Cavotricuspid Isthmus Research Articles

Registro español de ablación con catéter. XXIII informe oficial de la Asociación del Ritmo Cardiaco de la Sociedad Española de Cardiología (2023)

Introduction and objectivesWe report the results of the 2023 Spanish catheter ablation registry. MethodsProcedural data were collected and incorporated into the REDCap platform by all participating centers through a specific form. ResultsThere were 104 participating centers in 2023 compared with 103 in 2022. In 2023, the total number of ablation procedures was 26 207, indicating a stabilization of the increase observed in 2022 following the pandemic. The increase was mainly due to procedures for atrial fibrillation (AF), with a total of 9942 ablations, representing 38% of all substrates. Notably, pulse-field ablation represented 10.3% of all AF ablation procedures, leading single-shot ablation strategies to outnumber point-by-point AF ablation for the first time in the history of the registry. Cavotricuspid isthmus ablation remained the second most targeted substrate (19% of all substrates, n=5067). The overall acute success rate remained high (97%), with a downward trend in the complication rate (1.6% vs 1.8% in 2022) and mortality rate (0.03%; n=7). Compared with 2022, there was a significant increase in procedures performed using electro-anatomical mapping and zero-fluoroscopy techniques for cavotricuspid isthmus ablation (52% vs 26%), AV node re-entrant tachycardia (48% vs 34%), and accessory pathways (62% vs 22%). We registered 466 ablations in pediatric patients. ConclusionsThe data indicate a stabilization in the post-pandemic increase in ablation procedures, with an absolute and relative increase in AF as the predominant substrate. Success rates remained stable with a modest reduction in complication and mortality rates.

The role of the right atrial appendage and right atrium in post-radiofrequency ablation recurrence in different types of atrial fibrillation

To quantitatively evaluate the relationship between the anatomical parameters of the right atrium and the recurrence of atrial fibrillation (AF) after radiofrequency ablation, considering different types of AF, utilizing 256-slice spiral computed tomography (CT). A total of 297 patients with AF who underwent initial radiofrequency ablation were enrolled, divided into the paroxysmal atrial fibrillation (PaAF) group (n=230) and the persistent atrial fibrillation (PeAF) group (n=67). Subsequently, patients in each group were further stratified into recurrent and non-recurrent subgroups. In addition, 100 healthy outpatients were selected as the normal group. All patients underwent preoperative cardiac CT (CCT) examination. The volumes of the right atrium (RA), right atrial appendage (RAA), and left atrial (LA), RAA height, the length, short diameter, perimeter, and area of the RAA base, anteroposterior diameter of the RA, tricuspid annulus diameter, crista terminalis, and inferior vena cavotricuspid isthmus (CTI) on CCT images were measured. In both the PaAF group and the PeAF group, except for the crista terminalis thickness, the other measured parameters were greater than those in the normal group, and recurrent patients exhibited larger RAA base, crista terminalis and LA volume. Recurrent patients with PeAF presented larger RAVI, while recurrent patients with PaAF did not. The short diameter of the RAA base was an independent predictor of recurrence in patients with PaAF (p=0.001), while the height of the RAA, thickness of the crista terminalis, and hypertension were independent predictors of recurrence in PeAF (p<0.05). The ROC curve was used to analysis the predictive model in PaAF and PeAF group, the corresponding sensitivity and specificity were 0.604 and 0.864 in PaAF group, respectively (AUC=0.840, P=0.001), in PeAF group, the corresponding sensitivity and specificity were 0.967 and 0.892, respectively (AUC=0.959, P=0.001). The short diameter of RAA base > 22.15 mm had the highest predictive value for recurrence in PaAF patients, with a sensitivity of 0.887, and a specificity of 0.520 (AUC: 0.743, p=0.001). The RAA height > 28.95 mm has the highest predictive value for recurrence in PeAF, with a sensitivity of 0.633, and a specificity of 0.865 (AUC: 0.816, p=0.001). Recurrent patients both in the PaAF and PeAF groups demonstrated larger RAA base and RA structural parameters. Compared to patients with PaAF, recurrent patients with PeAF presented larger RA volume.

Anatomic obstacles in cavotricuspid isthmus detected by modified 2D transthoracic echocardiography and long-term outcomes in radiofrequency ablation of typical atrial flutter.

Although radiofrequency ablation of the cavotricuspid isthmus (CTI), responsible for sustaining atrial flutter, is a highly effective procedure, in extended patients' observations following this procedure, more than every tenth becomes unsuccessful. Therefore, this study aimed to provide helpful information about the anatomy of the CTI in transthoracic echocardiography, which can aid in better planning of the CTI radiofrequency ablation in patients with typical atrial flutter. 56 patients with typical atrial flutter after radiofrequency ablation were evaluated at the end of the 24-month observation period. With substernal modified transthoracic echocardiographic (mTTE) evaluation, we identified four main anatomical obstacles impeding radiofrequency ablation. These obstacles were tricuspid annular plane systolic excursion, cavotricuspid isthmus length, cavotricuspid isthmus morphology, and the presence of a prominent Eustachian ridge/Eustachian valve. All intraprocedural radiofrequency ablation data were collected for analysis and correlated with anatomical data. In the 24-month observation period, freedom from atrial flutter was 67.86%. The mean length of the isthmus was 30.34 ± 6.67 mm. The isthmus morphology in 56 patients was categorized as flat (n = 27; 48.2%), concave (n = 10; 17.85%), and pouch (n = 19, 33.9%). A prominent Eustachian ridge was observed in 23 patients (41.1%). Lack of anatomical obstacles in mTTE evaluation resulted in 100% efficacy, while the presence of at least two obstacles significantly increased the risk of unsuccessful ablation with more than two (OR 12.31 p = 0.01). Generally, 8 mm electrodes were the most effective for non-difficult CTI, while 3.5 mm electrodes used with a 3D system had highest performance for complex CTI. Notably, aging was the only factor that worsened the long-term outcome (OR 1.07 p = 0.044). Preoperative usage of mTTE evaluation helps predict difficulty in cavotricuspid isthmus radiofrequency ablation, thus allowing better planning of the radiofrequency ablation strategy using the most accurate radiofrequency ablation electrode.

Efficacy and safety of a novel temperature-controlled catheter for cavotricuspid isthmus ablation.

Maintaining an adequate temperature at the target site is essential for effective ablation. We hypothesized that a tissue temperature-controlled (T-Con) catheter for cavotricuspid isthmus (CTI) ablation could improve the procedural ablation parameters. To evaluate the efficacy and safety of the T-Con (DiamondTemp™) catheter for CTI ablation compared with non-irrigation (Non-Irri) and irrigation (Irri) catheters. We analyzed 150 patients who underwent prophylactic CTI ablation combined with pulmonary vein isolation. The Non-Irri, Irri, and T-Con catheter groups comprised 50 patients each, and the ablation procedural parameters and complications were compared between these groups. There were no significant differences in clinical background characteristics among the three groups. The Kruskal-Wallis and post hoc tests demonstrated that the T-Con group showed the lowest total radiofrequency energy delivery time among the three groups (median [25 and 75 percentiles]: 340 [209, 357], 147 [100, 199], and 83 [61, 109] s, respectively in the Non-Irri, Irri, and T-Con groups; T-Con versus Non-Irri, p < .01; T-Con versus Irri, p < .01). The total procedural time and acute reconnection rate in the T-Con group (264 s and 4%, respectively) were lower than those in the Non-Irri group (438 s and 24%) but were similar to those in the Irri group (268 s and 6%). No significant complications were observed in any group. The T-Con catheter achieved a short energy delivery time and a low acute reconnection rate, indicating its potential as an alternative catheter for CTI ablation.

Consistency of ablations with trainee and increasing independence during fellowship training-Analysis of ablation data by CARTONET.

Training in clinical cardiac electrophysiology (CCEP) involves the development of catheter handling skills to safely deliver effective treatment. Objective data from analysis of ablation data for evaluating trainee of CCEP procedures has not previously been possible. Using the artificial intelligence cloud-based system (CARTONET), we assessed the impact of trainee progress through ablation procedural quality. Lesion- and procedure-level data from all de novo atrial fibrillation (AF) and cavotricuspid isthmus (CTI) ablations involving first-year (Y1) or second-year (Y2) fellows across a full year of fellowship was curated within Cartonet. Lesions were automatically assigned to anatomic locations. Lesion characteristics, including contact force, catheter stability, impedance drop, ablation index value, and interlesion time/distance were similar over each training year. Anatomic location and supervising operator significantly affected catheter stability. The proportion of lesion sets delivered independently and of lesions delivered by the trainee increased steadily from the first quartile of Y1 to the last quartile of Y2. Trainee perception of difficult regions did not correspond to objective measures. Objective ablation data from Cartonet showed that the progression of trainees through CCEP training does not impact lesion-level measures of treatment efficacy (i.e., catheter stability, impedance drop). Data demonstrates increasing independence over a training fellowship. Analyses like these could be useful to inform individualized training programs and to track trainee's progress. It may also be a useful quality assurance tool for ensuring ongoing consistency of treatment delivered within training institutions.

Clinical outcomes of catheter ablation for atrial fibrillation, atrial flutter, and atrial tachycardia in wild-type transthyretin amyloid cardiomyopathy: a proposed treatment strategy for catheter ablation in each arrhythmia.

Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) is often accompanied by atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT), which are difficult to control because beta-blockers and antiarrhythmic drugs can worsen heart failure (HF). This study aimed to investigate the outcomes of catheter ablation (CA) for AF/AFL/AT in patients with ATTRwt-CM and propose a treatment strategy for CA. A cohort study was conducted on 233 patients diagnosed with ATTRwt-CM, including 54 who underwent CA for AF/AFL/AT. The background of each arrhythmia and the details of the CA and its outcomes were investigated. The recurrence-free rate of AF/AFL/AT overall in ATTRwt-CM patients with multiple CA was 70.1% at 1-year, 57.6% at 2-year, and 44.0% at 5-year follow-up, but CA significantly reduced all-cause mortality [hazard ratio (HR): 0.342, 95% confidence interval (CI): 0.133-0.876, P = 0.025], cardiovascular mortality (HR: 0.378, 95% CI: 0.146-0.981, P = 0.045), and HF hospitalization (HR: 0.488, 95% CI: 0.269-0.889, P = 0.019) compared with those without CA. There was no recurrence of the cavotricuspid isthmus (CTI)-dependent AFL, non-CTI-dependent simple AFL terminated by one linear ablation, and focal AT originating from the atrioventricular (AV) annulus or crista terminalis eventually. Twelve of 13 patients with paroxysmal AF and 27 of 29 patients with persistent AF did not have recurrence as AF. However, all three patients with non-CTI-dependent complex AFL not terminated by a single linear ablation and 10 of 13 cases with focal AT or multiple focal ATs originating beyond the AV annulus or crista terminalis recurred even after multiple CA. The outcomes of CA for ATTRwt-CM were acceptable, except for multiple focal AT and complex AFL. Catheter ablation may be aggressively considered as a treatment strategy with the expectation of improving mortality and hospitalization for HF.

In Silico TRials guide optimal stratification of ATrIal FIbrillation patients to Catheter Ablation and pharmacological medicaTION: the i-STRATIFICATION study.

Patients with persistent atrial fibrillation (AF) experience 50% recurrence despite pulmonary vein isolation (PVI), and no consensus is established for secondary treatments. The aim of our i-STRATIFICATION study is to provide evidence for stratifying patients with AF recurrence after PVI to optimal pharmacological and ablation therapies, through in silico trials. A cohort of 800 virtual patients, with variability in atrial anatomy, electrophysiology, and tissue structure (low-voltage areas, LVAs), was developed and validated against clinical data from ionic currents to electrocardiogram. Virtual patients presenting AF post-PVI underwent 12 secondary treatments. Sustained AF developed in 522 virtual patients after PVI. Second ablation procedures involving left atrial ablation alone showed 55% efficacy, only succeeding in the small right atria (<60 mL). When additional cavo-tricuspid isthmus ablation was considered, Marshall-PLAN sufficed (66% efficacy) for the small left atria (<90 mL). For the bigger left atria, a more aggressive ablation approach was required, such as anterior mitral line (75% efficacy) or posterior wall isolation plus mitral isthmus ablation (77% efficacy). Virtual patients with LVAs greatly benefited from LVA ablation in the left and right atria (100% efficacy). Conversely, in the absence of LVAs, synergistic ablation and pharmacotherapy could terminate AF. In the absence of ablation, the patient's ionic current substrate modulated the response to antiarrhythmic drugs, being the inward currents critical for optimal stratification to amiodarone or vernakalant. In silico trials identify optimal strategies for AF treatment based on virtual patient characteristics, evidencing the power of human modelling and simulation as a clinical assisting tool.

First experience with a vendor-neutral three-dimensional mapping system for cardiac magnetic resonance-guided electrophysiological procedures: a case report

Abstract Background Fluoroscopy-guided catheter ablation has become the gold standard for treatment of cardiac arrhythmias. High resolution electro-anatomical mapping systems have become fundamental to perform these procedures. Recently, interventional cardiac magnetic resonance (iCMR) has been proposed as an alternative for fluoroscopy to guide atrial flutter ablations. The clinical experience with iCMR and dedicated three-dimensional mapping systems is growing. NorthStar is currently the first available vendor-neutral mapping system. Case summary We performed a real-time CMR-guided cavotricuspid isthmus (CTI) catheter ablation (CA) on a 69-year-old man using a novel mapping system (NorthStar Mapping System, Imricor Medical Systems, MN, USA). Starting from the CMR imaging, a pre-rendered segmentation model was loaded on NorthStar and used to guide the catheters, display voltage and activation maps, show mapping and ablation points. NorthStar can also take full control of the CMR scanner (i.e. start/stop sequences for anatomical information, tissue characterization, and catheter visualization) and communicate with the recorder/stimulator system (Advantage-MR EP, Imricor Medical Systems, MN, USA). With comparable procedural time to standard fluoroscopy-guided CA, CTI bidirectional block was achieved, without any complication. Discussion Using the NorthStar Mapping System, we managed to achieve a successful CMR-guided CTI ablation without any complication. Its further use should be explored, especially in more complex arrhythmias where a substrate-guided ablation is critical, as it could significantly improve results in terms of arrhythmia recurrence.

Evaluation of the cavotricuspid isthmus contractile kinetics within an interventional CMR environment

Abstract Background Cavotricuspid isthmus (CTI)-dependent flutter is a common arrhythmia with recurrences following ablation up to 50%. Previous static morphological analysis have shown that CTI anatomical variability has an impact on ablation time and procedural success. However, whether the contractile kinetics of the CTI affect procedural success remains unknown to date. Purpose Assessment of the contractile kinetics of the CTI in a cardiac magnetic resonance (CMR) environment for patients (pts) referred for typical flutter ablation. Method 32 consecutive pts with typical right atrial (RA) flutter from our Heart Center were included in this study. RA wall contours during a single cardiac cycle were delineated on CMR 2D-images using the Tomtec software. CTIs were divided in 5 segments for detailed motion analysis as shown in the figure 1A. CTI length and displacement were measured both in caudo-cranial and postero-anterior directions. Quantification of the CTI kinetics was performed in Python by computing the 2D-Euclidean distance (between two extreme temporal positions of CTI points). Results The mean CTI length of the study population (mean age 66±10 years, 29 males) was 32±13 mm during RA systole and 49±15 mm during RA diastole, resulting in a mean CTI change of 17±7 mm over one cardiac cycle (maximum – minimum length). Figure 1A shows representative MRI views of the CTI during RA systole and diastole. Figure 1B shows examples of hypo- and hyperkinetics CTI from 2 representative pts. Figure 2C shows a gradual increase in segment displacement postero-anteriorly (8.1±7.3 vs 17.2±8.1 mm, p&amp;lt;0.05) and caudo-cranially (1.6±0.8 vs 4.5±2.4 mm) from the Eustachian valve toward the Tricuspid valve. Figure 2D indicates that the 2D-Euclidean displacement of the 5 segments varied between 8±7.7 mm and 18±8.5 mm depending on their location. Interestingly, the overall CTI displacement was 4.5 times greater forward than upward. Conclusion To our knowledge, this is the first study investigating the kinetics properties of the CTI in sinus rhythm of patients with typical RA flutter. The CTI showed displacements both in postero-anterior and caudo-cranial directions, with a gradual increase from the Eustachian to the Tricuspid valves. CTI displacement appeared highly variable across patients. Whether the kinetics of the CTI correlate with ablation success will be investigated shortly.

Validation of bidirectional cavotricuspid isthmus block using electrocardiographic imaging

Abstract Background The validation of bidirectional cavotricuspid isthmus (CTI) block following catheter ablation for typical atrial flutter (AFL) involves endocavitary manoeuvres using multiple catheters. The diagnostic capacity of electrocardiographic imaging (ECGi) as a non-invasive tool to confirm bidirectional CTI block may simplify the procedure but its benefit has not been investigated so far. Purpose To evaluate the diagnostic capacities of a novel imageless ECGi system in detecting bidirectional CTI block during AFL catheter ablation. Methods A total of 34 patients were consecutively included in a prospective single-centre study. Atrial activation maps were derived from a novel imageless ECGi system when pacing the septal and lateral aspects of the CTI, gauging the technology's capacities to detect bidirectional block by measuring transisthmic intervals (TII) and observing wave-front collision patterns. TII reflects the time taken for electrical activation to cross the CTI during pacing and we measured both the absolute value and the increase relative to its baseline value. The bidirectional CTI block was assessed by endocavitary manoeuvres using a multipole catheter as the gold-standard. We conducted a blind assessment of the diagnostic capacities of ECGi over endocavitary manoeuvres considering maps from the septal and lateral pacing to determine clockwise and counterclockwise CTI block, respectively. Results Our study established clear benchmarks for diagnosing CTI block using ECGi (Figure 1). Regarding the assessment of clockwise CTI block, the presence of a wave-front collision pattern at the CTI yielded a positive predictive value (PPV) of 91% and negative predictive value (NPV) of 69%. Furthermore, ROC analysis pinpointed 100 ms and 30 ms as the optimal threshold for TII absolute value (PPV=89%, NPV =78%) and TII increase from baseline (PPV=91%, NPV =65%), respectively. Taking together, the combination of these three parameters offered high diagnostic capacities (PPV=87%, NPV=90%). Regarding counterclockwise CTI block, the TII absolute value alone was a reliable predictor, with a threshold derived from ROC analysis of 115 ms providing a PPV of 77% and a NPV of 83% (Graphical abstract). Conclusion These results highlight the efficacy of ECGi in CTI block assessment, promising a streamlined and accurate diagnostic approach (Graphical abstract). The use of a single ablation catheter coupled with ECGi to assess the bidirectional CTI block offers a simplified and efficient alternative to traditional dual catheter techniques.ECGi-based CTI block assessment methodGraphical abstract

Using the impedance map to identify non-conductive structures during cavo-tricuspidal isthmus ablation

Abstract Background The ablation of the cavo-tricuspidal isthmus (CTI) is often affected by the anatomical variability of structures made of non-conductive tissue (NCS): the Eustachian valve, tricuspid valve leaflet and Tebesio's valve, the presence of which may be associated with failure of the isthmic block despite a large number of erogations and post-ablation recurrences. Since these structures have different conductive properties from atrial tissue, it is plausible that they are characterised by their own tissue impedance, and can therefore be identified through an impedance map. Objectives The objectives of the study were: 1) to characterise CTI by impedance map, in order to identify NCS; 2) to perform ablation of CTI aimed at isolating only conductive tissue by combining impedance map with the Maximum Voltage Gradient (MVG) technique, in order to evaluate the efficacy of this strategy in acute and during follow-up. Methods From 01/2021 to 09/2023 impedance map and CTI substrate map was performed, without the use of fluoroscopy, in all patients undergoing ablation of typical atrial flutter. A 15-ohm impedance reduction from the mean atrial impedance was considered the cut-off for defining the presence of NCS. Substrate maps were constructed according to the MVG technique (0.5-2.5 mV thresholds), in particular looking for high-voltage channels in which the impedance map detected the presence of NCS. Ablation was performed only in the high-voltage channels (W45, AI500). Results Our study included 48 patients with a mean age of 68±13 years, with 92% of them being men. The mean volume of the right atrium was 153 mL, and the mean number of points per map was 1205. With the use of impedence map, we were able to identify the presence of NCS in 25 patients (52%). The distribution of non conductive structures and the mean voltage by quadrants can be seen in Figures B-C. Importantly, we found that the mean number of radiofrequency applications required to achieve isthmic block was significantly lower in patients with identified NCS compared to those without (6.3 vs. 10; p=0.007). In 60% of the patients with NCS, radiofrequency was administered in high-voltage channels that were detected in the quadrant where the NCS was present (odds ratio 3.42, p=0.04). Furthermore, we successfully achieved acute isthmic blockade in all patients, and there were no instances of recurrence during a mean follow-up period of 186 days. Conclusions Our findings demonstrate that the combination of Impedence Map and the Maximum Voltage Gradient technique is an effective approach for achieving isthmic block with a reduced number of radiofrequency applications. The identification of NCS allows for a more precise search for high-voltage channels, enabling ablations to be performed in optimal contact with the tissue. This meticulous approach is crucial for the success of the procedure.

Optimizing outcomes in catheter ablation for typical atrial flutter: a comparative study of intracardiac echocardiography versus fluoroscopy guidance

Abstract Background Catheter ablation is a standard intervention for typical atrial flutters, specifically targeting the cavotricuspidal isthmus (CTI). Intracardiac echocardiography (ICE) plays a pivotal role in providing real-time visualization of anatomical structures during the electrophysiology procedure, thereby enhancing safety and potentially reducing reliance on fluoroscopy, leading to improved procedural outcomes. We aimed to conduct a comparative analysis of procedural and follow-up outcomes between ICE-guided and fluoroscopy-only guided catheter ablations for CTI in patients undergoing treatment for typical atrial flutter. Methods A retrospective analysis was conducted at our university center, encompassing 376 consecutive patients in a single-center study. Of these, 158 underwent procedures guided solely by fluoroscopy, while 218 received ICE-guided CTI ablation. Results ICE-guidance demonstrated a statistically significant reduction in fluoroscopy time (72 [36; 170] s vs. 888 [578; 1184] s; p&amp;lt;0.01), total procedure time (70 [52; 90] min vs. 90 [60; 105] min; p&amp;lt;0.01), total ablation time (692 [435; 998] s vs. 920 [629; 1373] s; p&amp;lt;0.01), and the duration from the first to last ablation (20.5 [12; 37] min vs. 41.0 [26.8; 59.3] min; p&amp;lt;0.01). Both groups achieved a 100% acute success rate without major complications. The ICE-guided group exhibited a significantly superior long-term success rate (ICE-guided group: 95.74%, fluoroscopy-only group: 89.26%; p=0.048) compared to the fluoroscopy-only group at an average follow-up length of 34 months. Conclusion The utilization of ICE-guidance for CTI ablation significantly reduces fluoroscopy exposure, procedure time, and ablation time, ultimately contributing to enhanced long-term success rates when compared to the conventional fluoroscopy-only approach.

Results of external validation for anatomical site recognition of ablation sites in atrial fibrillation using the CARTONET R12 model

Abstract Background CARTONET® is a cloud-based management system designed for retrospective analysis of ablation procedures using the CARTO system. Leveraging a proprietary machine learning model, it automates procedural information analysis. However, the efficacy and accuracy of the CARTONET R12 model's automated location identification remain unverified. Methods This study involved a total of 396 cases. Pulmonary vein isolation (PVI), including cavo-tricuspid isthmus (CTI) ablation, was performed in 313 patients (PVI group). PVI and additional ablation, such as a Box isolation and superior vena cava isolation (SVCI), was performed in 83 patients (PVI+ group). We compared the automated location identification of R12 model and the location identification of arrhythmia experts. Results In this study, 29,422 points were analyzed. The sensitivity of the pulmonary vein carina was low in both PVI group and PVI+ group. Excluding the inferior, anterior, and ridge segmentations, PVI group demonstrated significantly higher sensitivity compared to PVI + group. Regarding the ablation lines for box isolation, both the roof line and post line showed results below 30%. The pulmonary vein carina showed a low PPV in both PVI group and PVI+ group. In segmentations excluding the anterior, PVI group demonstrated significantly higher PPV compared to the group PVI+. Regarding the ablation lines for box isolation, both the roof line and post line showed results below 50%.The R12 model couldn't auto-identify CTI and SVC. Conclusion Excluding the carina, it can be said that in cases where PVI was performed, both PPV and sensitivity demonstrate high accuracy. Conversely, in cases where Box isolation was performed, accuracy decreases due to the low discrimination ability between ablation information near the roof, posterior wall, and inferior wall of the pulmonary veins and the ablation lines of Box isolation. Regarding the right atrium, it was found that the R12 model is entirely incapable of discriminating SVC and CTI, indicating a need for revisions in the current model.The segmentation of anatomyResults of the positive predict value

A novel method to identify critical isthmus of right atrial reentrant tachycardia; Functional substrate mapping characteristics during sinus rhythm

Abstract Background Right atrial tachycardia (AT) is a frequent rhythm disorder in patients with atrial scar mainly due to surgical incisions or congenital heart diseases. Despite the mounting evidence about AT mechanisms and types, data is scarce regarding the conduction properties as well as functional characteristics of atrial substrate during sinus rhythm that has role in the maintenance of the tachycardia. Purpose We sought to evaluate the relationship between the functional substrate mapping (FSM) characteristics of right atrium and the critical isthmus (CI) of re-entrant ATs in patients with underlying atrial scar. Methods Among patients with the history of right AT who underwent catheter ablation with 3-D mapping were retrospectively enrolled. Voltage map and isochronal late activation mapping (ILAM) were created during sinus / paced rhythm using multielectrode catheters to detect deceleration zones (DZ). Subsequently AT was induced with programmed stimulation and activation mapping was performed to detect CI of the tachycardia. Atrial tachyarrhythmia (ATa) recurrence was defined as detection of atrial fibrillation or AT (≥ 30 s) during the follow-up. Results A total of 24 patients [mean age: 46 ±15, gender: 13 (54 %) female] with right AT were included. A total of 37 ATs were mapped [16 (43.2%); localized reentry, 21 (56.7%), macroreentry]. Atrial low voltage zones comprised 23.3 ± 13.0 % of total right atrium. The mean value of bipolar voltage, EGM duration and conduction velocity during sinus rhythm corresponding to CI of ATs were 0.18 ± 0.10 mV, 121.7 ± 29.4 ms, 0.06 ± 0.04 m/s and, respectively. Total number of DZs per chamber was 1.1 ± 0.3, which were all located in the low-voltage zone (&amp;lt;0.5 mV) detected by high density mapping. All CIs of non- cavo-tricuspid-isthmus (CTI) dependent reentry were colocalized with DZs detected during FSM. The positive predictive value of DZs to detect CI of inducible ATs is 80.8%. During the mean follow-up of 11.7 ± 8.1 months, freedom from ATa was 87.5%. Conclusion Although, CTI-dependent macroreentry is the most common mechanism in patients with RA scar, our findings demonstrated the relevance of FSM to predict non-CTI dependent ATs. Conduction slowing manifested as DZs with continuous-fragmented signal morphology may guide to tailor ablation strategy in case of underlying RA scar.

Pulmonary vein isolation with additional substrate ablation for atrial fibrillation results in an increased risk for the development of atypical atrial flutter

Abstract Introduction Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) catheter ablation. Several extra pulmonary vein (PV) ablation strategies for substrate modification (PVI plus) have been employed to AF patients. It has not been proven that this approach decreases the recurrence of AF, and it could contribute to increase the risk of developing atypical atrial flutter. Methods Patients submitted to AF catheter ablation at our centre between 2005 and 2020 were included. Using logistic regression, we did a retrospective analysis of the association between the application of PVI plus strategies (such as ablation of the cavo tricuspid isthmus (CTI), ganglion plexus, isolation of the superior vena cava (SVC), mitral isthmus ablation and atrial roof line ablation) and the development of atypical flutter later submitted to ablation. Results Five hundred and seventy-five patients were included (64% males, age 57±12 years [between 14 and 81], 68.2% with paroxysmal AF) with &amp;gt; 1-year follow-up. Five hundred and five (87.8%) had PVI alone. From the 575 patients, 11 (1.9%) developed an atypical flutter during the follow-up, which was later submitted to ablation. The crude ODDS of a patient submitted to a PVI plus strategy developing atypical atrial flutter are 13.92 times higher than the one of those submitted to a stand-alone PVI technique, with a p value &amp;lt;0.001 (95% CI 3.96 – 48.87). When adjusted for age and history of heart failure, the ODDS of a patient submitted to a PVI plus strategy developing atypical atrial flutter are 16.29 times higher than the one of those submitted to a stand-alone PVI technique, with a p value &amp;lt;0.001 (95% CI 3.92 – 67.65). Conclusions Additional substrate ablation for AF significantly increases the risk of developing atypical auricular flutter.Characteristics of the study populationCharacterization of PIV plus strategies

A patient-based realistic simulation platform to train future electrophysiologists to complex ablation procedures

Abstract Title An immersive catheter ablation platform based on patients’ 3D heart model for the simulation and training of future electrophysiologists. Background Arrhythmias are on the rise worldwide due to the ageing of the population. Projections urge to train the next generation of electrophysiologists (EPs) to perform catheter (CATH) ablation (CA) of arrhythmias. Training of future EPs relies mostly on a companionship, where teaching of CATH steerability is made on patients (pts) referred for procedures. While several other domains have established the utility of simulators to speed up learning process, increase safety and establish procedure road maps, dedicated simulators for EPs based on pts’ real anatomy do not exist yet. Purpose To speed up the handling of steerable CATH on MRI-based 3D heart models to optimize ablation road maps in pts referred for complex arrhythmias. Methods ARTS is an Artificial Intelligence and Augmented Reality-based platform comprising two key components: HeARTS and ARTSim. HeARTS is designed to automatically generate 3D heart models from pts’ MRI scans. ARTSim is a CA simulator that utilizes the 3D heart models of the pts for the planning and simulation of CA procedures. This simulator incorporates innovative techniques for digitizing and tracking the movements of a physical catheter in real time, and enabling its navigation within a completely virtual heart. With this technology, the CATH can be precisely steered to various heart locations, including the right and left (LA) atrium, the coronary sinus, and the right and left (LV) ventricles. Results Panel A of the figure shows the mannequin used for the simulator, where a real ablation CATH is introduced within the pt’s heart through a venous introducer. Panel B shows right anterior oblique (RAO) and modified RAO views of a pt suffering from a typical right atrial flutter. Note the presence of yellow tags positioned along the cavotricuspid isthmus (CTI) that the trainee must reach for a programmable duration using the shaft and the handle of the CATH shown in panel A. Panel C shows the virtual ablation CATH in green positioned on the target dots of the CTI. The pink color indicates that the trainee reached the desired target, which became red when the CATH remained stable at the same location for a duration of 5 sec (i.e. stability) with a force &amp;gt;5g (i.e. efficacy) and &amp;lt;20g (i.e. safety). Conclusions Herein, we present ARTS, a realistic CA simulation platform for the training of future EPs, that offers all the typical characteristics of 3D navigation including steerability, stability measurements and the force applied. Importantly, ARTS is based on the true anatomy of the pts, hence might be used to establish and discuss roadmaps to optimize procedures efficacy and safety. Version 2.0, foreseen early 2024, will include 3D late gadolinium enhancement and transseptal puncture for virtual LA and LV procedures, and later on activation times and myocardial voltage.Figure

Vein of Marshall ethanol infusion related lesion durability. A randomized dual centre pilot study

Abstract Introduction Vein of Marshall ethanol infusion (VOM-EI) creates a local ablation which includes epicardial bridges, AF triggers, vein innervation and facilitates mitral isthmus (MI) ablation. Recent trials demonstrated that in persistent AF patients the addition of VOM-EI to RF catheter ablation (CA) increased success rate vs CA alone. Moreover, a novel CA strategy (VOM-EI, PVI, and specific linear lesions set) is associated with a high rate of freedom from AF. Nevertheless, in these studies VOM-EI and RFCA were performed as different step of the same procedure. We hypothesize that performing electro-anatomical mapping (EAM) right after the VOM-EI would lead to an overestimation of ethanol-induced scar because of a certain amount of reversible oedema. This could affect the durability of the lesion set and possibly the success rate. Aim We postulated that VOM-EI performed at least 1 month earlier than RFCA would show a significantly smaller EAM low voltage area as compared to the standard strategy. Methods Patients with recurrent persistent AF with no history of previous ablation were enrolled in this randomized, dual centre, pilot study. All included patients were randomized 1:1 to group 1 (experimental): VOM-EI and after at least one month later high-definition (HD)-EAM and RFCA (PVI, MI, LA dome, cavo-tricuspid isthmus). group 2 (control): to a standard procedure (VOM-EI then 5 minute later HD-EAM and RFCA). Primary endpoint was ethanol induced HD-EAM scar area. According to the endpoint patients with unsuccessful VOM-EI were excluded. Moreover patiets with or no branches morphology, VOM dissection, and mechanical leakage were also excluded because these are demonstrated to be related to a smaller VOM-EI related lesion. Clinical and procedure related data were also collected. Results Forty consecutive patients met the inclusion criteria. The two groups did not differ for baseline characteristics (see table 1). Mean ethanol-induced HD-EAM scar area was significantly smaller in 20 patients where VOM-EI was performed at least 1 month earlier as compared to the standard procedure group (2,5±2,4 vs 11,2±9,5 cm2, p=0,018). The set of linear lesions was successful achieved in all patients. Notably the two group did not differ for any procedural technical aspect of mitral isthmus block (table 1). Neither VOM-EI nor AF ablation procedure related complications were recorded. Conclusion This is the fist randomized pilot study to demonstrate that a consistent amount of ethanol-induced related lesion could be reversible at least in its endocardial aspect of the left atrium. This would possibly affect the long-term stability of the lesion set. Notably, we still had a high rate of block at first mitral line attempt which could possibly be related to a persistent effect of VEOM-EI on the epicardial aspect of the left atrium. Larger population, randomized trial is needed to confirm this preliminary result and if it would affect the procedure success.Table 1Picture 1

Incidence, types, and predictors of AF recurrence after AF ablation with pulsed field ablation. A single-centre experience

Abstract Background Pulsed field ablation (PFA) is an emerging method for the ablation of atrial fibrillation (AF). As there are few data on incidence, types, and predictors of AF recurrence after PFA for AF ablation, we are continuously analysing our cohort. Methods We report our outcome data after PVI with PFA. Each procedure was performed under deep sedation with propofol and fentanyl. Before transeptal puncture, unfractionated heparin was administered to maintain an ACT level &amp;gt;300sec throughout the procedure. Isolation of pulmonary veins was started after administration of 1mg of atropine with 8 applications per vein (4 in basket, 4 in flower configuration). In recent months we have routinely performed 2 additional ablations in flower configuration with an anterior twist at both right pulmonary veins. All veins were checked for entrance- and exitblock to confirm isolation in sinus rhythm. An additional ablation was performed if necessary. Results In total, 231 patients were analysed. Mean age was 62±10 years, 38% were female. Mean CHADS-VASc score was 2±1. 61% had paroxysmal AF (PAF), 36% persistent AF, and 3% patients had long-standing persistent AF. In 85% (n=197) first-pass isolation of all veins was possible. Primary PV isolation was achieved in all patients at the end of the procedure. In addition to PVI, the cavo-tricuspid isthmus (CTI) was blocked in 6% (using radiofrequency ablation in case of previously or during the procedure documented typical flutter) and the posterior wall was isolated in another 6% during the first procedure. Mean procedure time was 60±20 minutes (24-175 minutes), mean X-ray time 19±9 minutes. In 231 procedures, only two catheter-associated complications were documented. 38 patients (16%) had arrhythmia recurrence after a blanking period of 3 months and a mean follow-up of 273±177 days. Mean time to recurrence was 171±84 days. Women were more likely to have recurrences [OR 2.042 (CI 95% 1.012-4.121), p&amp;lt;0,05]. Patients who had undergone any type of cardiac surgery prior to ablation were also significantly more likely to have recurrence [OR 0.517 (CI 95% 0.116-0.212); p&amp;lt;0.001]. Patients with no other comorbidities were more likely to remain free from arrhythmias [OR 0.792 (95% CI 0.736-0.853); p&amp;lt;0,01]. The type of AF did not make a significant difference according to the risk of recurrence in this cohort. To date, we have performed 18 re-do procedures in patients after PVI with PFA. The recurrent arrhythmia was AF in 39% (n=7), atypical AT in 50% (roof-dependent: 28%, n=5; mitral isthmus dependent: 22%, n=4), and CTI-dependent flutter in 39% (n=7). All but one patient had PV reconnections, and all were successfully reablated. Conclusion PFA success rate is similar to that of thermal techniques. Procedure time is shorter in experienced operators and the complication rate is low in our cohort. Results from RCTs are needed to further evaluate this new method compared to other ablation techniques.

Durability of pulmonary vein isolation after radiofrequency-balloon ablation

Abstract Aims Recently a multi-electrode radiofrequency balloon (RFB) for pulmonary vein isolation (PVI) was introduced. To the best of our knowledge no data on PVI durability has yet been published. Objectives The aim of this single-center study was to investigate the incidence of pulmonary vein (PV) reconnectionafter RFB-guided PVI. Methods Patients undergoing second ablation for recurrent atrial tachyarrhythmia (ATa) following the initial RFB-PVI were investigated. Left arial (LA) electroanatomic mapping was used. The rate of PV reconnection, the type of recurrent ATaand procedural data were analyzed. Results Among 178 patients treated with RFB, 21 patients underwent a second procedure 11 ± 6 months after the initial PVI. 67% of these patients presented with atrial fibrillation (AF), 33% with atrial tachycardia. Regarding baseline characteristics, 71% of these patients were male, mean age was 67±10, mean BMI was 28±5, 67% had hypertension and 33% had coronary artery disease. Overall, 83 PVs including one left common PV (LCPV) were assessed. The rate of PV reconnection was 28% (23/83 PVs). 57% of patients (12/21) had at least one reconnected PV. Patient with PV-reconnection had more AF recurrence and less often atrial tachycardia (AT) (AF: 75%, AT: 25%) than patients with durably isolated PVs (AF: 56%, AT: 44%). Most reconnections were detected in septal PVs. Reconnections were distributed as follows: RIPV: 8/21, RSPV: 7/21, LIPV: 5/20, LSVP: 3/20, LCPV: 0/1. Precise localization of the gaps could be identified in 15/23 PVs. Most common gap locations were at the anterior carina (4/15) for septal PVs and anterior-inferior (3/15) at the LIPV. Ablation strategy was pure PV reisolation in 8/12 patients and PV reisolation with additional linear lesions in 4/12 patients. All patients with durably isolated PVs were treated with additional substrate modification. In total, following additional lesions were set: anterior line: 6, roof line: 11, cavotricuspid isthmus (CTI): 7, LAA-Isolation: 1, free wall of the right atrium: 1. Regarding procedural data of the index procedure, the number of applications was not a statistically significant predictor of reconnection (p=0.77). Conclusion We provide the first insight into durability of PVI after radiofrequency-balloon ablation. 72% of all PVs were still isolated. Our data on gap localization might help to identify regions where optimal balloon contact is difficult to achieve. More data on this topic might reveal predictors for PV reconnections.

Electrophysiologic characteristics and outcomes of atrial tachycardia ablation after mitral valve surgery

Abstract Background Atrial tachycardia (AT) is a commonly encountered rhythm disorder in patients with mitral valvular (MV) surgery. Radiofrequency (RF) ablation is the preferred therapeutic option in symptomatic patients. Purpose We aimed to evaluate the characteristics and ablation outcomes of AT in patients with previous mitral valve (MV) surgery. Methods A total of 100 symptomatic patients [mean age: 56 ±12, gender: 56 (56%) female] with documented AT were enrolled. Activation mapping was performed during tachycardia in all patients as well as entrainment mapping when needed. Voltage mapping was performed in sinus rhythm in the related atrium. Low voltage areas and signals with continuous-fragmented morphology were also tagged. Results In 127 procedures, a total of 158 ATs were documented [59 (37.3%) ATs were right-sided, 95 (60.1%) ATs were left-sided and 4(2.5%) AT was biatrial]. Mean number of ATs per procedure was 1.2±0.6. Macroreentry was the primary mechanism in right and left atrium (83.1% and 63.1%, respectively). Cavo-tricuspid isthmus (CTI) dependent macroreentry was the most frequent mechanism in right ATs whereas perimitral reentry was the most common mechanism in left ATs. Atrial low voltage zones comprised 45.5±25.1 % of total left atrium. The acute procedural success was 95.2%. Freedom from ATa after index procedure was 80% at 12 months and 65.6 % at 24 months. After multiple procedures, freedom from ATa was 77% during the mean follow-up duration of 39.7 ± 27.2 months. Conclusion Left ATs are more common compared to the right ATs and macroreentry is the major mechanism in both right &amp; left ATs. RF ablation of ATs has favourable long-term outcomes in patients with MV surgery.