Siontis, Konstantinos C.

Abstract Aims Artificial intelligence electrocardiography (AI-ECG) algorithms are emerging tools for identifying individuals at risk of atrial fibrillation (AF). We evaluated the predictive performance of a validated AI-ECG algorithm for incident AF in UK Biobank participants with AF risk factors, irrespective of prevalent cardiovascular disease, and its incremental value when added to clinical predictors. Methods and results The AI-ECG tool was applied to sinus rhythm ECGs from UK-Biobank participants with risk factors for AF but no AF. Model performance was evaluated using time-dependent ROC-AUC and Harrell’s C-index. Multivariable Cox regression was used to identify clinical risk factors associated with incident AF and to quantify the contribution of AI-ECG. A total of 21 842 participants (56% male) were included. The median follow-up time was 3.7 years (IQR 0.5–5.4) The ECG-AI tool achieved a ROC-AUC of 0.73 (95% CI 0.68–0.78) at 1 and 0.69 (95% CI 0.66–0.72) at 3 years. A multivariable Cox regression model using clinical parameters achieved a ROC-AUC of 0.71 (95% CI 0.66–0.75) at 1 and 0.71 (95% CI 0.68–0.74) at 3 years. By adding ECG-AI to the clinical Cox regression model, the ROC-AUC increased to 0.75 (95%CI 0.71–0.80) at 1 and 0.74 (95% CI 0.71–0.77) at 3 years. AI-ECG showed a hazard ratio of 1.23 per decile increase (95% CI 1.18–1.27). Conclusion An AI-ECG algorithm improved the prediction of incident AF when added to a clinical parameter-based model over a median follow-up time of 3.7 years among individuals with comorbidities predisposing to AF who may benefit from targeted screening and preventive strategies.

Abstract Aims Intracardiac echocardiography (ICE) is increasingly incorporated into atrial fibrillation (AF) ablation workflows, enabling real-time anatomic guidance and procedural precision. Nevertheless, ICE utilization shows substantial geographic variability, and its clinical benefit remains incompletely understood. This meta-analysis evaluated the efficacy, safety, and procedural performance of ICE-guided vs. non-ICE-guided AF ablation. Methods and results MEDLINE, the Cochrane Library, and Scopus were systematically searched through 3 August 2025. Three reviewers independently performed study selection, data extraction, and risk-of-bias assessment. Random-effects models were used to pool data from 44 AF ablation studies comprising 482 043 patients. ICE guidance was associated with lower odds of any complication (OR 0.69; 95% CI 0.53–0.89), including significant reductions in cardiac tamponade (OR 0.58; 95% CI 0.53–0.62) and mortality (OR 0.21; 95% CI 0.16–0.27). ICE-guided ablation was also associated with shorter total procedure and fluoroscopy times, reduced radiation exposure, and lower contrast agent utilization. Atrial tachyarrhythmia (AT) recurrence did not differ between groups (OR 0.92; 95% CI 0.79–1.06). However, ICE use was associated with higher odds of first-pass pulmonary vein isolation (OR 1.62; 95% CI 1.09–2.41) and successful isolation of all pulmonary veins at the end of the procedure (OR 2.12; 95% CI 1.37–3.27), and lower odds of repeat ablation (OR 0.65; 95% CI 0.59–0.72). Conclusion ICE-guided AF ablation is associated with superior procedural safety and efficiency and a similar risk of AT recurrence compared to non-ICE-guided approaches.

BACKGROUND: Cardiac radioablation is emerging as a treatment modality for refractory ventricular tachycardia. This study aimed to evaluate the effects of radiation on the coronary arteries in a swine model of proton beam cardiac radioablation. METHODS: Eighteen swine underwent single-fraction 30 to 40 Gy pencil-beam scanning proton therapy targeting the left ventricle and were euthanized 12 to 40 weeks later. Treatment planning was performed without restricting the dose to the coronary arteries. The maximum point dose (D max ) to the epicardial coronary arteries was calculated. In secondary analyses, the mean (D mean ) and minimum dose received by the highest irradiated 0.01 cm 3 (D 0.01 ) of each coronary artery were also calculated. Coronary artery segments were harvested from the D max sites for histological analysis, and the D max was correlated with stenosis severity. RESULTS: Ninety-six coronary arteries were analyzed. No stenoses were observed by computed tomography imaging preirradiation. By histological analysis posteuthanasia, 25/96 (26%) coronaries sampled at their D max sites had ≥75% stenosis. The median D max was 4.7 Gy for the <75% stenosis group and 29.7 Gy for the ≥75% stenosis group ( P <0.001). The AUC-ROC for the association between D max and stenosis ≥75% was 92.2%. A D max value of 20.1 Gy best predicted stenosis ≥75%, with sensitivity 92.3% and specificity 87.1%. The AUC-ROCs for the associations of D mean and D 0.01 with stenosis ≥75% were 84.8% and 91.6%, respectively. In histopathologic analysis, intimal hyperplasia was the most common coronary artery abnormality at the D max sites, and it was present in 61.5% of all arteries and in 93.9% of arteries with D max ≥20 Gy. CONCLUSIONS: In this preclinical model of proton beam cardiac radioablation, coronary stenoses occurred in a dose-dependent manner, with D max showing the closest correlation with stenosis ≥75%. These data provide for the first time a framework for dose constraint considerations for the coronary arteries during treatment planning for cardiac radioablation and thoracic malignancy radiation.

ABSTRACT Background Ventricular tachycardia (VT) is a life‐threatening arrhythmia frequently observed in structural heart diseases, including LMNA‐related cardiomyopathy, a genetic disorder associated with high risk of sudden cardiac death and progressive systolic dysfunction. While catheter ablation is an established therapeutic option for VT, its efficacy in cardiac laminopathy remains poorly defined. Objectives To synthesize available evidence on the role and outcomes of VT ablation in patients with cardiac laminopathy. Methods A systematic review and single‐arm meta‐analysis was performed in accordance with PRISMA guidelines. PubMed, Embase, and Cochrane databases were searched for studies reporting VT ablation outcomes in LMNA‐related cardiomyopathy. An inverse variance random‐effects model was applied for meta‐analysis of proportions. Results Seven studies (six cohorts, one abstract) comprising 62 patients (mean age 53.2 ± 9.7 years; 85% male; 88% with implantable cardioverter‐defibrillator) were included. An endocardial/endo‐epicardial approach was used in 93% of cases. Acute procedural success was achieved in 37% (95% CI: 14%–63%; I² = 27.4%), and 28% required multiple procedures. Over a median follow‐up of 26 (9–35) months, VT recurrence occurred in 91% (95% CI: 76%–100%; I² = 37.2%). All‐cause mortality was 54% (95% CI: 39%–70%; I² = 28%), predominantly from cardiac causes (51%, 95% CI: 25%–76%; I² = 53%), and 14% (95% CI: 1%–34%; I² = 42%) underwent heart transplantation. Conclusions In LMNA‐related cardiomyopathy, catheter ablation is associated with high VT recurrence, limited long‐term success, and substantial cardiovascular mortality and transplantation rates, underscoring the importance of ICD implantation and the need for alternative strategies, including variant‐specific and molecularly targeted therapies.

ABSTRACT Background Early catheter ablation for atrial fibrillation (AF) improves outcomes, but the optimal timing, especially in heart failure (HF) subtypes, remains unclear. Objective To evaluate the impact of ablation timing on outcomes in patients with HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). Methods We used the TriNetX database (2010–2024) to identify HF patients with AF who underwent ablation. Patients were classified as early ablation (≤ 1 year of first AF diagnosis) or delayed ablation (1–3 years), with propensity score matching (PSM) applied to balance the baseline characteristics. The primary outcome was AF recurrence, defined by repeat ablation, direct current cardioversion (DCCV), or antiarrhythmic drug (AAD) use after a 3‐month blanking period. Secondary outcomes included stroke, hospitalization, and mortality over 5 years. Results After PSM, delayed ablation was associated with higher AF recurrence in both HFrEF (HR = 1.28, p < 0.001) and HFpEF (HR = 1.21, p = 0.02), as seen in multivariate analysis. In HFrEF, delayed ablation was associated with higher incidence of re‐do ablation, AAD use, and DCCV, while in HFpEF, higher recurrence with delayed ablation was associated with increased AAD use. Both cohorts had similar stroke and mortality rates between early and delayed ablation. Conclusions Delayed ablation in HFrEF and HFpEF was linked to higher AF recurrence, driven by increased redo ablations, DCCV, AAD use in HFrEF, and higher AAD use in HFpEF. Stroke, HF hospitalization and mortality rates were similar, suggesting earlier ablation may enhance rhythm control over other outcomes.

Background: Ventricular tachycardia (VT) is a potentially life-threatening arrhythmia frequently observed in structural heart diseases, including cardiac laminopathy, a genetic cardiomyopathy associated with a high risk of sudden cardiac death (SCD) and progressive systolic dysfunction caused by pathogenic variants in LMNA -encoded lamin A/C. While catheter ablation is a key therapeutic strategy for VT management, its efficacy in cardiac laminopathy remains poorly defined. Objective: This systematic review and single-arm meta-analysis aims to synthesize the available evidence in the literature on the role of VT ablation for patients with cardiac laminopathy. Methods: A single-arm meta-analysis was conducted following PRISMA guidelines, systematically searching PubMed, Embase, and Cochrane databases for studies investigating VT ablation outcomes in patients with cardiac laminopathy. We applied an inverse variance random-effects model for a meta-analysis of proportions. Results: We included 6 cohort studies and 1 abstract comprising 62 patients with LMNA-related cardiomyopathy (mean age at 53.2 ± 9.7 years, 85% males, and 88% with an ICD). The predominant ablation strategy was endocardial/endo-epicardial in 93% of cases. Acute success rate following VT ablation was 37% (95% CI: 14 to 63%) and 28% of the patients required multiple procedures. Over a median follow-up of 26 (9-35) months, VT recurrence rate after ablation was 91% (95% CI: 76 to 100%; Figure A ). The all-cause mortality rate was 54% (95% CI: 39% to 70%; Figure B ), primarily driven by cardiac causes 51% (95% CI: 25 to 76%; Figure C ). There was an elevated rate of heart transplantation 14% (95% CI: 1 to 34%), highlighting overall poor outcomes in this patient population. Conclusion: Catheter ablation in cardiac laminopathy is associated with limited long-term efficacy, with high rates of VT recurrence, cardiovascular mortality and heart transplantation. These findings underscore the importance of ICD implantation for primary prevention and the pressing need to develop alternative treatment strategies. Further research is necessary to determine whether specific LMNA variants influence ablation outcomes and to explore emerging therapies targeting the underlying molecular mechanisms of cardiac laminopathy.

Background: Ventricular tachycardia (VT) is a major contributor to death among ischemic heart disease (IHD) patients. In this systematic review and meta-analysis, we evaluate the efficacy of catheter ablation in patients with ischemic cardiomyopathy. Methods: We conducted a meta-analysis by searching the electronic database up to April 2025. Seven studies, including 1192 patients, were identified. A random-effect model was used to estimate pooled risk ratios (RRs) and 95% confidence intervals (CIs). Trial sequential analysis was conducted to assess sample size adequacy. Results: Among Ischemic heart disease patients with ICDs, VT ablation was associated with a significant reduction in ICD shocks (RR = 0.50, 95% CI [0.34–0.74]), a trend toward reduced VT storm (RR = 0.64, 95% CI [0.40–1.04], p = 0.07), and lower rates of cardiovascular hospitalization (RR = 0.73, 95% CI [0.53–1.01], p = 0.06) compared to ICD alone. However, no significant differences were observed when compared to patients receiving ICD plus antiarrhythmic drugs (AADs). Additionally, VT ablation showed no significant impact on mortality or VT/VF recurrence compared to either ICD alone or ICD with AADs. Trial Sequential Analysis provided conclusive evidence for VT/VF recurrence outcomes, while further data are required for other outcomes. Conclusion: Among ischemic heart disease patients with ICD, VT ablation reduces ICD shocks, VT storm, and cardiovascular hospitalizations compared to ICD-only, but offers no significant advantage over ICD combined with antiarrhythmic drugs. VT ablation does not impact mortality or the recurrence of VT/VF. Trial Sequential Analysis confirmed conclusive evidence for VT/VF recurrence, while additional data is needed for other outcomes.

Background: Atrial fibrillation (AF) is the most common sustained arrhythmia with prevalence increasing over the last decade. However, data on recent temporal trends in incidence of AF have been inconsistent, with some reports of increasing trends over time and others indicating no change in incidence over time. Therefore, we aimed to determine how the incidence of AF has changed over the last decade in a community in the Midwest USA. Methods: Between 2013 and 2023, adults (aged 18 and older) with incident AF were identified in a 27-county region in the Midwest. AF was identified using diagnostic codes by employing an electronic algorithm requiring 1 inpatient code or 2 outpatient codes separated by >7 days but within 1 year. For total rates, age - and sex-adjusted incidence rates were standardized to the 2010 US total population. Poisson regression was used to calculate the incidence rate ratio of AF for 2023 vs 2013. Results: We identified 44,930 individuals with incident AF from 2013 to 2023. Of these, 56.4% were male, the mean (SD) age was 72.8 (13.5) years, and 95.8% were non-Hispanic white. The age-and sex-adjusted incidence rates (per 1,000) and 95% confidence intervals standardized to the 2010 US total population were 5.24 (5.07-5.41) in 2013, 5.73 (5.56-5.91) in 2018, and 5.44 (5.28-5.61) in 2023. Although a drop in incidence was observed corresponding to the COVID-19 pandemic, a small increase in the overall incidence of AF was observed over time. The overall incidence rate ratio (95% CI) for 2023 vs 2013 was 1.07 (1.02-1.11), P=0.003. The incidence rates were higher in men compared to women and increased with older age ( Figure 1 ). However, differences in AF incidence by sex were greatest in the youngest age group and attenuated with older age (incidence rate ratio (95% CI): 2.18 (2.10-2.28) for ages 18-64 years, 1.76 (1.70-1.83) for ages 65-74 years, 1.38 (1.33-1.42) for ages 75-84 years, and 1.23 (1.18-1.28) for ages 85 years and older). Conclusion: In this 27-county region in the Midwest, although small in magnitude, a statistically significant increase in AF incidence was observed over time from 2013 to 2023. Furthermore, the incidence of AF was higher in men compared with women, especially in younger age groups.

Background: Cardiac radioablation (CRA) is emerging as a treatment modality for refractory ventricular tachycardia (VT). This study aimed to evaluate the effects of radiation on the coronary arteries in a swine model of proton beam CRA. Methods: Eighteen domestic swine underwent 30–40 Gy pencil-beam scanning proton therapy in a single-fraction targeting the left ventricle with no attempt to spare coronary arteries and were euthanized 12-40 weeks later. Contrast-enhanced cardiac computed tomography (CT) was performed at baseline for treatment planning and at study end. Using dose-volume histograms, the maximum point (D max ), mean (D mean ) doses and the minimal doses received by the highest irradiated volumes of 0.01 cc (D 0.01cc ) for the left main, left anterior descending, circumflex, and right coronary artery, as well as the large diagonal and obtuse marginal branches were calculated. The D max location for each artery was mapped from the baseline planning CT onto the follow-up CT using deformable registration. Coronary artery segments were harvested from the D max sites for histological analysis. Receiver operating characteristic (ROC) analysis was performed to identify dose thresholds for predicting histologically severe coronary stenoses (≥75%). Results: Ninety-six coronary artery segments were analyzed. No stenoses were observed by CT imaging before irradiation. By histological analysis post-euthanasia, 25/96 (26%) coronary segments sampled at the Dmax site per artery had ≥75% stenosis. The median D max was 4.7 Gy for the <75% stenosis group and 29.7 Gy for the ≥75% stenosis group (p<0.001). The AUC-ROC for the association between D max and severe stenosis was 92.2%. A D max value of 20.1 Gy in a single fraction best predicted severe stenosis, with sensitivity of 92.3% and specificity of 87.1%. The AUC-ROC for the association between severe stenosis versus D mean and D 0.01cc was 84.8% and 91.6%, respectively. Based on histopathologic analysis, intimal hyperplasia was the most common coronary artery abnormality at the D max sites. Conclusion: In this pre-clinical model of proton beam CRA, coronary stenoses occurred in a dose-dependent manner, with D max being a better dosimetric predictor of stenosis than D mean and D 0.01cc . These data provide for the first time radiation dose constraint information for the epicardial coronary arteries that can be considered in treatment planning for CRA and radiation for thoracic malignancies.

Background: Dofetilide, a commonly prescribed class III antiarrhythmic for atrial fibrillation (AF), currently requires a 3-month amiodarone washout period per FDA guidelines. We evaluated the safety of initiating dofetilide within this 3-month washout period. Methods: We performed a retrospective cohort study across all Mayo Clinic sites and identified patients using centralized datamart that were transitioned from amiodarone to dofetilide in less than 90 days. Patients were included and confirmed by manual chart review if they had been on amiodarone for ≥ 12 weeks and if available amiodarone level >0.3 mg/ml at the time of dofetilide initiation. Serial ECGs were assessed during the hospitalization for dofetilide initiation and at 3-, 6-, and 12-months follow-up to evaluate QT interval. Primary safety end point was torsade de pointes. Results: The final cohort included 66 patients with a mean age of 65 ±14 years; 71.0% were male; and the average BMI was 29.6 ±5.1 kg/m 2 . Of the 66 patients, 65 had a history of AF: 31.8% paroxysmal, 54.5% persistent, and 12.1% long-standing persistent. Permanent pacemakers and ICDs were present in 27.3% and 22.7% of patients. Patients received amiodarone for a median of 7.8 months at a mean daily dose of 187.1±48.3 mg (range: 100 – 400 mg), with a mean transition period of 44.2±20.3 days. Of 66 patients, 16 (24 %) transitioned within 30 days of stopping amiodarone—including 5 (8 %) within 14 days—while the remaining 50 (76 %) was between 30 and 90 days. A total of 24.2% (16/66) patients required dofetilide dose reduction due to QT prolongation and 10.6% of patients (7/66) required drug discontinuation. There was no difference in either discontinuation rate or dose reduction rate in patients with a transition period ≤30 days vs > 30 days [6.25% vs. 12% (p=0.85) and 12.5% vs. 28% (p=0.36), respectively]. No cases of torsades de pointes were observed during dofetilide initiation or follow up. Conclusion: In this cohort, dofetilide initiation less than 90 days after amiodarone discontinuation was not associated with increased torsades de pointes risk. These data challenge and support reconsideration of the blanket 3-month washout and suggest that a monitored, expedited rhythm-control transition is feasible and safe.