RADIATION EXPOSURE IN ACCESSORY PATHWAY ABLATION PROCEDURES IN CARDIAC ELECTROPHYSIOLOGY: A RETROSPECTIVE ANALYSIS

Background. Radiofrequency catheter ablation (CA) has been the treatment of choice in patients with accessory pathway (AP)-mediated tachycardias. Most of these procedures are done under fluoroscopic guidance, leading to significant radiation exposure to the patient and the laboratory personnel. In this analysis, we have looked at the amount of radiation exposure in AP CA procedures performed without the support of a three-dimensional electroanatomic mapping system. We have analyzed changes in exposure indices over the study period and the impact of change in fluoroscopy frame rate (FFR). Objectives. The objectives of this study are to quantify radiation exposure in accessory pathway ablation procedures; to analyze the radiation exposure trend over time; and to evaluate the effect of fluoroscopy frame rate reduction on the radiation exposure indices in these procedures. Methods. All the AP ablation procedures performed at our institute from January 2016 to December 2019 were retrospectively analyzed. The collected data were age, sex, location of APs based on successful site of ablation on fluoroscopy, procedure time, fluoroscopy time, and dose-area product (DAP). Effective dose (ED) was estimated from DAP. The data of procedures performed before January 2018 (“pre” group) were compared with those of the procedures performed after that date (“post” group). Pre-group procedures were performed at an FFR of 7.5 frames per second (fps), and post-group procedures – at an FFR of 3.75 fps. Results. The total number of procedures included in the analysis was 635. The mean age of the patients was 39±14 years, and 401 of them (63%) were males. The most common location of the APs was left lateral (38%). Procedure time and radiation indices showed a significant decrease over the study period (p < 0.001). Post group procedures had significantly shorter procedure time and lower radiation exposure than pre group procedures. Conclusions. A decrease in the FFR was associated with a significant reduction in radiation exposure in AP ablation procedures

Redo ablation for atrial fibrillation recurrence post radiofrequency or cryoballoon ablation: a high volume single-centre experience

Funding Acknowledgements Type of funding sources: None. Introduction Atrial fibrillation (AF) ablation is a well-established procedure for the treatment of AF. The cornerstone of AF ablation is the complete and durable isolation of pulmonary veins (PV) through radiofrequency (RF) or cryoballoon (CB) ablation. However, PVI durability between RF or CB was not yet established, as reablation strategy and outcomes in patients (pt) undergoing a redo ablation. Purpose To compare RF versus CB regarding PVI status, reablation procedure and outcomes in pts undergoing a second procedure. Methods Single-centre retrospective study of consecutive pts who underwent a redo between 2016 and 2020. PVI status was assessed during electrophysiologic study with electroanatomic mapping system. Index procedures included second generation CB, conventional RF before 2018 and CLOSE protocol guided RF ablation after 2018. We assessed time-to-redo, number and location of reconnected PVs, procedural characteristics, acute and long-term outcomes between RF and CB index PVI. Results Seventy-four (55 RF and 19 CB) pts were included, 68,9% were male, most pts had paroxysmal AF (71,6%) and a mean CHA2DS2-VASc score of 1,14 ± 1,0. No statistically significant differences were noticed in clinical and echocardiographic characteristics between pts within RF or CB cohorts. Median time to reablation was significantly longer in the RF cohort (38,6 months ±33,6) compared to CB (17,0 months ±9,5) (p = 0,014). The number of reconnected PV was higher in CB than the RF cohort, although not significant (2,37 ±1,2 vs 1,75 ±1,4;p = 0,080). Right inferior PV was significantly more reconnected in pts within the CB compared to RF group (73,7% vs 45,6%;p = 0,034), without differences in the other PV reconnection rates. Regarding reablation procedure, all pts were submitted to RF-redo. Fluoroscopy time was shorter for CB than RF cohort (7,4 ±2,9 vs 13,3 ±8,4;p = 0,002). There were no significant differences between the type of reablation (PVI only vs PVI plus other lesions or cavotricuspid isthmus ablation), with no difference in overall acute success. After the redo procedure, no differences were observed in recurrence rate in the blanking period and after 91 days from reablation. Nevertheless, time-to-recurrence (&gt;91 days) was longer for RF than CB group (13,4 months ±10,7 vs 4,3 months ±1,5;p = 0,016). There were 2 pts in the RF group that were submitted to a third ablation procedure (p = 0,725). There were no differences between groups in the composite of adverse cardiovascular (CV) outcomes (stroke/transient ischemic attack, emergency room visit for AF, hospitalization for AF or CV death); p = 0,715. Conclusions After the index procedure, reablation occur later in RF than CB cohort. Although the number of reconnected PV were similar between groups, right inferior PV was significantly more reconnected in pts originally treated with CB. After redo, time-to-recurrence was shorter for CB cohort. Recurrence and composite of adverse CV outcomes were similar.

Prevalence and predictor factors of persistent pulmonary vein isolation in redo AF ablation procedure

Funding Acknowledgements Type of funding sources: None. Introduction Atrial fibrillation (AF) catheter ablation is a well-established procedure for the treatment of AF. The cornerstone of AF ablation is the complete isolation of pulmonary veins (PV). However, persistent PV isolation (PVI) is difficult to accomplish, with PV reconnection rates of &gt; 70%. The factors associated with persistent PVI are still uncertain. Purpose To assess the PVI status in patients (pts) undergoing a redo ablation and to determinate the predictors associated with persistent PVI. Methods Consecutive pts who underwent a redo ablation between 2016 and 2020 were identified in a single-centre retrospective study. PVI status was assessed during electrophysiologic study with electroanatomic mapping system. Index procedures included second generation cryoballoon (CB), conventional radiofrequency (RF) before 2018 and CLOSE protocol guided RF ablation after 2018. Persistent PVI was defined by the absence of reconnection of all pulmonary veins. Results We included 83 pts with a mean age of 55,9 ± 11,9 years; 71,1% (n = 59) were male with a mean CHA2DS2-VASc score of 1,14 ±1,0. Seventy-five percent had paroxysmal AF and undergone a redo 35,0 months (±30,9) after the index PVI. Seventeen pts (20,5%) had persistent PVI whereas 66 pts (79,5%) had at least one PV reconnected after the index procedure, with a reconnection rate of 51,8% for right superior and inferior PV, 47,0% for left superior PV and 36,1% for left inferior PV. No statistically significant differences were noticed between pts with persistent and non-persistent PVI in baseline (clinical and echocardiographic) characteristics. Regarding index ablation procedure, persistent PVI occurred more frequently in patients who underwent a "CLOSE" protocol-guided index PVI compared to RF pre-2018 and CB (45,5% vs 16,7%; p = 0,043). Twenty-nine percent of pts with persistent PVI had a "CLOSE" protocol-guided index PVI whereas only 9,1% of non-persistent PVI pts had a "CLOSE" protocol-guided index PVI (p = 0,043). In this cohort, "CLOSE" protocol-guided index PVI was the only predictor of persistent PVI (odds ratio 4.2, 95% confidence interval 1.1-15.9; p = 0.037). Conclusions In patients undergoing redo AF ablation procedures, only 20,5% had persistent PVI. "CLOSE" protocol-guided index PVI presented significantly higher rates of persistent PVI. "CLOSE" protocol-guided index PVI was the only predictor for persistent PVI in patients with AF recurrence requiring a redo procedure.

Outcome of catheter ablation of arrhythmias in adult congenital heart disease with high density multi-electrode mapping with automatic annotation algorithm

Funding Acknowledgements Type of funding sources: None. Introduction Arrhythmias are frequently encountered in adult congenital heart disease (ACHD) and respond poorly to pharmacological therapies. Catheter ablation is challenging due to anatomical variation and complexity of the arrhythmia substrate. High density multi electrode mapping (MEM) with automatic annotation of activation time may aid mapping of arrhythmia, decrease procedure time and improve the accuracy of targeting of ablation therapy. Purpose To compare the acute and long term outcomes and procedural characteristics of catheter ablation in ACHD patients with and without automatic annotation of activation with MEM. Methods Retrospective analysis of the acute and long term outcomes of ACHD patients in a single centre undergoing ablation procedures from 1 Jan 2014 to 18 August 2017 was undertaken. 2 groups were identified. Group 1 included patients who had arrhythmia mapping performed with the CARTO 3D electroanatomic mapping system without the use of automatic signal annotation. Most patients in this group had sequential mapping performed with the ablation catheter (78%), the rest had multi-electrode mapping with the PentaRay 20 pole catheter. Group 2 included patients who had arrhythmia mapping performed with the CARTO 3D electroanatomic mapping system using the automated CONFIDENSE mapping algorithm. Results Group 1: n = 27, mean age 44.6 +/-3 years. Male 46.6%. Group 2: n = 38, mean age 44.0 +/- 1.9 years. Male 56.7%. All patients had CHD of at least moderate complexity. 25% of patients in group 1 and 45% in group 2 were repeat ablations. 45 arrhythmias were induced in group 1 of which 29 were targeted and 74 arrhythmias were induced in group 2 of which 46 were targeted. Acute success rates (after attempts at reinduction) were 96.3% in group 1 and 94.7% in group 2. Recurrences of arrhythmia occurred significantly less in patients in group 2 compared to group 1 (44.7% and 70.4% respectively, p &lt; 0.05) after a follow up duration of 17.3+/-0.43 months in group 2 and 45.3 +/-1.19 months in group 1. Fluoroscopy time, procedure time and ablation time were not significantly different between groups. Conclusions The use of multi-electrode mapping with an automatic annotation algorithm was associated with a significantly lower risk of recurrence during the follow up period of this study.

Comparison of conventionally performed and electroanatomic mapping system guided catheter ablation for AV nodal reentrant tachycardia - prospective single-centre study

Funding Acknowledgements Type of funding sources: None. Introduction Radiofrequency (RF) catheter ablation in atrioventricular nodal reentry tachycardia (AVNRT) is highly effective. Three-dimensional electroanatomic mapping system (EAMS)-guided procedures are becoming more widespread. Purpose We aimed to compare EAMS-guided procedures to conventionally, only-fluoroscopy approach for slow pathway ablation. Methods 152 patients undergoing electrophysiological study and slow pathway ablation due to documented AV nodal reentrant tachycardia were included in our prospective single-centre study. In 102 patients the procedure was performed conventionally (Group 1) and 50 patients underwent an electroanatomic mapping system (EAMS) -guided approach (Group 2). Results In Group 2, 80% of the procedures were performed without the use of radiation. The procedure time (median (interquartile range): 65 (50-84) min vs. 75 (60-96.3) min, p =0.005) was significantly shorter in Group 1, with longer fluoroscopy time (4.2 (2.4-7.9) min vs. 0 (0-0) min, p &lt; 0.001). There was no difference either in the number of RF applications (mean ± standard deviation 10.8 ± 8.5 vs. 10.2 ± 7.7, p = 0.66) or in the ablation time (297 ± 237 s vs. 294 ± 196 s, p = 0.74). All patients were treated successfully. One recurrence occurred in each groups during the follow-up. Conclusions In our series, EAMS-guided approach for slow pathway ablation was associated with reduced fluoroscopy and longer procedure time compared to conventional, only-fluoroscopy approach. No difference was found in ablation time, success rate or recurrence.

Catheter ablation of focal atrial tachycardia in children using three-dimensional electroanatomic mapping system: a 6-year single-centre experience

Objective: This study demonstrates the clinical and electrophysiological details of catheter ablation conducted in children with focal atrial tachycardia using three-dimensional electroanatomic mapping systems. Patients and methods: Electrophysiological procedures were performed using the EnSite™ system. Results: Between 2014 and 2020, 60 children (median age 12.01 years [16 days–18 years]; median weight 41.5 kg [3–98 kg]) with focal atrial tachycardia and treated with catheter ablation were evaluated retrospectively. Tachycardia-induced cardiomyopathy was developed in 15 patients (25%). Most of the focal atrial tachycardia foci were right-sided (75%), and more than one focus was found in four patients. Radiofrequency ablation was performed in 47 patients (irrigated radiofrequency ablation in seven cases), cryoablation in 9, and radiofrequency ablation and cryoablation in the same session in 4 patients. The median procedural time was 163.5 minutes (82–473 minutes). Fluoroscopy was used in 29 of (48.3%) patients (especially for left-side substrate) with a mean time of 8.6 ± 6.2 minutes. The acute success rate was 95%. The procedure failed in three patients, and recurrence was observed in 3.5% of patients (2/57) during a median follow-up of 17 months (2–69 months). The second ablation was performed in four cases, of which three were successful. Overall success rate was 96.6% with no major complications observed, except in one patient with minimal pericardial effusion. Conclusion: Catheter ablation seems to be an effective and safe treatment in focal atrial tachycardia. Electroanatomic mapping system can facilitate the ablation procedure and minimise radiation exposure.

Fluoroless catheter ablation of supraventricular and ventricular arrhythmias in pregnancy: validation of a standard approach in a large multicenter registry

Background An increasing experience in zero- (ZF) or near-zero fluoroscopy catheter ablation (CA) supports the implementation of early, fluoroless approach for recurrent, symptomatic arrhythmias in pregnancy. Purpose The aim of the study was to evaluate the feasibility, efficacy, and safety of CA with a standardized ZF approach during pregnancy. Methods Data were derived from a large prospective multicenter registry (ELEKTRO-RARE-A-CAREgistry). Between 2012 and 2019, more than 2655 CA procedures were performed in women in intention-to-treat using a ZF fluoroscopy approach. The procedures were performer using: 1) femoral access, 2) double-catheter technique, without intracardiac echocardiography, 3) electroanatomic mapping system (Ensite, Abbott, USA) for mapping and navigation, 4) conscious, light sedation. Shared decision making approach was applied, including a pregnancy heart team consultations. Results The study group consisted of 18 pregnant women (mean age: 30.3±5.0 years; range: 19–38 years; mean gestational age during CA: 21.4±9.2 weeks; range: 7–36 weeks). All pregnant women had no overt structural heart disease. Among women in reproductive age, pregnant women referred for ZF-CA approach accounted for approximately 2% of procedures. In the study group, the major indications for CA included: AVNRT (n=10); OAVRT/WPW (n=2); focal idiopathic ventricular arrhythmia (n=4), AT (n=1) and AF (n=1). Five women had double substrate for CA. In AF case general anesthesia and transesophageal echocardiography were used to monitor ZF-transseptal puncture and right-sided pulmonary vein isolation. All procedures were successfully completed without fluoroscopy, and without serious maternal or fetal complications. The procedure and ablation application times were 55.0±30.0 min and 394±338 s, respectively. In one patient second procedure for idiopathic ventricular arrhythmia was postponed after delivery. Conclusion Implementation of pregnancy heart team and a standard fluoroless protocol for CA in daily electrophysiological practice allowed an early, safe, and effective CA of maternal supraventricular tachycardia and idiopathic ventricular arrhythmias in pregnancy. Funding Acknowledgement Type of funding source: None

Risk Factors for Early Recurrence Following Ablation for Accessory Pathways

Background: Atrioventricular reentrant tachycardia is common in children. Catheter ablation is increasingly used as a first-line therapy with a high acute success rate, but recurrence during follow-up remains a concern. The aim of this study was to identify risk factors for recurrence after accessory pathway (AP) ablation. Methods: Retrospective cohort study including patients who underwent AP ablation between 2013 and 2018. Cox proportional hazards model was used to examine the association between patient and procedural characteristics and recurrence during follow-up. Results: From 558 AP ablation procedure, 542 (97%) were acutely successful. During a median follow-up of 0.4 (interquartile range, 0.1–1.4) years, there were 42 (8%) patients with documented recurrence. On univariate analysis, early recurrence was associated with younger age, congenital heart disease, multiple AP, AP location (right sided and posteroseptal versus left sided), cryoablation (versus radiofrequency), empirical ablation, the lack of full power radiofrequency lesions (<50 W), radiofrequency consolidation time <90 seconds and the use of fluoroscopy without a 3-dimensional electroanatomic mapping system. On multivariable analysis, only multiple AP (hazard ratio, 2.78 [95% CI, 1.063–4.74]) and radiofrequency consolidation time < 90 seconds (hazard ratio, 4.38 [95% CI, 1.92–9.51]) remained significantly associated with early recurrence; this association remained true when analyzed in subgroups by pathway location for right and left free wall AP. Conclusions: In our institutional experience, radiofrequency consolidation time <90 seconds after ablation of AP was associated with an increased risk of early recurrence.

Clinical benefits of the orthogonal tri-axial technique in the left atrial appendage closure procedures

Background Intracardiac echocardiography (ICE) has been an alternative imaging guidance of transesophageal echocardiography (TEE) in the left atrial appendage closure (LAAC) procedures. However, its application experience is limited. Objective We aimed to analyze the clinical benefits of an orthogonal tri-axial (OTA) technique using ICE and electroanatomic mapping system (EAMS) in the LAAC procedures. Methods This retrospective study enrolled 52 atrial fibrillation (AF) patients with high risks of stroke and/or bleeding (CHA2DS2-VASc score 4.67±1.48; HAS-BLED score 2.87±0.94) who underwent the LAAC procedures following the OTA technique (ICE group). ICE probe was advanced into left atrium (LA) navigated by the EAMS. Evaluation of sizing and device implantation were performed from three orthogonal axes including axis-X: from left pulmonary veins (PVs) to LAA; axis-Y: from right PV ostium to LAA; axis-Z: from lower LA to LAA. Procedure-related parameters and clinical outcomes were compared to those from another 52 patients with comparable baseline characteristics who underwent LAAC following the TEE guidance (TEE group). All procedures were achieved under local anesthesia. Results The fluoroscopic exposure (99.5±113.6 vs 229.0±135.4mGy, P&lt;0.001) and time (5.9±4.7 vs 8.1±3.9min, P=0.011) and contrast consumption (66.5±54.9 vs 124.1±69.6ml, P&lt;0.001) in the ICE group were significantly lower than those in the TEE group, respectively, without increasing the procedural time (79.6±24.4 vs 82.3±39.5min, P=0.674). Similar proportions of Watchman (26 vs 32, P=0.236) and ACP (10 vs 13, P=0.478) devices were recorded between groups while more LAmbre devices were applied in the ICE group (16 vs 7, P=0.033). All procedures were accomplished successfully. The fluoroscopic exposure (22.9±32.7 vs 228.9±148.6mGy, P&lt;0.001) and time (1.9±2.9 vs 9.9±5.0min, P&lt;0.001), the contrast consumption (17.7±21.7 vs 124.6±62.8ml, P&lt;0.001) and the procedural duration (74.6±19.7 vs 88.1±20.6min, P=0.107) were lower in the last 25% cases in the ICE group compared to the first 25% cases. Both acute and long-term (during the 45-day and 6-month follow-ups) peri-device leaks (PDLs) were similar between groups. No procedure-related complications or thromboembolism events were observed. Conclusions The advantage of the ICE- plus EAMS-guided LAAC in fluoroscopic exposure and contrast consumption minimizing could be expected following the OTA technique. Procedural efficiency improves after the learning curve. Funding Acknowledgement Type of funding source: None