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The diagnosis of device infections, especially pocket infections, is challenging and relies primarily on clinical presentation. The prospective DIRT (Device associated Infections Role of new diagnostic Tools) study identified procalcitonin (PCT) as the most promising biomarker among other 14 biomarkers to aid the diagnosis of pocket infection. It also identified an optimized cut-off value of 0.05 ng/ml for a localized generator pocket infection.The present study aims to validate the proposed PCT cut-off value of 0.05 ng/ml for the diagnosis of pocket infection in an independent cohort.We prospectively enrolled 81 patients with pocket infections and 81 controls matched for age and renal function presenting for elective device exchange or lead revision. Patients with concomitant infectious or inflammatory diseases, end-stage renal failure, current active malignancy, or receiving immunosuppressive therapy were excluded.An elevated PCT over 0.05 ng/ml was found in 68% (n = 55) of pocket infections and 24% (n = 19) of controls, corresponding to a sensitivity of 68% and a specificity of 77% for diagnosing a pocket infection. In receiver operating characteristic (ROC) analysis, PCT showed an area under the curve of 0.75 (95% confidence interval, 0.68-0.83; P0.001). Sensitivity remained high with antibiotic pretreatment (65% compared to 69% without pretreatment) and in cases with minimal inflammatory signs (67% compared to 70% with extensive inflammation).Our study validates the cut-off value of 0.05 ng/ml PCT for diagnosis of a pocket infection, even in patients pre-treated with antibiotics or with minimal clinical signs of inflammation.

ZusammenfassungIm Gegensatz zum typischen Vorhofflattern handelt es sich beim atypischen Vorhofflattern um eine heterogene Gruppe von rechts- und linksatrialen Makro- bzw. Localized-Reentry-Tachykardien, deren kritischer Bestandteil zur Aufrechterhaltung der Tachykardie nicht der cavotrikuspidale Isthmus ist. Atypisches Vorhofflattern tritt gehäuft nach vorangegangener Katheterablation sowie nach herzchirurgischen Eingriffen auf. Die intraprozedurale Erfolgsrate während der Ablation ist hoch, wobei die Rezidivrate von strukturellen Veränderungen der Vorhöfe sowie des zugrundeliegenden Mechanismus abhängig ist. Dieser Artikel bietet einen Überblick über die Mechanismen sowie über Mapping- und Ablationsstrategien der häufigsten Formen von rechts- und linksatrialem atypischem Vorhofflattern. Dieser Beitrag ist Teil der Serie „EP-Basics“ zur gezielten Fortbildung im Bereich Invasive Elektrophysiologie. Grundlagen, Klinik und Therapie des atypischen Vorhofflatterns werden mit Fokus auf klinisch relevante Aspekte dargelegt. Vorgehensweise und Befunde der invasiven elektrophysiologischen Diagnostik und die Ablationsbehandlung bilden den Schwerpunkt dieses Artikels.

The rate of transvenous lead extraction (TLE) is increasing, with an increasing rate of complex devices being implanted. TLE is now a routine part of cardiac device management and up-to-date data on the safety and efficacy of TLE with modern tools and techniques is essential to management decisions regarding noninfectious indications for lead extraction. We present a contemporary, prospective review of TLE at our high-volume cardiac center. All patients who underwent TLE from June 2016 to June 2019 were enrolled in our local database, and baseline clinical data, procedural information, and outcome data were collected. In total, 561 leads were explanted (n = 153) or extracted (n = 408) from 341 patients over the study period. Patients were predominantly male (71%), with a mean age of 65 ± 17 years. The most common indication for lead removal was lead failure (45.2%, n = 154), followed by infection of the pocket or device (29.3%, n = 100). In total, complete success was achieved in 96.4% (n = 541) leads, clinical success in a further 2.1% (n = 12), and failure only in 1.4% (n = 8). There was an overall complication rate of 0.9% (3/341) for major complications and 1.5% (5/341) for minor complications. There were no deaths. In conclusion, our data suggest that there are ongoing improvements in the safety profile and success rates of lead extraction undertaken by experienced operators. The major complication rate now is1%.

Aims Battery electric vehicle (BEV) sales and use are rapidly expanding. Battery electric vehicles, along with their charging stations, are a potential source of electromagnetic interference (EMI) for patients with cardiac implantable electronic devices (CIEDs). The new ‘high-power’ charging stations have the potential to create strong electromagnetic fields and induce EMI in CIEDs, and their safety has not been evaluated. Methods and results A total of 130 CIED patients performed 561 charges of four BEVs and a test vehicle (350 kW charge capacity) using high-power charging stations under continuous 6-lead electrocardiogram monitoring. The charging cable was placed directly over the CIED, and devices were programmed to maximize the chance of EMI detection. Cardiac implantable electronic devices were re-interrogated after patients charged all BEVs and the test vehicle for evidence of EMI. There were no incidences of EMI, specifically no over-sensing, pacing inhibition, inappropriate tachycardia detection, mode switching, or spontaneous reprogramming. The risk of EMI on a patient-based analysis is 0/130 [95% confidence interval (CI) 0%–2%], and the risk of EMI on a charge-based analysis is 0/561 (95% CI 0%–0.6%). The effective magnetic field along the charging cable was 38.65 µT and at the charging station was 77.9 µT. Conclusions The use of electric cars with high-power chargers by patients with cardiac devices appears to be safe with no evidence of clinically relevant EMI. Reasonable caution, by minimizing the time spent in close proximity with the charging cables, is still advised as the occurrence of very rare events cannot be excluded from our results.

Introduction Electrogram (EGM) fractionation is often associated with diseased atrial tissue; however, mechanisms for fractionation occurring above an established threshold of 0.5 mV have never been characterized. We sought to investigate during sinus rhythm (SR) the mechanisms underlying bipolar EGM fractionation with high-density mapping in patients with atrial fibrillation (AF). Methods Forty-five patients undergoing AF ablation (73% paroxysmal, 27% persistent) were mapped at high density (18562 +/- 2551 points) during SR (Rhythmia). Only bipolar EGMs with voltages above 0.5 mV were considered for analysis. When fractionation (> 40 ms and >4 deflections) was detected, we classified the mechanisms as slow conduction, wave-front collision, or a pivot point. The relationship between EGM duration and amplitude, and tissue anisotropy and slow conduction, was then studied using a computational model. Results Of the 45 left atria analyzed, 133 sites of EGM fragmentation were identified with voltages above 0.5 mV. The most frequent mechanism (64%) was slow conduction (velocity 0.45 m/s +/- 0.2) with mean EGM voltage of 1.1 +/- 0.5 mV and duration of 54.9 +/- 9.4 ms. Wavefront collision was the second most frequent (19%), characterized by higher voltage (1.6 +/- 0.9 mV) and shorter duration (51.3 +/- 11.3 ms). Pivot points (9%) were associated with the highest degree of fractionation with 70.7 +/- 6.6 ms and 1.8 +/- 1 mV. In 10 sites (8%) fractionation was unexplained. The EGM duration was significantly different among the 3 mechanisms (p = .0351). Conclusion In patients with a history of AF, EGM fractionation can occur at amplitudes > 0.5 mV when in SR in areas often considered not to be diseased tissue. The main mechanism of EGM fractionation is slow conduction, followed by wavefront collision and pivot sites.

Detailed effects of electrode size on electrograms (EGMs) have not been systematically examined.We aimed to elucidate the effect of electrode size on EGMs and investigate an optimal configuration of electrode size and interelectrode spacing for gap detection and far-field reduction.This study included 8 sheep in which probes with different electrode size and interelectrode spacing were epicardially placed on healthy, fatty, and lesion tissues for measurements. Between 3 electrode sizes (0.1 mm/0.2 mm/0.5 mm) with 3 mm spacing. As indices of capability in gap detection and far-field reduction, in different electrode sizes (0.1 mm/0.2 mm/0.5 mm) and interelectrode spacing (0.1 mm/0.2 mm/0.3 mm/0.5 mm/3 mm) and the optimized electrode size and interelectrode spacing were determined. Compared between PentaRay and the optimal probe determined in study 2.Study 1 demonstrated that unipolar voltage and the duration of EGMs increased as the electrode size increased in any tissue (P.001). Bipolar EGMs had the same tendency in healthy/fat tissues, but not in lesions. Study 2 showed that significantly higher gap to lesion volume ratio and healthy to fat tissue voltage ratio were provided by a smaller electrode (0.2 mm or 0.3 mm electrode) and smaller spacing (0.1 mm spacing), but 0.3 mm electrode/0.1 mm spacing provided a larger bipolar voltage (P.05). Study 3 demonstrated that 0.3 mm electrode/0.1 mm spacing provided less deflection with more discrete EGMs (P .0001) with longer and more reproducible AF cycle length (P .0001) compared to PentaRay.Electrode size affects both unipolar and bipolar EGMs. Catheters with microelectrodes and very small interelectrode spacing may be superior in gap detection and far-field reduction. Importantly, this electrode configuration could dramatically reduce artifactual complex fractionated atrial electrograms and may open a new era for AF mapping.

BackgroundVentricular tachycardia (VT) originating in the right ventricular outflow tract (RVOT) is the most common form of idiopathic VT. Catheter ablation of right ventricular outflow tract tachycardia (RVOT-VT) is associated with high success rates. However, non-inducibility of VT on electrophysiological (EP) study can severely impact ablation outcome. We describe a novel catheter ablation strategy which proved feasible and safe in a case of highly symptomatic, non-inducible RVOT-VT.Case summaryA 51-year-old male with a history of non-sustained VT (NSVT) was referred to our hospital after two syncopal episodes resulting in collapse. Upon admission, a cluster of monomorphic NSVT (250–270 b.p.m.) resulted in haemodynamic instability and required transfer to the intensive care unit. On twelve-lead electrocardiogram, NSVT showed inferior axis and left bundle branch block, suggestive of RVOT-VT. Diagnostic workup including echocardiography, coronary angiography, and late enhancement computed tomography (CT) revealed no evidence of structural heart disease. On two EP studies, non-inducibility of clinical VT despite repeated ventricular pacing and isoproterenol infusion rendered precise mapping of triggered activity unfeasible. Therefore, a bailout ablation strategy was developed by performing a circumferential electrical RVOT isolation using a 3.5 mm irrigated-tip ablation catheter under the guidance of high-density electroanatomic mapping (CARTO® 3) and CT reconstruction of cardiac anatomy. No procedural complications occurred, and the patient remained arrhythmia-free during a 6-month follow-up period.DiscussionCatheter ablation is a first-line therapy for symptomatic and drug-refractory idiopathic RVOT-VT. Non-inducibility of RVOT-VT represents a relevant limitation for successful ablation which might be overcome by electrical RVOT isolation as a bailout ablation strategy.

Background: Femoral vascular access using the standard anatomic landmark-guided method is often limited by peripheral artery disease and obesity. We investigated the effect of ultrasound-guided vascular puncture (UGVP) on the rate of vascular complications in patients undergoing catheter ablation for atrial or ventricular arrhythmias. Methods: The data of 479 patients (59% male, mean age 68 years ± 11 years) undergoing catheter ablation for left atrial (n = 426; 89%), right atrial (n = 28; 6%) or ventricular arrhythmias (n = 28; 6%) were analyzed. All patients were on uninterrupted oral anticoagulants and heparin was administered intravenously during the procedure. Femoral access complications were compared between patients undergoing UGVP (n = 320; 67%) and patients undergoing a conventional approach (n = 159; 33%). Complication rates were also compared between patients with a BMI of >30 kg/m2 (n = 136) and patients with a BMI < 30 kg/m2 (n = 343). Results: Total vascular access complications including mild hematomas were n = 37 (7.7%). In the conventional group n = 17 (10.7%) and in the ultrasound (US) group n = 20 (6.3%) total vascular access complications occurred (OR 0.557, 95% CI 0.283–1.096). UGVP significantly reduced the risk of hematoma > 5 cm (OR 0.382, 95% CI 0.148, 0.988) or pseudoaneurysm (OR 0.160, 95% CI 0.032, 0.804). There was no significant difference between the groups regarding retroperitoneal hematomas or AV fistulas (p > 0.05). In patients with BMI > 30 kg/m2, UGVP led to a highly relevant reduction in the risk of total vascular access complications (OR 0.138, 95% CI 0.027, 0.659), hematomas > 5 cm (OR 0.051, 95% CI 0.000, 0.466) and pseudoaneurysms (OR 0.051, 95% CI 0.000, 0.466). Conclusion: UGVP significantly reduces vascular access complications. Patients with a BMI > 30 kg/m2 seem to particularly profit from a UGVP approach.

Die Katheterablation von Herzrhythmusstorungen hat sich fur die meisten tachykarden Arrhythmieformen als primare Behandlungsform etabliert. Hierbei ist die interventionelle Behandlung eines symptomatischen Vorhofflimmerns der medikamentosen Therapie uberlegen, sodass die Durchfuhrung einer Katheterablation zunehmend zum klinischen Alltag vieler Kliniken gehort. Die elektrische Isolation der Pulmonalvenen (PVI) stellt den Eckpfeiler der interventionellen Therapie sowohl von paroxysmalem als auch von persistierendem Vorhofflimmern dar. Dieser Artikel beschreibt die Durchfuhrung einer Pulmonalvenenisolation mittels Radiofrequenzablation in Punkt-fur-Punkt-Technik und soll eine praktische Anleitung fur die Arbeit im Herzkatheterlabor sein. Diese Arbeit setzt eine Reihe von Artikeln fort, die fur eine Weiterbildung im Bereich der speziellen Rhythmologie erstellt worden sind.

Aufgrund guter Ergebnisse, zunehmender Standardisierung und Fehlen von gleichwertigen Alternativen gehort die Durchfuhrung einer Katheterablation zunehmend zum klinischen Alltag vieler Kliniken. Dieser Artikel beschreibt die Durchfuhrung haufiger oder notwendiger Punktionen (Punktion der Leistengefase, transseptale Punktion, Perikardpunktion) im Rahmen einer Katheterablation und soll eine praktische Anleitung fur die Arbeit im Herzkatheterlabor darstellen. Diese Arbeit setzt eine Reihe von Artikeln fort, die fur eine Weiterbildung im Bereich der speziellen Rhythmologie konzipiert sind.

Beyond pulmonary vein isolation, the two main additional strategies: Cox-Maze procedure or targeting of electrical signatures (focal bursts, rotational activities, meandering wavelets), remain controversial. High-density mapping of these arrhythmias has demonstrated firstly that a patchy lesion set is highly proarrhythmogenic, favoring macro-re-entry through conduction slowing and providing pivots for localized re-entry. Secondly, discrete anatomical structures such as the Vein or Ligament of Marshall (VOM/LOM) and the coronary sinus (CS) have epicardial muscular bundles that are more frequently involved in re-entry than previously thought. The Marshall Bundle can be ablated at any point along its course from the mid-to-distal coronary sinus to the left atrial appendage. If necessary, the VOM may be directly ablated using ethanol infusion to eliminate PV contributions and produce conduction block across the mistral isthmus. Ethanol ablation of the VOM, supplemented with RF ablation, may be more effective in producing conduction block at the mitral isthmus than repeat RF ablation alone.

In this article, typical characteristics of focal atrial tachycardias are described and a systematic approach regarding diagnostics and treatment options in the field of invasive cardiac electrophysiology (EP) is presented. Subjects of this article include the definition of focal atrial tachycardias, knowledge about localizing the origin of such, and guidance on how to approach an invasive EP study (e.g., administration of medication during the EP study to provoke tachycardias). Further, descriptions will be found on how to localize the origin of focal atrial tachycardias with the help of the 12-lead ECG and invasive three-dimensional mapping to successfully treat focal atrial tachycardias with catheter ablation.Neben den typischen Eigenschaften fokaler atrialer Tachykardien soll in dieser Arbeit die systematische Herangehensweise an die Diagnostik und Therapie im Rahmen der invasiven Elektrophysiologie vorgestellt werden. Mit Hilfe dieses Übersichtsartikels soll gezeigt werden, wie fokale atriale Tachykardien definiert und wo sie lokalisiert sind, was bei der Durchführung der elektrophysiologischen Untersuchung wichtig ist (wie z. B. die Gabe von Medikamenten zur Provokation) und wie man mithilfe des Oberflächen-EKGs und dreidimensionaler Mappingverfahren die Lokalisation des Ursprungs der fokalen atrialen Tachykardien erkennen und diese so erfolgreich abladieren kann.

Background: COVID-19 might pose a risk for adults with congenital heart disease (ACHD). However, data regarding the rate of infection as well as myocardial involvement in ACHD patients are currently lacking. Methods: During the study period from January to June 2021, all consecutive outpatients from our ACHD clinic were eligible to participate. Clinical data were collected. An antibody test for COVID-19 was performed in all patients. Cardiovascular magnetic resonance imaging (CMR) was offered to those with a positive antibody test. Results: Overall, 420 patients (44.8% female, mean age 36.4 ± 11.6 years) participated. Congenital heart defect (CHD) complexity was simple in 96 (22.9%), moderate in 186 (44.3%), complex in 117 (27.9%), and miscellaneous in 21 (5.0%) patients. Altogether, 28 (6.7%) patients had a positive antibody test. Out of these, 14 had an asymptomatic course. The others had mainly mild symptoms and were managed as outpatients. Furthermore, 11 patients (39.3%) had even not been aware of their infection. Fourteen patients underwent a CMR without signs of myocardial involvement in any of them. Conclusions: We observed a number of undetected cases of COVID-19 infections in our ACHD population. Reassuringly, in all cases, the infection had a mild clinical course.

Background Ultralow temperature cyroablation (ULTC) is designed to create focal, linear, and circumferential lesions. The aim of this study was to assess the safety, efficacy, and durability of atrial and ventricular ULTC lesions in preclinical large animal models. Methods and results The ULTC system uses nitrogen near its liquid-vapor critical point to cool 11-cm ablation catheters. The catheter can be shaped to specific anatomies using pre-shaped stylets. ULTC was used in 11 swine and four sheep to create atrial (pulmonary vein isolation and linear ablation) and ventricular lesions. Acute and 90-day success were evaluated by intracardiac mapping and histologic examination. Cryoadherence was observed during all ULTC applications, ensuring catheter stability at target locations. Local electrograms were completely eliminated immediately after the first single-shot ULTC application in 49 of 53 (92.5%) atrial and in 31 of 32 (96.9%) ventricular applications. Lesion depth as measured on histology preparations was 1.96 ± 0.8 mm in atrial and 5.61 ± 2.2 mm in ventricular lesions. In all animals, voltage maps and histology demonstrated transmural and durable lesions without gaps, surrounded by intact collagen fibers without injury to surrounding tissues. Transient coronary spasm could be provoked with endocardial ULTC in the left ventricle in close proximity to a coronary artery. Conclusions ULTC created effective and efficient atrial and ventricular lesions in vivo without procedural complications in two large animal models. ULTC lesions were transmural, contiguous, and durable over 3 months.

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 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.

Background The need for pre‐ or peri‐procedural imaging to rule out the presence of left atrial thrombus in patients undergoing catheter ablation of atrial fibrillation (AF) is unclear in the era of uninterrupted direct oral anticoagulant (DOAC) regimen. We sought to examine the safety of catheter ablation in appropriately selected patients with paroxysmal AF without performing screening for left atrial thrombus. Patients and Methods Consecutive patients planned for radiofrequency AF catheter ablation between January 2016 and June 2020 were enrolled, and prospectively studied. All subjects were receiving uninterrupted anticoagulation with DOACs for at least 4 weeks before the procedure. All subjects were in sinus rhythm the day of the procedure. The primary outcome of the study was ischemic stroke or transient ischemic attack (TIA) during at 30 days. Results A total of 451 patients (age 59.7 ± 10.2 years, 289 males) with paroxysmal AF were included in the study. The mean CHA2DS2‐VASc score was 1.4 ± 1.2. The mean left ventricular ejection fraction and left atrial diameter were 60 ± 5% and 39.3 ± 4 mm, respectively. Regarding the anticoagulation regimen, apixaban was used in 197 (43.6%) patients, rivaroxaban in 148 (32.8%) patients, and dabigatran in 106 (23.5%) patients. None of the patients developed clinical ischemic stroke or TIA during the 30‐day post‐discharged period. Conclusions Catheter ablation can be safely performed in low‐risk patients with paroxysmal AF without imaging for the detection of left atrial thrombus in the era of uninterrupted DOAC anticoagulation., Catheter ablation can be safely performed in low‐risk patients with paroxysmal AF without imaging for the detection of left atrial thrombus in the era of uninterrupted DOAC anticoagulation.

AIMS The aim of this retrospective cohort study was to assess the influence of early recurrence (ER) after pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF) on long-term outcomes and to identify clinical variables associated with ER. METHODS We retrospectively collected clinical and procedural data from 1285 patients with paroxysmal AF who underwent PVI from 2011 to 2016. Kaplan-Meier, receiver operating characteristic (ROC) curve, logistic and Cox regression analyses were performed to analyze the influence of ER on long-term outcomes. RESULTS ER was observed in 13% of patients. Kaplan-Meier analyses showed significantly different outcomes in 1285 patients with and without ER (49% vs 74%, log rank P

This study was designed to evaluate the electromagnetic interference (EMI) effects and safety of the new security screening millimetre wave body scanners (MWBSs) for patients with rare cardiac implantable electronic devices (CIEDs). We identified 73 patients with either entirely subcutaneous implantable cardioverter-defibrillators (S-ICD) or leadless pacemakers (LPM) attending routine device follow-up. CIED programming was optimised for the detection of EMI occurrence, and high-voltage therapy was disabled. Patients then underwent millimetre wave body scans under continuous ECG monitoring. Scanning was performed at the recommended distance as well as in close proximity to the scanner emulating accidental exposure. CIED function was observed for EMI effects. There were no episodes of inhibition of pacing in the leadless pacemaker subgroup, no oversensing in the S-ICD subgroup and no spontaneous device reprogramming in any group. There was no change in pacing or sensing thresholds, and S-ICD vector eligibility remained unchanged after scanning with the MWBS. No CIEDs were identified by the MWBS during the study. No EMI events were detected during the use of MWBSs by patients with either S-ICDs or LPMs. This data should be reassuring for patients suggesting that they can undergo security body scans without worries or disclosure of their CIED status.

Aims We hypothesized that an epicardial approach using ethanol infusion in the vein of Marshall (EIVOM) may improve the result of ablation for perimitral flutter (PMF). Methods and results We studied 103 consecutive patients with PMF undergoing high-resolution mapping. The first 71 were treated with radiofrequency (RF) ablation alone (RF-group), and the next 32 underwent EIVOM followed by RF on the endocardial and epicardial mitral isthmus (EIVOM/RF-group). Contact force was not measured during ablation. Acute and 1-year outcomes were compared. Flutter termination rates were similar between the RF-group (63/71, 88.7%) and EIVOM/RF-group (31/32, 96.8%, P = 0.27). Atrial tachycardia (AT) terminated with EIVOM alone in 22/32 (68.6%) in the EIVOM/RF-group. Bidirectional block of mitral isthmus was always achieved in the EIVOM/RF-group, but significantly less frequently achieved in the RF-group (62/71, 87.3%; P = 0.05). Median RF duration for AT termination/conversion was shorter [0 (0–6) s in the EIVOM/RF-group than 312 (55–610) s in the RF-group, P Conclusion Ethanol infusion in the vein of Marshall may reduce RF duration required for PMF termination as well as for mitral isthmus block without severe complications, and the mid-term outcome may be improved by this approach.

Background No study to date has used high-density mapping to investigate the relationship between prior radiofrequency (RF) lesions for persistent atrial fibrillation (PsAF) ablation and subsequent atrial tachycardias (ATs). Methods From 41 consecutive patients who underwent AT ablation at a second procedure using an ultrahigh-density mapping system, 22 patients (38 ATs) were included as they also had complete maps with a multipolar catheter and three-dimensional (3D) mapping system at the time of the first PsAF ablation procedure. We, therefore, compared voltage maps from the first AF ablation procedure to those from the subsequent AT ablation procedure, as well as the lesion sets used for AF ablation vs the activation patterns in AT during the second procedure. Results In the 38 ATs, 211 of 285 analyzed atrial areas displayed low voltage area (LVA) (74%). Eighteen percent (38/211) existed before the index ablation for AF while 82% (173/211) were newly identified as LVA during the second procedure. Ninety-nine percent (172/173) of the newly developed LVA colocalized with RF lesions delivered for PsAF. Of the 38 ATs, 89.5% (34/38) AT circuits were associated with newly developed LVA due to RF lesions whilst 10.5% (4/38) AT circuits were associated with pre-existing LVA observed at the index procedure. No AT circuit was completely independent from index RF lesions in this series. Conclusions Analysis of detailed 3D electroanatomical mapping demonstrates that most ATs after PsAF ablation are involving LVAs due to index RF lesions.

BACKGROUND Use of lesion metric indices is a proposed strategy to support pulmonary vein isolation procedures and these indices show good correlations with lesion sizes. The aim of this in silico study is to provide a detailed analysis of radiofrequency (RF) settings, including high-power short-duration (HPSD) settings, and resulting lesion metric indices. METHODS AND RESULTS A software program was designed which simulated virtual RF ablations. Lesion metric indices (Ablation index: AI, Lesion size index: LSI) were calculated based on underlying RF settings (contact force [CF], power, duration). In series of calculations, the applied settings were varied within defined ranges (CF: 1-80 g, power: 1-60 W, duration: 1-60 seconds). Overall, n = 388 000 virtual ablations were calculated. The resulting lesion metric indices were compared with each other and analyzed in relation to respective RF settings. Increasing contact force from 1 to 10 g resulted in a 4.4-fold LSI value, whilst increasing contact force from 10 to 20g resulted in a 1.5-fold value (P