AIMS:Atrial fibrillation (AF) is highly prevalent among cardiac amyloidosis (CA) patients and contributes significantly to their morbidity and mortality. Evidence regarding AF ablation efficacy and safety in CA patients remains limited. The aim of our study is to evaluate baseline characteristics, clinical course and outcomes of AF ablation in a series of patients with transthyretin (ATTR) or light-chain (AL) CA from a multicentre international registry. METHODS AND RESULTS:Patients with CA who underwent AF ablation were included. Co-primary endpoints were: (i) atrial arrhythmia (AA) recurrence; (ii) a composite endpoint of all-cause mortality and heart failure hospitalization (HFH). 109 patients (mean age 72.4 ± 7.4 years, females 17.4%, persistent AF 64.2%, ATTR 78%, AL 22%) were included. Radiofrequency, cryo-balloon and pulsed-field ablation were performed in 67%, 15% and 18% of patients, respectively; 49.5% received pulmonary vein isolation plus additional ablations. Low voltage zones were documented in 34 out of 44 patients undergoing electro-anatomical mapping (77.3%). During a median follow-up of 22.7 months, 63 patients (58.3%) experienced AA recurrence (32.4% persistent AF recurrence), with no significant differences between CA subtypes (ATTR 59.5% vs. AL 54.2%, log-rank P = 0.55). The composite endpoint of HFH and all-cause death occurred in 27 patients (25%). Recurrence of persistent AF was associated with three-fold higher risk (OR 2.9, P = 0.02) of the composite endpoint. CONCLUSION:CA patients undergoing AF ablation present high prevalence of persistent AF. Freedom from AA after AF ablation is achieved in 42% of patients after a two-year follow-up. Patients with persistent AF recurrence have a three-fold higher risk of HFH and death.

AIMS:Little is known about the distribution and clinical course of patients with inherited arrhythmia syndrome (IAS) and concomitant atrial arrhythmias (AAs). The aim of the study is (i) to characterize the distribution of AAs in patients with IAS and (ii) evaluate the long-term clinical course of these patients. METHODS AND RESULTS:An international multicentre study was performed and involved 28 centres in 16 countries. Inclusion criteria were (i) IAS and (ii) electrocardiographic documentation of AAs. The primary endpoint was a composite of sudden cardiac death, sustained ventricular arrhythmias (VAs), or appropriate implantable cardioverter defibrillator (ICD) interventions. Strokes, inappropriate ICD shocks due to AAs, and the occurrence of sinus node dysfunction were assessed. A total of 522 patients with IAS and AAs were included. Most patients were diagnosed with Brugada syndrome (n = 355, 68%) and long QT syndrome (n = 93, 18%). The remaining patients (n = 71, 14%) presented with short QT syndrome, early repolarization syndrome, catecholaminergic polymorphic ventricular tachycardia, progressive cardiac conduction diseases, or idiopathic ventricular fibrillation. Atrial fibrillation was the most prevalent AA (82%), followed by atrial flutter (9%) and atrial tachycardia (9%). Atrial arrhythmia was the first clinical manifestation of IAS in 52% of patients. More than one type of AA was documented in 23% of patients. Nine patients (3%) experienced VA before the diagnosis of IAS due the use of anti-arrhythmic medications taken for the AA. The incidence of the primary endpoint was 1.4% per year, with a two-fold increase in patients who experienced their first AA before the age of 20 (odds ratio 2.2, P = 0.043). This was consistent across the different forms of IAS. Inappropriate ICD shock due to AAs was reported in 2.8% of patients, strokes in 4.4%, and sinus node dysfunction in 9.6%. CONCLUSION:Among patients with IAS and AAs, AA is the first clinical manifestation in about half of the cases, with more than one form of AAs present in one-fourth of the patients. The occurrence of AA earlier in life may be associated with a higher risk of VAs. The occurrence of stroke and sinus node dysfunction is not infrequently in this cohort.

Tachyarrhythmias are common in the pediatric and congenital heart disease patients. Ablation has been proved as an effective and safe therapeutic alternative in this population. There are international registries on the use of catheter ablation in children and congenital heart disease, but not from Latin America

Left bundle branch stimulation is a second-line strategy in patients where His bundle stimulation is not optimal. Currently, no cases of left bundle branch stimulation have been reported in patients with diffuse electrical cardiac disease or in the pediatric population.

Objective. To report the results of ventricular tachycardia (VT) catheter ablation in ischemic heart disease (IHD), and to identify risk factors associated with recurrence in a Mexican center. Materials and methods. We made a retrospective review of the cases of VT ablation performed in our center from 2015 to 2022. We analyzed the characteristics of the patients and those of the procedures separately and we determined factors associated with recurrence. Results. Fifty procedures were performed in 38 patients (84% male; mean age 58.1 years). Acute success rate was 82%, with a 28% of recurrences. Female sex (OR 3.33, IC 95% 1.66–6.68, p=0.006), atrial fibrillation (OR 3.5, IC 95% 2.08–5.9, p=0.012), electrical storm (OR 2.4, IC 95% 1.06–5.41, p=0.045), functional class greater than II (OR 2.86, IC 95% 1.34–6.10, p=0.018) were risk factors for recurrence and the presence of clinical VT at the time of ablation (OR0.29, IC95% 0.12–0.70, p=0.004) and the use of more than 2 techniques for mapping (OR 0.64, IC 95% 0.48–0.86, p=0.013) were protective factors. Conclusions. Ablation of ventricular tachycardia in ischemic heart disease has had good results in our center. The recurrence is similar to that reported by other authors and there are some factors associated with it.

Left bundle branch stimulation is a second-line strategy in patients where His bundle stimulation is not optimal. Currently, no cases of left bundle branch stimulation have been reported in patients with diffuse electrical cardiac disease or in the pediatric population.

INTRODUCTION:The coronavirus disease (COVID-19) pandemic has generated serious repercussions on the health system, reducing the number of all cardiology procedures worldwide. OBJECTIVES:Describe the impact of the COVID-19 pandemic on the procedures performed by the electrophysiology department in a national referral center. METHODS:We made a retrospective review of our data base and we compared procedures made in the past 3 years since 2017-2019 with the procedures made in the 2020. We divided the procedures into two large groups: Cardiac Implantable Electronic Devices (CIED) related procedures and electrophysiological procedures (EP) which included conventional and complex ablations. RESULTS:There was a significant reduction in all the procedures, the average of procedures performed in the last 3 previous years was 467, while in 2020, we performed only 319 (p = 0.01); this represents a reduction of 33.4% in the total number of procedures. There was no statistical difference regarding the CIED related procedures, the average of procedures in the past 3 previous years was 174, and in 2020 we performed 190 procedures (p = 0.46). Regarding the EP, the average of the past 3 previous years was 293, while in 2020, we performed only 129 procedures (p < 0.01). The reduction in the EP was 55.97%. The most affected months were April, May, and June. CONCLUSIONS:The COVID-19 pandemic considerably affected the number of the procedures in our center, reducing it by 33.4%. The reduction of procedures fundamentally affected the ablations, with a reduction of 55.97%. The number of CIED related procedures was not affected.

Atrial tachycardias originated at the left atrial appendage (LAA) are uncommon; often they are incessant and might induce tachycardiomyopathy, as discussed by Hillock et al. (Heart Rhythm;3(4):467–469, 2006). A case of a 21-year-old woman with incessant atrial tachycardia is presented, refractory to medical therapy, echocardiography showed global dilation with LV ejection fraction of 20%. After two failed endocardial ablations, an epicardial access was attempted. The earliest activation site was located at the tip of the epicardial aspect of the LAA. RFCA was successful at this site. The patient remains asymptomatic during a follow-up of 10 months; the ventricular function was completely recovered after 6 months (LVEF of 50%).

Ventricular tachycardia in Ebstein's anomaly patients is rare and increases the risk of sudden death up to 6 times. We present two cases of Ebstein's anomaly, the first of them with a history of Glenn surgery and biological prosthesis at tricuspid position and the second case without surgical repair. Both admitted to the emergency room due to ventricular tachycardia poorly tolerated. Detailed substrate characterization and pace mapping showed fragmented signals in the area of atrialized right ventricle and correlated were pace mapping reproduced morphology identical to the clinical VT, ablation at this sites were successful without recurrence during follow-up.

Background: Idiopathic ventricular fibrillation (IVF) in patients with normal baseline electrocardiograms (ECGs) is a rare disease. Little information is available on the clinical features and long-term follow-up of out-of-hospital cardiac arrest (OHCA) survivors presenting with "true" IVF and 12-lead ECGs that remain normal over time. Objective: To define the clinical and ECG characteristics, as well as long-term clinical outcomes of a large cohort of survivors of OHCA due to "true" IVF. Methods: OHCA survivors with VF as the presenting rhythm, normal baseline and follow-up ECGs with no signs of cardiac channelopathy including early repolarization or atrioventricular (AV) conduction abnormalities, and without structural heart disease were included in a registry. Results: A total of 245 OHCA survivors with IVF (median age: 38 years; males 59%) were recruited from 25 centres. All had normal baseline and follow-up ECGs, and no evidence of structural heart disease. An implantable cardioverter-defibrillator (ICD) was implanted in 226 patients (92%), while 18 patients (8%) were treated with drug therapy only. Over a median follow-up of 63 months (interquartile range: 25-110 months), 12 patients died (5%); in 4 of them (1.6%) the lethal event was of cardiac origin. Patients treated with antiarrhythmic drugs (AADs) only had a higher rate of cardiovascular death compared to patients who received an ICD (16% vs. 0.4%, p=0.001). The ECG and echocardiogram of all patients remained unchanged over time. Fifty-two patients (21%) experienced an arrhythmic recurrence. Age ≤ 16 years at the time of the first ventricular arrhythmia was the only predictor of arrhythmic recurrence on multivariable analysis (HR 0.41, 95% CI 0.18-0.92, p=0.03). Discussion: OHCA survivors of "true" IVF with normal baseline and follow-up ECGs frequently have arrhythmic recurrences, but a good prognosis when treated with an ICD. Children are a category of IVF patients at higher risk of arrhythmic recurrences.Funding: The study was supported by a grant of the Swiss Heart Foundation.Declaration of Interest: G.C. has received a research grant from the Swiss National Foundation. P.L. has received speaker fees and research grants from Boston Scientific, Abbott and Medtronic Research support from UCLH Biomedicine NIHR. F.L. is consultant and has received research support from Medtronic Plc, Abbott, Boston Scientific and Microport. S.B. has received speaker’s bureau from Medtronic and Microport. C.P. has received research grant from Biotronik and Biosense Webster. P.B. is consultant for Biotronik. A.A. is consultant to Abbott, Biosense Webster, Daiichi-Sankyo, Boston Scientific, Medtronic, Microport-CRM; and has received speaker fee from Daiichi-Sankyo, Boston Scientific, Medtronic, Microport-CRMEthics Approval Statement: Data were collected in accordance with regulations set by the local Institutional Ethics Committee and/or Institutional Review Board.

Aims To define the clinical characteristics and long-term clinical outcomes of a large cohort of patients with idiopathic ventricular fibrillation (IVF) and normal 12-lead electrocardiograms (ECGs). Methods and results Patients with ventricular fibrillation as the presenting rhythm, normal baseline, and follow-up ECGs with no signs of cardiac channelopathy including early repolarization or atrioventricular conduction abnormalities, and without structural heart disease were included in a registry. A total of 245 patients (median age: 38 years; males 59%) were recruited from 25 centres. An implantable cardioverter-defibrillator (ICD) was implanted in 226 patients (92%), while 18 patients (8%) were treated with drug therapy only. Over a median follow-up of 63 months (interquartile range: 25-110 months), 12 patients died (5%); in four of them (1.6%) the lethal event was of cardiac origin. Patients treated with antiarrhythmic drugs only had a higher rate of cardiovascular death compared to patients who received an ICD (16% vs. 0.4%, P=0.001). Fifty-two patients (21%) experienced an arrhythmic recurrence. Age <= 16 years at the time of the first ventricular arrhythmia was the only predictor of arrhythmic recurrence on multivariable analysis [hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.18-0.92; P=0.03]. Conclusion Patients with IVF and persistently normal ECGs frequently have arrhythmic recurrences, but a good prognosis when treated with an ICD. Children are a category of IVF patients at higher risk of arrhythmic recurrences.

Recent data suggests that high burden of premature atrial complexes after pulmonary vein isolation predicts recurrences of atrial arrhythmias. The present study sought to assess the role of premature atrial complexes burden in predicting atrial arrhythmias recurrences in patients with atrial fibrillation (AF) who have undergone second-generation cryoballoon ablation (CB-Adv).

BACKGROUND A proband of Brugada syndrome (BrS) is the first patient diagnosed in a family. There are no data regarding this specific, high-risk population.OBJECTIVES This study sought to investigate the Brugada probands diagnosed from 1986 through the next 28 years.METHODS We included 447 probands belonging to families with a diagnostic type 1 electrocardiogram Brugada pattern. The database was divided into 2 periods: the first period identified patients who were part of the initial cohort that became the consensus document on BrS in 2002 (early group); the second period reflected patients first diagnosed from 2003 to January 2014 (latter group).RESULTS There were 165 probands in the early group and 282 in the latter group. Aborted sudden death as the first manifestation of the disease occurred in 12.1% of the early group versus 4.6% of the latter group (p = 0.005). Inducibility during programmed electrical stimulation was achieved in 34.4% and 19.2% of patients, respectively (p < 0.001). A spontaneous type 1 electrocardiogram pattern at diagnosis was present in 50.3% early versus 26.2% latter patients (p = 0.0002). Early group patients had a higher probability of a recurrent arrhythmia during follow-up (19%) than those of the latter group (5%) (p = 0.007). The clinical suspicion and use of a sodium-channel blocker to unmask BrS has allowed earlier diagnoses in many patients.CONCLUSIONS Since being first described, the presentation of BrS has changed. There has been a decrease in aborted sudden cardiac death as the first manifestation of the disease among patients who were more recently diagnosed. These variations in initial presentation have important clinical consequences. In this setting, the value of inducibility to stratify individuals with BrS has changed. (C) 2016 by the American College of Cardiology Foundation.

Cryoablation is an energy alternative to radiofrequency for ablation of various arrhythmias, where its unique biophysical properties offer a greater safety profile. Since its first use for the surgical treatment of different arrhythmias until its conceptualization in the current technical transcatheter, cryoablation has proven not to be only a safe source of energy, but also an effective source in the long-term. While the radiofrequency has been the energy most used for isolation of pulmonary veins in atrial fibrillation ablation, technological advances in cryoballon have managed to simplify the procedure without sacrificing its effectiveness. Cryoablation has been widely used for arrhythmias located in high-risk locations, such as the ablation of the atrioventricular nodal reentrant tachycardia and septal accessory pathways, due to its theoretical null risk of complete AV block. This review intends to give the clinical applications of the cryothermy through a thorough understanding of their biophysical basis. (C) 2015 Instituto Nacional de Cardiologia Ignacio Chavez. Published by Masson Doyma Mexico S.A. All rights reserved.

Cryoablation is an energy alternative to radiofrequency for ablation of various arrhythmias, where its unique biophysical properties offer a greater safety profile. Since its first use for the surgical treatment of different arrhythmias until its conceptualization in the current technical transcatheter, cryoablation has proven not to be only a safe source of energy, but also an effective source in the long-term. While the radiofrequency has been the energy most used for isolation of pulmonary veins in atrial fibrillation ablation, technological advances in cryoballon have managed to simplify the procedure without sacrificing its effectiveness. Cryoablation has been widely used for arrhythmias located in high-risk locations, such as the ablation of the atrioventricular nodal reentrant tachycardia and septal accessory pathways, due to its theoretical null risk of complete AV block. This review intends to give the clinical applications of the cryothermy through a thorough understanding of their biophysical basis.

BACKGROUND Patients with Brugada syndrome and aborted sudden cardiac death or syncope have higher risks for ventricular arrhythmias (VAs) and should undergo implantable cardioverter-defibrillator (ICD) placement. Device-based management of asymptomatic patients is controversial. ICD therapy is associated with high rates of inappropriate shocks and device-related complications.OBJECTIVES The objective of this study was to investigate clinical features, management, and long-term follow-up of ICD therapy in patients with Brugada syndrome.METHODS Patients presenting with spontaneous or drug-induced Brugada type 1 electrocardiographic findings, who underwent ICD implantation and continuous follow-up at a single institution, were eligible for this study.RESULTS A total of 176 consecutive patients were included. During a mean follow-up period of 83.8 +/- 57.3 months, spontaneous sustained VAs occurred in 30 patients (17%). Eight patients (4.5%) died. Appropriate ICD shocks occurred in 28 patients (15.9%), and 33 patients (18.7%) had inappropriate shocks. Electrical storm occurred in 4 subjects (2.3%). Twenty-eight patients (15.9%) experienced device-related complications. In multivariate Cox regression analysis, aborted sudden cardiac death and VA inducibility on electrophysiologic studies were independent predictors of appropriate shock occurrence.CONCLUSIONS ICD therapy was an effective strategy in Brugada syndrome, treating potentially lethal arrhythmias in 17% of patients during long-term follow-up. Appropriate shocks were significantly associated with the presence of aborted sudden cardiac death but also occurred in 13% of asymptomatic patients. Risk stratification by electrophysiologic study may identify asymptomatic patients at risk for arrhythmic events and could be helpful in investigating syncope not related to VAs. ICD placement is frequently associated with device-related complications, and rates of inappropriate shocks remain high regardless of careful device programming. (C) 2015 by the American College of Cardiology Foundation.