Abstract Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia worldwide, typically driven by age, obesity, and other conventional cardiovascular risk factors. However, a subset of patients develop early-onset AF—often before 65 years of age in the absence of structural heart disease—suggesting alternative mechanisms beyond acquired risk. Emerging evidence implicates pathogenic variants in cardiomyopathy-associated genes as key drivers in this population. This review synthesizes contemporary evidence linking cardiomyopathy gene variants, particularly in TTN, LMNA, MYH7, and PKP2, to early-onset AF. Across multiple sequencing cohorts, pathogenic or likely pathogenic variants are identified in 5–20% of young AF patients, with prevalence rising sharply at younger ages. TTN truncating variants confer up to a two-fold increased risk of AF and a 10-fold higher risk of subsequent dilated cardiomyopathy, whereas LMNA mutations are associated with aggressive atrial fibrosis, conduction disease, and early recurrence after catheter ablation. Longitudinal studies demonstrate that genotype-positive AF patients face higher risks of heart failure, sudden cardiac death, and progression to overt cardiomyopathy. These findings redefine early-onset AF as a potential sentinel manifestation of inherited myocardial disease rather than an isolated electrical disorder. Genetic testing—especially in individuals with AF onset ≤45 years or a family history of cardiomyopathy—enables early detection, cascade screening, and personalized surveillance. Integrating genomics, advanced imaging, and electrophysiological management supports a precision medicine framework that may improve outcomes by identifying and intervening before structural disease develops.

Abstract Background Ablation of the atrioventricular (AV) node, following the insertion of a permanent pacemaker, is a treatment option for symptomatic atrial fibrillation (AF) where rate control is poor, despite maximally tolerated pharmacological intervention or percutaneous AF ablation [1], and yet there is limited data on long-term outcomes. Purpose The purpose of this study is to investigate post AV node ablation follow up outcomes, including the incidence and timeframe of conversion of paroxysmal to persistent AF; incidence and timeframe of upgrade to biventricular pacemakers; and mortality. Methods This observational descriptive study looked at the post-procedure follow-up outcomes of patients who underwent AV node ablation at our centre between March 2015 and June 2019. Retrospective analysis of prospectively collected data was analysed. The demographics of the patients, including their age, gender, co-morbidities, pre-ablation left ventricular ejection fraction (LVEF) and medications were recorded. The follow up outcomes investigated included the change in LVEF, the proportion of patients whose AF converted from paroxysmal to persistent, the proportion of patients requiring upgrade to biventricular devices, and deaths within 6 months of ablation. Outcomes were compared between those who had a biventricular pacemaker pre-ablation and those who had single/dual chamber pacemakers. Results 296 patients with a mean age of 72.7± 8.5 years and a female to male ratio of 54.1% : 45.9% were included. 94 patients (31.8%) had paroxysmal AF pre- ablation. 51.6% of those who had paroxysmal AF pre-ablation converted to persistent AF over a median period of 3 years (interquartile range, 3 years). Among those who had a biventricular pacemaker pre-ablation, 56.5% of those with paroxysmal AF converted to persistent, compared to 47.4% of those with a dual pacemaker pre-ablation p=ns Among patients with dual chamber pacemakers, those who remained in paroxysmal AF post-ablation had a mean CHADVASC score of 3.2 (range of 1-6) compared to 3.7 (range of 2-6) in those whose AF converted to persistent (p=0.19). 9 patients (3%) died within less than 6 months of the procedure, with 1 patient dying within 6 days. 13% of the patients originally having a single or dual chamber pacemaker required an upgrade to a biventricular pacemaker over a median period of 1.25 years (interquartile range 1.1 years). All the patients who required an upgrade to a biventricular pacemaker had normal LVEF pre-ablation except for one patient who had mild LV impairment. Conclusions A significant proportion of patients with paroxysmal AF converted to persistent AF following AV node ablation and having a biventricular pacemaker did not offer benefit in keeping people in paroxysmal AF.A considerable number of people required an upgrade to biventricular pacemaker over a short time frame even though they had normal LVEF pre AV nodal ablation.

Objectives Pulsed field ablation (PFA) is a promising new ablation modality for the treatment of atrial fibrillation (AF) that has recently become available in the UK National Health Service (NHS). We provide the first known economic evaluation of the technology.Methods A cost-comparison model was developed to compare the expected 12-month costs of treating AF using the pentaspline PFA catheter compared with cryoablation for a single hypothetical patient. Model parameters were based on a recent cost-effectiveness analysis by the National Institute for Health and Care Excellence where possible or published literature otherwise. Deterministic sensitivity, scenario and threshold analyses were conducted.Results Costs for a single patient treated with PFA were −3% (−£343) less over 12 months than those who received treatment with cryoablation. PFA was associated with 16% higher catheter costs but repeat ablation costs were over 50% less, driven by a reduction in repeat ablations required. Costs of managing complications were −£211 less in total for PFA compared with cryoablation.Conclusions Routine adoption of PFA with the pentaspline PFA catheter looks to be as affordable for the NHS as current treatment alternative cryoablation.

Introduction Radiofrequency (RF) is a widely used technology for Atrial Fibrillation (AF) ablation. However, settings for optimal lesion geometry to obtain transmural, durable, and safe lesions are still debated. High Power Short Duration (HPSD) is a novel strategy aiming to create more efficient lesions. We examine the safety and efficacy of the QDOT Micro catheter using its dual abilities, including QMODE+ defined by a very HPSD (90W/4secs) and conventional power temperature controlled QMODE. Methods All patients undergoing Pulmonary Vein Isolation (PVI) using vHPSD for AF at a single UK centre were included in a prospective registry. Patients with additional ablation lines, other than Cavotricuspid Isthmus (CTI), were excluded. Clinical data, procedural details, and data from the most recent follow-up including AF recurrence post 90-day blanking period were recorded. Recurrence was defined as >30 seconds documented AF, either by 12 lead ECG or by Holter-monitor in the event of symptoms. Results A total of 27 patients were treated using vHPSD with the QDOT Micro catheter between January 2023 and January 2024. Patient characteristics are outlined in table 1. At the time of procedure, 41% of patients had a prior electrical cardioversion and 67% were in sinus rhythm. No patients had any accessory pulmonary veins and 22.2% had a common left pulmonary vein ostium. Procedures were carried out using conscious sedation in 37% of cases, and under general anaesthetic in all other cases. A CTI line was performed in 33% of cases for documented atrial flutter. Average procedural time was 163 ± 44 minutes with an average fluoroscopy time of 22.3 ± 14.7 minutes. For all patients, a hybrid approach was undertaken with QMODE+ for the posterior wall and QMODE for the anterior wall. Ablation data is given in table 2. All 4 pulmonary veins were isolated in all cases. First pass isolation (FPI) was 69.2% in the left pulmonary veins (LPVs) and 73.1% in the right pulmonary veins (RPVs). Gap locations for failed FPI are shown in figure 1. Of note, there were 6 (37.5%) gaps in total found on the carina. No gaps were found on the anterior wall of the LPVs. QMODE+ was used for 75% of the LPV touch-ups and 50% of the RPV touch-ups. The safety profile demonstrated 2 (7.4%) pericardial effusions requiring percutaneous drainage and no other complications. Freedom from AF post 6 months was 83.3% among the 18 patients (67%) who had a clinic follow-up in this time. Conclusion The QDOT Micro catheter resulted in good outcomes from ablation with a 100% acute efficacy and 83.3% 6-month efficacy, comparable to conventional RF strategy. Gaps in FPI were most likely found at the carinas. Procedural time, including pre and post ablation care, was under 3 hours. The safety profile was reasonable, but the higher-than-expected rate of pericardial effusion requires further investigation. Expansion of the study with more patients and longer follow-ups is pending. Conflict of Interest No known conflicts

Abstract Introduction Premature ventricular contraction (PVC) is a frequently encountered finding in routine ECGs, that in certain individuals may be followed by reduction in ejection fraction (EF). This may be improved or even reversed with a medical or interventional reduction of ectopic burden. Objective The primary objective of this study is to assess the potential effectiveness of cardiac ablation in suppressing PVC and subsequently enhancing the EF. Further we aim to establish predictive factors of the success of the intervention. Methods In a retrospective data analysis at a single medical centre, we examined records of 116 patients who underwent ectopic ablation, with 10 patients having more than 1 ablation. Demographic information, heart-related conditions along with the presence of a scar on MRI, was collected. The study also recorded pre- and post-procedure PVC burden and EF measurements. Results Demographics and procedural details are in table 1. It was found that patients participating in this study were predominantly male (66.4%), on average 60.1 (± 13.6) years old, overweight (BMI 29.8 ± 5.4) with no additional heart disease (56%) and no scarring on MRI (55%).The PVC burden before ablation (27.9 ± 12.7) significantly reduced to 8.0 ± 11.2 post-ablation (p < 0.005), marking an average relative reduction of 68.1% (± 44.1%). Successful interventions, defined by a reduction exceeding 50%, were observed in 79% of patients. The EF increased from 39.6 ± 8.9 to 47.5 ± 10.7 post-ablation (p < 0.005), corresponding to an average increase by 8.4 ± 8.5. Notably amongst the patients who had a successful ablation, 36% of patients achieved normalized EF (>55%) and 42% showed an improvement of at least 5%. A strong correlation emerged between the relative change in PVC and the ejection fraction measured after ablation, with an increase by 0.10 for every percent reduction (p < 0.00). The relative increase in the EF% was significantly higher in patients where the PVC burden was reduced by at least 50% (figure 1). Linear fixed effect modelling explored the influence of patient characteristics on the model. Patients with higher BMI had a lower EF after ablation with same relative reduction in PVC (p < 0.03). Similarly, a scar on MRI and associated heart condition was associated with reduced improvement in ejection fraction (p < 0.02). Also, for every increase in age patients had a reduction of 0.2 EF after ablation (p < 0.01). Right heart PVC’s were ablated more successfully, and had higher EF post ablation (p < 0.01). Conclusion In conclusion, reduction in PVC burden increases the EF after treatment. Increasing BMI, age and presence of associated heart disease can negatively impacted LVEF post ablation. Further research could improve the model that predicts improvement in LV function post successful PVC ablation.Figure 1Table 1

Background The Micra VA (leadless) pacemaker was approved by the FDA for use in 2016. Whilst initial studies evaluated the safety and efficacy of the device for a mean follow up of 12 months, very few studies have evaluated complications and device function beyond 1 year.Objective: To evaluate the short and long term complication rate and device function associated with the Micra VA (leadless) pacemaker at our centre. Methods A prospective analysis of all Micra VA implants performed at Royal Papworth Hospital was carried out. This included pacing checks for up to 24 months post device insertion, evaluating complications and specifically noting thresholds and R-wave amplitude changes. Results A total of 24 Micra leadless pacemakers were implanted at our centre between 2017 and 2020. The age range for the patients was 37 to 92 years, mean age 71 ± 13 yrs. 8 out of 24 (33%) patients had poor venous access, with bilateral subclavian obstruction, requiring the use of a leadless pacemaker. 2 out of 24 had bilateral previous pacemaker infections and extraction. For the remaining patients, 12/24 (50%) had atrial fibrillation with slow ventricular response as the primary indication for the device. 6 out of 24 (25%) patients had a history of LV impairment (4 patients severe LVSD, 2 moderate LVSD). One patient had a previous cardiac transplant.The implant was successful for all patients. One patient required the procedure to be repeated under general anaesthetic as she did not tolerate the insertion of the femoral sheath under sedation. 2 patients (8%) required repositioning of the device during the case, as initial placement was unsatisfactory. 23/24 patients had the device placed in the septum and 1 patient in the RV apex. This patient had undergone multiple previous tricuspid valve surgeries, which made septal positioning challenging, and so an apical placement was accepted. Mean procedure time was 62 ± 16 mins. Mean fluoroscopy time was 5.8 ± 4.2 mins. Implant threshold was 0.6 V ± 0.4 V. Threshold at 1 year follow up was 0.5 V ± 0.2 V and 0.6 V ± 0.2 V at 2 years. Paired T testing showed no statistically significant difference in threshold values at implant, and year 1 (p = 0.7, n =13), or implant and year 2 (p = 0.78, n =6). The R wave at implant was 9.5 ± 4.1mV, and 9.8 mV ± 2.5mV at year 1, again with no statistically significant difference (p = 0.87, n = 13). Mean battery life at 2 year follow up was 7 ± 0.5 years. Pacing percentages varied from 0.1% to 99.99%. Conclusion Although are numbers are small, particularly for follow up over 2 years (n = 6), the initial results are encouraging, and support a low complication rate, and no evidence of premature battery failure or issues with device threshold requiring re intervention. It is imperative that further studies are carried out to give a picture of longer term follow up for the leadless Micra VA pacemaker focussing on these two key issues. Conflict of Interest nil

OBJECTIVES The goal of this study was to develop a risk score model for patients with Brugada syndrome (BrS). BACKGROUND Risk stratification in BrS is a significant challenge due to the low event rates and conflicting evidence. METHODS A multicenter international cohort of patients with BrS and no previous cardiac arrest was used to evaluate the role of 16 proposed clinical or electrocardiogram (ECG) markers in predicting ventricular arrhythmias (VAs)/sudden cardiac death (SCD) during follow-up. Predictive markers were incorporated into a risk score model, and this model was validated by using out-of-sample cross-validation. RESULTS A total of 1,110 patients with BrS from 16 centers in 8 countries were included (mean age 51.8 +/- 13.6 years; 71.8% male). Median follow-up was 5.33 years; 114 patients had VA/SCD (10.3%) with an annual event rate of 1.5%. Of the 16 proposed risk factors, probable arrhythmia-related syncope (hazard ratio [HR]: 3.71; p < 0.001), spontaneous type 1 ECG (HR: 3.80; p < 0.001), early repolarization (HR: 3.42; p < 0.001), and a type 1 Brugada ECG pattern in peripheral leads (HR: 2.33; p < 0.001) were associated with a higher risk of VA/SCD. A risk score model incorporating these factors revealed a sensitivity of 71.2% (95% confidence interval: 61.5% to 84.6%) and a specificity of 80.2% (95% confidence interval: 75.7% to 82.3%) in predicting VA/SCD at 5 years. Calibration plots showed a mean prediction error of 1.2%. The model was effectively validated by using out-of-sample cross-validation according to country. CONCLUSIONS This multicenter study identified 4 risk factors for VA/SCD in a primary prevention BrS population. A risk score model was generated to quantify risk of VA/SCD in BrS and inform implantable cardioverter-defibrillator prescription. (C) 2021 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.

Abstract Introduction Little is known regarding the aetiology or outcome of atrial fibrillation (AF) occurring in young adults. This retrospective analysis was performed to explore the demographics and efficacy of AF ablation in this population. Methods Patients were included who had undergone ≥1 AF ablation under the age of 40 between 2006-2018. Recurrence was defined as return of either documented AF or previous symptoms for >30s following a 3-month blanking period. Initial exploratory co-variates were included in a univariate analysis and those terms with P-value of <0.1 were then used to generate a Cox proportional-hazards multivariate model. Results 124 patients (33.6 ± 4.7 yrs, 77% men), initially presenting with paroxysmal AF (pAF; n = 97) or persistent AF (n = 27), underwent 175 AF ablation procedures. 22.6% (n = 28) also had atrial flutter. Time from symptom onset to first ablation was 50.7 ± 46.2 months. Relevant cardiovascular-related demographics were analysed: hypertension in 8.9% (n = 11); diabetes in 1.6% (n = 2); positive family history of AF in 12.9% (n = 16); and family history of sudden cardiac death in 2.4% (n = 3). Mean CHA2DS2-VASc score was 0.35. Of those patients with documented echocardiogram imaging (n = 91), 26.4% (n = 24) had LA dilatation and 6.6% (n = 6) had LV dysfunction. Patients with LA dilatation underwent more ablations (2.3 ± 0.3) compared to controls (1.5 ± 0.1; p < 0.001). Ablation strategy was pulmonary vein isolation (PVI) only in 67.2% (n = 119), with additional ablation in the remaining: roof line in 18.9% (n = 33); cavotricuspid isthmus line in 13.1% (n = 23); mitral isthmus line in 2.3% (n = 4); superior vena cava isolation in 2.3% (n = 4); complex fractionated atrial electrograms in 14.9% (n = 26). Mean procedure time was 155 ± 41 min, mean ablation time was 1657 ± 991 s and mean fluoroscopy time was 32.6 ± 23.4 min. General anaesthesia was used in 43.4% (n = 76). Complications included femoral haematoma (n = 2), tamponade (n = 1) and pulmonary vein stenosis (n = 2). 90 days of follow-up was available for 137 procedures performed for pAF (n = 105) and persistent AF (n = 32). For pAF, overall recurrence was 61.9% for first ablations and 62.9% overall. Recurrence was 56.3% for persistent AF. Factors significantly associated with increased AF recurrence in univariate analysis were male gender (hazard ratio (HR) 2.3, 95% confidence interval (CI): 1.2-4.4, p = 0.011), hypertension (HR 0.5, CI: 0.2-1.1, p = 0.067), family history of sudden cardiac death (HR 6.8, CI: 1.6-29.0 , p = 0.010) and enlarged LA size (HR 2.2, CI: 1.3-3.6, p = 0.003). In multivariate analysis, the only significant predictor of poor outcome was enlarged LA size (HR 2.0, 95% CI: 1.2-3.5, p = 0.011). Conclusions Young patients with AF may have structurally abnormal hearts, and therefore do not only present with lone AF. LA size may be used as a predictor for success. Surveillance imaging may be useful to detect future structural change, which will be the subject of future prospective studies. Abstract Figure. AF ablation recurrence in young adults

Abstract Introduction. Radiofrequency catheter ablation (RFA) is 1st line treatment in symptomatic adult patients with Wolff-Parkinson-White syndrome (WPW). Patients with WPW are often quoted a high success rate for RFA but does this reflect reality? There is a paucity of recent literature and ongoing service developments in the UK may have a negative impact on success by reducing individual operator experience of adult WPW cases (i.e. increasing numbers of cardiac electrophysiologists in each department, patients more likely to undergo RFA as children). In contrast, technological developments (e.g. 3D mapping, steerable sheaths) may have a positive impact on success of RFA in WPW. Methods. We collected data on all patients with WPW scheduled for 1st time ablation between Jan 2006 and Dec 2018. All patients undergoing re-do RFA during this time were excluded. For comparison, we divided this timeframe into three periods: 2006-9, 2010-13 and 2014-18. Results. The number of patients scheduled for RFA and the outcome is listed in the Table. The overall success rate was 86.5% and this figure remained constant throughout the 13 year time-frame. Significant complications occurred in 1.17% of cases. 19.9% of patients scheduled for an ablation had no ablation attempted for various reasons (‘safe’ pathway, proximity to AV node etc). Conclusion. In our centre, the number of adult cases of WPW scheduled for RFA year-on-year remains constant. The complication rate is in line with published literature. The RFA success rate is lower than the published data. As expected, success rate of RFA for WPW varies according to accessory pathway location. 1 in 5 cases scheduled for ablation did not proceed to ablation. This highlights an area where more effective resource planning from the outset can be undertaken. Table 2006-9 2010-13 2014-18 Patients scheduled for RFA, n 181 152 179 Patients who underwent RFA, n 162 121 127 Overall RFA success rate, % (n) 85.6 (160) 86.6 (119) 87.4 (127) Success rate by AP location, % (n) Free wall Left 91.5 (71) 91.8 (49) 95.3 (64) Right 76.9 (13) 77.8 (9) 60.0 (5) Septal Anterior 77.8 (9) 88.9 (9) 100.0 (4) Mid 75.0 (8) 90.0 (10) 66.7 (3) Posterior 86.0 (57) 82.9 (41) 79.6 (49) RFA success rate in patients with Wolff-Parkinson-White syndrome. AP = accessory pathway, RFA = radiofrequency catheter ablation

BACKGROUND:The widely accepted model for atrial fibrillation (AF) ablation involves overnight hospital stay post-procedure. Day case AF ablation has been carried out at Royal Papworth Hospital (RPH) since early 2017. We evaluated the feasibility, safety and efficacy of day case AF ablation at RPH.METHOD:This was a retrospective, single-centre study of consecutive AF ablations at RPH between March 2017 and April 2018. Demographic, procedural and outcome data were analysed.RESULTS:Over the study period, 452 AF ablations were performed in 448 patients. One hundred and twenty-nine (129) (28.5%) were planned day cases; of these 128 were discharged on the same day. Two hundred and eighty-three (283) procedures resulted in at least one night admission. There was no significant difference in age or sex between the groups. Of note, day case procedures were significantly shorter, more likely to commence in the morning and less likely to require general anaesthetic than overnight stays. Patients listed as day cases also had less far to travel. The overall complication rate was 3.3%, with no significant difference between groups. Follow-up data was available for 448 cases (99.1%). Procedural success rates were comparable between groups. The overall cost saving attributable to providing AF ablation as a day case was £67,200 over the 13-month period.CONCLUSIONS:Day case AF ablation is efficacious and associated with a low event rate, even without strict standardisation of patient selection or procedural protocols, in a high-volume centre. Substantial reduction in health care expenditure can be achieved with more widespread implementation of outpatient AF ablation.

Catheter ablation is an important adjunct to device implantation for secondary prevention of ventricular tachycardia (VT). However, several factors may influence the success of ablations in terms of long-term freedom from VT recurrence. A thus far little examined factor is the use of general anaesthetic (GA) versus conscious sedation during the procedure, which has been shown to improve outcomes in persistent atrial fibrillation (AF) ablation. Patients with structural heart disease VT undergoing ablations from January 2015 to March 2019 were retrospectively followed up at a single centre. End points were recurrent VT or device therapy (shock or anti-tachycardia pacing) at one year. Hazard ratios (HR) were generated using a multivariate Cox-regression proportional hazards model including variables of age at ablation, sex, amiodarone use at time of ablation, scar age, left ventricular ejection fraction, use of GA, and diagnosis of: diabetes mellitus (DM), hypertension (HTN), renal impairment or AF. 79 patients (74 male, mean age 68.2+/- 10.3 years) were included. A substrate-based strategy of late potential ablation was employed. 69 had ischaemic and 10 had non-ischaemic cardiomyopathy. Mean scar age was 13.8 +/- 9.8 years; EF was 40-50% in 27 patients, 30-40% in 26 and < 30% in 26. 37 patients had implantable cardioverter defibrillators and 30 had cardiac resynchronisation therapy (CRT) defibrillator devices, 1 had a CRT- pacemaker device and 4 had dual chamber pacemakers. Comorbidities were: DM (16), HTN (31), renal impairment (13), AF (31). 62 patients (79.5%) were on amiodarone at the time of ablation. Mean procedure duration was 234.8 +/- 44.5 min and mean radiofrequency energy application time was 2247 +/- 862 s. 61 were first procedures and 18 were repeat procedures. One patient suffered a complication of groin haematoma. 62 patients (78.5%) underwent VT ablation under GA and 17 (21.5%) under sedation of midazolam and fentanyl. Patient characteristics did not differ between groups. Significant factors which increased freedom from VT recurrence or device therapy were HTN (88.9% vs 59.4%, HR 0.72, 95% confidence interval (CI): 0.007-0.75, p= 0.028), amiodarone treatment (50.0% vs 76.3%, HR 0.036, 95% CI: 0.003-0.404, p = 0.036) and ablation under GA rather than sedation (50.0% vs 75.0%, HR 0.055, 95% CI: 0.006-0.495, p = 0.01) (Fig 1). In patients with structural heart disease undergoing VT ablation, outcomes are improved with the use of GA over conscious sedation. Abstract Figure 1

OBJECTIVES A new etectroanatomic mapping system (Rhythmia, Boston Scientific, Marlborough, Massachusetts) using a 64-electrode mapping basket is now available; we systematically assessed its use in complex congenital heart disease (CHD). BACKGROUND The incidence of atrial arrhythmias post-surgery for CHD is high. Catheter ablation has emerged as an effective treatment, but is hampered by limitations in the mapping system's ability to accurately define the tachycardia circuit. METHODS Mapping and ablation data of 61 patients with CHD (35 mates, age 45 +/- 14 years) from 8 tertiary centers were reviewed. RESULTS Causes were as follows: Transposition of Great Arteries (atrial switch) (n = 7); univentricutar physiology (Fontans) (n = 8); Tetralogy of Fattot (n = 10); atrial septat defect (ASD) repair (n = 15); tricuspid valve (TV) anomalies (n = 10); and other (n = 11). The total number of atrial arrhythmias was 86. Circuits were predominantly around the tricuspid valve (n = 37), atriotomy scar (n = 10), or ASD patch (n = 4). Although the majority of peri-tricuspid circuits were cavo-tricuspid-isthmus dependent (n = 30), they could follow a complex route between the annulus and septat resection, ASD patch, coronary sinus, or atriotomy. Immediate ablation success was achieved in all but 2 cases; with follow-up of 12 +/- 8 months, 7 patients had recurrence. CONCLUSIONS We demonstrate the feasibility of the basket catheter for mapping complex CHD arrhythmias, including with transbaffle and transhepatic access. Although the circuits often involve predictable anatomic landmarks, the precise critical isthmus is often difficult to predict empirically. Ultra-high-density mapping enables elucidation of circuits in this complex anatomy and allows successful treatment at the isthmus with a minimal lesion set. (C) 2019 by the American College of Cardiology Foundation.

OBJECTIVES The goal of this study was to characterize, in detail, focal atrial tachycardia (AT) arising from the crista terminalis to investigate associations with other atrial arrhythmia and to define long-term ablation outcomes. BACKGROUND The crista terminalis is known to be the most common site of origin for focal AT, but it is not well characterized. METHODS This study retrospectively identified a total of 548 ablation procedures for AT performed at a single center over a 16-year period, of which 171 were arising from the crista terminalis. RESULTS Compared with patients with other AT sites of origin, crista terminalis AT patients were older (57.3 vs. 47.3 years), more commonly female (72.9% vs. 59.1%), were more commonly associated with coexistent atrioventricular nodal re-entry tachycardia (17.1% vs. 9.7%), and were more likely to be inducible with programmed stimulation (81.5% vs. 58.9%). There was preferential conduction in the superior-inferior axis along the crista terminalis. Acute ablation success rate was high (92.2%) and improved significantly when three-dimensional mapping was used (98.5%). Recurrence in the first 12 months after a successful ablation was 9.7%. Only 2 patients developed atrial fibrillation over the long-term follow-up of >7 years. CONCLUSIONS This large series characterized the clinical and electrophysiological features and immediate and long-term ablation outcomes for AT originating from the crista terminalis. Features of the tachycardia suggest that age-related localized remodeling of the crista terminalis causes a superficial endocardial zone of conduction slowing leading to re-entry. Ablation outcomes were good, with long-term freedom from atrial arrhythmia. (C) 2019 by the American College of Cardiology Foundation.

BACKGROUND Spatial resolution in cardiac activation maps based on voltage measurement is limited by far-field interference. Precise characterization of electrical sources would resolve this limitation; however, practical charge-based cardiac mapping has not been achieved. METHODS A prototype algorithm, developed from first principles of electrostatic field theory, derives charge density (CD) as a spatial representation of the true sources of the cardiac field. The algorithm processes multiple, simultaneous, noncontact voltage measurements within the cardiac chamber to inversely derive the global distribution of CD sources across the endocardial surface. RESULTS Comparison of CD to an established computer-simulated model of atrial conduction demonstrated feasibility in terms of spatial, temporal, and morphologic metrics. Inverse reconstruction matched simulation with median spatial errors of 1.73 mm and 2.41 mm for CD and voltage, respectively. Median temporal error was less than 0.96 ms and morphologic correlation was greater than 0.90 for both CD and voltage. Activation patterns observed in human atrial flutter reproduced those established through contact maps, with a 4-fold improvement in resolution noted for CD over voltage. Global activation maps (charge density-based) are reported in atrial fibrillation with confirmed reduction of far-field interference. Arrhythmia cycle-length slowing and termination achieved through ablation of critical points demonstrated in the maps indicates both mechanistic and pathophysiological relevance. CONCLUSION Global maps of cardiac activation based on CD enable classification of conduction patterns and localized nonpulmonary vein therapeutic targets in atrial fibrillation. The measurement capabilities of the approach have roles spanning deep phenotyping to therapeutic application. TRIAL REGISTRATION ClinicalTrials.gov NCT01875614. FUNDING The National Institute for Health Research (NIHR) Translational Research Program at Royal Papworth Hospital and Acutus Medical.

Background Identification and elimination of nonpulmonary vein targets may improve clinical outcomes in patients with persistent atrial fibrillation (AF). We report on the use of a novel, noncontact imaging and mapping system that uses ultrasound to reconstruct atrial chamber anatomy and measures timing and density of dipolar, ionic activation (ie, charge density) across the myocardium to guide ablation of atrial arrhythmias. Methods The prospective, nonrandomized UNCOVER AF trial (Utilizing Novel Dipole Density Capabilities to Objectively Visualize the Etiology of Rhythms in Atrial Fibrillation) was conducted at 13 centers across Europe and Canada. Patients with persistent AF (>7 days, <1 year) aged 18 to 80 years, scheduled for de novo catheter ablation, were eligible. Before pulmonary vein isolation, AF was mapped and then iteratively remapped to guide each subsequent ablation of charge density-identified targets. AF recurrence was evaluated at 3, 6, 9, and 12 months using continuous 24-hour ECG monitors. The primary effectiveness outcome was freedom from AF >30 seconds at 12 months for a single procedure with a secondary outcome being acute procedural efficacy. The primary safety outcome was freedom from device/procedure-related major adverse events. Results Between October 2016 and April 2017, 129 patients were enrolled, and 127 underwent mapping and catheter ablation. Acute procedural efficacy was demonstrated in 125 patients (98%). At 12 months, single procedure freedom from AF on or off antiarrhythmic drugs was 72.5% (95% CI, 63.9%-80.3%). After 1 or 2 procedures, freedom from AF was 93.2% (95% CI, 87.1%-97.0%). A total of 29 (23%) retreatments because of arrhythmia recurrence were performed with average time from index procedure to first retreatment being 7 months. The primary safety outcome was 98% with no device-related major adverse events reported. Conclusions This novel ultrasound imaging and charge density mapping system safely guided ablation of nonpulmonary vein targets in persistent AF patients with 73% single procedure and 93% second procedure freedom from AF at 12 months. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT02825992 EU/NCT02462980 CN.

BackgroundMaintenance of sinus rhythm has been associated with lower mortality, but whether atrial fibrillation (AF) ablation per se benefits hard outcomes such as mortality and stroke is still debated.ObjectiveTo determine whether AF ablation is associated with a reduction in all-cause mortality and stroke compared with medical therapy alone.MethodsLiterature search looking for both randomized and observational studies comparing AF catheter ablation vs. medical management. Data pooled using random-effects. Risk ratios (RR) with 95% confidence intervals (CI) used as a measure of treatment effect. The primary and secondary outcomes were all-cause mortality and occurrence of cerebrovascular events during follow-up, respectively.ResultsThirty studies were eligible for inclusion, comprising 78,966 patients (25,129 receiving AF ablation and 53,837 on medical treatment) and 233,990patient-years of follow-up. The pooled data of studies revealed that ablation was associated with lower risk of all-cause mortality: 5.7% vs. 17.9%; RR=0.44, 95% CI 0.32–0.62, p<0.001. In a sensitivity analysis by study design, a survival benefit of AF ablation was seen in randomized studies, with no heterogeneity (mortality risk 4.2% vs. 8.9%; RR=0.55, 95% CI 0.39–0.79, p=0.001, I2=0%), and also in observational studies, but with marked heterogeneity (6.1% vs. 18.3%; RR=0.39, 95% CI 0.26–0.59, p<0.001, I2=95%). The mortality benefit in randomized studies was mainly driven by trials performed in patients with left ventricular (LV) dysfunction and heart failure.The pooled risk of a cerebrovascular event was lower in patients receiving AF ablation (2.3% vs. 5.5%; RR=0.57, 95% CI 0.46–0.70, p<0.001, I2=62%), but no difference was seen in randomized trials (2.2% vs. 2.1%; RR=0.94, 95% CI 0.46–1.94, p=0.87, I2=0%).ConclusionsAblation of atrial fibrillation associates with a survival benefit compared with medical treatment alone, although evidence is restricted to the setting of heart failure and LV systolic dysfunction.

Cardiac implantable electronic devices include implantable loop recorders, pacemakers and implantable cardioverter defibrillators. The prevalence of these devices is increasing and they are therefore increasingly likely to be encountered at post mortem. This review will provide an overview of the different types of device, including their indications, their normal form and function, as well as the complications, both procedural and longer term, that are associated with them. An understanding of these devices will facilitate a greater understanding of the underlying disease processes affecting the patient, and which may have contributed to their death. Interrogation of the device itself may also provide clarity on cause of death for a large proportion of patients where post mortem examination alone has failed to do so.