) remained stable at 61%, with no new wall motion abnormalities or pericardial effusion. The patient reported marked improvement in symptoms and normalization of daily activity tolerance. No procedural complications or hospital readmissions occurred. Decision-Making: Given the patient’s high surgical risk and recurrent symptoms, the multidisciplinary team determined that repeat sternotomy carried elevated morbidity. RFA offered a targeted, minimally invasive solution that leveraged electrophysiology tools and preserved structural integrity while maximizing safety. Conclusions: This first-in-human case illustrates the feasibility of intracardiac RFA for recurrent SAM. The patient experienced sustained LVOT gradient reduction, preserved EF, and marked symptomatic improvement. This novel approach may offer a viable option for select patients with recurrent subaortic obstruction and prior sternotomy, warranting further investigation to define lesion durability, depth of tissue effect, and conduction system safety.

Background: Critical congenital heart disease (CCHD) screening algorithms based on pulse oximetry have up to 27% false positive rate at high altitudes (>2500 m) despite altitude-specific cutoff changes. We examined the added value of an adult-based AI model applied to phonocardiography (AI-PCG) in the digital stethoscope EKO Core 500 in these settings. Research Question: What is the diagnostic performance of AI-PCG model compared to pulse oximetry in detecting neonatal CCHD across different altitudes in Latin America? Methods: This observational, prospective, case-control study included newborns born at different altitudes from 0 to 4380 meters in Peru, Mexico, Colombia and Bolivia. All underwent preductal and postductal oximetry at least 18 hours after birth, electrocardiography and PCG with the digital stethoscope. All CCHD cases were confirmed by echocardiography. Non-CCHD cases were defined by echocardiography or clinically if they were alive for 1 month and had 1) negative pulse oximetry, 2) no hospitalization due to cardiac or pulmonary causes and 3) no cyanosis or pneumonia. Those with abnormal pulse oximetry, genetic syndromes or murmur detection underwent echocardiography. Diagnostic performance metrics [area under the receiving operating characteristic curve (AUROC), sensitivity, specificity and false positive rate] were evaluated per modality. Results: A total of 1152 newborns were enrolled, 725 at <2500 m [13 (1.8%) with CCHD] and 427 at >2500 m [6 (1.4%) with CCHD]. Out of 19 CCHD cases, 17 had positive pulse oximetry and 9 had a positive AI-PCG model. One newborn with severe coarctation of the aorta and atrial septal defect had negative pulse oximetry and AI-PCG model. Pulse oximetry showed superior AUROC (0.932 vs 0.664), sensitivity (89.5% vs 47.4%), specificity (97% vs 85.5%) and lower false positive rate (3% vs 14.5%) compared to the AI-PCG model across altitudes. Diagnostic accuracy varied with altitude (Figure): at <2500 m, pulse oximetry showed higher AUROC (0.999 vs 0.612) and lower false positive rate (0.1% vs 16%) than AI-PCG model, but at >2500 m, pulse oximetry had similar AUROC (0.794 vs 0.774) and lower false positive rate (7.8% vs 11.9%) than the AI-PCG model. Conclusion: Pulse oximetry has superior diagnostic performance than an adult-based AI-PCG model when screening for neonatal CCHD at <2500 m, but similar performance is found >2500 m.

Background There is a global mismatch between the number of adults with congenital heart disease and adult congenital heart disease (ACHD) cardiologists, potentially impacting patient outcomes. This survey explores factors influencing trainees and cardiologists' career choices in ACHD. Methods An online, anonymous global survey on demographics, ACHD as a career choice, encouraging and deterring factors assessed via a 5‐point Likert scale and open‐ended questions on recommending ACHD was distributed through targeted emails and social media. Responses meeting a 75% completion criterion were analyzed using descriptive statistics and thematic analysis. Results Among 811 included responses, most were from women (53.5%), aged 31 to 40 years (48.3%), White individuals (43.3%), non‐Hispanic individuals (85%), from outside the ACHD field (79.0%), and from North America (42.7%). Only 30.9% of non‐ACHD physicians considered specializing in ACHD despite 78.9% recommending it. Encouraging factors included awareness of ACHD significance, mentor influence, and clinical exposure. Key deterrents were inadequate financial incentives, limited job opportunities, and lengthy training. Regional variations showed that longer training duration and lack of compensation incentives were the main deterrents in North America. Suggested solutions included structured training programs, salary improvements, and early ACHD exposure during medical education. Conclusions Less than a third of respondents considered ACHD as a career largely due to inadequate financial incentives, limited job opportunities, and long training duration. Addressing these barriers could enhance recruitment and help meet the growing demands of the ACHD population.

Abstract Background and Aims There is a paucity of data on arrhythmia burden in patients with congenitally corrected transposition of the great arteries (ccTGAs). The present study sought to quantify the incidence of atrial arrhythmia (AA), ventricular arrhythmia (VA), and complete atrioventricular block (CAVB) in patients with ccTGA and identify associated factors. Methods An international, multi-centre, retrospective cohort study was conducted in 29 tertiary hospitals (six countries) between 1990 and 2018. Primary analyses consisted of determining the incidence of a combined outcome consisting of AA, VA, or CAVB, along with its individual components. Factors associated with the different types of arrhythmias were assessed by uni-variable and multi-variable Cox regression analyses. Results A total of 1131 patients with ccTGA were followed for 9.0 (interquartile range 4.0–17.2) years. Cumulative rates of the primary endpoint at 10, 15, and 20 years were 44.5%, 51.0%, and 58.8%, respectively. AA, VA, and CAVB occurred in 2.1, 1.4, and 2.0 cases per 100 person-years, respectively. In multi-variable analyses, surgery/intervention conferred a greater than three-fold higher risk of AA [hazard ratio (HR) 3.01, 95% confidence interval (CI) 1.90–4.78, P &lt; .001]. Furthermore, surgery/intervention was significantly associated with a greater risk of VA (HR 1.73, 95% CI 0.98–3.05, P = .003) and CAVB (HR 3.65, 95% CI 2.20–6.05, P &lt; .001). The left bundle branch block was associated with a higher risk of VA (HR 4.03, 95% CI 1.59–10.23, P = .003) and the right bundle branch block with a higher risk of CAVB (HR 3.71, 95% CI 1.81–7.63, P &lt; .001). Conclusions The arrhythmia burden in patients with ccTGA is substantial, with a high incidence of AA, VA, and CAVB.