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Aims: Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) is often accompanied by atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT), which are difficult to control because beta-blockers and antiarrhythmic drugs can worsen heart failure (HF). This study aimed to investigate the outcomes of catheter ablation (CA) for AF/AFL/AT in patients with ATTRwt-CM and propose a treatment strategy for CA., Methods and Results: A cohort study was conducted on 233 patients diagnosed with ATTRwt-CM, including 54 who underwent CA for AF/AFL/AT. The background of each arrhythmia and the details of the CA and its outcomes were investigated. The recurrence-free rate of AF/AFL/AT overall in ATTRwt-CM patients with multiple CA was 70.1% at 1-year, 57.6% at 2-year, and 44.0% at 5-year follow-up, but CA significantly reduced all-cause mortality [hazard ratio (HR): 0.342, 95% confidence interval (CI): 0.133-0.876, P = 0.025], cardiovascular mortality (HR: 0.378, 95% CI: 0.146-0.981, P = 0.045), and HF hospitalization (HR: 0.488, 95% CI: 0.269-0.889, P = 0.019) compared with those without CA. There was no recurrence of the cavotricuspid isthmus (CTI)-dependent AFL, non-CTI-dependent simple AFL terminated by one linear ablation, and focal AT originating from the atrioventricular (AV) annulus or crista terminalis eventually. Twelve of 13 patients with paroxysmal AF and 27 of 29 patients with persistent AF did not have recurrence as AF. However, all three patients with non-CTI-dependent complex AFL not terminated by a single linear ablation and 10 of 13 cases with focal AT or multiple focal ATs originating beyond the AV annulus or crista terminalis recurred even after multiple CA., Conclusion: The outcomes of CA for ATTRwt-CM were acceptable, except for multiple focal AT and complex AFL. Catheter ablation may be aggressively considered as a treatment strategy with the expectation of improving mortality and hospitalization for HF., Competing Interests: Conflict of interest: H.K. has received grants from Medtronic Japan, Nihon Kohden, Abbott Medical Japan, Fukuda Denshi, Boston Scientific Japan, Japan Lifeline, Nipro, and Biotronik Japan. K.T. has received honoraria from Bayer Yakuhin, Daiichi Sankyo, Kowa, MSD, Sanofi, and Takeda Pharmaceutical and grants from Astellas Pharma, Abbott Vascular Japan, Bayer Yakuhin, Boehringer Ingelheim Japan, Boston Scientific Japan, Bristol-Myers, Chugai Pharmaceutical, Daiichi Sankyo, Goodman, Japan Lifeline, Medtronic Japan, Mitsubishi Tanabe Pharma, MSD, Novartis Pharma, Otsuka Pharmaceutical, Sanofi, Takeda Pharmaceutical, and Terumo. All remaining authors have declared no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Data on the hybrid atrial fibrillation (AF) treatment are lacking in patients with structural heart disease undergoing concomitant CryoMaze procedures. The aim was to assess whether the timely pre-emptive catheter ablation would achieve higher freedom from AF or atrial tachycardia (AT) and be associated with better clinical outcomes than surgical ablation alone., Methods and Results: The trial investigated patients with non-paroxysmal AF undergoing coronary artery bypass grafting and/or valve repair/replacement with mandatory concomitant CryoMaze procedure who were randomly assigned to undergo either radiofrequency catheter ablation [Hybrid Group (HG)] or no further treatment (Surgery Group). The primary efficacy endpoint was the first recurrence of AF/AT without class I or III antiarrhythmic drugs as assessed by implantable cardiac monitors. The primary clinical endpoint was a composite of hospitalization for arrhythmia recurrence, worsening of heart failure, cardioembolic event, or major bleeding. We analysed 113 and 116 patients in the Hybrid and Surgery Groups, respectively, with a median follow-up of 715 (IQR: 528-1072) days. The primary efficacy endpoint was significantly reduced in the HG [41.1% vs. 67.4%, hazard ratio (HR) = 0.38, 95% confidence interval (CI): 0.26-0.57, P < 0.001] as well as the primary clinical endpoint (19.9% vs. 40.1%, HR = 0.51, 95% CI: 0.29-0.86, P = 0.012). The trial groups did not differ in all-cause mortality (10.6% vs. 8.6%, HR = 1.17, 95%CI: 0.51-2.71, P = 0.71). The major complications of catheter ablation were infrequent (1.9%)., Conclusion: Pre-emptively performed catheter ablation after the CryoMaze procedure was safe and associated with higher freedom from AF/AT and improved clinical outcomes., Competing Interests: Conflict of interest: none declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Coherent mapping (CM) uses a new algorithm to identify critical conduction isthmuses of atrial tachycardias (ATs). We analysed our experience of ablation of AT in patients with congenital heart disease (CHD) with this new technology., Methods and Results: All patients with CHD who had CM of AT using the high-density mapping PENTARAY™ catheter and three-dimensional electroanatomic mapping system Carto3 between June 2019 and June 2021 were included retrospectively (n = 27). As a control group, 27 patients with CHD and mapping of AT without CM between March 2016 and June 2019 were included. In total, 54 ablation procedures were performed in 42 patients [median age 35 (interquartile range, IQR 30-48) years] and 64 ATs were induced and mapped (thereof 50 AT intraatrial re-entrant tachycardia and 14 AT ectopic AT). The median procedure duration was 180 (120-214) min and median fluoroscopy time was 10 (5.2-14) min. Acute success was 100% (27/27) in the Coherence group and 74% (20/27) in the non-Coherence group (P = 0.01). During follow-up [median 26 (12-45) months], AT recurred in 28/54 patients, thereof 15 patients needed a re-ablation procedure. Log-rank test showed no difference in recurrence rate between the two groups (P = 0.29). Three minor complications occurred (5.5%)., Conclusion: Mapping of AT in patients with CHD using the PENTARAY™ mapping catheter and the CM algorithm led to excellent acute success. All ATs were possible to map and no complications related to the PENTARAY™ mapping catheter were observed. Thus, the use of the CM algorithm represents a promising tool in patients with CHD and complex AT., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Atrial tachycardias (ATs) frequently develop after a surgical Maze procedure. We aimed to elucidate the electrophysiologic mechanisms and their arrhythmogenic substrates of these ATs., Methods and Results: We retrospectively reviewed 20 patients (14 females, mean age of 55.5 ± 8.6 years) with post-Maze ATs who underwent high-resolution mapping at three institutions. The slow conduction areas, reentry circuits, voltage signals, complex electrograms, and their correlation with the surgical incisions and lesions placed in the surgical Maze procedures were analyzed. Thirty-six ATs with a mean cycle length of 260.0 ± 67.6 ms were mapped in these patients. Among them, 22 (61.1%) were anatomical macro-reentrant ATs (AMAT), 12 (33.3%) non-AMATs (localized ATs), and 2 (5.6%) focal ATs, respectively. Epicardial conduction bridges were observed in 6/20 (30.0%) patients and 7/36 (19.4%) ATs. Different arrhythmogenic substrates were identified in these ATs, including slow conduction regions within the previous lesion areas or between the incisions and anatomical structures, the prolonged activation pathways caused by the short lesions connecting the tricuspid annulus, and the circuits around the long incisions and/or lesions., Conclusions: Reentry is the main mechanism of the post-Maze ATs. The pro-arrhythmic substrates are most likely caused by surgical incisions and lesions. The slow conduction regions and the protected channels yielded from these areas are the major arrhythmogenic factors., Competing Interests: Conflict of interest: M.C. and L.Z. report receiving lecture fees from Boston Scientific. All remaining authors have declared no conflicts of interest., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Aims: The incidence of in-hospital post-interventional complications and mortality after ablation of supraventricular tachycardia (SVT) vary among the type of procedure and most likely the experience of the centre. As ablation therapy of SVT is progressively being established as first-line therapy, further assessment of post-procedural complication rates is crucial for health care quality., Methods and Results: We aimed at determining the incidence of in-hospital mortality and bleeding complications from SVT ablations in German high-volume electrophysiological centres between 2005 and 2020. All cases were registered by the German Diagnosis Related Groups-and the German Operation and Procedure Classification (OPS) system. A uniform search for SVT ablations from 2005 to 2020 with the same OPS codes defining the type of ablation/arrhythmia as well as the presence of a vascular complication, cardiac tamponade, and/or in-hospital death was performed. An overall of 47 610 ablations with 10 037 SVT ablations were registered from 2005 to 2020 among three high-volume centres. An overall complication rate of 0.5% (n = 38) was found [median age, 64; ±15 years; female n = 26 (68%)]. All-cause mortality was 0.02% (n = 2) and both patients had major prior co-morbidities precipitating a lethal outcome irrespective of the ablation procedure. Vascular complications occurred in 10 patients (0.1%), and cardiac tamponade was detected in 26 cases (0.3%)., Conclusion: The present case-based analysis shows an overall low incidence of in-hospital complications after SVT ablation highlighting the overall very good safety profile of SVT ablations in high-volume centres. Further prospective analysis is still warranted to guarantee continuous quality control and optimal patient care., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Aims: Interventional cardiology procedures may expose patients and staff to considerable radiation doses. We aimed to assess whether exposure to ionizing radiation during catheter ablation of supraventricular tachycardia (SVT) can be completely avoided., Methods and Results: In this prospective randomized study, patients with SVT (atrioventricular re-entrant tachycardia n = 94, typical atrial flutter n = 29) were randomly assigned in a 1:1 ratio to catheter ablation with conventional fluoroscopic guidance (CF group) or with the EnSite Precision mapping system [zerofluoro (ZF) group]. Acute procedural parameters, increased stochastic risk of cancer incidence and 6-month follow-up data were assessed. Between May 2019 and August 2020, 123 patients were enrolled. Clinical parameters were comparable. Median procedural time was 60.0 and 58.0 min, median fluoroscopy time and estimated median effective dose were 240 s vs. 0 and 0.38 mSv vs. 0 and arrhythmia recurrence was 5% and 7.9% in the CF and ZF groups, respectively. The acute success rate was 98.4% in both groups. No procedure-related complications were reported. At an average age of 55.5 years and median radiation exposure of 0.38 mSv, the estimate of increased incidence was approximately 1 in 14 084. The estimated mortality rate was 1 per 17 857 exposed persons., Conclusions: The procedural safety and efficacy of the zero-fluoroscopic approach are similar to those of conventional fluoroscopy-based ablation for atrioventricular nodal re-entrant tachycardia and atrial flutter. Under the assumption of low radiation dose, the excessive lifetime risk of malignancy in the CF group due to electrophysiology procedure is reasonably small, whilst totally reduced in zero fluoroscopy procedures., Competing Interests: Conflict of interest: N.S. and L.G. reports consulting fees from Abbott, not related to the present study., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Aims: An incomplete understanding of the mechanism of atrial tachycardia (AT) is a major determinant of ablation failure. We systematically evaluated the mechanisms of AT using ultra-high-resolution mapping in a large cohort of patients., Methods and Results: We included 107 consecutive patients (mean age: 65.7 ± 9.2 years, males: 81 patients) with documented endocardial gap-related AT after left atrial ablation for persistent atrial fibrillation (AF). We analysed the mechanism of 134 AT (94 macro-re-entries and 40 localized re-entries) using high-resolution activation mapping in combination with high-density voltage and entrainment mapping. Voltage in the conducting channels may be extremely low, even <0.1 mV (0.14 ± 0.095 mV, 51 of 134 AT, 41%), and almost always <0.5 mV (0.03-0.5 mV, 133 of 134 AT, 99.3%). The use of multipolar Orion, HDGrid, and Pentaray catheters improved our accuracy in delineating ultra-low-voltage areas critical for maintenance of the circuit of endocardial gap-related AT. Conventional ablation catheters often do not detect any signal (noise level) even using adequate contact force, and only multipolar catheters of small electrodes and shorter interelectrode space can detect clear fractionated low-amplitude and high frequency signals, critical for re-entry maintenance. We performed a diagnosis in 112 out of 134 AT (83.6%) using only activation mapping and in 134 out of 134 AT (100%) using the combination of activation and entrainment mapping., Conclusion: High-resolution activation mapping in combination with high-density voltage and entrainment mapping is the ideal strategy to delineate the critical part of the circuit in endocardial gap-related re-entrant AT after AF ablation., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Aims: Recurrent atrial tachycardia is common after repair of many types of congenital heart disease, and surgical ablation with a maze procedure represents a potential treatment strategy. The objective of this study is to report a single-centre 19 years' experience with maze surgery in congenital heart patients., Methods and Results: Patients undergoing maze procedure concomitantly with cardiac surgical procedures were retrospectively analysed. The maze procedure was classified as therapeutic if the patient demonstrated preoperative atrial arrhythmias, or as prophylactic if done because the patient was considered high risk for post-operative arrhythmias. Acute outcomes and longer-term freedom from atrial arrhythmias were analysed. Maze surgery was performed in 166 patients: 137 in the therapeutic group, and 29 in the prophylactic group. The most common congenital heart lesion was single ventricle for the therapeutic group (27%) and Ebstein's anomaly for the prophylactic group (76%). Surgery consisted of a right atrial maze in 63%, left atrial maze in 4%, and bilateral maze in 33%. There were no direct complications or mortality related to the maze procedure itself. For the therapeutic group, freedom from arrhythmias was 82% and 67% at 1 and 5 years post-maze. Younger age at the time of surgery correlated with a lower long-term recurrence risk., Conclusion: Maze procedure at the time of an elective anatomic surgery is reasonably effective to prevent and treat atrial arrhythmias in patients with congenital heart disease at short- and mid-term, with low morbidity and mortality., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Aims: The circuit of pulmonary vein-gap re-entrant atrial tachycardia (PV-gap RAT) after atrial fibrillation ablation is sometimes difficult to identify by conventional mapping. We analysed the detailed circuit and electrophysiological features of PV-gap RATs using a novel high-resolution mapping system., Methods and Results: This multicentre study investigated 27 (7%) PV-gap RATs in 26 patients among 378 atrial tachycardias (ATs) mapped with Rhythmia™ system in 281 patients. The tachycardia cycle length (TCL) was 258 ± 52 ms with P-wave duration of 116 ± 28 ms. Three types of PV-gap RAT circuits were identified: (A) two gaps in one pulmonary vein (PV) (unilateral circuit) (n = 17); (B) two gaps in the ipsilateral superior and inferior PVs (unilateral circuit) (n = 6); and (C) two gaps in one PV with a large circuit around contralateral PVs (bilateral circuit) (n = 4). Rhythmia™ mapping demonstrated two distinctive entrance and exit gaps of 7.6 ± 2.5 and 7.9 ± 4.1 mm in width, respectively, the local signals of which showed slow conduction (0.14 ± 0.18 and 0.11 ± 0.10m/s) with fragmentation (duration 86 ± 27 and 78 ± 23 ms) and low-voltage (0.17 ± 0.13 and 0.17 ± 0.21 mV). Twenty-two ATs were terminated (mechanical bump in one) and five were changed by the first radiofrequency application at the entrance or exit gap. Moreover, the conduction time inside the PVs (entrance-to-exit) was 138 ± 60 ms (54 ± 22% of TCL); in all cases, this resulted in demonstrating P-wave with an isoelectric line in all leads., Conclusion: This is the first report to demonstrate the detailed mechanisms of PV-gap re-entry that showed evident entrance and exit gaps using a high-resolution mapping system. The circuits were variable and Rhythmia™-guided ablation targeting the PV-gap can be curative., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Successful catheter ablation of scar-related atrial tachycardia depends on correct identification of the critical isthmus. Often, this is a represented by a small bundle of viable conducting tissue within a low-voltage area. It's identification depends on the magnitude of the signal/noise ratio. Ultra-high density mapping, multipolar catheters with small (eventually unidirectional) and closely-spaced electrodes improves low-voltage electrogram detection. Background noise limitation is also of major importance for improving the signal/noise ratio. Electrophysiological properties of the critical isthmus and the characteristics of the local bipolar electrograms have been recently demonstrated as hallmarks of successful ablation sites in the setting of scar-related atrial tachycardia., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Aims: In the management of both ventricular and supraventricular tachycardia in patients with congenital heart disease (CHD) catheter ablation has now been recognized as one of the mainstays., Methods and Results: We review our initial experience of using the Rhythmia mapping system in a cohort of 12 adult CHD patients presenting with multiple arrhythmia substrates. A total of 78 arrhythmia maps were attempted in a total of 15 procedures, but possible due to the dilatation of the target chamber only 44% of maps were able to reconstruct the entire arrhythmia. All patients underwent pre-procedure 3D imaging (either cardiac magnetic resonance or computed tomography), but image integration was suboptimal. A median of two maps per patient were finally analysed and acquisition took in median 22 min with a median number of 12 574 (8230-18 167) mapping points. Procedural data with a total duration amounting to in median 285 (194-403) min, with a median total fluoroscopy exposure of 7.5 (5.2-10.7) min. After a median of 1.5 procedures [median of 12 (8-16 months)], nine patients remained in stable sinus rhythm or atrial paced rhythm, while three patients had further sustained recurrences. One of these passed away in end-staged heart failure., Conclusion: This initial experience of using high-density mapping for arrhythmia management in patients with CHD allowed rapid acquisition of multiple maps with high accuracy to identify surgical scars and fibrosis, however, it was limited by large atrial volumes and a high percentage of incomplete maps resulting in modest clinical success., (© The Author(s) 2019. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Sedation is not consistently used during electrophysiology procedures because of concerns regarding effects on tachycardia inducibility. We designed this study to assess the effect of conscious sedation on tachycardia inducibility and patient comfort during supraventricular tachycardia ablation., Methods and Results: Patients with narrow QRS tachycardia and no pre-excitation undergoing an electrophysiology study were randomly assigned to sedation or placebo group. Patients in the sedation group received intermittent doses of midazolam and fentanyl, while those in the placebo group received normal saline as placebo. The physician and the patient were blinded to the allocation. Information was collected on tachycardia inducibility, patient discomfort, and complications. A total of 103 patients were included in the study. Proportion of patients with difficult tachycardia induction (27.4% vs. 32.7%) or with non-inducibility (5.8% vs. 3.8%) were not different between the sedation and placebo groups. Patient discomfort as measured by the Wong-Baker scale was significantly less in the sedation group (1.45 ± 1.08 vs. 2.24 ± 1.2, P < 0.0007) compared to the placebo group. There was no difference in incidence of hypotension or hypoxia between the two groups., Conclusions: Conscious sedation with intermittent midazolam- and fentanyl-reduced patient discomfort during electrophysiology study and ablation of supraventricular tachycardia without affecting tachycardia inducibility. Sedation administered in the absence of an anaesthetist was safe.

Aims: Unexplained scar-related atrial tachycardia (AT) has been frequently encountered in clinical practice. We hypothesized that idiopathic, isolated fibrotic atrial cardiomyopathy (ACM) underlies this rhythm disorder. This study was aimed to characterize the underlying substrate and to explore the aetiology of this unexplained scar-related AT., Methods and Results: Twenty-six (11 men, aged 46 ± 13 years) of 52 non-surgical scar-related AT patients identified by three-dimensional voltage mapping were enrolled in this prospective observational study. Multimodality image examinations (echocardiography, cardiac magnetic resonance, 99Tc single-photon emission computed tomography), ventricular voltage mapping, and intracardiac pressure curve recording ruled out ventricular involvement. Catheter ablation was acutely successful for all the patients, and pacemaker implantation was performed in seven patients who presented sinus node dysfunction or atrial standstill after termination of the AT. In three patients with multiple AT recurrences, the diseased areas of the right atrium were resected and dechannelled via mini-invasive surgical interventions. Histological examinations revealed profound fibrosis without amyloidosis or adipose deposition. Viral and familial investigations yielded negative results. Fibrosis progression over a median of 45 (5-109) months of follow-up manifested as atrial arrhythmia recurrence in seven patients and atrial lead non-capture due to newly developed atrial standstill in two patients. Two patients suffered four ischaemic stroke events before receiving anticoagulation treatment., Conclusion: Isolated, fibrotic ACM may underlie the idiopathic scar-related ATs. This novel cardiomyopathy has unique clinical characteristics with high morbidity including stroke and warrants specific therapeutic strategies. Further investigations are required to determine the aetiology and mechanism.

Aim: Intra-atrial re-entrant tachycardia (IART) is a common complication in patients with congenital heart disease (CHD) and is related to increased morbidity and mortality. Few reports have been published about factors associated to IART severity. The aim of this study is to analyse factors associated to severe clinical presentation of IART., Methods and Results: Observational study of all consecutive CHD patients who underwent a first IART ablation from January 2009 to December 2015 (94 patients, 39.4% female, and age: 36.55 ± 14.9 years). Severe clinical presentation was defined as heart failure, syncope, shock, electromechanical dissociation (EMD), or aborted sudden death. The majority of patients had moderately or highly complex cardiac defect (90.4%). Types of IART included cavotricuspid isthmus(CTI) dependent in 51% (48), non-CTI-related in 22.3% (20), and both types in 27.7% (26). In 38 patients (40.4%), a severe event occurred and in 16 (17%), the symptoms included shock, syncope, sudden death, or EMD. In 21 (22.3%), severe symptoms were the first manifestation of IART. In multivariate analysis, transposition of the great arteries (TGA) with right systemic ventricle (OR 5.32, 95% C.I. 1.6-7.02, P = 0.0005) and severe dilation of the venous atrium (VsA) (OR 4.17; 95% CI 1.4-8.12, P = 0.0009) were factors independently associated with severity., Conclusion: In our series of 94 CHD patients with a high proportion of moderately to highly complex cardiac defects, severe consequences of IART were frequent. Transposition of the great arteries with systemic right ventricle and severe dilation of VsA were independently associated to severity. Early invasive procedures should be considered for these high-risk patients.

Aims: A persistent left superior vena cava (PLSVC) is the most common thoracic venous anomaly. This venous anomaly can impact the evaluation and treatment of supraventricular tachyarrhythmia (SVA). The aim of this study was to assess the proportion and characteristics of PLSVC in adult SVA patients., Methods and Results: From July 2002 to July 2012, clinical and procedural data from databases of 10 cardiac electrophysiology laboratories in the Yeungnam region of the Republic of Korea were reviewed. Of 6662 adult SVA patients who underwent an EP study or catheter ablation of SVA during the 10-year study period, 18 patients had PLSVC (mean age 47.6 ± 14.8 years, 10 men). The proportion of PLSVC in adult SVA patients was 0.27% (18/6662). SVA type and procedural outcomes of radiofrequency (RF) catheter ablation in these patients were investigated and the results were as follows: successful slow pathway modification in six of seven patients with atrioventricular nodal reentrant tachycardia (AVNRT), successful ablation of accessory pathway in three of four patients with atrioventricular reentrant tachycardia, and successful ablation of atrial tachycardia (cavotricuspid isthmus-dependent in two, septal macroreentry in one, focal from the PLSVC in one) in three of four patients. In one patient with junctional tachycardia, catheter ablation failed. In two patients with atrial fibrillation, catheter ablation was successful., Conclusion: Among adult SVA patients who underwent an EP study or RF catheter ablation during the 10-year study period, 0.27% had PLSVC. The most common type of SVA was AVNRT. The success rate of catheter ablation was 82% in SVA patients with PLSVC. There were no procedure-related complications.

Aims: The relationship between ventricular pre-excitation and left ventricular dysfunction has been described in the absence of sustained supraventricular tachycardia in a series of case reports. There have been no systematic studies about the effect of ventricular pre-excitation with different accessory pathway locations on ventricular wall motion and left ventricular (LV) systolic function., Methods and Results: Thirty patients were selected for each of 4 groups, including those with right septal pathways (Group 1), right free-wall pathways (Group 2), left free-wall pathways (Group 3), and non-pre-excited patients undergoing electrophysiological evaluation for supraventricular tachycardia. We analysed the influence of the location of the accessory pathway on ventricular wall motion, systolic function, ventricular synchronism, and LV size. Right-sided accessory pathways were associated with abnormal motion of the interventricular septum, LV dyssynchrony, decreased LV systolic function, and increased LV diameter. Eighteen of 60 cases (30.0%) with right-sided accessory pathways had LV dyssynchrony, and these patients had lower LV ejection fraction and higher LV end-diastolic diameter., Conclusion: Right-sided accessory pathways may impair ventricular wall motion and LV systolic function, resulting in decreased LV ejection fraction and increased LV end-diastolic diameter. These effects occurred in patients with LV dyssynchrony. These effects, including LV dyssynchrony, resolved after radiofrequency ablation. A right-sided free-wall accessory pathway may have more detrimental effects than a septal accessory pathway. Left ventricular dyssynchrony and abnormal interventricular septal motion appeared to be responsible for the pathogenesis of LV dysfunction and remodelling.

Aims: The objectives of this study were to assess the acute and long-term outcomes of catheter ablation in incisional atrial tachycardia (IAT) using remote magnetic navigation (RMN) in patients after heart surgery., Methods and Results: A total of 46 patients with IAT after heart surgery who underwent catheter ablation using RMN were included. Of these patients, 22 patients had acquired heart disease (AHD) and the remaining 24 patients had various types of congenital heart disease (CHD). In these 46 patients, 57 re-entry circuits were found in 56 procedures. The re-entry circuits were mainly distributed in right atrium (RA). Acute success of first ablation reached in 42 of 46 (91%) patients. Mean procedure duration was 115 ± 39 min, ablation duration was 678 (920.5) s, X-ray time was 4 (4.8) min, and X-ray dose was 3 (6.0) gy cm2. After a mean follow-up of 28 ± 19 months, 39 of 46 (85%) patients were free from IAT. No major complications were observed. There were no significant differences in procedure durations (AHD 113 ± 40 min vs. CHD 119 ± 38 min), ablation durations [AHD 643 (1027) s vs. CHD 712 (929) s], X-ray time [AHD 4 (4.5) min vs. CHD 4 (5.0) min], circuits in RA (AHD 85% vs. CHD 86%), acute success rates (AHD 91% vs. CHD 92%), and long-term success rates (AHD 86% vs. CHD 83%) between the two groups (P > 0.05)., Conclusion: Catheter ablation of IAT in patients after heart surgery using RMN is safe and effective. No significant differences related to success rates and procedure characteristics were found between patients with AHD and CHD.

Aims: Subclinical brain damage due to microembolization could occur during catheter ablation procedures. We evaluated the microembolic signals (MESs) detected by transcranial Doppler during ablation of supraventricular tachycardias (SVTs) or idiopathic ventricular arrhythmias (VAs) with the use of different approaches., Methods and Results: This study included 36 patients (23 men, 49 ± 21 years) who underwent catheter ablation of SVTs (n = 27) or idiopathic VAs (n = 9). Left-sided ablation was performed by either a transaortic (Group 1, n = 11) or transseptal approach (Group 2, n = 9). A sole right-sided ablation was performed in the remaining 16 patients (Group 3). The MESs were counted throughout the procedure, and then analysed offline with a frequency analysis. The mean number of radiofrequency applications, total energy delivery time, total application energy, and total procedure time were 5.8 ± 5.0, 4.3 ± 3.3 min, 6625 ± 4633 J, and 81 ± 40 min, respectively, and there was no significant difference in the parameters between the three groups. The mean total number of MESs was 3.8 ± 3.1 in Group 1, 75 ± 58 in Group 2, and 0.3 ± 0.6 in Group 3 (P = 0.001). Few MESs were detectable during the radiofrequency energy deliveries in all groups. In Group 2, 19 ± 18 MESs were detected during the transseptal puncture period, and subsequently a relatively even distribution of emboli formation was observed. A frequency analysis suggested that 99, 91, and 100% of MESs were gaseous, in Group 1, Group 2, and Group 3, respectively. No neurological impairment was observed in any patients after the procedure., Conclusion: The retrograde aortic approach might potentially have a lower risk of subclinical brain damage than the transseptal approach during left-sided catheter ablation., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.)

Aims: The clinical characteristics of atrial tachycardias (AT) ablated from the non-coronary aortic sinus (NCS) are thus far described only in small series. We aimed to outline, in a large cohort of patients, the clinical, electrocardiographic, electrophysiological characteristics of this tachycardia., Methods and Results: We analysed data pertaining to clinical, electrocardiographic, and electrophysiological characteristics of 43 consecutive patients from an overall cohort of 441 with AT who were successfully ablated from the NCS. The tachycardias ablated from the NCS were paroxysmal (98%) and adenosine sensitive (35/35). The patients were aged 54.6 ± 12.4 years, showing female preponderance (74%). No P wave pattern was predictive of the location of ablation. Electrophysiological findings suggested a possible micro-reentrant mechanism. During tachycardia, atrial electrograms recorded in the NCS preceded the A in the His region by 10.9 ± 7.4 ms. Fractionated atrial electrograms were noted at the site of ablation in 42 patients during the tachycardia. Radiofrequency ablation terminated the tachycardia within 5 s in 88%, with thermal automaticity seen only in 3 patients. The site of ablation at the base of the NCS was adjacent to the presumed site of the retroaortic node, a remnant of the initial atrio-ventricular canal musculature., Conclusions: AT ablated from the NCS is a paroxysmal arrhythmia in middle-aged women, with distinct electrocardiographic and electrophysiological characteristics. We suspect the retroaortic node to be involved in the tachycardia circuit., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For Permissions, please email: journals.permissions@oup.com.)

Aims: We sought to investigate focal atrial tachycardias (ATs) in patients with congenitally corrected transposition of the great arteries (ccTGA)., Methods and Results: We identified three cases of focal ATs with ccTGA from 2007 to 2015. The clinical findings, electrocardiography, electrophysiological features, and ablation were reported. All three cases had {S,L,L}-type ccTGA. The AT P waves shared the following features: narrow in width, positive in leads I and aVL, and negative/positive in lead V1. All ATs had focal activation pattern with early activation at the anteroseptal area, and further mapping demonstrated earliest atrial activation (EAA) inside the pulmonary sinus cusps (PSCs), especially the right PSC. In Cases 1 and 2, double potentials were recorded at the EAA sites. Conduction delay between the two potentials during atrial extrastimulus was observed. After successful ablation, the second potential during sinus rhythm was further delayed in Case 1 and was eliminated in Case 2. However, only one potential was recorded in Case 3. All three cases were successfully managed by ablating the sites with EAA, which preceded the P-wave onset by 60, 80, and 42 ms, respectively. During ablation, no junctional rhythm was observed. Incomplete left bundle branch block was induced during mapping in Case 1, but no other complications occurred. All patients were free from tachycardia during follow-up periods of 36, 7, and 5 months, respectively., Conclusion: Anteroseptal AT in patients with ccTGA could be eliminated by ablation inside the PSC., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)

Aims: The transseptal approach is used for left atrial access during the ablation of atrial fibrillation (AF) and other left-sided arrhythmia substrates. Transseptal puncture (TP) is commonly performed with fluoroscopic guidance, contrast injection, and pressure monitoring. In many centres, additional techniques [intracardiac echocardiography (ICE), transoesophageal echocardiography (TEE), radiofrequency needle] are used to facilitate TP but its use adds costs. In this retrospective study, we studied the safety and complication rate when TP was routinely done with fluoroscopic guidance, contrast injection, and pressure monitoring using ICE or TEE only in selected cases., Methods and Results: This study analysed 4690 consecutive TP performed between 2000 and 2015: 3408 (72.6%) were ablation of AF, left-sided atrial flutter, or left-sided atrial tachycardia (non-AP group); 1153 (24.6%) were ablation of left-sided accessory pathway, AP group; and 129 (2.8%) were ablation of ventricular tachycardia. Transseptal puncture was done under fluoroscopy, pressure monitoring, and commonly using contrast media injection. In 27 procedures, ICE or TEE was used to guide the TP. We found 34 tamponades (Tx) that required pericardial drainage of which 28 (0.59%) could possibly be TP related and six could not. The total complication rate for all Tx was 0.72%. A higher rate of tamponades was observed in the AF (non-AP) group than in the AP group (0.88 vs. 0.17%, P < 0.02). The highest rate of tamponades was registered during the operators 51-100 cases, 1.3%, and decreased to 0.4% in cases 101-200, P = 0.04., Conclusion: TP can safely be done under fluoroscopy and pressure monitoring without routine use of additional techniques. With experience, operators should be able to further decrease complication rate., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.)

Aims: Supraventricular arrhythmias are a major cause of morbidity and mortality in adult patients with congenital heart disease (CHD). Intraoperative ablation offers an alternative for patients who failed ablation procedures or are requiring concomitant surgical intervention. We present our long-term results with the surgical treatment of arrhythmias in adults with CHD (ACHD) undergoing elective cardiac surgery and the clinical predictors for arrhythmia recurrence., Methods and Results: Between 2002 and 2013, 80 consecutive patients with CHD, mean age of 39 years, underwent intraoperative ablation with monopolar irrigated radiofrequency during cardiac surgery procedures. Significant clinical predictors of arrhythmia recurrence were determined by univariate analysis. We performed 47 right-sided Maze procedures, and 33 Cox-Maze III procedures. In 75 survivors, the ablation was effective immediately. Over an average follow-up period of 72 months (12-155 months), arrhythmias recurred in nine (20%) patients after right-sided Maze, and in six (19%) patients after Cox-Maze III. Eleven patients were controlled with medical therapy, three underwent catheter ablation of the arrhythmia, and one required a permanent pacemaker. Preoperative arrhythmia length ≥3 years (P ≤ 0.001), tetralogy of Fallot (P ≤ 0.006), and preoperative atrial fibrillation (P ≤ 0.016) were associated with recurrence arrhythmia. Conversely, NYHA class <3 (P ≤ 0.047) was associated with a lower risk of recurrence., Conclusion: Surgical treatment of unresponsive supraventricular arrhythmia during concomitant cardiac surgery in ACHD is a safe and effective procedure. Freedom from arrhythmias recurrence is 75% after 6 years of follow-up. Long-term recurrence of arrhythmia in these patients seems to be strongly correlated to preoperative arrhythmia duration., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)

Aim: Data on arrhythmia outcome following device closure of atrial septal defect (ASD) are lacking. This study provides medium-term follow-up data on atrial arrhythmias in patients who were ≥40 years of age at the time of transcatheter ASD closure., Methods and Results: It is a retrospective review. Mean age of the 159 patients was 57 years. Median follow-up was 3.6 years (range 6 months-10.9 years). Patients were classified, according to arrhythmia status prior to ASD closure, into Group I, no history of atrial arrhythmia (n = 119, mean age 55.5 years); Group II, paroxysmal atrial arrhythmia (n = 18, mean age 55.7 years); and Group III, persistent atrial fibrillation (n = 22, mean age 65.7 years). Group III patients were significantly older, had larger left atrial size, and had higher mean pulmonary arterial pressure than Group I and II patients (P < 0.001). Prior to closure, radiofrequency ablation was carried out in 12/18 (66%) of Group II and 3/22 (14%) of Group III. After device closure, 7 patients (6%) of Group I developed new atrial fibrillation. Fifty per cent (9/18) of Group II but only 9% (2/22) of Group III were in sinus rhythm on follow-up., Conclusion: Device closure alone in patients with persistent atrial arrhythmia is not likely to restore sinus rhythm in the medium term. New atrial arrhythmia occurred in 6% of patients who were in sinus rhythm prior to device closure. At least 50% of the patients with paroxysmal atrial arrhythmia continue to have significant atrial arrhythmia following device closure, and the role of ablation prior to closure in patients with a history of arrhythmia requires refinement., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)

Aims: Non-fluoroscopic catheter ablation is becoming routine. In experienced centres, fluoroscopy is rarely required. The use of a traditional catheterization lab (cath lab) may no longer be necessary. We began performing catheter ablations at a paediatric centre outside the traditional cardiac cath lab in 2013. The purpose of this study was to compare procedural features of paediatric catheter ablation performed outside the cath lab to those performed within a cath lab., Methods and Results: We prospectively looked at patients presenting to the paediatric centre with supraventricular tachycardia (SVT) undergoing catheter ablation outside the cath lab in a standard operating room (OR group). We compared retrospectively to a control group matched for age, type, and location of arrhythmia who had ablations in a traditional cath lab (CL group). Catheter visualization was exclusively by electro-anatomic mapping. Fifty-nine patients with SVT underwent catheter ablation in the OR from October 2013 to December 2015. Thirty-three patients had accessory pathways, 29 were manifest, and 13 of those were left sided. Twenty-six had atrioventricular nodal re-entrant tachycardia. Transseptal puncture with transoesophageal echocardiography guidance was used for 10 left-sided pathways, whereas the other 3 had patent foramen ovales. Procedure time did not differ significantly between groups (OR group mean 131 min, range 57-408; CL group mean 152 min, range 68-376; P = 0.12). Acute success was similar in both groups [OR group: 58/59 (98.3%) and CL group: 57/59 (96.6%)]. There were no major complications in either group. There was no fluoroscopy used in either group., Conclusion: Although performing paediatric catheter ablations outside the traditional cath lab is early in our experience, we produced similar outcomes and results without encountering procedural difficulties of performing ablations in a non-conventional setting. Larger multi-centred trials will be essential to determine the feasibility of this practice., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)

Aims: Aim of this study was to compare a minimally fluoroscopic radiofrequency catheter ablation with conventional fluoroscopy-guided ablation for supraventricular tachycardias (SVTs) in terms of ionizing radiation exposure for patient and operator and to estimate patients' lifetime attributable risks associated with such exposure., Methods and Results: We performed a prospective, multicentre, randomized controlled trial in six electrophysiology (EP) laboratories in Italy. A total of 262 patients undergoing EP studies for SVT were randomized to perform a minimally fluoroscopic approach (MFA) procedure with the EnSite TM NavX TM navigation system or a conventional approach (ConvA) procedure. The MFA was associated with a significant reduction in patients' radiation dose (0 mSv, iqr 0-0.08 vs. 8.87 mSv, iqr 3.67-22.01; P < 0.00001), total fluoroscopy time (0 s, iqr 0-12 vs. 859 s, iqr 545-1346; P < 0.00001), and operator radiation dose (1.55 vs. 25.33 µS per procedure; P < 0.001). In the MFA group, X-ray was not used at all in 72% (96/134) of cases. The acute success and complication rates were not different between the two groups (P = ns). The reduction in patients' exposure shows a 96% reduction in the estimated risks of cancer incidence and mortality and an important reduction in estimated years of life lost and years of life affected. Based on economic considerations, the benefits of MFA for patients and professionals are likely to justify its additional costs., Conclusion: This is the first multicentre randomized trial showing that a MFA in the ablation of SVTs dramatically reduces patients' exposure, risks of cancer incidence and mortality, and years of life affected and lost, keeping safety and efficacy., Trial Registration: clinicaltrials.gov Identifier: NCT01132274., (© The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Radiofrequency catheter ablation (RFCA) for arrhythmias in the context of short-term medical missions (MM) in a developing country has not been reported so far. We describe here our experience with RFCA and pacemaker implantation in Morocco with a fully portable electrophysiological (EP) system under the auspice of the Monaco-Morocco Cardiology Association., Methods and Results: Since November 2007, two to three MM (mean duration 4 days including transportation) per year were conducted (including two physicians and one nurse from Monaco) and were alternately located in Marrakech, Fes, Agadir, Casablanca, Rabat, Essaouira, and Oujda. All patients' files were sent by local teams and/or referring Moroccan cardiologists before MM. Each case was discussed with the Monaco EP team before the MM. Pacemakers and leads were donated by companies (Sorin Group, Medtronic, Saint-Jude Medical). The EP system (EP Tracer, CardioTek) as well as diagnostic/ablation catheters were brought for RFCA procedures. After the procedures, follow-up was performed by local teams. Procedures took place in gynaecological or orthopaedic operating room, or, when available, in the interventional cardiology cathlab. Thirty-one RFCA were performed during 11 MM (atrioventricular node re-entrant tachycardia = 12; atrioventricular re-entrant tachycardia/Mahaïm fibre = 15; typical atrial flutter = 3; ventricular ectopy = 1). Acute success was 93.5% for RFCA. Two major RFCA-related complications occurred (air embolism and complete atrioventricular block). No complication was related to pacemaker implantations (n = 44; mean 4 pacemakers per mission)., Conclusion: Radiofrequency catheter ablation for arrhythmias in developing countries is technically challenging but feasible, despite technical and cultural difficulties., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.)