JACC: Clinical Electrophysiology

Background: Catheter ablation is the most effective rhythm control strategy for atrial fibrillation (AF); however, recurrence remains common. Current post-ablation management follows largely population-level protocols, constrained by the absence of tools that can anticipate not merely whether, but when, an individual patient will experience recurrence. The emergence of multimodal artificial intelligence (AI) presents a new opportunity to address this unmet clinical need. Objective: To develop a predictive model for time-to-AF-recurrence post-ablation using pre-procedural bi-atrial imaging, clinical covariates, and procedural characteristics, within a novel multimodal AI and survival analysis framework. Methods: We analyzed a retrospective cohort of 437 AF patients who underwent catheter ablation with follow-up censored at 36 months. MARTA-AF (Multimodal AI Recurrence and Time-to-event Analysis post-Ablation in AF) was trained on pre-procedural bi-atrial images, and covariates/procedural characteristics, and integrated into a survival model to generate time-varying recurrence probability estimates. Model interpretability was achieved by quantifying contribution of covariates/procedural characteristics to predicted survival probabilities. Results: MARTA-AF successfully predicted time-varying recurrence risk up to three years post-ablation. Patients were effectively stratified into low- and high-risk groups, with statistically significant discrimination sustained over the follow-up period. The model demonstrated consistent performance across clinically relevant subgroups, including sex, age, and AF type. Incorporation of right atrial shape features improved time-to-AF-recurrence prediction. Interpretability analyses identified key recurrence predictors. Conclusions: MARTA-AF delivers individualized, time-varying AF recurrence risk forecasts and enables stratification into clinically meaningful risk groups. This framework has the potential to transform post- ablation management into a proactive paradigm and to support informed clinical decision-making prior to ablation.

Catheter ablation is an established rhythm-control strategy for atrial fibrillation, but outcomes in persistent atrial fibrillation (PsAF) remain heterogeneous across evolving strategies and energy modalities. An updated synthesis is needed to define current effectiveness and adverse-event profiles in the modern ablation era. We conducted a systematic review and meta-analysis of prospective clinical trials of catheter ablation for PsAF published from 2010 through December 2025. We included randomized and nonrandomized prospective interventional studies reporting effectiveness and adverse events, and pooled outcomes using random-effects models. Prespecified subgroup analyses evaluated ablation strategy (pulmonary vein isolation [PVI] vs PVI with adjunctive lesion sets [PVI+]), ablation modality (radiofrequency [RF], cryoballoon [CRYO], and pulsed field [PF]), and endpoint definition (recurrence-only vs composite measures). Thirty-two studies (9,194 patients) met inclusion criteria; 28 (7,948 patients) contributed to effectiveness analyses. The pooled 12-month arrhythmia-free proportion was 0.65 (95% CI, 0.61-0.68), with substantial heterogeneity. Effectiveness was numerically higher with PVI+ than PVI-only (0.66 [0.60-0.72] vs 0.63 [0.59-0.67]), similar for PF (0.65 [0.57-0.72]) and RF (0.65 [0.61-0.69]), and slightly lower for CRYO (0.64 [0.54-0.74]). Recurrence-only endpoints yielded higher effectiveness than composite endpoints (0.67 [0.63-0.71] vs 0.60 [0.55-0.64]). Safety analyses included 32 studies (9,002 patients). Adverse events were low but heterogeneous (0%-14.56%); pooled vascular access and pericardial complication incidences were each 1%, while thromboembolic events, accessory organ injury, and mortality were rare (pooled 0%). PF ablation showed numerically lower overall complication incidences than RF and CRYO. In contemporary trials, catheter ablation for PsAF shows moderate effectiveness and low overall adverse-event risk. Adjunctive strategies and PF ablation are promising, but no approach is consistently superior. These findings support tailored, patient-specific ablation selection in PsAF.

The heart maintains systemic perfusion through the coordinated function of its four chambers: the left and right atria and ventricles. Each chamber has distinct structural, functional, and molecular properties tailored to its role in circulation, which may result in chamber-specific differences in myofilament structure and regulation between atria and ventricles. To test this hypothesis, we employed muscle mechanics and X-ray diffraction to investigate functional and structural differences in porcine left atrial (LA) and left ventricular (LV) tissue. Here, we report the first X-ray diffraction study of atrial tissue, demonstrating that under resting conditions, myosin filaments in LA adopted a more ON-like, structurally distinct configuration compared with those in LV. Under contracting conditions, LV generated greater force and exhibited higher sinusoidal stiffness than LA across multiple calcium concentrations. LA showed faster kTR than in LV, with no calcium-dependence, in contrast to the calcium-dependence of kTR seen in LV. Structurally, the distinct myosin head configuration seen in the relaxed LA persisted during contraction. Furthermore, using the troponin inhibitor MYK-7660 to inhibit active contraction, we showed that, unlike LV, LA showed no direct calcium-dependent thick filament activation, reconciling discrepancies between fast rat and slow porcine ventricular myocardium regarding calciums role in thick filament regulation. Altogether, our study reveals that LA myosin filaments adopt a molecular architecture and regulatory mechanism distinct from their LV counterparts, suggesting that myosin filament structure and regulation have evolved differently to meet the unique functional demands of each cardiac chamber. Moreover, atrial disease is often associated with cardiomyopathy-related genetic variants, highlighting the atrial myocardium as an important therapeutic target and understanding atrial-specific regulatory mechanisms provides new insights into therapeutic strategies for atrial diseases.

Optogenetic defibrillation uses light-gated ion channels to terminate cardiac arrhythmias through targeted illumination. Previous studies assessed the feasibility of using either cation (e.g. ChR2) or anion (e.g. GtACR1) non-selective channels, both of which depolarise resting cardiomyocytes upon photoactivation. In contrast, recently identified light-gated K+-channels (e.g. WiChR) suppress cardiomyocyte activity while maintaining the membrane potential near its resting state. Here, we use biophysically detailed simulations to compare the defibrillation potential of ChR2, GtACR1, and WiChR. Single-cell simulations show that activation of ChR2 and GtACR1 markedly increase diastolic intracellular Ca2+ concentration (by 42.6% and 52.6%, respectively), whereas WiChR induces only minimal changes (4.0% increase), suggesting a lower pro-arrhythmogenic risk. WiChR activation, however, slightly increases intracellular Na+ levels (by 15.1% compared to 0.1% and 3.4% for ChR2 and GtACR), consistent with the residual Na+ permeability of all currently available K+-selective channelrhodopsins. Simulations of human ventricles and atria demonstrate that GtACR1 most effectively terminates re-entrant arrhythmias at low light intensities, while WiChR achieves comparable efficacy at light levels [≥]5 mW/mm2. Complementary tissue-scale simulations reveal that defibrillation is either based on depolarisation within the excitable gap, followed by fast Na+ channel inactivation (depolarising variants ChR2 and GtACR1), or based on a reduction in membrane resistance supporting arrhythmia termination at sufficiently high light levels (large-conductance ion channels GtACR1 and WiChR). Overall, our findings identify channelrhodopsin ion selectivity as a key determinant of both arrhythmia termination success and mechanisms underlying defibrillation. Key points summaryO_LIWe use computational simulations to compare non-selective cation (ChR2), anion (GtACR1), and K+-selective channelrhodopsins (WiChR) for optogenetic termination of re-entrant arrhythmia. C_LIO_LISingle-cardiomyocyte simulations suggest that ChR2 and GtACR1 activation can cause progressive accumulation of intracellular Ca2+, which is minimised when using WiChR. C_LIO_LISimulations of human left ventricles and atria indicate that GtACR1 is most effective in terminating re-entrant arrhythmia at low light intensities, while WiChR becomes similarly effective at higher intensities. C_LIO_LITissue-scale simulations indicate distinct defibrillation mechanisms: Excitable gap extinction by de-novo action potential initiation followed by inactivation of fast Na+ channels for depolarising channelrhodopsins (ChR2, GtACR1), and reduction in membrane resistance for the large-conductance channels (GtACR1, WiChR), effectively clamping the membrane potential at each channels reversal potential at high light levels. C_LI

Background Atrial fibrillation (AF) is a leading cause of stroke, cardiovascular morbidity, and mortality. Atrial myopathy, characterized by progressive metabolic, electrical, and structural changes, creates the arrhythmogenic substrate that drives AF. Defining the key drivers of atrial myopathic processes is essential for targeted therapies that can mitigate AF progression. Here we explore how reduced ERBB4 expression contributes to the development of left atrial myopathy. Methods We analyzed the Cleveland Clinic Biobank to compare left atrial ERBB4 levels in patients grouped by AF diagnosis. To investigate the impact of reduced ERBB4 levels on atrial tissue substrate, we created mouse models of cardiac-specific Erbb4 deficiency using Mlc2a (myosin light chain 2a)-Cre. Comprehensive physiological assessments were performed. Transcriptomic analyses of the left atrium were performed in an Erbb4 haploinsufficient mouse model and compared with human atrial datasets. Molecular validation of key dysregulated pathways was performed. Results We found that left atrial ERBB4 levels are reduced in patients with AF. Adult cardiomyocyte-specific Erbb4 heterozygous (Erbb4fl/+;Mlc2a-Cre) mice exhibited prolonged P-wave duration in the absence of ventricular dysfunction. Left atrial transcriptomic analysis in Erbb4 haploinsufficient mice showed upregulation of pathways related to fibrosis, apoptosis, and coagulation, and downregulation of pathways related to fatty acid metabolism and mitochondrial function, mirroring changes observed in pressure overload mouse models. A cross-species transcriptomic comparison revealed significant overlap between ERBB4-correlated gene expression and functional pathways in adult human atria and mice with Erbb4 haploinsufficiency. Validating the transcriptomic data, protein and functional assays demonstrated increased fibrosis, apoptosis, and oxidative stress in the mutant left atrial tissue. Conclusion Left atrial ERBB4 levels are reduced in AF patients. A mouse model of Erbb4 deficiency and human atrial transcriptomic analyses highlight a role for ERBB4 in supporting normal atrial metabolism while protecting against inflammation, apoptosis, and fibrosis.

Background. Peripheral artery disease (PAD) may amplify procedural risk during atrial fibrillation (AF) catheter ablation, but dedicated evidence is lacking. We aimed to evaluate the association between PAD and in-hospital outcomes among adults undergoing AF ablation in the National Inpatient Sample (NIS). Methods. We identified inpatient AF ablation hospitalizations in the 2016 through 2020 National Inpatient Sample using ICD-10-PCS procedure codes and a concurrent AF diagnosis. PAD was identified from ICD-10-CM diagnosis codes used in prior claims-based PAD studies. Stabilized inverse probability of treatment weighting based on the propensity score was used to balance baseline differences. The primary outcome was in-hospital mortality. Fourteen secondary outcomes and 2 composite end points were prespecified. Results. Among 22,166 AF ablation hospitalizations, 899 (4.06%) involved patients with PAD. Compared with patients without PAD, those with PAD were older and had a substantially greater cardiovascular, renal, and smoking/tobacco comorbidity burden. In-hospital mortality did not differ significantly (1.39% vs 1.06%; aOR, 1.32; 95% CI, 0.66 - 2.64; P= 0.44). PAD was associated with higher odds of major bleeding (aOR, 1.62; 95% CI, 1.17 - 2.24; P = 0.004), vascular or access-site complications (aOR, 1.80; 95% CI, 1.04 - 3.12; P = 0.04), acute kidney injury (aOR, 1.31; 95% CI, 1.05 - 1.64; P = 0.02), and composite major adverse hospital events (aOR, 1.29; 95% CI, 1.05 - 1.59; P = 0.02). Total hospital charges were 13% higher (charge ratio, 1.13; 95% CI, 1.04 - 1.22; P = 0.003). Major bleeding, vascular/access-site complications, cardiac arrest, and composite major adverse in-hospital events remained elevated in sensitivity analysis. Conclusion. PAD was independently associated with higher bleeding risk, vascular or access-site complications, acute kidney injury, and composite major adverse hospital event during AF ablation, identifying a clinically relevant subgroup with elevated periprocedural risk.

Drug-induced inhibition of the delayed rectifier potassium (IKr) current predisposes to early afterdepolarisations (EADs) and cardiac arrhythmias. Here, we sought to determine the contribution of action potential duration (APD), APD variability and spontaneous calcium release from the sarcoplasmic reticulum (SR) in the formation of EADs. In isolated sheep ventricular myocytes, EADs were induced by combined inhibition of IKr with dofetilide and {beta}-adrenergic stimulation. The onset of EADs was preceded by increased beat-to-beat variability of APD. To isolate the role of APD in EAD initiation, the sarcoplasmic reticulum (SR) was depleted of calcium with caffeine. The first beat post-caffeine was associated with prolonged APD but not an EAD. During {beta}-AR stimulation, increasing ryanodine receptor open probability had no effect on APD but increased APD variability and induced both EADs and delayed afterdepolarisations (DADs). Targeting RyR open probability with K201 reversibly abolished afterdepolarisations. APD variability was a better predictor of EADs than APD alone. During an EAD, changes in [Ca2+]i preceded those of membrane depolarisation and the changes in [Ca2+]i were in the form of calcium sparks. In silico modelling demonstrated that membrane time constant effects account for the delay between changes in [Ca2+]i and membrane potential. In summary, using a drug-induced model of action potential prolongation with {beta}-AR stimulation, EADs are preceded by increased APD variability and an increase in Ca2+ sparks. Targeting SR function abolishes EADs. These results suggest a key role for SR Ca2+ overload in the formation of EADs and indicate that EADs and DADs share common mechanisms. Key PointsO_LIDrugs that prolong the cardiac action potential and ECG QT interval are a major cause of early afterdepolarisations and dangerous ventricular arrhythmias initiated by early afterdepolarisations. C_LIO_LIProlongation of the action potential is widely assumed to be the primary driver of these events. C_LIO_LIWe show that early afterdepolarisations are instead preceded by increased beat-to-beat variability of action potential duration and that this variability has better sensitivity and specificity for early afterdepolarisations than action potential duration. C_LIO_LISmall, spontaneous calcium release events known as calcium sparks occur before membrane depolarisation driving early afterdepolarisations. C_LIO_LISuppressing calcium release from the sarcoplasmic reticulum abolishes early afterdepolarisations, identifying calcium handling instability as potentially a key mechanism of drug-induced arrhythmia. C_LI

Background and Aims: Clinical interpretation of the precordial leads V1-V6 assumes that Wilson's central terminal (WCT) has a fixed anatomical location. Consequently, a positive signal corresponds to electrical activation spreading from WCT towards the respective electrode, and vice versa. However, the location of WCT has never been systematically investigated. Yet, a better understanding of WCT location could improve the interpretation of the precordial leads. This work aims to characterize the spatial expansion and location of the physical WCT i.e., the electrical potential defined by the WCT, during the P-wave on the body surface. Methods: An intensive analysis of body surface potential maps (BSPMs) during atrial depolarization in an in silico patient cohort and clinical data was conducted. Results: During the P-wave, the location of WCT was not stationary but the spatial extent and location varied across time as well as across individuals. Four distinct spatial patterns of WCT distribution on the body surface were identified in silico, and three of these were found in the clinical cohort. WCT signals agreed with BSPM signals at commonly assumed positions of WCT only for a small fraction of the P-wave. Conclusion: The spatial extension and location of WCT changes during the P-wave and thus should be considered when interpreting the precordial leads.

BACKGROUNDIn addition to lethal ventricular arrhythmias, arrhythmogenic cardiomyopathy (ACM) is associated with conduction abnormalities, bradycardias, and reduced expression of the scaffolding junctional protein zonula occludens-1 (ZO-1). Reduced ZO-1 expression is also seen in dilated cardiomyopathy, which is far more common than ACM. Conduction abnormalities are likewise a feature of ZO-1 cardiac-specific knockout (ZO-1cKO) mice. However, the role of ZO-1 in sinoatrial node (SAN) automaticity has not been studied. OBJECTIVETo investigate the role of ZO-1 in SAN automaticity and elucidate the mechanisms by which ZO-1 deficiency leads to SAN dysfunction. METHODSZO-1 cardiac-specific knockout (ZO-1cKO) mice were generated by crossing ZO-1 floxed mice with MHC-nuclear Cre mice. SAN/atrial tissue and isolated SAN cells were examined using optical mapping, single-cell patch clamp, and quantitative PCR techniques to assess functional alterations caused by ZO-1 loss. RESULTSZO-1cKO mice exhibited enlarged atria and SAN area compared to control mice, with normal left ventricular function. Electrocardiograms showed sinus bradycardia, sinus pauses and atrioventricular block. Optical mapping revealed a caudal shift in the SAN leading region and reduced intra-atrial conduction velocity in ZO-1cKO mice. Patch-clamp recordings from isolated SAN cells showed reduced spontaneous action potential frequency and diastolic depolarization rate, while voltage-clamp revealed a marked reduction in pacemaker current (If). CONCLUSIONZO-1 expression is essential for SAN automaticity. Its loss impairs SAN impulse generation by reducing pacemaker current and hampering atrial conduction, leading to bradyarrhythmia, conduction delay and block. These findings help explain impulse generation and conduction abnormalities in ACM and other cardiomyopathies.

Background: Response to cardiac resynchronization therapy (CRT) is heterogeneous in patients with non-left bundle branch block (non-LBBB) heart failure. Whether pre-implant substrate or procedural characteristics provide the more stable framework for predicting 1-year echocardiographic response remains uncertain. Methods: We retrospectively analyzed 120 non-LBBB patients undergoing CRT. The primary logistic model included left ventricular end-diastolic diameter (LVEDD), left ventricular ejection fraction (LVEF), left atrial diameter, log-transformed NT-proBNP, baseline QRS duration, fragmented QRS burden across V1?V6 leads, and pulmonary artery pressure. Missing predictor data were handled using multiple imputation with 20 datasets. Model performance was assessed using bootstrap internal validation and recalibration. A prespecified procedural extension added pacing strategy, posterolateral biventricular left ventricular lead location, left ventricular pacing threshold, and right ventricular lead position. Exploratory phenotyping and sensitivity analyses were performed. Results: Echocardiographic response occurred in 51 patients (42.5%). LVEDD (OR, 0.899 [95% CI, 0.826?0.978]; P=0.013) and LVEF (OR, 1.068 [95% CI, 1.000?1.140]; P=0.050) were the most informative predictors. The primary model showed apparent AUC 0.811 and Brier score 0.173, with optimism-corrected AUC 0.766 and calibration slope 0.765. Procedural extension showed no retained incremental value after validation. Exploratory phenotyping identified three response patterns with moderate stability. Conclusions: In non-LBBB CRT, baseline structural, biomarker, and electrocardiographic substrate provided the most stable framework for predicting 1-year echocardiographic response. Procedural variables added limited retained value, suggesting that pacing strategy should be interpreted alongside baseline substrate.

Cardiovascular disease is the leading cause of death worldwide. Sudden cardiac death (SCD) accounts for roughly 50% of all cardiac deaths. The electrocardiogram (ECG) is widely used for early diagnosis of cardiac disease. However, the complexity of accurate interpretation limits the ECG's efficacy. Modern deep learning methods have been applied to assist clinicians in diagnosis. We applied Neural Architecture Search (NAS), an automated machine learning technique, to identify optimal deep learning architectures for classifying cardiac arrhythmias from ECGs. We applied the Differentiable Architecture Search strategy to an AutoFormer search space to identify optimal self-attention architectures for arrhythmia classification. We trained, validated, and tested the resulting model on the PhysioNet Challenge 2021 dataset (n = 88,253), comprising ECGs across three continents. We performed a hyperparameter optimisation on the NAS output, exploring input patch size, class weighting, and loss function. We evaluated performance using the PhysioNet Challenge metric and the area under the receiver operating characteristic curve (AUROC). The NAS converged towards minimal architectural configurations (embedding dimension: 384, depth: 4, self-attention heads: 4, MLP ratio: 1) with a validation challenge metric of 0.66 (PhysioNet Challenge 21 Winner: 0.63). The NAS-created network achieved an AUROC of 0.97 and a challenge metric of 0.71 during testing. Normal Sinus Rhythm and Sinus Tachycardia achieved AUROCs of 0.99. Low-QRS Voltage and T-wave abnormality were the worst-performing arrhythmias, with AUROCs of 0.89 and 0.90, respectively. We interpret that architectural simplicity drives performance in arrhythmia classification. Because SCD is unexpected, prevention strategies in free-living environments require lightweight computational resources suitable for wearable devices. Class imbalance fundamentally limits classification performance for rare arrhythmias such as Low-QRS Voltage and T-wave inversion, irrespective of hyperparameter choices. However, the self-attention mechanism can autonomously abstract clinical representations, simplifying clinical deployment by eliminating the need for an explicit feature-extraction pipeline.

AimsHeart failure with preserved ejection fraction (HFpEF) afflicts millions annually and current treatments provide symptomatic relief. Here, we investigate the therapeutic potential of synthetic human Relaxin-2 (RLX) at reversing diastolic dysfunction (DD) and reducing arrhythmia vulnerability. Methods and ResultsMale ZSF1 rats were placed on a normal diet (ND, N=10 controls) or a high-fat diet (HFD, N=11), resulting in the development of DD in 11-weeks, based on serial echocardiograms (enlarged left atrium (LA), wall thickness, doppler flow: E/e). Once HFpEF was confirmed, control and HFpEF rats were randomly treated with Relaxin (400{micro}g/kg/day RLX, N=6) or the vehicle (N=5) for 2-weeks using implanted minipumps. Echocardiograms were repeated at weeks 1 and 2, then hearts were isolated, optically mapped, subjected to programmed electrical stimulation (PES) and tissues dissected for immuno-fluorescence (IF), and qPCR analysis. Circulating levels of glucose, RLX and NT-pro-ANP were measured, pre- and post-treatment. Echocardiograms indicated that RLX reversed DD by reducing LA dimensions and E/e. Optical mapping revealed that 1/3 of HFpEF hearts exhibited sustained atrial and ventricular arrhythmia which were blocked by RLX as it tended to increase conduction velocity (CV). Based on IF, RLX increased Nav1.5, Connexin-43, {beta}-catenin and Wnt1 expression. There were no significant changes in fibrosis in this HFpEF model. NT-pro-ANP was elevated in HFpEF and reduced towards control values by RLX. qPCR analysis showed that RLX decreased DKK1 and MMP1A and increased SCN5A expression compared to Vehicle treatment (N=6 and 5, respectively). ConclusionsThe ZSF1 model showed clear signs of HFpEF, including DD, enlargement of the LA, enhanced hemodynamic stress, increased vulnerability to sustained AF and VF, and elevated glucose and blood pressure. RLX treatment largely reversed DD, hemodynamic stress, and suppressed sustained arrhythmias. RLX elicited cardiac genomic changes, most likely through Wnt/canonical signaling, demonstrating RLXs potential as a therapy for HFpEF.

The cardiac autonomic nervous system is a key driver of various cardiac disorders and arrhythmias. However, investigating neuronal regulation of the human heart has proven difficult due to immitted and reliable experimental models. Here, we present a novel microphysiological system utilizing a compartmentalized microfluidic device (MFD) to integrate co-cultured human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs) and sympathetic neurons (hiPSC-SNs). MFD is composed of two wide-open chambers separated by microfluidic microchannels. hiPSC-SNs were characterized by confocal imaging and RT-qPCR for the expression of peripherin, tyrosine hydroxylase, and {beta}-tubulin III, as well as high levels of dopamine {beta}-hydroxylase and nicotinic acetylcholine receptors. Furthermore, patch-clamp techniques confirmed their functional maturity, showing spontaneous action potentials and positive responses to nicotine (1{micro}M). Co-culturing hiPSC-CMs and hiPSC-SNs within the MFD facilitated axonal projection into the cardiomyocyte chamber, establishing a physical connection between the two cell types. After 10 days of co-culture, functional integration was confirmed by a significant increase in the action potential frequency and beating rate of hiPSC-CMs, as recorded by patch-clamp and video motion tracking, respectively. Notably, nicotine application in the neuronal chamber accelerated these rates in hiPSC-CMs chamber, whereas the administration of the {beta}-blocker, propranolol (5{micro}M), effectively decreased the beating rates. Collectively, these data demonstrate the feasibility of differentiating hiPSCs into functional sympathetic neurons and establishing a robust neuro-cardiac interface. This microphysiological system represents a powerful platform for investigating disorders characterized by impaired neuro-cardiac interactions, offering a valuable tool for both disease modeling and pharmacological screening.

Background: Congenital junctional ectopic tachycardia (cJET) is a rare, potentially life-threatening arrhythmia suspicious for a genetic basis, yet its molecular underpinnings remain incompletely defined. The POPDC2 gene, involved in cardiac pacemaking and membrane trafficking of interacting ion channels, has not previously been conclusively linked to human tachyarrhythmias. This study investigates a novel POPDC2 variant (p.Leu245Pro) identified in a family with autosomal dominant cJET. Methods: Exome sequencing was performed to identify co-segregating variants in the affected family. Functional analysis of the POPDC2 p.Leu245Pro variant was conducted by molecular dynamics (MD) simulations, a membrane targeting assay, and a bimolecular fluorescence complementation assay. Additionally, the impact of the variant on Nav1.5 and TREK-1 currents was characterized in Xenopus oocytes. Results: The p.Leu245Pro POPDC2 variant showed a destabilization of the POPDC1-POPDC2 dimer interface, resulting in impaired heterodimer formation and membrane localization. Electrophysiological studies in Xenopus oocytes demonstrated that the mutant protein significantly affected Nav1.5 and TREK-1 currents. These findings support a functional impact of the POPDC2 p.Leu245Pro variant relevant to cardiac conduction. Conclusions: Our results provide the first functional evidence implicating POPDC2 in cJET and support its role as a novel candidate gene in tachyarrhythmic disease. This study enhances the understanding of genetic contributions to cJET and suggests further investigation of POPDC2 in other forms of supraventricular tachyarrhythmias.

BACKGROUNDIn tetralogy of Fallot (ToF), changes to right ventricular (RV) function (as seen by strain or TAPSE) relate to altered myocardial structure. Direct three-dimensional anatomical evidence supporting these changes remains limited. OBJECTIVESTo non-destructively characterize myocardial architecture in pediatric ToF hearts using Hierarchical Phase-Contrast Tomography (HiP-CT) and structure tensor analysis. METHODSTwenty ToF and control pediatric hearts were imaged at the European Synchrotron, ESRF. Myocyte orientation was assessed through structure tensor analysis and distributed high-performance computing. A region-specific framework was developed for analysis of the RV. The predominant direction of myocardial aggregates (their helical angle) was compared across ventricular regions. RESULTSSignificant differences in orientation were found in all ToF segments vs controls (left ventricle, RV inlet, RV outflow tract, septum; p < 0.001). Myocytes in the ToF RV inlet were more circumferential overall, with regional heterogeneity. Contrary to traditional models, no discrete middle layer was found in the ToF RV, instead, a shift towards more circumferentially orientated myocytes and disrupted septal and outflow components was observed. RV contribution to the septum was greater in ToF (47.3% vs 34.0% ; p = 0.0026) with extension of ventricular insertion points disrupting septal architecture. There were more longitudinally oriented myocytes in the ToF RVOT, consistent with hypertrophied septo-parietal trabeculations. LV structure in ToF demonstrated a greater proportion of circumferentially oriented myocytes vs controls. CONCLUSIONSWe reveal profound alterations in ToF myocardial organization which broadly align with clinical observations and provide the first open-access HiP-CT congenital heart disease data as a basis for future computational modelling.

Background: Echocardiographic assessment of tricuspid regurgitation (TR) remains valve-centric, and right-heart remodeling is not captured. Strain parameters carry prognostic value but are evaluated in isolation. Objectives: To develop integrated right atrial (RA) and right ventricular (RV) remodeling indices using automated echocardiography and assess their utility for TR severity grading, phenotyping, and prognostic stratification. Methods: We analyzed 8,231 patients with functional TR (mild-or-greater) from two tertiary centers (2023-2024) using an automated AI-based echocardiographic solution. The RA remodeling index (RA reservoir strain/RA volume index) and RV remodeling index (RV free wall strain/RV end-diastolic area) were derived automatically; patients were classified into four RA-RV remodeling phenotypes. The primary outcome was all-cause death or heart failure (HF) hospitalization. Results: During median follow-up of 19.3 months, the primary outcome occurred in 574 patients (7.0%). Both indices outperformed individual components for severe TR discrimination (RA: AUC 0.857 vs. 0.757; RV: 0.710 vs. 0.601; both P<0.05). After multivariate adjustment, the RA (HR per unit decrease, 1.27; 95% CI, 1.09-1.49; P=0.002) and RV remodeling indices (2.32; 1.76-3.06; P<0.001) were independently associated with the primary outcome; on mutual adjustment, only the RV index retained significance and provided incremental prognostic value ({Delta}C-index +0.010; NRI +0.237; both P<0.05). The four phenotypes showed progressively divergent risk (log-rank P<0.001), with combined remodeling (Low RA/Low RV) carrying the highest risk. Conclusions: Automated integrated RA and RV remodeling indices improved TR severity discrimination and enabled clinically meaningful right-heart phenotyping. The RV index conferred incremental prognostic value, whereas the RA index better reflected atrial-stage remodeling and disease burden.

Background: Quantitative lipid assessment is central to identifying rupture-prone coronary plaques and represents a therapeutic target for lipid-lowering therapy. Near-infrared spectroscopy (NIRS)-derived lipid core burden index (LCBI) is well validated and widely used for detecting lipid-rich lesions. Optical frequency domain imaging (OFDI) is increasingly adopted for guiding percutaneous coronary intervention (PCI) due to its high-resolution structural imaging capabilities. Depolarization-sensitive OFDI (depOFDI) provides intrinsic lipid contrast and may enable combined structural and compositional plaque characterization within a single OFDI-based platform. Objective: To define an OFDI-derived lipid metric and evaluate its agreement with NIRS-derived LCBI. Methods: Thirty-three patients underwent both polarization-sensitive OFDI and NIRS-intravascular ultrasound imaging during PCI. After exclusion of 4 datasets, 29 co-registered pullbacks were analyzed. A signal-to-noise-corrected depolarization metric was used to identify lipid-rich regions and generate depOFDI chemograms. maxLCBI4mm value and location, as well as total LCBI, were computed and compared with NIRS. Results: depOFDI demonstrated strong agreement with NIRS, showing high correlation for maxLCBI4mm (r^2 = 0.862) and total LCBI (r^2 = 0.867), along with strong spatial concordance for the location of the maxLCBI4mm (r^2 = 0.900). Bland-Altman analysis of LCBI4mm showed minimal bias (10.7) with 95% limits of agreement of [81.4 to 102.8]. Conclusions: depOFDI enables accurate quantification of lipid burden alongside the high-resolution structural information inherently provided by OFDI. Because depolarization metrics can be derived from polarization-diverse detection available in many commercial OFDI systems, this approach provides a practical pathway toward comprehensive plaque characterization within existing PCI workflows, without the need for additional imaging modalities.

Background Non-vitamin K antagonist oral anticoagulants (NOACs) are the guideline-recommended standard for stroke prevention in atrial fibrillation (AF), yet bleeding risks limit real-world adherence. Percutaneous left atrial appendage closure (LAAC) offers a mechanical alternative without definitive comparative synthesis. Objectives To evaluate percutaneous LAAC versus NOAC therapy by synthesizing all contemporary NOAC-era randomized controlled trials (RCTs). Methods Five databases and registries (PubMed, MEDLINE, Embase, Cochrane CENTRAL, ClinicalTrials.gov) were searched from inception to 8 May 2026 for RCTs comparing percutaneous LAAC against NOACs in adults with non-valvular AF. Risk of bias was assessed using Cochrane RoB 2. Ischemic stroke was pooled using a random-effects DerSimonian-Laird model; primary efficacy composite and non-procedural bleeding were evaluated via pre-specified narrative synthesis. Results Four RCTs (CHAMPION-AF, OPTION, PRAGUE-17, CLOSURE-AF) comprising 5,890 patients were included. LAAC achieved noninferiority for the primary efficacy composite in three trials and demonstrated a statistically significant 45-56% reduction in non-procedural bleeding across the three moderate-risk trials. CLOSURE-AF did not meet noninferiority but retained a directionally consistent bleeding reduction. Pooled ischemic stroke analysis (HR 1.31; 95% CI 0.96-1.80; I^2=0%) showed no statistically significant increase in stroke risk, though a consistent directional trend toward more ischemic events was observed. Conclusions LAAC significantly reduces non-procedural bleeding in moderate-risk AF patients, though this benefit attenuates in very high-risk populations. A consistent, statistically nonsignificant ischemic stroke trend and population-dependent efficacy establish LAAC as a shared decision-making alternative to NOACs rather than a universal replacement, pending 5-year CHAMPION-AF data.

BackgroundWomen experience drug-induced Torsades de Pointes (TdP) at approximately twice the rate of men across more than 50 QT-prolonging drug classes, yet the quantitative ionic basis of this sex disparity remains incompletely characterised. The slow delayed rectifier current (IKs) is reduced by [~]45% in female compared with male human ventricular cardiomyocytes, reducing the repolarization reserve available to compensate pharmacological IKr block. MethodsWe implemented the OHara-Rudy (ORd) 2011 undiseased human ventricular epicardial action potential model in Python and parameterised sex variants using the most robustly established human ionic difference: GKs reduced by 45% in females [Kurokawa et al., 2016]. We simulated graded IKr blockade (0-95% in steps of 5%) at three physiologically relevant pacing rates (2 Hz, 1 Hz, 0.5 Hz) after 60 beats of warm-up to approach electrophysiological steady state. Action potential duration at 90% repolarization (APD90), triangulation (APD90-APD30), and repolarization failure (defined as APD90 > 500 ms, a conservative cellular risk marker informed by clinical QTc safety thresholds, or failure to repolarize within the cycle length) were quantified. All simulations used SciPys Radau solver (rtol = 10-, atol = 10-8) with a Numba-JIT-compiled right-hand side for computational efficiency. ResultsAt baseline (0% block), the female model exhibited longer APD90 than the male at all pacing rates (+2.8 ms at 2 Hz; +4.6 ms at 1 Hz; +4.6 ms at 0.5 Hz). Under progressive IKr blockade, the absolute sex difference in APD90 amplified non-linearly: at 85% block and 1 Hz pacing the female APD90 exceeded the male by 60.4 ms (versus 4.6 ms at baseline; 13-fold amplification). At slow pacing (0.5 Hz), the sex gap was most pronounced: at 85% block, female APD90 was 1127 ms versus 939 ms for the male (+188 ms; 20% more prolonged). The critical APD threshold (>500 ms) was reached by female cells at 5 percentage points lower IKr block than male cells at 1 Hz pacing (55% vs. 60% block), both reported at the first simulated 5%-grid block level exceeding the criterion. Repolarization failure occurred 5 percentage points earlier in females at 1 Hz (90% vs. 95% block). Action potential triangulation was consistently greater in the female model at all block levels and pacing rates. ConclusionA 45% reduction in IKs conductance is sufficient in this model to produce measurably greater APD90 prolongation under IKr blockade across all tested pacing rates. The non-linear amplification of the sex gap is consistent with the hypothesis that reduced IKs repolarization reserve contributes to greater female susceptibility to drug-induced QT prolongation, and supports testing sex-specific parameterizations in CiPA-style in silico cardiac safety workflows.

Cardiogenic shock (CS) is associated with high short-term mortality and the use of temporary mechanical circulatory support (tMCS) devices, especially left-sided microaxial flow pumps (Impella, Abiomed), has increased in recent years. However, few studies have investigated tMCS's effect on right ventricular-pulmonary artery (RV-PA) hemodynamics and its impact on clinical outcomes. We retrospectively analyzed all adult patients implanted with Impella 5.5 at our institution with acute myocardial infarction or acute decompensated heart failure-induced CS between 2019 to 2023. We found that Impella 5.5 led to an early improvement in RV-PA hemodynamics, even in patients with poor baseline RV function. In addition, we found that RV function itself did not predict death, post-heart transplant right ventricular-primary graft dysfunction, or post-left ventricular assist device severe RV failure. However, an increase in right atrial:pulmonary capillary wedge pressure ratio (RA/PCWP) despite tMCS support was a powerful prognosticator. Our study sheds important insight into anticipated hemodynamic changes after Impella 5.5 placement, supports the use of early tMCS even in patients with marginal RV function in the setting of left heart disease, and highlights the importance of serial assessment of RA/PCWP as a key determinant of CS outcomes.