Background Functional substrate mapping techniques are increasingly utilised in clinical practice but can involve protracted mapping and procedure time. Objective We incorporated magnetic resonance imaging (MRI) and computed tomography (CT) derived ventricular scar data into the functional mapping workflow to assess the efficacy and outcome compared to conventional ablation strategies. Methods In this prospective multicenter registry, 166 patients with post-infarct Ventricular Tachycardia (VT) were enrolled into a prospective propensity matched registry. Cardiac MRI/CT scans were performed to target focused regions for functional mapping and ablation (Sense2). This was compared to a group that underwent mapping without image guidance (Sense) and a group that underwent activation/entrainment or substrate guided mapping and ablation without functional mapping or image guidance (Institutional). Results In the Sense2 group (145.8±28.7 mins), the mean procedural time was significantly shorter compared to the Sense group (171.0±51.1 mins) and Institutional group (221.4±73.9 mins), (p<0.0001). Similarly, mapping time was shorter (25.4 ± 7.3mins) compared to Sense (47.2 ± 8.9). Ablation time was significantly reduced in the Sense2 (18.1±11.6 mins) compared to the Sense (21.6±12.7 mins) and to the Institutional (25.9±13.9 mins) (p=0.006). Patients in the Sense2 and Sense had higher freedom from VT (p<0.001 for both) and improved survival (p<0.05 for both) compared to Institutional group. Conclusion Sense2, integrating imaging with functional mapping, reduced the procedural times by enabling focused substrate maps to be performed and improved outcomes in terms of VT freedom compared to Institutional ablation. The improved survival requires corroborating with multi- centre randomized trials.
BACKGROUND:Accurate prediction of ischemic stroke or systemic embolism is central to atrial fibrillation (AF) management, yet the transportability of available risk scores to Chinese populations remains uncertain. OBJECTIVE:Externally validate and compare published stroke risk scores in Chinese patients with non-valvular AF. METHODS:We systematically retrieved and externally validated 17 published models in a retrospective cohort of 1,283 adults hospitalized with non-valvular AF at a Chinese tertiary-care center. Discrimination was evaluated using the 4-year Uno C-index and time-dependent areas under the curve (AUC). Models providing absolute risks also underwent calibration, Brier score, and reclassification analyses. Sensitivity analyses accounted for death as a competing event and separately evaluated patients not receiving OAC at baseline. RESULTS:During 4 years of follow-up, 103 primary outcomes occurred, corresponding to 2.85 events per 100 person-years. Across models, 4-year Uno C-indices ranged from 0.572 to 0.767, compared with 0.690 for CHA2DS2-VASc. GARFIELD-AF 2017, GARFIELD-AF 2021, and ATRIA had higher Uno C-indices than CHA2DS2-VASc. However, no model had significantly higher time-dependent AUC at any time point. For 1-year calibration, CHA2DS2-VASc had predicted and observed risks of 3.39% and 3.54%, respectively, with an observed-to-expected ratio of 1.04, whereas several other models underestimated risk. Brier scores and reclassification measures showed no consistent advantage Competing-risk analyses lowered cumulative incidence without changing comparative patterns. Among patients not receiving OAC at baseline, no model outperformed CHA2DS2-VASc. CONCLUSION:Candidate models did not consistently outperform CHA2DS2-VASc in this external validation; CHA2DS2-VASc remains practical, while other models may require population-specific validation and recalibration.
BACKGROUND:Ablation of frequent premature ventricular complexes (PVCs) can improve left ventricular ejection fraction (LVEF) in patients with systolic dysfunction, especially in suspected PVC-induced cardiomyopathy. However, many patients fail to normalize LVEF despite successful ablation, and current tools do not reliably distinguish true PVC-induced cardiomyopathy from underlying cardiomyopathy exacerbated by PVCs. OBJECTIVE:To develop and externally validate a machine learning (ML) model using routinely available clinical, echocardiographic, and electrocardiographic variables to predict LVEF recovery after PVC ablation. METHODS:In this retrospective multicenter study, 256 patients with LVEF <50% undergoing successful PVC ablation at three international referral centers were included. Predictors were selected using the Boruta algorithm, and five ML models were trained. Performance was assessed with 10-fold cross-validation and ROC curve analysis. The best-performing model underwent calibration and threshold analysis and was externally validated in an independent cohort from three additional centers. RESULTS:The Random Forest model showed the best performance, with an AUC of 0.88 (95% CI 0.79-0.98) in the internal test set and good calibration (Hosmer-Lemeshow p=0.562). External validation confirmed consistent discrimination (AUC 0.83, 95% CI 0.72-0.95). Key predictors included baseline PVC burden, QRS duration in sinus rhythm, and preprocedural LVEF. CONCLUSION:This ML-based tool, built on widely available variables, accurately estimates the probability of LVEF recovery after PVC ablation and may support clinical decision-making and patient counselling.
Orthotopic heart transplantation (OHT) creates a surgically altered electrophysiologic substrate defined by the suture-line scar, residual recipient atrial tissue, and autonomic denervation, that fundamentally alters the mechanisms, presentation, and management of atrial tachyarrhythmias. This narrative review synthesizes current evidence on the mechanisms, mapping strategies, procedural safety considerations, and outcomes of catheter ablation (CA) for atrial arrhythmias after OHT, based on a structured search of PubMed and Embase (1995-2025). Atrial flutter (AFL), particularly cavotricuspid isthmus (CTI)-dependent macro-reentry, is the dominant arrhythmia in stable OHT recipients. The ablation isthmus is anatomically redefined by suture lines rather than the native inferior vena cava, and CA achieves acute success rates exceeding 90% for CTI-dependent flutter, with a significant survival benefit over medical management alone (median 11.3 vs. 5.8 years; p = 0.026). Atrial fibrillation (AF) is uncommon in stable recipients and, when present, most often arises from residual recipient atrial tissue or donor-recipient conduction bridges; ablation requires individualized electroanatomic mapping rather than routine pulmonary vein isolation. Atrioatrial conduction (AAC) develops in approximately 20-30% of patients presenting with arrhythmias, with a mean onset of 10.1 years post-transplant. Procedural considerations unique to OHT include protamine hypersensitivity risk, rhythm misclassification due to dual atrial physiology, anticoagulation complexity, and drug-immunosuppressant interactions, which collectively strengthen the rationale for ablation over pharmacologic therapy. CA is feasible, effective, and associated with improved survival in appropriately selected OHT recipients. Prospective multicenter registries with standardized reporting are needed to advance evidence-based practice in this population.
Antiarrhythmic drugs can be an important treatment option for patients with heart rhythm disorders, but not all patients and scenarios are represented in trials related to antiarrhythmic drug use. This Heart Rhythm Society scientific statement identifies common clinical scenarios for which little guidance exists, at least partly because they are understudied. It also provides as much practical advice as possible, sourcing available evidence and the clinical proficiency of a diverse group of experienced clinicians, and provides the rationale for each recommendation.
BACKGROUND:Spontaneous monomorphic ventricular tachycardia (VT) recorded by cardiac implantable devices exhibits distinct initiation patterns, but their clinical significance remains unclear. OBJECTIVE:To determine whether spontaneous VT initiation morphology on cardiac implantable device electrograms is associated with the number of inducible VTs, substrate characteristics, and outcomes in patients with structural heart disease. METHODS:We retrospectively studied 113 patients with structural heart disease who underwent catheter ablation for monomorphic VT and had analyzable spontaneous VT episodes recorded by an implantable cardioverter-defibrillator. Spontaneous VT was classified as having a matching-morphology initiation if the initiating beat matched the sustained VT (Type A); and a different-morphology initiation if the initial beat differed from the subsequent VT beats (Type B). RESULTS:Among 257 spontaneous VT episodes 147 were Type A and 110 were Type B. Of 113 patients, 58 had Type A only, 47 had Type B only, and 8 had both types. Type B initiation was associated with longer pre-VT RR intervals and more frequent ventricular-paced baseline rhythm. During ablation, the Type B only group had more inducible VT morphologies (P = 0.012), which remained significant after multivariable adjustment (incidence rate ratio 1.47, 95% confidence interval 1.15-1.87; P = 0.002), despite similar scar extent (P = 0.184). Acute procedural outcomes, complications, VT recurrence, and composite outcomes were not significantly different between groups. CONCLUSION:VT with an initiation morphology distinct from the subsequent VT is associated with a greater number of inducible VT morphologies despite comparable gross scar extent.
BACKGROUND:Transvenous lead extraction (TLE) is increasingly performed, and accurate procedural risk assessment is essential. Female sex has been reported as a possible risk factor for major complications, but previous analyses rarely balanced procedural and clinical characteristics between sexes, leaving unclear whether the association reflects sex itself or greater anatomical-procedural susceptibility. OBJECTIVE:To assess whether female sex remains independently associated with major complications during TLE after extensive propensity-score balancing of clinical and procedural confounders. METHODS:We retrospectively analyzed 4290 patients undergoing non-laser TLE at three high-volume centers by one primary operator (2006-2024). Women were matched 1:1 to men on ten clinical and procedural covariates. Major complications (HRS/EHRA criteria) were the prespecified primary endpoint. Multivariable logistic regression including female sex and all matching covariates was performed; Kaplan-Meier and Cox mortality analyses were secondary and exploratory. RESULTS:After matching, 1197 women and 1197 men were well balanced. Despite comparable procedural complexity, major complications were more frequent in women (3.76% vs 1.50%; p<0.001), including hemopericardium (2.54% vs 0.75%; p=0.001) and rescue cardiac surgery (2.17% vs 0.75%; p=0.006); procedural success was similar. Female sex remained independently associated with major complications (OR 2.72, 95% CI 1.52-4.85; p<0.001), as did longer lead dwell time (OR 1.12 per year; p<0.001); higher hemoglobin was protective (OR 0.86 per g/dl; p=0.026). CONCLUSION:After extensive balancing of confounders, female sex remained independently associated with major complications during TLE, supporting further investigation of sex-related procedural vulnerability and refinement of TLE risk models.
BACKGROUND:The optimal right ventricular pacing burden (%RVP) threshold associated with heart failure (HF) in patients with leadless pacemakers (LPs) remains unclear, whereas thresholds of 20% and 40% have been commonly used in studies of transvenous pacemakers. OBJECTIVE:To assess the current %RVP cutoffs and explore how increased %RVP influences the HF risk in LPs. METHODS:This registry-based observational study included patients who underwent LP implantation from 2015 to 2025. Patients with a prior HF diagnosis were excluded. %RVP was obtained through PaceMateLIVE, a vendor-neutral remote monitoring platform. The primary outcome was the first recorded HF diagnosis. RESULTS:We included 3167 patients with single-chamber LPs. The mean age was 76±13 years, and 45% were female. The median baseline %RVP was 71% [8-98%]. Over 2.4 years, the median absolute %RVP difference was 5.5% [0.7-21.6%], and 577 (18%) patients had the primary outcome. Patients with higher baseline %RVP at 20% and 40% cutoffs had increased risks of HF compared to those with lower %RVP (P<0.05). A multivariable Cox model showed that time-varying %RVP was associated with a higher hazard of HF (per 10% increase, hazard ratio 1.035 [1.013-1.059]). CONCLUSIONS:Baseline RVP thresholds of 20% and 40% may help identify patients with LPs who are at increased HF risk. However, HF hazard increased progressively with increasing RVP burden. Given the lack of established upgrade pathways for current LP systems, careful patient selection and follow-up may be particularly important for patients expected to have a high pacing burden.
Background Atrial arrhythmias are common after tetralogy of Fallot (TOF) repair but rare following ventricular septal defect (VSD) repair. While postoperative factors may contribute, preoperative electrophysiological differences could also underlie this different arrhythmia risk. Objective To compare preoperative atrial electrophysiology between pediatric patients with TOF and VSD. Methods Intraoperative epicardial mapping was performed in the atria (right atrium (RA), left atrium (LA), pulmonary vein (PV) and Bachmann’s Bundle (BB)) of 26 TOF and 41 VSD children. Potential voltage and morphology, as well as conduction properties were analyzed. Results Despite a lower prevalence of LA dilatation in TOF patients than VSD patients (29% vs 81%, p = 0.004), TOF exhibited lower potential voltages in the LA and PV (LA: 3.4±1.7mV vs 5.3±2.5mV; PV: 1.8 (1.1, 5.6)mV vs 4.7 (1.4, 8.9) mV, both p<0.01) with more low-voltage areas (LA: 12.9 (0.0, 53.7)% vs 4.4 (0.0, 29.0)%; PV: 23.9 (3.6, 47.0)% vs 7.0 (0.0, 35.9)%, both p<0.01), a higher prevalence of conduction block (LA: 0.6 (0.0, 6.5)% vs 0.0 (0.0, 1.2)%, p<0.001) and potentials containing 2 deflections (short double potentials (LA: 12.1 (0.5, 41.8)% vs 8.8 (1.3, 18.9)%, p=0.032); long double potentials (LA: 0.1 (0.0, 13.8)% vs 0.0 (0.0, 2.2)%, p=0.034)). Conclusion Pediatric TOF patients have particularly at the LA and PV more atrial electrophysiological abnormalities than VSD patients, suggesting that atrial electrophysiological alterations at these sites are more pronounced in TOF patients.
Focal activation patterns (FAPs) are frequently reported during atrial fibrillation (AF), yet their prevalence, stability, origin, and clinical significance vary considerably across studies. This variability largely reflects differences in mapping technologies, spatial resolution, analytical approaches, and criteria used to define FAPs. In this review, we summarize the methodologies used to identify FAPs, including spatial and temporal definitions, mapping strategies, and analytical techniques, and discuss how these methodological differences influence the interpretation of focal activity. We further examine evidence demonstrating that focal and rotational activation patterns may represent different manifestations of the same underlying conduction dynamics, depending on mapping resolution and analysis. Finally, we highlight current limitations and propose priorities for future research, including standardized identification criteria, cross-platform validation, and harmonized analytical workflows. Greater methodological consistency will be essential to accurately define the mechanistic and clinical significance of FAPs in AF.
Magnetic and electromagnetic fields are increasingly encountered in consumer, medical, and industrial environments, creating frequent clinical uncertainty for patients with cardiac implantable electronic devices. This review synthesises current evidence on the mechanisms by which external fields interact with pacemakers and implantable cardioverter-defibrillators, distinguishing static magnetic field effects from time-varying electromagnetic interference. Static fields may activate device magnet response when brought close to the generator, whereas time-varying fields may induce lead signals causing oversensing, pacing inhibition, or inappropriate therapy. We integrate physical principles, device behaviour, manufacturer guidance, occupational regulations, and real-world exposure data into a practical clinical framework. Most everyday and occupational exposures are manageable with appropriate separation, task modification, and patient-specific assessment. A mechanism-based approach can support proportionate counselling, avoiding both unnecessary restriction from work and under-recognition of genuine risk.
BACKGROUND:Long-term rhythm outcomes following cryoballoon ablation (CBA) in early persistent atrial fibrillation (AF) remain incompletely characterized. OBJECTIVE:To evaluate 3-year AF burden trajectories, subsequent recurrence patterns detected by implantable loop recorder (ILR), and association with healthcare resource utilization (HCRU). METHODS:The COOL-PER trial was a prospective, multicenter, single-arm study enrolling patients with early persistent AF (duration ≤3 years). An ILR was implanted 7-90 days before CBA for continuous rhythm monitoring. RESULTS:Among 130 enrolled patients, 123 completed 3-year follow-up (mean age 60.5±8.4 years; 25.2% female). Median AF burden decreased from 99.9% [IQR 53.1-100.0] at baseline to 0.1% [0.0-4.2], 0.5% [0.0-9.1], and 0.7% [0.0-9.5] at 1, 2, and 3 years (all P<0.001). Of 47 patients recurrence-free at 1 year, 25 (53.2%) developed subsequent recurrence, and 20 (80.0%) detected by ILR alone. Compared with first-year recurrence, subsequent recurrence was less often persistent (4.0% vs 28.9%; P=0.001) with lower AF burden (0.1% [0.0-1.6] vs 2.8% [0.4-18.7]; P=0.010). Persistent-type recurrence and AF burden ≥10% were both associated with more additional rhythm control interventions (78.3% vs. 30.8% vs. 0%; 78.6% vs. 39.1% vs. 0%; both P<0.001) and cardiovascular hospitalization (17.4% vs. 3.8% vs. 0%, P=0.045; 14.3% vs. 4.3% vs. 0%, P=0.029). CONCLUSIONS:CBA achieved durable AF burden suppression over 3-years in early persistent AF. Subsequent recurrence after the first year was common, predominantly detectable by ILR only. Subsequent recurrences were often paroxysmal with lower AF burden and associated with lower HCRU, supporting the value of continuous long-term rhythm monitoring for characterizing rhythm status beyond the first post-ablation year.
BACKGROUND:Delayed recurrence of atrial fibrillation (AF) after index ablation is increasingly recognised, but its clinical and procedural phenotypes remain poorly described. OBJECTIVE:To characterise patients undergoing very late redo (VLR) AF ablation (>5 years after prior ablation) and compare pulmonary vein (PV) findings across redo interval groups. METHODS:Consecutive patients undergoing redo AF ablation at Alfred Health and Cabrini Health (2007-2025) were included and grouped by redo interval (<1 year, 1-5 years, >5 years). RESULTS:Of 596 patients undergoing redo AF ablation, 71 (12%) patients underwent VLR AF ablation (median redo interval 7.1 years [IQR 5.9-8.2]). VLR patients had a mean age of 62.1 years; 72% were male, and median CHA2DS2-VASc was 2 (IQR 1-3) with 57.7% having paroxysmal AF at redo procedure. PV reconnection (any) was less likely with increasing time from index PVI: At <1 year 80.1% (189/236), 1-5 years 65.1% (188/289), >5 years 49.3% (35/71); p<0.001. Each additional year from index to redo ablation was associated with an 8.6% lower expected number of reconnected PVs (RR 0.91, 95% CI 0.88-0.95; p<0.001). In total 32/71 (45%) of patients undergoing VLR AF ablation developed recurrent AF at a median follow-up of 243 days (IQR 103-1097) from repeat procedure. CONCLUSION:The likelihood of PV reconnection declines significantly with increasing time to redo AF ablation, with the majority of patients > 5 years having enduring PV isolation. This suggests a greater contribution from non-PV triggers and/or AF substrate in this cohort.
BACKGROUND:Guidelines and early clinical data indicate left bundle branch area pacing (LBBAP) may help avoid pacing induced cardiomyopathy, but the impact of LBBAP on atrial fibrillation (AF) is less certain. OBJECTIVE:To compare new onset AF in patients with LBBAP leads with RVP leads. METHODS:RVP leads (N=5225) and LBBAP leads (N=4970) in the RV port of dual chamber pacemakers were identified in the LATITUDE remote monitoring database. Patients without prior AF were propensity score matched requiring an exact match on percent RV pacing group (<1%, 1-39%, 40-98%, ≥99%) based on a 90-day baseline period and a 0.01 caliper on age, sex, pacing mode, lower rate limit, percent RA pacing (continuous), and percent RV pacing (continuous within exact match groups). Time spent in atrial tachy response mode was used to identify AF burden. Landmark analysis was performed as time to first 24-hour AF episode. RESULTS:Propensity matching yielded 7886 patients (3943 LBBAP and 3943 RVP). No propensity match characteristics were significantly different between groups. The overall percentage of patients with 24-hour AF was significantly lower in the LBBAP group over 21 months of follow-up (13% LBBAP vs 15% RVP, P=0.037). When stratified into percent RV pacing ≥ or <40%, the RVP group had significantly more 24-hour AF observed when percent pacing was >40% (LBBAP<40%: 13%; RV<40%: 13%; LBBAP≥40%: 13%; RV≥40%: 16%; P=0.004). CONCLUSION:LBBAP was associated with a lower incidence of onset of new AF than RVP in pacemaker patients with a high pacing burden.
