Atrial Tachycardia Research Articles

Initial experience and early outcomes of posterior wall ablation using pulsed-field ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background The success rate of pulmonary vein isolation (PVI) is lower in patients with persistent compared to paroxysmal atrial fibrillation (AF). In patients with persistent AF, additional isolation of the posterior wall is under investigation to improve ablation success. Pulsed field ablation (PFA) might be superior to conventional methods for posterior wall isolation due to its safety profile and might allow for posterior wall ablation (PWA) rather than posterior wall isolation (PWI) based on its efficiency. Purpose To report our initial experience with PWA using a multipolar PFA catheter. Methods Consecutive patients with PWA during their first PFA procedure for AF between May 2021 and October 2022 at our institution were included. For PWA, the multipolar PFA ablation catheter was used in flower configuration only. With the wire in each of the pulmonary veins and the sheath angulated posteriorly, we first performed 2 x 2 sets of anchor lesions with the catheter rotated by ~30° between sets. Next, with the wire retracted back into the device, single sets of two applications were delivered in an overlapping fashion and without catheter rotation between lesion sets to cover the entire posterior wall between the superior and inferior pulmonary veins. Finally, completeness of PWA was verified by 3D electro-anatomical mapping. Results PWA using PFA was performed in 163 patients (mean age 67 years, 71% male). In 55 patients (34%), PWA was added to PVI during the first AF ablation procedure and the remaining 108 patients (66%) had undergone a median of two (interquartile range 1-3) previous AF ablation procedures using either cryoablation and/or radiofrequency ablation. Of all patients, 45 (28%) had paroxysmal, 93 (57%) persistent AF, and 22 patients (15%) left atrial reentry tachycardia. Median procedure duration and fluoroscopy time were 120 (70-190) min, and 18 (9-36) min, respectively. 3D-EAM showed no residual electrical signal (>0.05 mV) on the posterior wall at the end of the procedure in any patient. No cardiac tamponade, stroke, phrenic nerve injuries, atrio-esophageal fistula, or clinically manifest coronary spasm occurred. A repeat ablation was performed in seven patients (4%) and 3D-EAM showed persisting posterior wall isolation in six (86%) and recurrent roof dependent atrial flutter in one patient. Despite PWA, low-voltage signals were found in four (67%) cases on the superior aspect of the posterior wall. Conclusions Left atrial PWA can be performed safely and efficiently using PFA. Early data on the durability of PWA are promising. The impact of PWA on arrhythmia-free outcome needs to be evaluated in larger, prospective randomized trials.

Re-do ablation procedure characteristics after pulmonary vein isolation using pulsed field ablation for atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) has recently been introduced as a novel routine ablation technology for paroxysmal atrial fibrillation (PAF). A few small clinical studies and registries have reported an initial clinical success rate of approx. 80% after 1 year. Here, we present the results from re-do ablation after PVI using PFA for AF. Methods In symptomatic AF patients, re-do ablation in conscious sedation using a contact force sensing catheter and 45W RF energy was performed. In all patients, pre- and post-ablation high-density bipolar voltage 3D maps using a pentaspline diagnostic catheter were performed. Procedural parameters and acute success were assessed. Results Eighteen patients (age 67 years; 17% female; 56% PAF) from a total of 304 patients (age 67 years; 42% female; 47% PAF) (6%) treated with PFA as initial AF therapy underwent a re-do ablation 212 days after the index procedure. Mean CHA2DS2-VASc-score was 1,7 in the re-do group vs. 2,5 in the index procedure group. Mean duration since first AF diagnosis and BMI were not significantly different. In 12/18 (67%) patients, reconnection of at least 1 PV was found (LSPV 2x; LIPV 4x; RSPV 2x; RIPV 2x, left carina 4x; right carina 2x). All reconnected PVs were successfully reisolated. In 11/18 (61%) of patients, an atrial flutter (AFL) or tachycardia (AT) was identified (roof 5x; mitral isthmus 5x; anterior/septal 3x; cavotricuspid isthmus 5x). In 5/12 (42%) of patient with reconnection of at least 1 PV, AT/AFL occurred. In contrast, in all 6 patients (100%) with persistently isolated PVs AT/AFL occurred. All tachycardias were successfully ablated. Conclusions Re-do ablation rate after PFA for AF was relatively low (6%), involving mostly male patients. PV reconnection rate was 67%, site of PV reconnection was predominantly left-sided. In 61%, predominantly left-sided AT/AFL occurred. Notably, in all patients with persistently isolated PVs AT/AFL was observed.

Electrophysiological findings during re-do procedures after single-shot pulmonary vein isolation for atrial fibrillation with pulsed field ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) is a novel non-thermal ablation modality which applies electroporation to destabilize the cell membranes, leading to selective ablation of the atrial myocardium whilst sparing surrounding tissues and structures. It’s discriminating nature and potential for minimal adnexal injury opens new, promising horizons into catheter ablation of AF. However, one of the major issues to address is long-term results of the technique. Purpose To investigate the electrophysiological findings and type of arrhythmias during redo-ablation in 15 patients who underwent pulmonary vein isolation (PVI) for atrial fibrillation (AF) using single-shot PFA. Methods We investigated patients who underwent redo-ablation due to occurrence of AF/ atrial flutter (AFL) or tachycardia (AT) following initial PVI with PFA. We report the electrophysiological findings and ablation strategy during redo-ablation. Results Out of 447 patients undergoing index PVI with PFA, 15 patients (age: 61.8±10.4 years; 8 (53%) males; left atrial volume index (n=10): 39.4±14.6 mL/m2) were referred for redo-ablation after index PFA. Indication for the index ablation was paroxysmal-AF in 8 patients, persistent-AF in 6 and long-standing-persistent-AF in one patient. Mean time-to-recurrence was 5.0±1.8months. Three patients received additional posterior-wall-isolation during index PFA. Thirteen (85%) patients suffered AF recurrence and 5/13 had concomitant AFL. In the remaining 2 patients, one had a recurrence of (box-dependent) AFL, and one had AT. No patients had all PVs reconnected. Reconnection in zero, one, two or three PVs was found in 33%, 20%, 20%, and 27% of patients, respectively. All 7 patients with zero or one reconnection with AF recurrence received additional/repeat posterior-wall-isolation during re-ablation, while in the others PVs were re-isolated. In 1/3 patients who had posterior-wall ablation during index PFA, durable isolation of the posterior wall was confirmed during re-do procedure. Patients with only AFL/AT had no reconnection of PVs, and the substrate was successfully ablated. Conclusion We observed durable PVI in 62% of the PVs in patients with AF/AFL recurrence after PFA PVI. In one-third of patients all PVs were isolated. The predominant recurrent arrhythmia following PVI-only was AF. Concomitant (33%) or isolated (14%) AFL/AT recurrence was observed in 47% of patients.

The tip of the eventberg: incidental rhythm disturbances by remote monitoring following pulmonary vein isolation

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Implantable loop recorders (ILR) are increasingly used for continuous rhythm monitoring following pulmonary vein isolation (PVI) for atrial fibrillation (AF). However, the impact of non-AF episodes in this patient population is unknown. Purpose Firstly, the aim of our study was to asses the incidence of clinically important non-AF events. Secondly, we wanted to identify possible risk factors leading to incidental non-AF events. Methods In this retrospective single center study, all patients implanted with ILR following PVI in our center between 2016 and 2022 were analysed. The indication to ILR implantation and remote monitoring after successful PVI was based on patient preference. Transmissions were carefully reviewed by two independent electrophysiologists. Bradycardic events were defined as documented symptomatic bradycardia, AV-Block II˚, AV-Block III˚ or Sick-Sinus Syndrom. Tachycardic events were defined as documented symptomatic supraventricular tachycardia (non-AF) or ventricular tachycardia >160/min with at least 30 seconds duration. Results A total of 219 patients underwent PVI and consequent ILR implantation. We evaluated a mean 2.1±1.1 years of follow up (FU) with a median 68 events/patient (25th–75th IQR: 13-590 events/patient). Overall, 49 patients (22.4%) developed at least one bradycardic event, 6 patients (2.7%) were later implanted with a pacemaker. In univariate logistic regression analysis age, persistent AF, left atrial diameter and prior cardioversion correlated with an increased risk of bradycardic events. Upon a multivariate logistic regression age and prior cardioversion predicted bradycardic events. At least one tachycardic non-AF event was observed in a total of 9 patients (3.6%). Supraventricular tachycardia was observed by 4 patients (1.8%), one (0.4%) were ablated by an atrioventricular nodal reentry tachycardia (AVNRT), others (1.4%) were ectopic atrial tachycardia treated conservatively. Sustained wide complex tachycardia was recorded in 5 patients (2.2%), thereof two (0.9%) received a secondary prophylactic implantable cardioverter defibrillator (ICD). The multivariate analysis did not show any statistically significant value predicting tachycardic events. Conclusion Use of ILR for rhythm monitoring following PVI could increase the early detection of incidental rhythm events, especially bradycardic episodes. However, to asses this possibly beneficial effect further prospective, multicenter studies are needed.

Zero or minimal fluoroscopy catheter ablation: feasibility, efficacy, and safety results

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Fluoroscopy has been used to guide catheter ablation since the beginning of this technique, despite its important secondary effects on both patients and operators. However, three-dimensional electroanatomic mapping systems (3D-EAMP) enable ablation of some substrates using zero or minimal fluoroscopy. The aim of this study is to explore the feasibility, efficacy and safety of a zero or minimal fluoroscopy approach in our center. Methods We performed a retrospective observational study with consecutive patients that underwent catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT), accessory pathways (AP), focal atrial tachycardia and typical atrial flutter in our center, between January 2020 and November 2022. Vascular access was obtained by ultrasound guidance. The objective was zero-fluoroscopy for all patients except those with left AP, in which minimal fluoroscopy was allowed for the transseptal access (ablations with retrograde aortic approach were excluded). Results 319 consecutive patients were included. 56% were male, mean age was 55 ± 16 years. The following substrates were included: AVNRT (43%), typical atrial flutter (41%), AP (12%) and focal atrial tachycardia (5%). We achieved zero-fluoroscopy use in 99.3% of right substrates, using fluoroscopy in just two cases to introduce catheters through femoral access. Mean fluoroscopy time in left AP was 6.1 minutes. Ablation was successful in 97% of cases, and we just experienced three complications (moderate pericardial effusion, femoral hematoma and femoral arteriovenous fistula, all of them solved without requiring intervention). After a mean follow- up of 17 ± 14 months, we noticed three recurrences, performing in all of them a successful second ablation procedure. Baseline characteristics and procedure details are shown in table 1. Conclusions Catheter ablation of simple substrates with zero or minimal fluoroscopy using 3D mapping systems is feasible, effective and safe, with high success rate and low complications rate.

Case series of catheter-based arrhythmia ablation in pregnant women

Abstract Funding Acknowledgements Type of funding sources: None. Background Antiarrhythmic drugs (AADs) should be used with caution in treating arrhythmias during pregnancy because of side effects, but catheter ablation is a rarely used procedure. Aim To investigate the efficacy and safety of catheter ablation in cardiac arrhythmias during pregnancy. Methods A double-center retrospective case series study was performed. We studied a population of patients undergoing catheter ablation for cardiac arrhythmias during pregnancy between April 2014 and September 2021 in two cardiovascular centers in Hungary. Results 14 procedures [14 electrophysiology studies (EPS), 13 ablations] performed on 13 gravid women (age 30.3±5.2 years, primipara n=6) were studied. The mean gestation period was 24.0 (20.0-27.0) weeks at the time of intervention, and the mean duration of arrhythmia was 44.0±53.0 months. Of the pregnant women 38.5% had comorbidities and 15.4% had structural heart disease. During EPS, 12 patients had inducible arrhythmias. Focal atrial tachycardia was confirmed in 3, AVRT via manifest accessory pathway (AP) in 3 (WPW syndrome) AVRT via counceled AP in 1 case. AVNRT was confirmed in 3, sustained ventricular tachycardia in 2 cases (25-25-8.3-25-16.6%). 11 radiofrequency ablations (RFA) (84.6%) and 2 cryoablations (15.4%) were performed. The electroanatomical mapping system was CARTO in 11 cases (84.6%) and NavX-EnSite in 2 cases (15.4%). Intracardiac echocardiography (ICE) was used in 5 cases (38.5%). Transseptal puncture was performed in 2 cases (15.4%) due to left lateral AP. The average procedure time was 76.0±33.0 min. All the procedures (100.0%) were performed without fluoroscopy. No complications occurred during the procedures. In the long term, arrhythmia-free survival was achieved in all cases (100.0%), but in two patients, we used AADs to achieve freedom of arrhythmia. With AADs, the mean birth weight was lower than that of fetuses of gravidas not taking drugs (2110±1314 vs. 3253±458 g). APGAR was within the normal range in all cases [9.0/10.0 (IQR) (9.0-10.0/9.3-10.0)]. Conclusions Zero-fluoroscopic catheter ablation during pregnancy is an effective and safe treatment method when needed. Catheter ablation for persistent maternal arrhythmias has a more beneficial effect on fetal development than the use of AADs. Indeed, long-term outcome and safety need to be investigated in a larger patient population.

A novel method to define critical isthmus of left atrial tachycardia; late potential mapping during sinus rhythm

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial tachycardia (AT) is a commonly encountered rhythm disorder in patients with underlying atrial scar. The role of late potential (LP) based mapping in the detection of AT critical isthmus has yet to be systematically evaluated. Purpose We aimed to investigate the relationship between the atrial LPs (ALP) localization in sinus rhythm and the critical isthmus of re-entrant ATs in patients with underlying atrial low-voltage areas. Methods Thirty-five symptomatic patients [mean age: 62 ±9, gender: 25 (71.4%) female] with left AT, who had undergone catheter ablation, were enrolled. Voltage and LP mapping were performed in sinus rhythm in both atriums. Low voltage areas and signals with continuous-fragmented morphology were tagged. Isochronal late activation mapping (ILAM) was also performed in all procedures. After induction of AT, activation mapping was performed during tachycardia in all patients to detect critical sites of the tachycardia. Results Activation mapping indicated single re-entry in 30 patients and ≥1 re-entry in 5 patients. Localized re-entry was observed in 20 (51.2%) patients, macro re-entry in 18 (46.1%), and biatrial re-entry in 1(2.5%). The mean fractionated electrogram duration in the AT termination site was calculated at 134.3±46.7 ms and the mean bipolar voltage at 0.17±0.12 mV. The ALPs were tagged in 25 (64.1%) patients on the anterior wall, 12 (34.3%) on the roof, 5 (12.8%) on the septal wall and 2 (5.7%) in the Bachmann’s Bundle region. All ALPs were in the latest activated zones of ILAM in patients with localized re-entry and predicted successful ablation sites to terminate the AT. Freedom from atrial tachyarrhythmias (ATAs) was 78.7% at six months during a mean follow-up duration of 338 ±226 days. Conclusion Our findings demonstrated the utility of ALPs during sinus rhythm to predict the successful termination sites for left ATs. These areas displayed continuous-fragmented signal morphology during sinus/paced rhythm in correlation with the critical isthmus of AT detected during activation mapping.

Clinical features of cardiac sarcoidosis in a cohort treated with epi- and endocardial VT ablation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Clinical presentation of cardiac sarcoidosis is a chamaeleon. Detection of granuloma in the histopathology proofs the diagnosis of sarcoidosis, however myocardial biopsy is associated with a high sampling error. However, a prompt immune suppressive therapy would influence the patient’s prognosis significantly. Analyzing our cohort of epicardial (and endocardial) VT ablation respectively we intend to identify additional markers supporting the diagnosis sarcoidosis. Method In the last 4 years 130 patients (mean age 49 y, 63 % male ) were hospitalized for epicardial (and endocardial) VT ablation. 19 patients had the diagnosis sarcoidosis or were newly diagnosed. Mean follow up time was 4,3 a. ECG criteria, primary manifestation, histological findings, therapy, history of VT ablation, distribution of scar in MRI and anatomical mapping, PET CT findings, presence of atrial tachycardias, valve disease and comorbidities were documented. Results 6 of 15 (40 %) patients showed right bundle block , 6 of 19 (31 %) had AV nodal disease, 4 patients primarily presented with AV-block III, 14 patients (73 %) primarily presented themselves with ventricular arrhythmias (3 with cardiac arrest), in 93 % patients biopsy revealed elevated CD 68 macrophages and CD 3 T- lymphocytes, 6 of 16 were positive for granuloma (37,5 %). All patients were treated with steroids, 13 patients with a combination of immune suppressive therapy. All were treated with VT ablation, mean 2 ablations per patient. 6 of 6 (100 %) patients showed positive PET CT. Analyzing the scar distribution the most common locations in the 17 segment model were segment 2,3,4 and 5 and septal RV. (septal substrate in 66 %). There was a high correlation between the scar findings in the MRI and the anatomical mapping. No patient died during follow up, 1 patient had high urgent transplant after withdrawal of the steroids. Statistical analysis (Kendall-Tau-b) found a significant correlation between presence of CD3 Lymphocytes, fibrosis, VT as primary manifestation, the presence of ICD, positive PET-CT and septal substrate. Conclusion Patients presenting with ventricular arrhythmias combined with a positive PET CT, elevated CD3 T lymphocytes and CD68 macrophages in the biopsy and septal substrate are suspective of sarcoidosis and immune suppressive therapy should be considered. Further data are warranted to proof that observation and to differentiate from other cardiac diseases.

Baseline rhythm during catheter ablation for atrial tachycardia predicts procedural and clinical outcome

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial tachycardias (AT) occurring after previous ablation in patients with a history of atrial fibrillation (AF) are increasingly observed in clinical practice. Catheter ablation is the treatment of choice but an optimal workflow to improve patient outcome has not been defined. The prognostic implications of baseline rhythm at the beginning of AT ablation are unknown. Purpose The aim of this study was to assess procedural and clinical outcome depending on baseline rhythm during AT ablation. Methods A total of 380 patients with a history of AF who underwent catheter ablation for consecutive AT after previous ablation were analysed. Results In our study population (69 (61–75) years, 56.6% male), 140 patients (36.8%) presented in baseline sinus rhythm (SR), 208 (54.7%) with AT and 32 (8.4%) with AF at the beginning of the procedure. Patients in SR or with AT underwent shorter procedures (SR: 173 (132–213) minutes vs. AT: 161 (120–203) minutes vs. AF: 226 (154–249) minutes; P=0.002) with more frequent termination to SR (SR: 87.9% vs. AT: 81.3% vs. AF: 56.3%; P<0.001) than patients with AF. Periprocedural AT cycle length was longer in patients presenting in SR than in those with AT or AF (SR: 320 (265–370) ms vs. AT: 270 (240–310) ms vs. AF: 245 (193–278) ms; P<0.001). Acute procedural success did not differ between patients in SR or with AT but was higher compared to those with AF (SR: 96.4% vs. AT: 97.1% vs. AF: 87.5%; P=0.033). During a median follow-up of 290 (181–680) days, patients in baseline SR developed arrhythmia recurrences less often (SR: 36.4% vs. AT: 49.5% vs. AF: 68.8%; P=0.002) compared to patients with AT or AF. Conclusions Baseline rhythm during AT ablation predicts procedural and clinical outcome. Whereas acute procedural success does not differ between patients in SR or with AT, patients presenting in SR have a more favourable mid-term success rate. Restoration of SR prior to ablation might improve long-term outcome by reducing the risk for recurrent arrhythmia.

Catheter ablation as first-line treatment in patients with atrial fibrillation: a Bayesian network meta-analysis

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Clinical trials suggest that early catheter ablation (CA) can be superior to anti-arrhythmic drugs (AADs) in "naïve" patients with AF. A low power to examine the outcomes, the use of a single technology ablation, and the short follow-up period are significant limitations of the studies. The EARLY-AF (Early Aggressive Invasive Intervention for Atrial Fibrillation) trial recently reported the results over three years of follow-up. Our research aims to update the comparison among different CA technologies with AADs as reference treatment. Interest outcomes included freedom from atrial tachycardia recurrences (ATRs) for efficacy and serious adverse events (AEs) for safety. Methods A systematic literature search was carried out up to Oct 31, 2022. We considered studies of patients with untreated atrial fibrillation who were enrolled in a trial in which they had been assigned to undergo initial rhythm-control therapy with cryoballoon (CRYO) or radiofrequency (RF) CA in at least one arm or to receive antiarrhythmic drugs (AADs). A Bayesian random-effects network meta-analysis (NMA) model comparing ATRs and AEs among the treatment arms was performed using MetaInsight V 4.0.0 web-based tool. Estimates are presented as Odds Ratio (OR) with a 95% Credible Interval (CrI). The surface under the cumulative ranking area (SUCRA) probabilities was selected to calculate the ranking and hierarchy of the different treatments. The larger SUCRA indicates the greater likelihood of becoming the best intervention. Results Six randomised control trials (RCTs) and one observational study (OBS) with 1,418 patients (mainly paroxysmal AF) were included. The follow-up period ranged from 12 to 36 months. The NMA demonstrates that ATRs were significantly lower with CRYO (OR [95% CrI], 0.36 [0.17-0.72]) and RF (OR [95% CrI], 0.39 [0.16-0.72]) compared with AADs. No significant difference was observed between CRYO and RF (OR [95% CrI], 1.09 [0.39-2.4]). The higher SUCRA value for CRYO (79%) indicated the likelihood that the treatment is the best, followed by RF (70%) and AADs (8%) (Figure 1). A total of 228 AEs were observed in 1,565 patients. The cumulative AEs associated with RF (OR [95% CrI], 1.31 [0.65-2.72]) and CRYO (OR [95% CrI], 0.72 [0.39-1.29]) were statistically similar in comparison with AADs. The indirect comparison showed no significant difference between the two ablative techniques. The probability of avoiding an AE was highest for CRYO (91%), followed by AADs (45%) and RF (14%) (Figure 2). In both analyses, the assessment of inconsistency for all studies was not significant (P > 0.05). Conclusions Our NMA demonstrated a lower rate of ATRs in patients treated with CRYO or RF CA than AADs. Furthermore, CA had a safety profile comparable to AADs. These results suggest recommending CA as a first-line treatment when early rhythm control is warranted, mainly in patients with paroxysmal AF.

Dipole charge density mapping demonstrates superiority in catheter ablation of post-surgical atrial tachycardias

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial tachycardia (AT) frequently occurs after cardiac surgery or surgical ablation procedures. The novel dipole charge density-based mapping system (AcQMap) provides global chamber mapping and can detect multiple slow conduction zones and re-entry isthmuses; therefore, it has a potential added value in post-surgical AT ablation. We aimed to test the hypothesis that AcQMap guided catheter ablation (CA) procedures are safe, feasible, and may provide improved outcome compared to conventional sequential 3D mapping (CARTO) based CA. Methods Consecutive patients undergoing CA for post-surgical ATs guided by the AcQMap or the CARTO system were enrolled. Procedural safety characterized by procedural complications, and efficiency characterized by procedure duration, fluoroscopy use, radiofrequency (RF) application and duration, were analyzed. Acute success, one-year outcome as freedom from AT and atrial fibrillation were assessed. Results A total of 40 patients (mean age 58.2±13.0 years, 42.5% female), underwent CA of AT using the AcQMap (n=20) and CARTO mapping system (n=20). No differences were found in procedural complication (AcQMap 3 vs. CARTO 2 patients, p=0.63). There were no differences in procedure duration (188.1 vs. 153.8 minutes, p=0.08), fluoroscopy dose (165.0 IQR 121.0-254.0 vs. 107.0 IQR 28.8-284.0 mGy, p=0.16), RF application number (30.0 IQR 18.8-63.5 vs. 25.5 IQR 10.5-44.3, p=0.20) or duration (1397.0 IQR 690.5-1869.8 vs. 1238.0 IQR 499.0-2074.8 s, p=0.47). Acute success was 95.0% in AcQMap group and 80.0% in CARTO group (p=0.15). A total number of 70 ATs were mapped in 40 patients (35 in the AcQMap group and 35 in the CARTO group, average 1.6 ± 0.7). Four patients had focal ATs, 26 patients had macro re-entrant ATs, and 9 patients had ATs with both mechanisms. In one patient AT was not mappable with the CARTO system, empiric ablation was performed. There were no differences in AT mechanism between the patient groups (p=0.53). Cumulative AT recurrence rates were lower in AcQMap group compared to CARTO group (18.8% vs. 52.6%, p=0.01). Freedom from all arrhythmias was 75.0% in the AcQMap and 36.8% in the CARTO group (p < 0.01). Conclusions The AcQMap system is safe and feasible. Our data suggest that patients treated with AcQMap-guided CA developed fewer AT recurrences as compared to CARTO-guided procedures.

Prevalence of sustained atrial arrythmias and treatment with zero fluoroscopy or near zero fluoroscopy catheter ablation in Slovenian orthotopic heart transplant recipients

Abstract Funding Acknowledgements Type of funding sources: None. Background Due to advances in surgical techniques and immunosuppression survival of heart transplant (HT) recipients has improved significantly, with that the prevalence of sustained atrial arrhythmias (SAA) in these patients is increasing. In HT recipients antiarrhythmic therapy options are limited. Radiofrequency ablation (RFA) represents a viable but underutilized option after other etiologies of SAA such as acute allograft rejection and vasculopathy are excluded. Limiting radiation exposure in HT recipients, who are exposed to 3,5 times (1) greater radiation dose compared to general population and are significantly more susceptible to develop malignancies, is essential. Purpose Our aim was to analyse prevalence and type of SAA in Slovenian orthotopic HT recipients and analyse feasibility and procedural outcomes of zero (ZF) or near zero fluoroscopy (NZF) RFA treatment approaches. Methods We performed a retrospective analysis of HT recipients between 2002 and 2022. We re-evaluated all available ECGs of suspected arrhythmias of included patients for presence and type of SAA. We further analysed HT patients that underwent RFA for SAA at our centre. All procedures were performed primarily with 3D electroanatomical mapping system and intracardiac echocardiography guidance. Either ZF or NZF approaches were used. The primary endpoint of all procedures was SAA termination and acute success was deemed when subsequent attempts to reinduce SAA failed. Long-term success was defined as the absence of any spontaneous SAA during 12-month follow-up. Results Among 364 consecutive HT recipients 19 patients (5,2%) were evaluated for SAA. Of those 7 (37%) presented as typical atrial flutters (AFL), 9 (47%) as atypical AFL, 2 (11%) as focal atrial tachycardia (FAT) and 1 (5%) as slow-fast atrioventricular nodal reentry tachycardia. In 2 (11%) patients with AFL, SAA was a result of acute allograft rejection. In 10 (53%) patients SAA occurred in first 3 months after HT. In the remaining 9 patients SAA occurred late, median 6,6 years after HT (25th-75th IQR: 7,7 years). RFA was performed in 7 (37%) patients. In all patients procedures were acutely successful however in 2 patients additional RFA procedures were needed for long-term success. All in all, 10 RFA procedures were performed (Table 1). All cases had macro or micro reentrant AFL with a median of 2,0 re-entry circuits mapped (25th-75th IQR: 3,3 re-entry circuits) during the procedure – that included typical cavotricuspid isthmus AFL, perimitral AFL, and several right atrium (RA) scar-related or incision related AFL. In 2 cases additional RA FAT were ablated. Five (50%) procedures were performed with ZF. No major procedure related complications were observed. Conclusion In HT recipients ZF or NZF RFA of SAA appears to be feasible and safe, but still underutilised, treatment option. Our case series demonstrates favourable acute and long-term outcomes however larger data is needed to support these results.

Pulsed field versus cryoballoon ablation of atrial fibrillation: A comparison of efficacy and safety in a 400 patient cohort

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Boris Schmidt, KR Julian Chun and Stefano Bordignon received speaking honoraria from Medtronic and Boston Scientific Background The cryoballoon (CB) is one of the most commonly used single shot devices for pulmonary vein isolation in patients with atrial fibrillation (AF). Pulsed field ablation (PFA) is a new non-thermal, tissue selective approach for pulmonary vein isolation. Purpose We sought to compare procedural safety and efficacy of these single shot ablation techniques. Methods Consecutive AF patients (paroxysmal / persistent AF) who underwent CB based pulmonary vein isolation (PVI) between November 2020 and February 2022 were enrolled and compared with patients who underwent PFA ablation in the same time period. Patients that underwent ablation beyond PVI (except for cavo-tricuspid isthmus ablation) were excluded. CB PVI was performed using the second-generation CB (CB 28 mm) with 240 sec based freeze protocol and bonus freeze delivery in case of time-to-isolation (TTI) >75 sec. PFA was performed using the Farawave catheter, using the 31 or 35 mm device. All procedures were performed under deep sedation. Results Data from 400 consecutive patients were collected. Most baseline characteristics like age (CB: 67,5 ± 15,3; PFA: 68,4 ± 11; p=0,49), BMI (CB: 28,6 ± 6,3; PFA: 27,9 ± 5,6; p=0,27) and gender (male) (CB: 54%; PFA: 59%; p=0,31) were comparable between the two groups. All PVIs were successfully completed. In 98% (196) of patients in the CB group and 100% (200) in the PFA group, PVI was performed using solely CB or PFA respectively, meaning additional touch up ablation was only needed in 4 CB patients (2%; p=0,044) and 4 veins. Procedure time was significantly shorter in the PFA group (CB: 53 ± 15,3 minutes; PFA: 36,8 ± 13,5 minutes; p<0,001), whereas no difference in fluoroscopy time (CB: 8,1 ± 4,4 minutes; PFA: 7,8 ± 3,3 minutes; p=0,2) was observed. The rate of concomitant CTI-ablation was equal in both groups (CB: 1,5%; PFA: 1,5%; p=1,0). Complication rate was 3,5% with PFA and 6,5% in CB (p=0,17), a difference mostly driven by persistent phrenic nerve palsies (CB: 1,5%; PFA: 0%; p=0,08). All patients are out of the blanking period. There were 80 recurrences in blanking time (CB: 41; PFA: 39; p=0,8). In CB 19,5% of blanking time recurrences were atrial tachycardias compared to 35,9% in PFA (p=0,1). The average time to blanking recurrence was 14,1 ± 21,5 days in CB and 20,5 ± 23,2 in PFA (p=0,2). In total, there were 7 repeat procedures (4 in CB and 3 in PFA; p=0,7) during blanking time due to arrhythmias, despite of antiarrhythmic drugs and/or cardioversion. At the time of this analysis, the first hundred patients in each group reached one-year follow-up. Recurrence free survival after one year for patients with PAF was 82,6% in CB and 80,0% in PFA. In patients with persistent AF it was 70,8% in CB and 67,8% in PFA. Conclusion Cryoballoon and pulsed field ablation are both highly effective and safe techniques for PVI. PFA had a shorter procedure time, whereas the one year follow up was similar for both techniques.

Ultrasound-guidance for femoral venipuncture reduces access site complications after ablation of atrial fibrillation and other left atrial tachycardias: a retrospective single- center analysis

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Access site complications are significant adverse events related to ablation therapy. Periprocedural continuation of anticoagulation is common practice and leads to a reduction of cerebrovascular ischemic events but may increase the likelihood of access site complications. Methods 619 consecutive patients who underwent left-atrial ablation for AF were assessed for venipuncture associated complications after either landmark or ultrasound-guided venipuncture using data on hospital readmissions, outpatient visits or a structured telephone interview. AV-fistula, pseudoaneurysm and need of either interventional or surgical treatment of a vascular complication as well as blood transfusion were considered as access site complications. Continuous data are given as mean ± standard error of the mean, categorical data are expressed as number and percentages. Differences between groups were determined by Student’s t-test, chisquare-test, and Fisher’s exact test using SPSS software. A p-value of <0.05 was deemed significant. Results The patients' mean age was 69.1 ± 10.8 years and 51.5% were female. Mean BMI was 28.4 ± 5.5 kg/m2. Procedural safety was preserved with low observed rates of serious adverse events. The rate of postprocedural stroke (0.2% vs. 0%), pericardial effusion (0.8% vs. 0.6%) and in-hospital mortality (0% vs. 0%) did not differ between the groups. After conventional landmark-guided venipuncture the vascular complication rate was 4.8% (12/248). The rate of access site complications was significantly reduced to 0.8% (3/371) (p<0.01, OR 0.194, 95%-CI: 0.0529-0.712) when real time ultrasound-imaging was used for femoral venous cannulation. Severe bleeding complications related to the access site that required surgical or interventional treatment did not occur in the ultrasound group, compared to 2.0% (5/248) in the landmark-guided group (p = 0.010). The absolute risk reduction for access site complications using ultrasound-guidance was 3.2%, resulting in a number needed to treat (NNT) of 32 and a NNT of 50 for severe access site complications. Discussion Ultrasound-imaging while performing venipuncture identifies complex or uncommon anatomical conditions and facilitates safe cannulation of the common femoral vein. The use of ultrasound visual guidance for femoral sheath introduction had a remarkable beneficial effect on the occurrence of vascular access site complications in this retrospective single-center analysis. Outstandingly, the total rate of vascular access site complications had been significantly reduced resulting in a reduction of interventional or surgical treatment down to 0,0% in the us-guidance group, this may lead to fewer interruptions of OAC ant therefore lower risk of peri-interventional cerebrovascular events.

Vein of Marshall dependent Atrial Tachycardia Post Hybrid Atrial Fibrillation Ablation; A Case Report

Vein of Marshall dependent Atrial Tachycardia Post Hybrid Atrial Fibrillation Ablation; A Case Report

Do immune checkpoint inhibitors share the same pharmacological feature in the risk of cardiac arrhythmias?

BackgroundDespite the available evidence showing an association between cardiac arrhythmia and Immune Checkpoint Inhibitors (ICIs), few studies have compared this risk between ICIs. ObjectivesWe aim to evaluate Individual Case Safety Reports (ICSRs) of ICIs-induced cardiac arrhythmias and compare the reporting frequency of cardiac arrhythmias among ICIs. MethodsICSRs were retrieved from the European Pharmacovigilance database (Eudravigilance). ICSRs were classified based on the ICI reported (pembrolizumab, nivolumab, atezolizumab, ipilimumab, durvalumab, avelumab, cemiplimab, and dostarlimab). If more than one ICI was reported, the ICSR was classified as a combination of ICIs. ICSRs of ICI-related arrhythmias were described and the reporting frequency of cardiac arrhythmias was assessed by applying the reporting odds ratio (ROR) and its 95 % confidence interval (95 %CI). ResultsA total of 1262 ICSRs were retrieved, of which 147 (11.65 %) were related to combinations of ICIs. A total of 1426 events of cardiac arrhythmias were identified. The three most reported events were atrial fibrillation, tachycardia, and cardiac arrest. Ipilimumab was associated with a reduced reporting frequency of cardiac arrhythmias compared to all other ICIs (ROR 0.71, 95 %CI 0.55–0.92; p = 0.009). Anti-PD1 was associated with a higher reporting frequency of cardiac arrhythmias than anti-CTLA4 (ROR 1.47, 95 %CI 1.14–1.90; p = 0.003). ConclusionThis study is the first comparing ICIs for the risk of cardiac arrhythmias. We found that ipilimumab was the only ICI associated with a reduced reporting frequency. Further high-quality studies are needed to confirm our results.

C46 ELECTROPHYSIOLOGICAL ASSESSMENT OF ATRIAL TACHYCARDIA SUBSTRATES IN PATIENTS WITH REPAIRED TETRALOGY OF FALLOT

Abstract Introduction Adults with repaired tetralogy of Fallot (rToF) experience episodes of atrial tachycardia (AT) and radiofrequency catheter ablation (RFCA) is often required but systematic evaluation of the mechanisms and recurrences is lacking. Methods Between January 2013 and October 2021, 20 rToF patients with AT referred for catheter ablation were enrolled. Electrophysiologic study with 3D electroanatomic mapping with multi–electrode mapping catheters was done, with right atrial bipolar voltage and activation mapping of the AT. Three mechanisms were searched: intra–atrial re–entrant tachycardias (IART), focal (FAT), other. Critical isthmus (CI) for IART was identified with activation mapping. FATs were localized according to the earliest uni/bipolar signal. All induced AT were treated. RFCA was aimed at the earliest activation point for FAT and at the critical isthmus for IART, anchoring lesion to fixed obstacles (valve annuli or scar). Written informed consent was provided. Results Among 20 adult (age 46±14 years) and mainly females (n=11, 55%) enrolled pts, 36 AT were documented: 25 (70%) IART, 10 (27%) FAT and only 1 (3%) had a typical atrioventricular nodal reentrant tachycardia. Mean tachycardia cycle length was 307±95 ms. Two ATs were induced in 11 pts, 3 in 4 pts and 4 in 2 during index EPS. Among IART, cavo–tricuspid isthmus (CTI) was the prevalent CI (n=14, 60%), while incisional IART (IARTinc, atriotomy and superior and inferior vena cava orifices, SVC and IVC, respectively) was the second mechanism (n=9, 39%). In two pts, due to non–inducibility, a pre–emptive lesion set comprising in one case CTI and in the second case CTI+SVC–atriotomy–IVC line was performed. Among FAT, in 3 cases the AT was mapped in the coronary sinus, in two at the tricuspid annulus, other at the crista terminalis, right appendage base, posterolateral scar or between atriotomy and SVC. During a median follow–up of 23 months (interquartile range, 6–37) recurrence occurred in 8 pts (25% of pts, 22% of tachycardias). Pts with recurrences were younger (43±7 vs. 48±17 y, p=0.04); no differences were found according to critical isthmus location (4 CTI and 4 IARTinc, 50%, p=ns). Conclusions Among rToF pts with AT, IART is the prevalent mechanism and CTI is the prevalent CI; atriotomy scar, however, is involved in a substantial portion of the critical isthmuses of the IART; FAT location is much more variable. Long–term freedom from AT in this clinical setting is encouraging.

P164 PERCUTANEOUS LEFT STELLATE GANGLION BLOCK IN REFRACTORY LEFT ATRIAL TACHYCARDIA

Abstract Percutaneous left stellate ganglion block (PLSGB) has been recently implemented for the acute treatment of refractory ventricular arrhythmias (VAs). The beneficial effect on supraventricular arrhythmias susceptibility and their ventricular response is well characterized in animal models, less so in humans. Available data suggest a significant prolongation of atrial refractory period, a reduction in inducibility and duration of atrial fibrillation and of all spontaneous intra– and postoperative atrial arrhythmias after thoracic and cardiac surgery. Here we describe a case of PLSGB for focal atrial tachycardia (AT). Case: we present a 68–year–old men with hypertension, obesity, OSAS and previous anterior myocardial infarction in the setting of a trivessel coronary disease, treated with PCI and complicated by apical aneurysm, with a LVEF of 38% and a moderate mitral and aortic regurgitation. He was on chronic antiarrhythmic therapy with bisoprolol 1.25 mg and ranolazine. He presented in the ED due to palpitations, pre–syncopal episodes, and worsening dyspnea. The ECG showed very frequent, self–limiting episodes of AT with a 1:1 atrioventricular (AV) conduction and a variable heart rate (HR) between 100 and 160 bpm, alternating with sinus rhythm at 45–50 bpm, sometimes conducted with aberrancy. Isolated and repetitive premature ventricular beats (PVB, maximum 8 beats) were also documented. Amiodarone, lidocaine, and intravenous unloading therapy were tried, without benefit. Coronary angiography was negative. PLSGB with an ultrasound–guided lateral approach (local bolus of lidocaine 100 mg+ropivacaine 20 mg) was performed, without complications, inducing palpebral ptosis. Over the next 15 hours we observed the disappearance of non–sustained VAs, the reduction of PVBs, and a progressive reduction of AT burden, of mean hourly HR (from 84 to 50 bpm, –40%) and of mean HR during AT (from 158 to 84 bpm, –47%, with AV 1:1 conduction). The patient subsequently underwent ablation of an extra systolic focus found near the ostium of the right inferior pulmonary vein, with no recurrences after 18 months. Conclusions This case highlights the potential efficacy of PLSGB in the acute treatment of supraventricular arrhythmias refractory to medical therapy. Prospective studies will help us to identify the extent, time of onset, and duration of its benefit depending on the type and mechanism of the underlying arrhythmia and the clinical characteristics of the patient.

P145 IVABRADINE IN TETRALOGY OF FALLOT AND POSTOPERATIVE JUNCTIONAL ECTOPIC TACHYCARDIA

Abstract Introduction Ivabradine is a selective inhibitor of sodium’s If current; it acts at the level of the sinus node causing a bradycardizing effect without effect on inotropism and atrioventricular conduction. In fact, the If channel, located in pacemaker cells, is activated in hyperpolarization and allows the membrane potential to become gradually more positive until the threshold potential is reached. Previous studies have actually shown the usefulness of ivabradine not only for slowing sinus rate but also in case of atrial tachycardia and ectopic junctional tachycardia. Case report: Our patient, suffering tetralogy of Fallot, undergoes transannular patch correction surgery at the age of 6 months. During the stay in postoperative intensive care presents numerous episodes of junctional tachycardia. Therapy with amiodarone ev is undertaken, with a discrete response; on the ECG, frequent isolated and repetitive supraventricular extrasystoles (pairs and triplets) are observed. After the infusion ev is undertaken, oral therapy with amiodarone and beta–blocker is associated, but not obtaining a good rhythm control. In addition, the presence of numerous and sustained episodes of high frequency arrhythmia affects the hemodynamic parameters of the child. For the persistence of arrhythmic episodes, ivabradine therapy is undertaken at a dose of 0.05 mg/kg orally twice a day. Stable sinus rhythm is observed, so amiodarone therapy is subsequently discontinued and ivabradine therapy continued. No arrhythmias are observed either during hospitalization or in the subsequent follow–up after discharge, carried out with seriated Holter ECGs. After about 3 months, therapy is discontinued, in the absence of supraventricular and ventricular arrhythmias. Conclusions Ivabradine is a selective inhibitor of the sodium channel at the level of pacemaker cells; born as a bradycardizing drug for its action on the sinus node, its usefulness has also been demonstrated in the treatment of supraventricular arrhythmias due to enhanced automatism and atrial reentry. It is, therefore, conceivable the presence of If channels also in ectopic foci, which would allow its use as a real antiarrhythmic drug, exploiting its peculiar action not interfering with inotropism and atrium and intraventricular conduction.

P88 CARDIAC INVOLVEMENT IN FOUR NOVEL NESPRIN–1 GENETIC VARIANTS

Abstract Background Nesprins are proteins encoded by synaptic nuclear envelope (SYNE)–1 and –2 genes, that concur, together with lamin A/C and emerin, to nuclear envelope function. Almost 140 disease–related variants were identified, mostly resulting in central nervous system and skeletal muscle disorders; only a few were associated with cardiomyopathy, mostly with relatively late onset and no specific arrhythmic profile. Purpose To describe cardiac involvement in 4 novel SYNE1 variants. Methods 189 patients underwent genetic analysis in our center (2019–2022) for suspected genetic cardiomyopathy (TruSight Cardio panel, Illumina); 72% had a positive genetic report, including pathogenic/likely pathogenic or variants of undetermined significance (VUS). Among them, 4 (2%) males presented with a sole SYNE1 heterozygous VUS (figure). Results None had muscle or neurological involvement. Patients 1 and 2 had negative family history (FH) and underwent pacemaker implantation under 50 years old for high–grade atrioventricular block (AVB). Transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) showed a mildly impaired left ventricular ejection fraction (LVEF) without oedema or fibrosis. During 3 and 6 years of follow–up (FU), several non–sustained episodes of fast ventricular tachycardia (VT) and of atrial tachycardia occurred. Patient 3 is a 55–year–old man with negative FH and a left bundle branch block (LBBB) known since the age of 45.In 2021, while playing football, he suffered a cardiac arrest due to ventricular fibrillation treated with two DC shocks; ECG showed first–degree AVB and LBBB; TTE and CMR revealed a mildly impaired LVEF without oedema or fibrosis. A subcutaneous ICD was implanted, which recorded 3 atrial fibrillation episodes in a 1–year FU. Patient 4 is a 49–year–old man, with FH of sudden death (mother’s brothers at 40 and 50 years) and of polycystic kidney, who underwent renal transplant. He had left anterior fascicular block and suffered 2 episodes of sustained monomorphic VT from the right ventricle treated with ablation. TTE and CMR showed mild LV concentric hypertrophy with normal LVEF, segmental abnormalities in right and LV strain, no fibrosis. Conclusions SYNE1 genetic variants were found to be associated with a complex cardiac phenotype, including early onset conduction disease, atrial and ventricular arrhythmias, and cardiomyopathy. Further studies are needed to determine the functional significance of the variants.