Search

Funding Acknowledgements Type of funding sources: None. Introduction In a previous retrospective study it was demonstrated that an electrophysiological triad was able to identify critical isthmus in atrial flutter (AFL) patients. This triad is based in the Carto® electroanatomical mapping (EAM) version 7, which displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to the activation and voltage maps. This study aimed to prospectively assess the ability of an electrophysiological triad to identify and localize the AFL’s critical isthmus. Methods Prospective analysis of a unicentric registry of individuals who underwent left AFL ablation with Carto® EAM. All patients with non-left AFL, lack of high-density EAM, less than 2000 collected points or lack of mapping in any of the left atrium walls or structures were excluded. Ablation sites of arrhythmia termination were compared to an electrophysiological triad constituted by: areas of low-voltage (0.05 to 0.3mV), sites of deep histogram valleys (LAT-Valleys) with less than 20% density points relative to the highest density zone and a prolonged LAT-Valley duration that included 10% or more of the TCL. The longest LAT-Valley was designated as the primary valley, while additional valleys were named as secondary. Results A total of 12 patients (9 men, median age 72 IQR 67-75 years) were included. All patients presented with left AFL and 67% had a previous atrial fibrillation and/or flutter ablation. The median TCL and number collected points were 250 (230─290) milliseconds and 3150 (IQR 2340─3870) points, respectively. All AFL presented with at least 1 LAT-Valley in the analysed histograms, which corresponded to heterogeneous low-voltage areas (0.05 to 0.3mV) and encompassed more than 10% of TCL. Eleven of the 12 patients presented with at least 1 secondary LAT-Valley. All arrhythmias were effectively terminated after undergoing radiofrequency ablation in the primary or the secondary LAT-Valley location. Conclusion In a prospective analysis, an electrophysiological triad was able to identify the AFL critical isthmus in all patients. Further studies are needed to assess the usefulness of this algorithm to improve catheter ablation outcomes.

Background Current sudden cardiac death (SCD) risk stratification relies heavily on the assessment of left ventricular ejection fraction (LVEF), but markers that could refine risk assessment are needed. Total fibrosis mass (TFM) and “gray zone” of myocardial fibrosis (GZF) on late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) have been proposed as potential arrhythmogenic substrates. The aim of our study was to determine whether TFM and GZF can predict the occurrence of ventricular arrhythmias in patients with previous myocardial infarction. Methods We performed a single centre retrospective study enrolling all consecutive patients with previous myocardial infarction undergoing LGE-CMR before implantable cardioverter-defibrillator (ICD) implantation for primary or secondary prevention. TFM and GZF were defined as myocardial tissue with signal-intensities >6 SD and 2–6 SD above the mean of reference myocardium, respectively. The primary endpoint was a composite of sudden arrhythmic death, appropriate ICD shock, ventricular fibrillation (VF), or sustained ventricular tachycardia (VT) as detected by the device. Results A total of 55 patients (mean age 62±12 years, 87% male, mean LVEF 30% ± 8%) were included. During a mean follow-up period of 34±15 months, 10 patients reached the primary endpoint (8 appropriate ICD shock, 2 sustained VT or VF). Patients who attained the primary endpoint had similar TFM (28.6g ± 14.5 vs. 23.1g ± 14.5; P=0.283) but larger GZF (25.3g ± 11.0 vs 15.6g ± 7.3; P=0.001). After adjustment for LVEF, GZF remained independently associated with the composite arrhythmic endpoint (adjusted hazard ratio [aHR]: 1.10; 95% CI: 1.03–1.17; P=0.005), whereas TFM did not (aHR: 1.02; 95% CI: 0.98–1.06; P=0.394). Decision tree analysis identified 16.4g of GZF as the best cut-off to predict life-threatening arrhythmic events. The primary endpoint occurred in 9 out of the 22 patients (41%) with GZF >16.4g, but in only 1 of the 33 patients (3%) with GZF ≤16.4g – Figure. Conclusions The extent of GZF seems to be a better predictor of ventricular arrhythmias than TFM. This LGE-CMR parameter may be useful to identify a subgroup of patients with previous myocardial infarction at an increased risk of life-threatening arrhythmic events. Funding Acknowledgement Type of funding sources: None.

Funding Acknowledgements Type of funding sources: None. INTRODUCTION Catheter ablation outcomes for drug-resistant ventricular tachycardia (VT) in nonischemic cardiomyopathy (NICM) are suboptimal when compared to ischemic cardiomyopathy. We aimed to analyse the long-term efficacy and safety of percutaneous catheter ablation in this subset of patients. METHODS Single-center observational retrospective registry including consecutive NICM patients who underwent catheter ablation for drug-resistant VT during a 10-year period. The efficacy endpoint was defined as VT-free survival after catheter ablation, while safety outcomes were defined by 30-days mortality and procedure-related complications. Independent predictors of VT recurrence were assessed by Cox regression. RESULTS In a population of 68 patients, most were male (85%), mean left ventricular ejection fraction (LVEF) was 34 ± 12%, and mean age was 58 ± 15 years. All patients had an implantable cardioverter-defibrillator. Twenty-six (38%) patients underwent epicardial ablation (table 1). Over a median follow-up of 3 years (IQR 1-8), 41% (n = 31) patients had VT recurrence and 28% died (n = 19). Multivariate survival analysis identified LVEF (HR= 0.98; 95%CI 0.92-0.99, p = 0.046) and VT storm at presentation (HR = 2.38; 95%CI 1.04-5.46, p = 0.041) as independent predictors of VT recurrence. The yearly rates of VT recurrence and overall mortality were 21%/year and 10%/year, respectively. No patients died at 30-days post-procedure, and mean hospital length of stay was 5 ± 6 days. The complication rate was 7% (n = 5, table 1), mostly in patients undergoing epicardial ablation (4 vs 1 in endocardial ablation, P = 0.046). CONCLUSION LVEF and VT storm at presentation were independent predictors of VT recurrence in NICM patients after catheter ablation. While clinical outcomes can be improved with further technical and scientific development, a tailored endocardial/epicardial approach was safe, with low overall number of complications and no 30-days mortality. Abstract Figure.

Funding Acknowledgements Type of funding sources: None. Background Previous studies have shown an adverse prognosis for patients with transvenous implantable cardioverter-defibrillators (ICD) who receive both appropriate and inappropriate shocks. There is a paucity of data regarding the prognosis of inappropriate shocks in patients with a subcutaneous ICD (S-ICD). Purpose To assess and characterize S-ICD appropriate (AS) and inappropriate shocks (IAS) and their impact on mortality. Methods Single center observational registry of 162 consecutive patients who underwent S-ICD implantation for primary and secondary prevention between November 2009 and September 2020. Only follow-up data of at least 6 months was analysed to identify predictors of both IAS and AS and their mortality impact. Results A total of 144 patients were included in the analysis. Mean age was 42.2 ± 16.6 years and 75% of the patients were male. One hundred and four patients (72.2%) implanted the S-ICD in primary prevention. The most common etiology was ischemic cardiomyopathy (22.9%) followed by hypertrophic cardiomyopathy (18.8%) and dilated idiopathic cardiomyopathy (14.6%). During a mean follow-up of 42.3 ± 29.9 months a total of 48 patients (33.3%) experienced at least one S-ICD shock. Twenty-nine (20.1%) patients received AS due to VT/VF and 31 patients (21.5%) received IAS. Eighteen (58.1%) of the IAS were due to oversensing/noise/discrimination errors and the remaining due to supraventricular tachycardia. Overall, patients with AS (HR 4.93, 95% CI 1.58-15.36, p = 0.006) and higher number of total AS (HR 1.10, 95% CI 1.00-1.20, p = 0.044) were associated with higher mortality during follow-up. S-ICD IAS therapy did not affect overall mortality (HR 1.71, 95% CI 0.21-14.0, p = 0.616). Conclusions: In patients with S-ICD, those who receive AS, in contrast to IAS, seem to have a worse prognosis. Large scale studies are needed to confirm this hypothesis and to explain this findings. Abstract Figure. Survival curves for AS and IAS

Background and aim Prophylactic implantation of an implantable cardioverter-defibrillator (ICD) is class 1 recommendation for heart failure (HF) patients with reduced ejection fraction (HFrEF) even though its proven advantage is weaker among nonischemic aetiology. In fact, in an era where both optimal medical therapy (OMT) and cardiac resynchronization therapy (CRT) significantly reduce sudden cardiac death (SCD), it is questionable whether ICD still have additional value. The aim of this study was to assess the current benefit of ICDs in preventing sudden cardiac death through resuscitated cardiac arrest (RCA), appropriate therapy for sustained ventricular tachycardia (VT) or fibrillation (VF) in a contemporary population of idiopathic HFrEF patients. Methods Single-centre retrospective study of consecutive symptomatic (NYHA class II to IV) idiopathic HFrEF patients with an ICD (either alone or in association with CRT), and remote monitoring with the corresponding software (MerlinTM, LatitudeTM, CarelinkTM, MicroPortTM or BiotronikTM) to assure appropriate event supervising. Idiopathic aetiology was assumed after excluding other probable causes. Coronary angiogram was required to exclude ischemic aetiology. Only those with prophylactic ICD implantation were included. RCA was defined as collapse with clinical signs of cardiac arrest and VF or VT appropriately terminated by ICD. In order to be sustained, VT episode had to have last at least 30 seconds. Results From 781 remote monitoring controlled patients, a total of 187 consecutive symptomatic idiopathic HFrEF patients with an ICD (125 men, mean age 64±18 years) were enrolled. Patients were on optimal medical therapy (ACEi/ARB: n=168, 90%; BB: n=154, 82%; mineralocorticoid antagonists: n=91, 49%; CRT: n=130, 70%; see Table). After a median follow-up of 99 months (IQR 62.2), RCA occurred in 10.7% (n=20) and 36.9% (n=69) had appropriately terminated VT. Both left ventricular ejection fraction (LVEF) improvement and CRT implantation did not independently reduce the incidence of RCA and VT requiring ICD therapy (OR, 1.02; 95% CI, 0.99–1.05; P=0.146 and OR, 0.85; 95% CI, 0.34–2.13; P=0.728; respectively). All cause mortality was 20 (10.7%). Inappropriate therapy was given as shocks to 41 patients (21.9%) and as antitachycardia pacing (ATP) to 30 (16%), opposing with appropriately given therapy to 43 (23%) and 63 (33.7%) patients, respectively (see Figure), contributing to a net clinical benefit (NCB) of 18.8%, favouring ICD implantation. Conclusion In this contemporaneous real-world population of symptomatic idiopathic HFrEF patients, episodes of impending cardiac death were frequent. Prophylactic ICD implantation seems to have added further benefit reducing SCD on top of optimal medical therapy, LVEF improvement and coexisting CRT. Funding Acknowledgement Type of funding source: None

Background Catheter ablation (CA), has gained wider acceptance as an attractive option for treating symptomatic AF. Although traditionally seen as a safe procedure, there is limited and conflicting data on procedure-related early morbimortality, with new evidence suggesting early mortality may be as high as 0.5%-1%. Purpose We aimed to assess the rates of early and late morbimortality of post-atrial fibrillation (AF) ablation in high-volume centers. Methods Prospective registry of 2 high-volume ablation centers, comprising 3722 consecutive patients (mean age 61.1±11.2, 66.4% male, n=2471), who underwent AF ablation from 2005 to 2019. Early mortality was defined as death during initial admission or during the first 45 days after ablation. Median follow-up time was 5.4 years. Results Most patients were treated with radiofrequency (97%) while 3% were treated with cryoablation. Early mortality was 0.08% (n=3), with a median time from ablation to death of 22 days. Cumulative mortality at 3, 6 and 12 months was 0.08%, 0.16% and 0.19%, respectively. At 3 and 5 years, mortality remained low at 0.48% and 0.73%, respectively. Early mortality was higher among patients who had suffered procedural complications (fistula and stroke, p Conclusion Early mortality following ablation is very low ( AF catheter ablation morbimort Funding Acknowledgement Type of funding source: None

Background Epicardial adipose tissue (EAT) has recently been shown to be associated with the presence, severity, and recurrence of atrial fibrillation (AF). Although the pathophysiological mechanisms underlying this association remain to be established, several hypotheses have been put forward, including direct adipocyte infiltration, oxidative stress, and the secretion of adipokines causing inflammation and fibrosis of atrial tissue. We hypothesized that the volume of EAT and the amount of left atrium (LA) fibrosis assessed by non-invasive imaging would be significantly correlated in patients with AF, and that both would predict time to relapse after pulmonary vein isolation (PVI). Methods Sixty-eight patients with AF being studied for a first PVI procedure underwent both cardiac computerized tomography (CT) and cardiac magnetic resonance (CMR) within less than 48h. EAT was quantified on contrast-enhanced CT images. LA fibrosis was quantified on isotropic 1.5mm 3D delayed enhancement CMR for image intensity ratio values >1.20. Radiofrequency PVI was performed using an irrigated contact force-sensing ablation catheter, guided by electroanatomical mapping. After PVI, patients were followed for AF recurrence, defined as symptomatic or documented AF after a 3-month blanking period. Pearson's correlation coefficient was used for gauging the correlation between EATLM volume and LA fibrosis. The relationship between these two variables and time to AF recurrence was assessed by Cox regression. Results Most of the 68 patients (46 men, mean age 61±12 years) had paroxysmal AF (71%, n=48). The mean body mass index (BMI) was 28.0±4.0 kg/m2. Patients had a median EATLM volume of 2.4 cm3/m2 [interquartile range (IQR) 1.6–3.2 cm3/m2], and a median estimated amount of LA fibrosis of 8.9 g (IQR 5–15 g), corresponding to 8% (IQR 5–11%) of the total LA wall mass. The correlation between EATLM and LA fibrosis was statistically significant but weak (Pearson's R = 0.38, P=0.001) – Figure 1. During a median follow-up of 22 months (IQR 12–31), 31 patients (46%) suffered AF recurrence. Four predictors of relapse were identified in univariate Cox regression: EATLM (HR 2.19, 95% CI 1.65–2.91, P Conclusion The weak correlation between EAT and LA suggests that LA fibrosis is not the main mechanism by which EAT and AF are linked. EAT was more strongly associated with AF recurrence than LA fibrosis, which supports the existence of other, more important mediators between EAT and this arrhythmia. Correlation between EAT and LA Funding Acknowledgement Type of funding source: None

Introduction Computed tomography (CT) is often performed before atrial fibrillation (AF) ablation to assess the anatomy of the pulmonary veins and exclude left atrial (LA) and left atrial appendage (LAA) thrombus. With the growing use of new oral anticoagulants (NOACs), a reassessment of the need for systematic thrombus exclusion in this context seems warranted. Objective To evaluate the prevalence of thrombus in LA/LAA in pre-ablation CT in a contemporary cohort of patients predominantly anticoagulated with NOACs. Methods We evaluated 789 consecutive patients (mean age 61±12 years; 38% female; 84% with paroxysmal AF) who underwent pre-ablation CT between Oct/2015 and Oct/2019. ECG-gated CT-angiography was performed using a dual-source 64-slice CT after iodinated contrast injection. Whenever necessary, a second dedicated acquisition was made 60 seconds after the first set of images. Presence of thrombus was defined as a persistent opacification defect. For each patient, thromboembolic risk was assessed with the CHA2DS2-VASc score. Results The median interval between CT and AF ablation was 1 day (IQR 1 – 2 days). The median CHA2DS2-VASc was 2 points (IQR 0 – 3 points), with 590 patients (75%) having CHA2DS2-VASc ≥1. Among the 199 patients (25%) with CHA2DS2-VASc = 0, 118 (59,3%) were anticoagulated with a NOAC and 14 (7%) with a vitamin K antagonist; 67 (34%) were not anticoagulated. Conversely, amongst the 590 patients with CHA2DS2-VASc ≥1, 84% were anticoagulated with a NOAC (n=494), 11% used vitamin K antagonists (n=62), and 34 patients were not anticoagulated (23 with CHA2DS2-VASc = 1). On cardiac CT, 521 (66%) patients were in sinus rhythm. Overall, only one LAA thrombus was found (0.12% [1/789]; 95% CI: 0.0–0.7%) – in a patient with CHA2DS2-VASc = 0, anticoagulated with a NOAC. The median effective radiation dose was 3.2 mSv (IQR 2.1–4.8 mSv). There were 5 minor allergic reactions to iodinated contrast. No strokes were documented within the first 24 hours after ablation. Conclusion In this contemporary cohort of patients with predominantly paroxysmal AF and anticoagulated with NOAC, the prevalence of intracavitary thrombus was extremely low (0.12%). While these findings do not compromise the multipurpose role of pre-ablation CT, they should nevertheless inform future discussions on the risk/benefit and cost/benefit of performing systematic exclusion of LA/LAA thrombi prior to AF ablation. Funding Acknowledgement Type of funding source: None

Background Epicardial adipose tissue has been implicated in the pathophysiology of atrial fibrillation (AF), but its relevance to clinical practice remains uncertain. The aim of this study was to compare the performance of the amount of epicardial fat with previously published clinical scores of AF-relapse risk after pulmonary vein isolation (PVI). Methods We assessed 575 patients (354 men, age 61±11 years, 449 paroxysmal AF) with symptomatic AF undergoing cardiac CT prior to a PVI procedure. Epicardial fat was quantified on contrast-enhanced images using a new simplified semi-automated method. The study endpoint was symptomatic and/or documented AF recurrence at 12 months. Epicardial fat was compared against the following scores: MB-LATER, APPLE, DR-FLASH, and ATLAS. Results Median follow-up was of 22 months (IQR 12–35), 232 patients relapsed, 130 patients (27%) within the first 12 months. After adjustment for BMI and other univariate predictors of relapse, three variables emerged independently associated with time to AF recurrence: non-paroxysmal AF (HR 2.03, 95% CI: 1.53–2.69, p Conclusion Pericardial fat volume is a strong independent predictor of AF relapse after PVI, outperforming clinical scores of post-PVI AF. The underlying mechanisms of this association deserve further study. ROC Curve Analysys Funding Acknowledgement Type of funding source: None

Background Patients with ischemic (IHD) and nonischemic (NICM) dilated heart disease and reduced left ventricular ejection fraction are at increased risk of ventricular tachycardias (VTs) or sudden cardiac death. VT catheter ablation is an invasive treatment modality for antiarrhythmic drugs-resistant VT that reduces arrhythmic episodes, improves quality of life and improves survival in patients with electrical storm. Direct comparison of the outcomes from combined and non-combined endoepicardial ablations is limited by patient characteristics, follow-up durations, protocols heterogeneity and scarcity of randomized trials. We aim to investigate the long-term clinical outcomes of these 2 strategies in the IHD and NICM populations. Methods Multicentric observational registry including 316 consecutive patients who underwent combined (C-ABL) and non-combined (NC-ABL) endoepicardial ventricular tachycardia (VT) ablation for drug-resistant VT between January 2008 and July 2019. Chagas' disease patients were excluded. Primary and secondary efficacy endpoints were defined as VT-free survival and all-cause death after ablation. Safety outcomes were defined by 30-days mortality and procedure-related complications. Results Most of the patients were male (85%), with IHD (67%) and a mean age of 63±13 years. During a mean follow-up of 3±2 years, 117 (37%) patients had VT recurrence and 73 (23%) died. Multivariate survival analysis identified storm (ES) at presentation (HR=2.17; 95% CI 1.44–3.25), IHD (HR=0.53, 95% CI 0.36–0.78), left ventricular ejection fraction (LEVF) (HR=0.97, 95% CI 0.95–0.99), New York Heart Association (NYHA) functional class III or IV (HR=1.79, 95% CI 1.13–2.85) and C-ABL (HR=0.49, 95% CI 0.27–0.92) as independent predictors of VT recurrence. In 135 patients undergoing two or more ablation procedures only C-ABL (HR=0.36, 95% CI 0.17–0.80) and ES at presentation (HR=2.42, 95% CI 1.24–4.70) were independent predictors of arrhythmia recurrence. The independent predictors of all-cause mortality were ES (HR=2.17, 95% CI 1.33–3.54), LVEF (HR=0.95, 95% CI 0.92–0.98), age (HR=1.03, 95% CI 1.01–1.05), NYHA functional class III or IV (HR=2.04, 95% CI 1.12–3.73), and C-ABL (HR=0.22, 95% CI 0.05–0.91). The survival benefit was only seen in patients with a previous ablation (P for interaction=0.04) – Figure 1. Mortality at 30-days was similar between NC-ABL and C-ABL (4% vs. 2%, respectively, P=0.777), as was the complication rate (10.3% vs. 15.1% respectively, P=0.336). Conclusion A combined endo-epicardial approach appears to be associated with greater VT-free survival and overall survival in ischemic and nonischemic patients undergoing repeated VT catheter ablations. Both strategies seem equally safe. Survival analysis for C-ABL vs NC-ABL Funding Acknowledgement Type of funding source: None

Background Contemporary risk models to predict the recurrence of atrial fibrillation (AF) after pulmonary vein isolation have limited predictive ability. Models with high specificity seem particularly suited for the setting of AF ablation, where they could be used as gatekeepers to withhold intervention in patients with low likelihood of success. Machine learning (ML) has the potential to identify complex nonlinear patterns within datasets, improving the predictive power of models. This study sought to determine whether ML can be used to better identify patients who will relapse within one year of an AF ablation procedure. Methods We assessed 484 patients (294 men, mean age 61±12 years, 76% with paroxysmal AF) who underwent radiofrequency pulmonary vein isolation (PVI) for symptomatic drug-refractory AF. Using this dataset, a machine-learning model based on Support Vector Machines (SVM) was developed to predict AF recurrence within one year of the procedure. The following variables were used to feed the model: type of AF (paroxysmal vs. non-paroxysmal), previous ablation procedure, left atrium (LA) volume, and epicardial fat volume (both derived from pre-ablation cardiac CT). The algorithm was trained in a random sample of 70% of the study population (n=339) and tested in the remainder 30% (n=145). Results A total of 130 patients (27%) suffered AF recurrence within one year of the procedure. The ML model predicted AF recurrence with 75% accuracy (95% CI 67–82%), yielding a sensitivity and specificity of 25% (95% CI 13–41%) and 94% (95% CI 88–98%), respectively. The corresponding positive and negative predictive values were 62% (95% CI 39–81%) and 77% (95% CI 67–82%), respectively. The relative weight of the variables in the ML model was: epicardial fat 56%, type of AF 23%, previous ablation 14%, and LA volume 7%. A high-risk subgroup representing 10.8% of patients was identified with the ML algorithm. In this subgroup, one-year recurrence was 62%, representing 24% of the total number of recurrences. Conclusion A machine-learning model showed high specificity in the identification of patients who relapse during the first year after AF ablation. In the future, these tools may be useful to improve patient selection. Funding Acknowledgement Type of funding source: None

Background Epicardial adipose tissue (EAT) has been linked to the presence and burden of atrial fibrillation (AF). However, it is still unclear whether this relationship is causal or simply a surrogate marker of other risk factors commonly associated with AF. Purpose The purpose of this study was to assess the relationship between these factors and EAT, and to compare their performance in predicting AF recurrence after an ablation procedure. Methods We assessed 575 consecutive patients (mean age 61±11 years, 62% male) undergoing AF ablation preceded by cardiac CT in a high-volume ablation center. EAT was measured on cardiac CT using a modified simplified method. Patients were divided into 2 groups (above vs. below the median EAT volume). Cox regression was used to assess the relationship between epicardial fat, risk factors, and AF relapse. Results Patients with above-median EAT volume were older (p0.10). Conclusion Classic cardiovascular risk factors are more prevalent in patients with higher amounts of epicardial fat. However, unlike these risk factors, EAT is a powerful predictor of AF recurrence after ablation. These findings suggest that EAT is not merely a surrogate marker, but an important participant in the pathophysiology of AF. EAT, cvrf and AF burden Funding Acknowledgement Type of funding source: None

Introduction Epicardial adipose tissue has been implicated in the pathophysiology of atrial fibrillation (AF) and was recently shown to be an independent predictor of AF relapse rate and severity after pulmonary vein isolation (PVI). However, its impact in older patients hasn't been analyzed. The aim of this study was to assess the relative importance of pericardial fat in an older population of patients undergoing pulmonary vein isolation (PVI). Methods Single-center retrospective study of symptomatic drug-resistant AF patients undergoing PVI from November/2015 to June/2019. Baseline demographics, clinical and imaging data including cardiac CT and clinical outcomes were collected and analyzed. Population was dichotomized according to age above or below 70 years of age and groups were compared. Epicardial fat volume was quantified by contrast-enhanced cardiac CT using a semi-automated method. The study endpoint was symptomatic and/or documented AF recurrence after a 3-month blanking period. Results We assessed 575 patients (354 males, mean age 61±11 years, 449 paroxysmal AF), 145 of which were 70 or older. Compared to the younger cohort, these patients had an higher prevalence of women, lower BMI (27 kg/m2 [IQR 24–30] vs 28 kg/m2 [IQR 25–30] kg/m2, p=0.012), higher CHA2DS2-VASc score (3 [IQR 2–4] vs 1 [IQR 1–2], p Median epicardial fat volume was 2.96 cm3/m2 [IQR 2.99–4.00] in the overall population and was higher in older patients (HR 2.21 cm3/m2 [IQR 1.44–3.17] vs HR 1.87 cm3/m2 [IQR 1.24–2.90]; p=0.016). During follow-up, 232 patients relapsed (40%), with similar recurrence rates between younger and older patients (40% vs 42%, p=0.63) according to Kaplan-Meier survival curve analysis (HR 1.10, 95% CI 0.82–1.48; log-rank p=0.519). Epicardial fat volume remained an independent predictor of AF relapse in the older subset of patients (HR 1.06 for every 1 cm3/m2 increase in epicardial fat volume [95% CI 1.28–2.00]; p Conclusion Patients over 70 years old with drug-refractory symptomatic AF presented with higher epicardial fat volume. Epicardial fat burden showed similar predictive power for AF relapse after PVI in this subset of patients, representing a useful tool for intervention decision across this age spectrum. Funding Acknowledgement Type of funding source: None

Few data exist on the incidence of spontaneously occurring ventricular tachycardia (VT) in the paediatric population. VT is often an unexpected finding in patients with otherwise normal hearts.[1 2][1] These arrhythmias have a wide range of clinical presentation, going from infrequent ectopy to

BACKGROUND The number of lead removal of cardiac implantable electronic devices (CIED) has increased in recent years. The recent European registry (ELECTRa) did not include all European centers and not all lead extractions are possible to be performed transvenously. AIMS We aim to analyze all lead extraction procedures (transvenous or open surgery) performed in our center and the short- and long-term follow-up of these patients (pts). METHODS We retrospectively reviewed all lead extractions performed from 2008 to 2017. We analyzed pts´ characteristics (personal history, cardiovascular risk factors, indication for device implantation, laboratory tests); indications for extraction; techniques used and personnel that participate in the procedure, complications peri- and post-procedural and short and long-term follow-up. RESULTS A total of 189 pts (330 leads) were included (mean 69 ± 14 years, 73% male). The follow-up was 54 (IQR 20-87) months. Median time after implant was 47 (IQR 19-98) months. Lead explant was performed in 30 patients (16%) and lead extraction (at least one lead implanted >1 year or a lead requiring assistance of specialized equipment) in 159 (84%). Indications for removal are presented in figure A. In those who were infected, isolation of the microorganism was possible in 35% and Staphylococcus aureus was the most common agent (51%). 101 procedures (53%) occurred in the operating room, while 89 (47%) were performed in the electrophysiology laboratory, but 47% of those with the participation of a surgeon. On the total, cardiac surgeons were responsible for 75% of the procedures. Removal was tried in 330 leads (98 atrium lead, 199 right ventricle lead (79 defibrillator lead) and 33 coronary sinus lead). Of those, 298 were completely removed, 14 were partially removed ( CONCLUSION Although being a low volume center (19 procedures/year) and including pts with transvenous and open surgery, lead removal was associated with a high success rate with low all cause complication and mortality rates. Emergent surgery due to acute complications was very rare (0.5%) and open heart surgery was mostly programmed and not associated with a worse outcome. Abstract Figure.

Introduction Direct comparisons of long-term clinical outcomes of endocardial vs. epicardial catheter ablation techniques for drug-resistant ventricular tachycardia (VT) have been scarcely reported. We aim to compare the long-term efficacy and safety of endocardial vs. epicardial catheter ablation (END-ABL and EPI-ABL, respectively) in a propensity score (PS) matched population. Methods Single-center observational registry including 215 consecutive patients who underwent END-ABL (181) or EPI-ABL (n=34) for drug-resistant VT between January 2007 and June 2018. Efficacy endpoint was defined as VT-free survival after catheter ablation, while safety outcomes were defined by 30-days mortality and procedure-related complications. A propensity score was used to match patients in a 1:1 fashion according to the following variables: VT storm at presentation, left ventricular ejection fraction (LVEF), New York Heart Association (NYHA) class III/IV at presentation, ischemic ethology, presence of implantable cardioverter-defibrillator (ICD), and previous endocardial catheter ablation. Independent predictors of VT recurrence were assessed by Cox regression. Results The PS yielded two groups of 31 patients each well matched for baseline characteristics (Table 1). Over a median follow-up of 2 years (IQR 1–3), 58% (n=18) ENDO-ABL patients had VT recurrence vs. 26% (n=8) in the EPI-ABL group (P=0.020). The yearly rates of VT recurrence were 28%/year for END-ABL vs. 11%/year for EPI-ABL (P=0.021). Multivariate survival analysis identified previous endocardial ablation (HR= 3.52; 95% CI 1.17–10.54, p=0.026) and VT storm at presentation (HR=3.57; 95% CI 1.50–8.50, p=0.004) as independent predictors of VT recurrence. EPI-ABL was independently associated with fewer VT recurrences (HR=0.28; 95 CI 0.12–0.69, p=0.005), but only in patients with a previous endocardial ablation (p for interaction = 0.004) – Figure A. No patients died at 30-days post-procedure. Hospital length of stay was similar between END-ABL and EPI-ABL (5 vs. 4 days respectively, p=0.139), as was the complication rate (6.5% vs. 12.9% respectively, p=0.390), although driven by different causes (Table 1). Conclusion VT storm at presentation and previous catheter ablation were independent predictors of VT recurrence. In patients with a previous failed endocardial catheter ablation, epicardial ablation seems to provide greater VT-free survival than repeat endocardial ablation. Both strategies seem equally safe.

Introduction Pulmonary vein (PV) reconnection is a common cause of relapse after catheter ablation of atrial fibrillation (AF). However, some patients have AF recurrence despite durable PV isolation. The aim of this study was to assess the PV isolation status at the time of a second catheter ablation (redo) procedure, and its relationship with subsequent AF relapse. Methods Consecutive patients with symptomatic drug-resistant AF who underwent redo procedures from January 2006 to December 2017 were identified in a single-center observational registry. Pulmonary vein isolation status was assessed during the electrophysiologic study with a circular mapping catheter. Additional radiofrequency (RF) energy applications were also recorded. AF relapse was defined as symptomatic or documented AF/atrial tachycardia/atrial flutter after a 3-month blanking period. Results We identified 240 patients (77 [32%] females, median age 61 [IQR 53–67] years, 85 [35%] with non-paroxysmal AF) undergoing redo procedures during the study period. At the time of redo, 17 (7%) of the patients presented bidirectional conduction block of all PVs. PV reconnection occurred in 157 (65%) of cases in the left superior vein, 142 (59%) in the left inferior vein, 177 (73%) in the right superior vein, and 163 (68%) in the right inferior vein (table). All of the PVs were reconducted in 91 (38%) patients. Additional RF applications were performed in the left atrium (LA) roof, LA posterior wall, cavotricuspid isthmus, mitral isthmus, superior vena cava, coronary sinus, and left atrial appendage ostium, at the operator's discretion (table 1). Over a median follow-up of 2-years (IQR 1–5), 126 patients (53%) suffered AF recurrence, yielding a mean relapse rate of 17%/year. In multivariate Cox regression analysis, the lack of PV reconnection at the time of redo emerged as an independent predictor of subsequent relapse (HR 1.97, 95% CI 1.12–3.49, p=0.019) even after adjustment for univariate predictors including non-paroxysmal AF, body mass index, female sex, and active smoking. Conclusion In patients undergoing redo AF ablation procedures, less than 10% present with complete PV isolation. Despite being relatively infrequent, this finding is independently associated with greater likelihood of subsequent recurrence, suggesting that other mechanisms, not fully addressed by additional RF applications, are at play.

Introduction Pericardial adipose tissue has been implicated in the pathophysiology of atrial fibrillation (AF), but its relevance to clinical practice remains uncertain. The aim of this study was to assess the relative importance of pericardial fat as predictor of recurrence after pulmonary vein isolation (PVI). Methods We assessed 453 patients (278 men, age 61±13 years, 348 paroxysmal AF) with symptomatic AF undergoing cardiac CT prior to a PVI procedure. Pericardial fat was quantified on contrast-enhanced images using a new simplified semi-automated method. The study endpoint was symptomatic and/or documented AF recurrence. Results Over a median follow-up of 14 months (IQR 7–23), 170 patients (38%) relapsed. Survival analysis showed significant differences in AF-free survival across tertiles of pericardial fat (Figure). Pericardial fat volume was weakly correlated to body mass index [(BMI), Pearson's R=0.34]. After adjustment for BMI and other univariate predictors of relapse, three variables emerged independently associated with time to AF recurrence: non-paroxysmal AF (HR 2.08, 95% CI: 1.51–2.87, p Conclusion Pericardial fat volume is a strong independent predictor of AF relapse after PVI, outperforming classic risk markers such as LA volume and type of AF. The underlying mechanisms of this association deserve further study. Meanwhile, this simple parameter may help select patients who are more likely to derive sustained benefit from AF ablation.

Introduction Despite advances in antiarrhythmic and device therapy, ventricular tachycardia (VT) is a major cause of increased morbidity and mortality. During scar-mediated monomorphic VT ablation, the search for critical isthmus sites continues to be the primary goal during successful ablative procedures. However, catheter ablation based on conventional mapping techniques is associated with low success rates and is limited to patients with stable VT. Objective The aim of the study was to evaluate, in patients with history of VT, the success of a strategy based on substrate mapping and ablation during sinus rhythm. Methods Retrospective single center analysis of patients undergoing VT ablation from November 2015 to November 2017. Clinical profiles and procedural details were determined. We used high-density structural map to identify voltage abnormalities as well a functional map of sinus rhythm activation to identify the regions of late potentials. Radiofrequency applications were performed in the areas with the latest activation. Recurrence of VT was considered the end-points of the follow-up. Results A total of 22 patients were included in the analysis, 95% male, with an median age of 65,5 (57–71) years old. The majority of the patients (18) with ischemic cardiomyopathy, 3 with nonischemic cardiomyopathy, and 1 with arrhythmogenic right ventricular cardiomyopathy were included. Epicardial mapping was performed in 27% of the cases. CARTO mapping system was used in 10 patients and Rhythmia in the remaining cases. Areas with the latest activation corresponded to regions of abnormal voltage in 21 patients. During a 26,5 (21,5–29,3) months of follow-up, the observed VT recurrence rate was 35%. 25% of the patients needed hospital admission due to arrhythmias and one patient died due to an arrhythmic cause. Treatment success was higher in epicardial approach (100% VS 50%, p=0,03). The location of the scar in the left ventricle was not a determinant of success (anterior-66,7% VS lateral/inferior-61,5%, p=0,806). Conclusion A substrate-based approach that targets regions of late activation within the scar seems attractive and may be a simple way to perform VT ablation with success. In our population, this strategy seams successful, especially in epicardial approach. Substrate modification strategies aiming to eradicate all potential reentrant circuits may be the most successful way to treat VT and avoid recurrences.

Magnetic versus Manual Ablation of Atrial FibrillationIntroduction Whether or not the potential advantages of using a magnetic navigation system (MNS) translate into improved outcomes in patients undergoing atrial fibrillation (AF) ablation is a question that remains unanswered. Methods and Results In this observational registry study, we used propensity-score matching to compare the outcomes of patients with symptomatic drug-refractory AF who underwent catheter ablation using MNS with the outcomes of those who underwent catheter ablation using conventional manual navigation. Among 1,035 eligible patients, 287 patients in each group had similar propensity scores and were included in the analysis. The primary efficacy outcome was the rate of AF relapse after a 3-month blanking period. At a mean follow-up of 2.6 ± 1.5 years, AF ablation with MNS was associated with a similar risk of AF relapse as compared with manual navigation (18.4% per year and 22.3% per year, respectively; hazard ratio 0.81, 95% CI 0.63–1.05; P = 0.108). Major complications occurred in two patients (0.7%) using MNS, and in six patients (2.1%) undergoing manually navigated ablation (P = 0.286). Fluoroscopy times were 21 ± 10 minutes in the manual navigation group, and 12 ± 9 minutes in the MNS group (P < 0.001), whereas total procedure times were 152 ± 52 minutes and 213 ± 58 minutes, respectively (P < 0.001). Conclusions In this propensity-score matched comparison, magnetic navigation and conventional manual AF ablations seem to have similar relapse rates and a similar risk of complications. AF ablations with magnetic navigation take longer to perform but expose patients to significantly shorter fluoroscopy times.

Background Clinical significance and prognosis of a cardioinhibitory response to head-up tilt (HUT) test with a very prolonged asystole (≥30 seconds) is poorly studied. Our aim was to evaluate the treatment (including pacemaker implantation) and prognosis (syncope recurrence, syncope-related trauma, and overall mortality) of patients with a very prolonged asystole on a HUT test. Methods and Results A retrospective study was conducted in two centers between January 2003 and December 2013 and included a total of 2,263 consecutive HUT tests (sensitized with isosorbide dinitrate) performed in 2,247 patients with syncope of unknown etiology. Cardioinhibitory response with asystole was observed in 149 (6.6%) of these tests (44.3% women, mean age 37 ± 18 years old, 16.1% in the nonpharmacological phase), with a median duration of asystole of 10 (6–19) seconds. Very prolonged asystole (≥30 seconds) was documented in 11 (0.5%) patients (45% women; mean age 40 ± 19 years; only one in the nonpharmacological phase, 9 minutes after HUT). The longest pause lasted 63 seconds. In all patients, avoidance of triggering factors and physical counterpressure maneuvers were recommended. Telephone follow-up was performed: in one patient, fludrocortisone was started; tilt training was conducted in one patient and none received a pacemaker. After a median follow-up of 42 (30–76) months, four patients (36%) had syncopal recurrences, one patient had a syncope-related injury (scalp laceration), and no patient died.

Aims To evaluate the incidence and clinical significance of diaphragmatic myopotential (dMP) oversensing in pacemaker (PM)-dependent patients with CRT-Ds. Methods and results We retrospectively evaluated patients with CRT-Ds implanted at our institution between January 2000 and August 2006. PM-dependent patients were identified, and the incidence of inappropriate detections due to dMP oversensing and their possible clinical implications (inappropriate therapies, syncope, and death of any cause) were evaluated. CRT-Ds were implanted in 122 patients, 37 were or became PM dependent. During a mean follow-up of 22+ 17 months, 7(18.9%) PM-dependent patients revealed inappropriate detections due to dMP oversensing. All oversensing episodes occurred in CRT-Ds with automatic gain control (AGC) sensing and integrated bipolar (IBP) leads in the RV apex. These detections led to inappropriate shocks in 2(5.4%) patients and syncope in 1(2.7%). Five (13.5%) patients died. Conclusion dMP oversensing in PM-dependent patients with CRT-Ds is an important problem, particularly in CRT-Ds with AGC sensing and IBP leads, with over 20% of patients with these devices revealing inappropriate detections. The clinical impact of dMP oversensing is less marked but relevant, with both inappropriate therapies and syncope occurring in this small group of 37 patients and the possibility of related deaths.

Whether or not the potential advantages of using a magnetic navigation system (MNS) translate into improved outcomes in patients undergoing atrial fibrillation (AF) ablation is a question that remains unanswered.In this observational registry study, we used propensity-score matching to compare the outcomes of patients with symptomatic drug-refractory AF who underwent catheter ablation using MNS with the outcomes of those who underwent catheter ablation using conventional manual navigation. Among 1,035 eligible patients, 287 patients in each group had similar propensity scores and were included in the analysis. The primary efficacy outcome was the rate of AF relapse after a 3-month blanking period. At a mean follow-up of 2.6 ± 1.5 years, AF ablation with MNS was associated with a similar risk of AF relapse as compared with manual navigation (18.4% per year and 22.3% per year, respectively; hazard ratio 0.81, 95% CI 0.63-1.05; P = 0.108). Major complications occurred in two patients (0.7%) using MNS, and in six patients (2.1%) undergoing manually navigated ablation (P = 0.286). Fluoroscopy times were 21 ± 10 minutes in the manual navigation group, and 12 ± 9 minutes in the MNS group (P0.001), whereas total procedure times were 152 ± 52 minutes and 213 ± 58 minutes, respectively (P0.001).In this propensity-score matched comparison, magnetic navigation and conventional manual AF ablations seem to have similar relapse rates and a similar risk of complications. AF ablations with magnetic navigation take longer to perform but expose patients to significantly shorter fluoroscopy times.

Aims To evaluate the usefulness of three-dimensional (3D) electroanatomical mapping of the pulmonary veins (PV) for guiding radiofrequency (RF) ablation of focal atrial fibrillation (AF) in a single session and to correlate the electrophysiological results with the six month clinical outcome. Methods and Results Sixteen consecutive patients with idiopathic paroxysmal AF (more than 1 episode/month) were studied. A non-fluoroscopic mapping system was used to generate 3D electroanatomic maps of the left atrium and deliver RF energy. In patients with frequent ectopies, mapping was performed using the ‘hot-cold’ approach (looking for the earliest electrogram in the 3D reconstruction). In patients with infrequent/no ectopies, double/multiple potentials recorded at the PV were tagged. Pacing at these sites to test for inducibility of ectopy or atrial fibrillation was used to define PV foci. The therapeutic endpoint was defined as suppression of premature beats, dissociation of PV potentials and inability to induce AF. Twenty-five foci were identified (multiple foci in 38%). In the 4 pts with frequent ectopies, Group A, these were suppressed by 4±4·7 applications. In the 12 pts with infrequent/no ectopies, Group B, an average 4·7±1·8 applications were delivered per focus; the endpoint was achieved in eight of the patients (13 of 21 foci). By 180 days follow-up, 11 patients were free of symptoms and in sinus rhythm, two had paroxysmal AF episodes and 3 have symptomatic ectopies and are receiving antiarrhythmic drugs. The overall success rate at six months was thus 69%, 100% for group A and 58% for group B. Conclusion Electroanatomic guided RF ablation of paroxysmal AF was highly successful in patients with frequent ectopies. The use of electroanatomical mapping for precise anatomical localization of multiple potentials and for guiding the PV ostia isolation allowed successful RF ablation in 50% of pts with infrequent/no ectopies.

Introduction: Risk stratification of Brugada syndrome (BrS) remains controversial and recommendations for an implantable cardioverter-defibrillator (ICD) are not well established. The objective of this study was to assess the long-term prognosis of BrS patients with an ICD. Methods and Results: Of 55 consecutive patients with BrS assessed between April 2002 and October 2012, 36 (mean age 41.7±13.8 years; 81.8% male) underwent ICD implantation. Nineteen (52.8%) were asymptomatic, 11 (30.6%) had previous history of syncope (arrhythmic cause suspected in eight) and six (16.7%) had aborted sudden cardiac death (SCD). Spontaneous type 1 electrocardiographic (ECG) pattern was present in 25 (69.4%) patients and electrophysiological study (EPS), performed in 26 (72.2%), was positive in 22 (84.6%). During a mean follow-up of 74±40 months (>5 years in 72% of cases), seven (19.4%) patients had appropriate shocks (annual event rate 2.8%). These patients most frequently had aborted SCD (54.1% vs. 6.9%; p=0.008) and nonsustained ventricular tachycardia (57.1% vs. 10.3%; p=0.016) during follow-up. Spontaneous type 1 ECG pattern, syncope and positive EPS were not significantly associated with appropriate shocks. Multivariate analysis revealed that aborted SCD was an independent predictor of appropriate shocks (HR 8.07, 95% CI 1.58–41.2; p=0.012). ROC curve analysis demonstrated that aborted SCD had moderate discriminatory power to predict appropriate shocks (AUC 0.751), with sensitivity of 57% and specificity of 93%. In terms of ICD-related complications, eight (22.2%) patients had inappropriate shocks during the follow-up period, mainly due to sinus tachycardia (five patients); one patient had lead infection and another had a lead fracture. Conclusion: In this population of BrS patients with ICD, the long-term rate of appropriate shocks was 2.8%/year. Aborted SCD was associated with a higher risk of appropriate shocks, whereas syncope and spontaneous type I ECG pattern did not predict this event. Resumo: Introdução: A estratificação de risco na síndrome de Brugada (SB) permanece controversa e as recomendações para cardiodesfibrilhador (CDI) não estão bem definidas. O objetivo deste estudo foi avaliar o prognóstico a longo prazo de doentes com SB e CDI implantado. Métodos e resultados: De 55 doentes consecutivos com SB avaliados entre abril/2002-outubro/2012, 36 (idade média 41,7±13,8 anos; 81,8% homens) implantaram CDI. Dezanove (52,8%) eram assintomáticos, 11 (30,6%) tinham história de síncope (oito com suspeita de causa arrítmica) e seis (16,7%) foram reanimados de morte súbita (MS). O eletrocardiograma (ECG) com padrão tipo 1 espontâneo estava presente em 25 (69,4%) doentes e foi realizado estudo eletrofisiológico (EEF) em 26 (72,2%), sendo positivo em 22 (84,6%). Durante o período de seguimento médio de 74±40 meses (>5 anos em 72% dos casos), sete (19,4%) doentes tiveram choques apropriados (incidência anual 2,8%). Estes doentes tinham mais frequentemente história de MS abortada (54,1 versus 6,9%; p=0,008) e taquicardia não mantida (57,1 versus 10,3%; p=0,016) durante o seguimento. Padrão ECG tipo 1 espontâneo, síncope e EEF positivo não se associaram significativamente à ocorrência de choques apropriados. Em análise multivariada a MS abortada manteve-se preditor independente de choques apropriados (HR 8,07 IC95% 1,58-41,2; p=0,012). Em análise de curvas ROC a MS abortada apresentou um poder discriminatório moderado para predizer choques apropriados (AUC 0,751) – sensibilidade 57% e especificidade 93%. Relativamente às complicações relacionadas com o CDI, oito (22,2%) doentes tiveram choques inapropriados durante o período de seguimento, sobretudo por taquicardia sinusal (cinco doentes), um infeção de elétrodo e outro fratura de elétrodo. Conclusão: Na população estudada de doentes com SB e CDI implantado a incidência de choques apropriados foi 2,8%/ano. A MS abortada associou-se a um maior risco de choques apropriados, enquanto a síncope e o padrão de ECG tipo 1 espontâneo não foram preditores deste evento. Keywords: Brugada syndrome, Implantable cardioverter-defibrillator, Prognosis, Syncope, Sudden cardiac death, Appropriate shocks, Palavras-chave: Síndrome de Brugada, Cardiodesfibrilhador, Prognóstico, Síncope, Morte súbita, Choques apropriados

An 18-year-old patient, with hypertrophic cardiomyopathy and an implantable cardioverter defibrillator for 6 years, was admitted with inappropriate shocks as a consequence of a lead fracture (Sprint Quattro, Medtronic). The device was explanted and replaced with a new subcutaneous defibrillator (Cameron SQ-RX), without complications. This was the first time that a subcutaneous cardioverter defibrillator had been used in the Iberian Peninsula. The new implantable defibrillator, with subcutaneous lead and generator, can lower the risk of complications, including lead fracture or infection. Furthermore, this device has good rhythm diagnostic performance and therapeutic efficacy. Following the case report, we present a brief review of the new defibrillator with subcutaneous implantation.

Supraventricular tachycardias (SVTs) are the most common arrhythmias in children, with Wolff-Parkinson-White (WPW) syndrome the most prevalent entity. Percutaneous catheter ablation is now the standard of care for SVT in pediatric patients, although specific techniques are required due to their age.To evaluate the results of percutaneous catheter ablation of arrhythmias in children at our institution.This was a retrospective study of the clinical records of patients aged 18 years who underwent electrophysiologic study and ablation between January 2002 and December 2006. The following variables were evaluated: demographic data, type of arrhythmia, associated structural heart disease, type of energy used, immediate and late success rate and incidence of complications.During this period, 101 procedures were performed in 97 patients agedor = 18 years. The mean age of the patients was 15.9 +/- 2.5 years (range: 7.7-18 years), and fifty-five (56.7%) were male. The arrhythmias treated were, in decreasing order of frequency: WPW syndrome (58.4%), atrioventricular reentrant tachycardia (25.7%), atrial tachycardia (5.9%), right ventricular outflow tract (RVOT) tachycardia (5%), ventricular tachycardia (2%), atrial fibrillation (2%) and frequent extrasystoles originating in the left atrium (1%). There was associated structural heart disease in six patients. Cryoablation was performed in four cases (parahisian accessory pathways in three and anterolateral accessory pathway in one). The immediate success rate was 94.1%. The six unsuccessful cases corresponded to five with parahisian accessory pathways (the procedure was not completed due to very high risk of inducing complete atrioventricular block [AVB]) and one case of RVOT tachycardia associated with arrhythmogenic right ventricular dysplasia. There were complications in two procedures (2%): one case of right bundle branch block and one of ventricular tachycardia requiring electrical cardioversion. The mean follow-up was 17.6 months. In 87.1% of cases there was clinical and ECG success on long-term followup. Three patients (3%) required repeat procedures, and were asymptomatic in later follow-up.Percutaneous catheter ablation of arrhythmias in children proved to be a safe and effective treatment.