Macroreentrant Atrial Tachycardia Research Articles

Tachyarrhythmias in congenital heart disease.

The prevalence of congenital heart disease (CHD) in adult patients has risen with advances in diagnostic and surgical techniques. Surgical modifications and hemodynamic changes increase the susceptibility to arrhythmias, impacting morbidity and mortality rates, with arrhythmias being the leading cause of hospitalizations and sudden deaths. Patients with CHD commonly experience both supraventricular and ventricular arrhythmias, with each CHD type associated with different arrhythmia patterns. Macroreentrant atrial tachycardias, particularly cavotricuspid isthmus-dependent flutter, are frequently reported. Ventricular arrhythmias, including monomorphic ventricular tachycardia, are prevalent, especially in patients with surgical scars. Pharmacological therapy involves antiarrhythmic and anticoagulant drugs, though data are limited with potential adverse effects. Catheter ablation is preferred, demanding meticulous procedural planning due to anatomical complexity and vascular access challenges. Combining imaging techniques with electroanatomic navigation enhances outcomes. However, risk stratification for sudden death remains challenging due to anatomical variability. This article practically reviews the most common tachyarrhythmias, treatment options, and clinical management strategies for these patients.

Implementation of near zero fluoroscopy in supraventricular tachycardia ablation procedures: a single center experience

Abstract Background Supraventricular tachycardia (SVT) are common cardiac arrhythmias, and catheter ablation has proven to be a very effective treatment, but exposes patients and healthcare providers to radiation. "Near Zero Fluoroscopy" (NZF) techniques, utilizing advanced imaging, aim to reduce radiation exposure while maintaining efficacy. Purpose To present an analysis of near-zero fluoroscopy in SVT ablation procedures, in a tertiary center, since its implementation. Methods We prospectively enrolled 446 SVT-diagnosed patients for this study. All of them underwent NZF procedures using the same specific 3D mapping system, between January/19 and December/22. Patients with atrial fibrillation or macroreentrant atrial tachycardias or when a different mapping system was used, were excluded. All patients provided informed consent. Results Our population had 266 (60%) females and a median age of 39 (IQR 24-51) years. AVNRT was the most frequent arrhythmia documented (229 cases, 51%), followed by Accessory Pathways (AP) (201 cases, 45%) and focal atrial tachycardia (AT) (16 cases, 4%). The ablation success rate was high (405/418, 97%). There was no ablation attempt in 12 patients (9 APs and 3 ATs) and the unsuccessful ablations (7/418 cases, 1,67%) were APs. Overall, fluoroscopy time was 1.1 minutes (IQR 0-2.6). There was no statistically significant difference in the distribution of fluoroscopy time among the types of SVT based on the Kruskal-Wallis test (p 0.14). Observing trends of fluoroscopy use through time, we acknowledge the presence of a learning curve, leading towards shorter times of X-ray during procedures along the first 3 years of implementation of a near-zero strategy. Median times (IQR) of fluoroscopy were as follows: 2019 – 2.25 (0.45-3.4) min; 2020 – 1 (0-2.5) min; 2021 – 0 (0-1.9) min; 2022 – 0.55 (03.05) min. (see BoxPlot) Pairwise comparisons using the Wilcoxon rank-sum test with continuity correction revealed statistically significant differences in medians between all pairs of years, with p-values adjusted for multiple comparisons using the Bonferroni method (p<0.01). In 2022, fluoroscopy time increased, when compared to 2021. We believe this finding can be explained by the fact that in 2022, our department received a new fellow and a young EP consultant (coming from a center where NZF was not the standard for SVT ablation), both being in the lab on a daily basis, explaining this upward trend in fluoroscopy time. There were no acute complications requiring hospital admission or active treatment. Conclusion Our results emphasize the potential of near-zero fluoroscopy techniques to enhance safety and reduce radiation exposure while maintaining a high level of procedural efficacy in the treatment of SVT cases. Absence of acute complications highlighted the safety of these approaches.

Identification of deceleration zones during sinus rhythm for locating critical isthmuses in left atrial macroreentrant tachycardias

Abstract Introduction Ablation of left atrial (LA) macroreentrant tachycardias (LAMT) poses considerable challenges, with issues such as tachycardia cycle length variations, multiple reentrant circuits, and tachycardia termination during entrainment maneuvers. Evaluating deceleration zones (DZ) through atrial pacing during sinus rhythm, and their correlation with potential critical conduction isthmuses (CI) in LAMT, remains unexplored. This approach may facilitate LAMT ablation. Objective To investigate the presence of DZ through atrial pacing during sinus rhythm and their association with LAMT critical conduction isthmuses (CI). Methods Patients who underwent LAMT high-density activation mapping with a 16-pole grid catheter were included. Conventional mapping (activation, voltage and entrainment mapping during tachycardia) was performed to localize the CI. Atrial pacing with three atrial extrastimuli (S2/S3/S4 with 500/500/300 ms coupling interval) was performed during sinus rhythm from the distal coronary sinus (CS). Isochronal late activation mapping (ILAM) of the S3 and S4 cycles was compared. Deceleration zones (DZ) were defined as an offset in the color scale of the activation map in an area with at least a radius of 10 mm. ILAMs were evaluated blindly, and DZs were compared with CIs defined by conventional mapping during tachycardia and validated by radiofrequency application termination. Results 18 p (60.50 ± 11.63 yo, 11 male) and 21 procedures were included. LAMT termination was successful in 18 out of 21 procedures (85.71%) and failed in 3 due to the epicardial component of the reentrant circuit. ILAM during CS pacing was achieved in 13 patients and was not possible in 5 p due to multiple LAMTs leading to empiric linear ablation in 1 and to recurrent induction of LAMT or AF during the pacing protocol. A DZ was identified in 13 out of 16 maps (81.25%) in the S3 map, which was more pronounced in the S4 map. In all these 13 maps, the final ablation site was within the DZ in the S4 map, terminating the tachycardia with focal RF applications in 11 and with extended in 2. Conclusions Deceleration zones identified through atrial pacing during sinus rhythm are prevalent in LAMT patients. These zones generally correspond to the critical conduction isthmus and offer a valuable method for mapping the reentrant circuit when mapping during stable LAMT is not feasible.

Localization of critical isthmus in left atrial macroreentrant tachycardias: insights from peak frequency mapping during sinus rhythm and coronary sinus pacing

Abstract Background Successful ablation of left atrium macroreentrant tachycardia (LAMRT) has advanced significantly, benefiting from an enhanced understanding of reentrant mechanisms and technological innovations. However, challenges like difficult inductions and the presence of multiple coexistent LAMRTs can complicate tachycardia mapping, potentially resulting in recurrences during follow-up. Consequently, there is a growing need for strategies that focus on pinpointing the critical isthmus of conduction (CIC) in LAMRT circuits outside of tachycardia episodes. Peak frequency (PF) mapping, with its ability to discern near-field (NF) from far-field (FF) electrograms (EGMs) in low voltage areas, emerges as a valuable tool for precisely identifying these critical isthmuses. Purpose This study aims to investigate whether the accurate identification of the CIC in LAMRT circuits is achievable through PF mapping during sinus rhythm or coronary sinus pacing. Methods Patients with sustained LAMRT undergoing radiofrequency (RF) ablation were enrolled. Utilizing a 16-pole grid catheter (HD-Grid), bipolar voltage and activation maps were generated during LAMRT. PF maps were retrospectively computed. Voltage, activation, and PF maps were also created during sinus rhythm and coronary sinus pacing (500 ms). Potential CICs (P-CICs) were defined as areas with low voltage (<0.2 mV) and high PF (>250 Hz), covering a surface area of <2 cm2 by adjusting the PF threshold above 250 Hz. Only instances of LAMRT terminated by focal RF lesions (boundary <1.5 cm diameter) were included. Confirmed CICs (C-CICs) were identified at sites where LAMRT termination occurred due to RF application. The localization of P-CICs found during LAMRT, sinus rhythm (SR), and coronary sinus pacing (CSP) mapping, in relation to that of CIC, was analyzed, considering them matching if separated by <10 mm. Results Twenty-four consecutive patients with 26 atrial tachycardias (ATs) were prospectively enrolled, including 18 LAMRTs (270±63 ms) terminated by 2.2±2.9 focal RF lesions after 9.4±8.2 sec of energy delivery. A P-CIC was consistently identified at the tachycardia termination site during LAMRT mapping, with a visual cutoffs discrimination score (1-5) of 4.1±0.7, a mean P-P voltage cutoff <0.22±0.09 mV, and a mean PF cutoff >330±67 Hz in all patients. Importantly, P-CICs found during SR and CSP mapping matched those found during LAMRT mapping in all patients (figure). Conclusion PF mapping demonstrates precision in identifying the critical isthmus in LAMRT circuits during actual tachycardia episodes. Notably, the consistent identification of the CIC through PF mapping during sinus rhythm or coronary sinus pacing exhibits a high correlation with findings during LAMRT mapping. This approach holds promising potential for reducing arrhythmia recurrences, especially in scenarios involving multiple or unmappable LAMRTs.

The characterization of functional conduction block in patients with multiple types of atrial tachycardia- A discussion on the mechanism of multiple atrial tachycardia.

High-resolution mapping offers superior accuracy in delineating conduction features; however, certain characteristics are still linked to elevated recurrence rates of atrial tachycardia (AT), suggesting the influence of additional mechanisms. This study systematically assessed the substrate of functional conduction block (FCB) regions in relation to the mechanisms of multiple ATs. In this study, the Carto system facilitated the mapping of ATs in 13 patients undergoing ablation, each presenting with more than two AT variants. FCB regions were marked and further analyzed. A total of 33 sustained ATs were mapped across the patient cohort. FCB regions showed convertibility in 7 of 13 patients (54%). Three kinds of presentations can be summarized by the FCB region: Firstly, the FCB region could act as the main obstacle sustaining the localized reentrant pathway, for which rounding obviously has a direct correlation with the mechanism of the AT (27%). Secondly, the FCB regions could act as obstacle lines to reorganize the propagation of the reentry in localized AT and macroreentrant AT (55%). Lastly, the FCB region could act as a bystander and may not be related to the mechanism of the ATs (18%). The potentials in FCB regions mostly performed low voltages or fragmented potentials (FPs) in the ATs which they did not perform the conduction block (90%). In multiple ATs, FCB regions may not be uncommon. The participation of FCB regions in the mechanism of ATs showed three different kinds of performance. The dynamic nature of this substrate may provide insight into the reasons for the high recurrence of related ATs.

Electrophysiologic mechanism and ablation strategy for macroreentrant biatrial tachycardias after Cox-maze procedures

BackgroundDifferent types of recurrent atrial tachycardia (AT) after Cox-maze procedures have been reported, whereas biatrial tachycardia (BiAT) has not been systematically analyzed. ObjectiveIn this study, we retrospectively investigated the electrophysiologic characteristics of BiAT after Cox-maze procedures by use of an ultrahigh-density mapping system. MethodsOf a consecutive 76 patients who underwent catheter ablation of AT after Cox-maze procedures, 12 BiATs were identified. High-density activation mapping was performed in both the left atrium and right atrium in combination with entrainment pacing to confirm the circuit. ResultsWe classified these BiATs into 2 groups. In group 1 (7 patients), the bidirectional block of maze linear lesions to prevent the macroreentrant AT was achieved; the posterior interatrial connections were involved in the circuit. In group 2 (5 patients), the bidirectional block of maze linear lesions was not blocked, and the most common gap was located at the end of the linear lesion near the annulus. In group 1, all the ATs were terminated by targeting the corresponding left atrium end of the posterior interatrial connections. In group 2, the ATs were terminated by targeting the gap near the annulus. ConclusionThe optimal ablation strategy for BiATs after the maze procedure should be based on detailed demonstration of the circuit by high-density mapping.

Association between left atrial low-voltage area and induction and recurrence of macroreentrant atrial tachycardia in pulmonary vein isolation for atrial fibrillation.

The relationship between induction and recurrence due to atrial tachycardia (AT) and left atrial (LA) matrix progression after atrial fibrillation (AF) ablation remains unclear. One hundred fifty-two consecutive patients with paroxysmal and persistent AF who underwent pulmonary vein isolation (PVI) and cavo-tricuspid isthmus (CTI) ablation and achieved sinus rhythm before the procedure were classified into three groups according to the AT pattern induced after the procedure: group N (non-induced), F (focal pattern), and M (macroreentrant pattern) in 3D mapping. The total rate of AT induction was 19.7% (30/152) in groups F (n = 13) and M (n = 17). Patients in group M were older than those in groups N and F, with higher CHADS2/CHA2DS2-VASc values, left atrial enlargement, and low-voltage area (LVA) size of LA. The receiver operating characteristic curve determined that the cut-off LVA for macroreentrant AT induction was 8.8 cm2 (area under the curve [AUC]: 0.86, 95% confidence interval [CI]: 0.75-0.97). The recurrence of AT at 36months in group N was 4.1% (5/122), and at the second ablation, all patients had macroreentrant AT. Patients with AT recurrence in group N had a wide LVA at the first ablation, and the cut-off LVA for AT recurrence was 6.5 cm2 (AUC 0.94, 95%CI 0.88-0.99). Adjusted multivariate analysis showed that only LVA size was associated with the recurrence of macroreentrant AT (odds ratio 1.21, 95%CI 1.04-1.51). It is important to develop a therapeutic strategy based on the LVA size to suppress the recurrence of AT in these patients.

Atrial Reentry Tachycardia: Mechanisms and Diagnosis

Atrial tachycardia (AT) is a group of arrhythmias that differ in electrophysiological mechanisms and clinical course. There are three main forms of AT: focal AT, macroreentries, and localized reentries also known as “microreentries”. Macroreentries, as a rule, occur in the presence of fibrous changes in the myocardium, for example, in “atrial” cardiomyopathy or as a result of catheter or surgical interventions in the atria. Focal AT can also occur in the absence of structural pathology of the heart.
 The aim. To analyze modern ideas about electrophysiological mechanisms and diagnosis of atrial reentry tachycardia.
 In our research we used data from the literature as well as findings of our own previous studies. The work analyzed global data on the distribution of various types of AT. The data of electrocardiographic (ECG) diagnosis, electrophysiological methods of diagnosis and pharmacological tests were also analyzed to determine the mechanism of occurrence and course of AT. The main ECG differences of different types and localizations of AT were determined. The diagnostic value of various stimulation protocols in the differential diagnosis of focal and macro-reentrant AT was also analyzed.
 Conclusions. Atrial tachycardias with a reentrant mechanism are common in the general population. Differential diagnosis with other types of tachycardia is carried out on the basis of ECG data, the response to adenosine administration, the nature of the response during entrainment, and endocardial, particularly electroanatomical, mapping.

Effective ablation of atrial tachycardia with an epicardial circuit-insights from endocardial scars sites: a case study.

A previous study reported primary macroreentrant atrial tachycardia (AT) in the left atrium (LA), including the epicardial circuit on a left atrial anterior wall (LAAW) scar, without any prior cardiac intervention (Miyazawa et al. in J Cardiovasc Electrophysiol 2019; 30: 263-264). However, determining the target for terminating macroreentrant ATs is challenging. The mapping revealed a centrifugal pattern but did not fully elucidate the AT circuit. The reentrant mechanism of these ATs was confirmed using entrainment pacing. The earliest excitation site (EES) was traditionally selected as the ablation site, typically located in healthy tissue. However, our two cases provide new insights into AT termination, including the epicardial bridge across the endocardial LAAW scar, using minimum ablation points, without the need to ablate the healthy EES.

Catheter ablation for atypical atrial flutter: characterization and recurrence predictors

Abstract Background Atypical atrial flutter (AFLA) is a macro-reentrant atrial tachycardia not using the cavotricuspid isthmus. Due to recent innovations in technology, catheter ablation has emerged as the most viable option to treat AFLA. Data related to electrophysiologic characteristics and predictor prognostic factors is limited. Purpose Our study aimed to analyze long-term outcomes after catheter ablation and to identify predictors for atrial arrhythmia (AA) recurrence (documented atrial fibrillation (AF), atrial tachycardia, or atrial flutter). Methods We performed a retrospective single-center review of all consecutive patients treated for AFLA ablation in our center from October 2008 to July 2022. All patients underwent radiofrequency ablation with a 3D mapping system. Results From 64 patients (mean age 61.0 ± 11.28 years, 60.9% male and mean follow-up period (FUP) 58.5 ± 47.79 months) 32 (50.0%) had history of previous catheter ablation (35.9% PVI), 14 (21.9%) previous cardiac surgery and 18 (28.1%) corresponded to AFLA not related to ablation or previous cardiac surgery. Most patients (79.7%) had paroxysmal AFLA, 50% concomitant AF, 50% were on anthyarrhytmic drugs (AAD) and 35.9% underwent previous electrical cardioversion (ECV). Mean left ventricular ejection fraction was 55.1 ± 10.44%, 25 (39.1%) patients had moderate to severe left atrial (LA) dilatation and 11 (17.2%) right atrial (RA) dilatation. Low-voltage areas (LVA) were identified in 38 (59.4%) patients. A total of 81 AFLA were present or induced (1.3 ± 0.74 AFLA per patient) and in 7 (10.9%) patients an atrial arrhythmia was not induced. The LA was involved in 70.3% and the RA in 29­.7%. The location of the circuit is described in the table 1 as well as ablation details. Acute procedural success was achieved in 87.5%. AA recurrence occurred in 32.8% at 1 year, 35.9% at 2 years and 40.6% at FUP (14.1 ± 41.41 months after ablation), for which 3.1% had re-ablation (17.0 ± 23.99 months after index ablation), 5 (7.8%) ECV and 15 (23.4%) maintained or initiated AAD. 10 (15.6%) went to the emergency department (ED) due to AA (mean time since ablation until the first ED visit 31.4 ± 69.07 months). One patient had an ischemic stroke and 6 patients cardiovascular (CV) hospitalization. There were 5 non-CV deaths and there were no CV deaths. Female gender was an independent predictor of AA recurrence (15 (60.0%) vs 11 (31.4%), hazard ratio (HR): 3.496 [95% CI: 1.761 – 200.000], p=0.046) as well as moderate or severe LA dilatation (14 (51.9%) vs 3 (17.6%), HR 3.257 [95%CI 1.715 – 38.462], p=0.033). The presence of fibrosis or the ablation strategy were not associated with recurrence. Conclusion AFLA most frequently originated in the LA, LVA were frequent, as well as the presence of structural changes and previous ablation or cardiac surgery. In our cohort study, female gender and the severity of LA dilatation were independent predictors of AA recurrence.

Transverse conduction across the crista terminalis with pseudo-focal activation pattern in patients with upper loop reentry atrial tachycardia

Abstract Background Upper loop reentry (ULR) is a rare form of macroreentrant atrial tachycardia (AT) and an area of slow conduction exists in the crista terminalis (CT) where ablation is successful in eliminating the circuit. Transverse conduction across the CT during ULR AT has not yet been fully investigated. Purpose To investigate the transverse CT conduction during ULR AT Methods One hundred and five consecutive patients with macroreentrant AT were enrolled. The diagnosis of ULR was made based on endocardial activation mapping and entrainment pacing from multiple sites around the superior vena cava (SVC). Pseudo-focal pattern was defined as follows; (1) unsuccessful termination of ULR AT after extensive ablation along the CT and (2) distance from the earliest activation site (breakthrough) to the linear scar along the CT >5 mm and a later activation site exists between the breakthrough and the CT. Results Nine (8.6%) of the 105 patients were diagnosed with ULR AT and studied. Seven (77.8%) of the ULR patients had a history of cardiac surgery or cavotricuspid isthmus ablation. Pseudo-focal pattern was observed in 4 (44.4%) patients who exhibited a linear scar along the CT connecting the SVC with the inferior vena cava. The median missing tachycardia cycle length (TCL) was 49.5 ms on the endocardial activation map. The median distance between the early-meets-late line (linear scar along the CT) and the breakthrough was 12 mm. RF application at the breakthrough successfully eliminated the ULR AT in all patients. Conclusions Nearly half of the patients with ULR AT exhibited pseudo-focal pattern suggesting a transverse conduction across the CT utilizing an epicardial connection such as the intercaval bundle. Ablating the breakthrough site is a better therapeutic option than ablating within the linear scar along the CT.Patient characteristicsRepresentative case

Abnormal Atrial Potentials Recorded During Sinus Rhythm or Pacing Represent Substrates for Reentrant Atrial Tachycardia.

Abnormal atrial potentials (AAPs) recorded during sinus rhythm/atrial pacing may indicate areas of slow conduction capable of supporting reentrant atrial tachycardia (AT). Therefore, we sought to examine the relationship between AAPs and AT circuits. One hundred twenty-three reentrant ATs in 104 patients were analyzed. AAPs, consisting of fragmented potentials and split potentials, were assessed using the Rhythmia LUMIPOINT algorithm. There was 93±13% overlap between areas with AAPs during sinus rhythm/atrial pacing and areas of slow conduction along the reentry circuit during AT. The cumulative area of AAPs was smaller in patients with localized-reentrant ATs compared with anatomic macro-reentrant ATs (20.0 [14.6-30.5] versus 28.9 [21.8-35.6] cm2; P=0.021). Patients with perimitral ATs had larger areas of AAPs on the lateral wall whereas patients with roof-dependent ATs had larger areas of AAPs on the roof and posterior wall (P≤0.018 for all comparisons). The patchy scar that was associated with localized-reentrant AT exhibited a larger area of AAPs at its periphery than the scar that did not participate in localized-reentrant AT (3.1 [2.4-4.5] versus 1.0 [0.7-1.6] cm2; P<0.001). AAPs recorded during sinus rhythm/atrial pacing are associated with areas of slow conduction during reentrant AT. The burden and distribution of AAPs may provide actionable insights into AT circuit features, including in cases in which ATs are difficult to map.

Electrophysiologic Determinants of Isoelectric Intervals on Surface Electrocardiograms During Atrial Tachycardia: Insights From High-Density Mapping

BackgroundSubstrate abnormalities can alter atrial activation during atrial tachycardias (ATs) thereby influencing AT-wave morphology on the surface electrocardiogram. ObjectivesThis study sought to identify determinants of isoelectric intervals during ATs with complex atrial activation patterns. MethodsHigh-density activation maps of 126 ATs were studied. To assess the impact of the activated atrial surface on the presence of isoelectric intervals, this study measured the minimum activated area throughout the AT cycle, defined as the smallest activated area within a 50-millisecond period, by using signal processing algorithms (LUMIPOINT). ResultsATs with isoelectric intervals (P-wave ATs) included 23 macro–re-entrant ATs (40%), 26 localized–re-entrant ATs (46%), and 8 focal ATs (14%), whereas those without included 46 macro–re-entrant ATs (67%), 21 localized–re-entrant ATs (30%), and 2 focal ATs (3%). Multivariable regression identified smaller minimum activated area and larger very low voltage area as independent predictors of P-wave ATs (OR: 0.732; 95% CI: 0.644-0.831; P < 0.001; and OR: 1.042; 95% CI: 1.006-1.080; P = 0.023, respectively). The minimum activated area with the cutoff value of 10 cm2 provided the highest predictive accuracy for P-wave ATs with sensitivity, specificity, and positive and negative predictive values of 96%, 97%, 97%, and 95%, respectively. In re-entrant ATs, smaller minimum activated area was associated with lower minimum conduction velocity within the circuit and fewer areas of delayed conduction outside of the circuit (standardized β: 0.524; 95% CI: 0.373-0.675; P < 0.001; and standardized β: 0.353; 95% CI: 0.198-0.508; P < 0.001, respectively). ConclusionsReduced atrial activation area and voltage were associated with isoelectric intervals during ATs.

Compatibility of a novel temperature-controlled, irrigated radiofrequency catheter with ultra-high-density mapping.

Compatibility of DiamondTemp (DT) radiofrequency (RF) catheter with the Rhythmia mapping system has not been manufacturer-reported nor its tracking accuracy reported. Consecutive patients undergoing macroreentrant atrial tachycardia ablation guided by Rhythmia and ablated using DT were prospectively enrolled. Following catheter configuration, ablation lines were performed and remapped to measure the RF tag to effective-ablation-line-center (RFT-ALC) distance. Among 20 consecutive patients (54 maps), 40 ablation lines were evaluated. Overall, the RFT-ALC distance was 3.88 ± 2.95 mm, and the operator assessment of accuracy was high. No complications occurred. The use of DT catheter guided by the Rhythmia mapping system is feasible and accurate.

Prediction of atrioventricular conduction disturbance after ablation of persistent atrial fibrillation.

The prevalence of atrioventricular conduction disturbance (AVCD) in patients with persistent atrial fibrillation (AF) has not yet been fully investigated. We sought to identify the predictors of AVCD in patients with AF by analyzing the relationship between pre-ablation heart rate during AF and the PR interval in sinus rhythm after ablation. We analyzed pre-ablation 24-h Holter electrocardiogram (ECG) and 12 lead ECG 12months after ablation of 121 consecutive patients with persistent AF who underwent their first ablation procedure and maintained sinus rhythm at 12months. AVCD was defined as a first-degree atrioventricular block (AVB), second-degree AVB, high-degree AVB, or third-degree AVB observed on ECG at 12months after ablation. Seventeen out of 121 patients (14.0%) had AVCD at 12months. In the group with AVCD, total heartbeat (THB) and maximum heart rate (Max HR) were significantly lower, and the prevalence of concomitant Cavo-tricuspid isthmus-dependent atrial flutter before ablation and the appearance of macro reentrant atrial tachycardia (AT) during the procedure were significantly higher than those in the group without AVCD. Multiple regression analysis revealed that maximum HR and macro reentrant AT were significant predictors of AVCD. Receiver operating characteristic curve analysis revealed that Max HR of <165.0bpm predicts AVCD with a sensitivity of 76.47% and a specificity of 74.00%. In patients with persistent AF, low Max HR and the presence of macro reentrant AT during the ablation procedure were predictors of AVCD.

AB-452674-1 HIGH-FREQUENCY ELECTROGRAM CHARACTERISTICS IN REGIONS OF LOW VOLTAGE ACCURATELY DISCRIMINATE SITES OF LEFT ATRIAL TACHYCARDIA TERMINATION

Localization of the critical isthmus of conduction of left atrial (LA) macroreentrant tachycardia (LAMRT) circuits within scar tissue is challenging (Panel A). Low voltage (LV) has been used as a marker for the arrhythmic substrate. However, voltage amplitudes due to near-field (NF) vs. far-field (FF) electrogram (EGM) components are not clearly differentiated. The peak frequency (PF) associated with bipolar EGM’s is a novel parameter which may distinguish them (Panel B). To compare the ability of LV vs. LV with high PF (LVHF) to discriminate the LAMRT termination region. Bipolar voltage and activation maps were generated with a 16-pole grid catheter (HD-Grid) during LAMRT (Panels A,B). PF maps were retrospectively computed (Panel C). LAMRT’s were only included if terminated by focal RF lesions (boundary <1.5cm diameter). The LA mapped surface was sub-regioned into the termination (T-ZONE) and non-termination (NT-ZONE) zones. The T-ZONE was centered about the termination site and allowed to extend to a rectangular kernel >0.5cm and <1.5cm across perpendicular axes. The NT-ZONE encompassed the remainder of the mapped surface area (SA). Sensitivity (SE) and specificity (SP) of T-ZONE vs. NT-ZONE discrimination was measured according to the %T-ZONE vs. %NT-ZONE SA occupied at LV thresholds (range 0.1-1.0mV) in 0.1mV increments (Panel E). LVHF at PF cutoffs of 150Hz (LVHF150), 200Hz (LVHF200), 250Hz (LVHF250) and 300Hz (LVHF300) were also assessed for TZONE discrimination (Panel F). 16 consecutive patients with 24 ATs were prospectively enrolled and 13 LAMRT’s were terminated by 2.85±2.82 focal RF lesions. The T-ZONE occupied 0.82±0.30cm2 (41±19 EGM points) vs. 158.6±42.2cm2 (2967±1227 points) for the NT-ZONE. T-ZONE voltage was significantly lower vs. the NT-ZONE (0.12±0.05mV vs. 0.60±0.28mV, P<0.001 respectively). T-ZONE PF was significantly higher than the NT-ZONE PF (345±76Hz vs. 255±34Hz, P<0.001). ROC discrimination of the T-ZONE resulted in AUC’s of 0.69- LV, 0.86- LVHF150, 0.88- LVHF200, 0.86- LVHF250 and 0.78- LVHF300. LVHF200 yielded the best improvement of AUC vs. LV unconstrained by high PF (19.1%)(Panel E). At a 0.2 mV cutoff, LVHF200 yielded a balanced SE/SP of 0.86/0.83 respectively vs. SE/SP of 0.90/0.54 for LV alone. During AT, systematic identification of EGM regions of high frequency within LV can significantly improve the specificity of discrimination of the site of AT termination.

Utility and limitations of coherent mapping algorithm utilizing vectors and global propagation patterns in atrial tachycardia.

A novel mapping algorithm utilizing vectors and global patterns of propagation (Coherent™, Biosense Webster) has been developed to help identify the mechanism of atrial tachycardia (AT). We aimed to determine the diagnostic accuracy of coherent mapping compared with that of ripple mapping. This study included 41 consecutive patients with 84 ATs (47 reentrant and 37 focal ATs). Two independent electrophysiologists confirmed the diagnoses using coherent mapping before the ripple map-guided ablation. AT termination was achieved in 75 of 84 ATs (89%) at first ablation lesion set. Four of the remaining nine ATs, which were terminated before an index radiofrequency (RF) application, were non-inducible after RF delivery at the first lesion set, whereas the other five ATs were terminated at the second lesion set. Diagnostic agreement between coherent and ripple maps was achieved in 51 of 84 ATs (61%): 28 of the 47 macroreentrant ATs (60%) and 23 of the 37 focal ATs (62%; P=0.826). In typical macroreentrant ATs, including left atrial roof, perimitral, and cavotricuspid isthmus-dependent ATs, coherent maps achieved diagnostic agreement in 23 of 29 ATs (79%), which was higher than that in other ATs (51%, P=0.018): 13 of 26 macroreentrant ATs (50%) and 15 of 29 focal ATs (52%, P=1.000). Ripple map-guided AT ablation achieved a high termination rate in the first lesion set. Coherent mapping yielded a favorable diagnostic accuracy for typical macroreentrant ATs, though its value for diagnosing other ATs was limited.

Catheter ablation for supraventricular arrhythmias in adults with congenital heart disease: Recurrence rates and predictors of acute procedural success

AimsTo define the cohort of adult congenital heart disease (ACHD) patients undergoing catheter ablation for supraventricular arrhythmia in a large tertiary centre, characterise outcomes, and determine factors associated with arrhythmia recurrence. MethodsSingle centre retrospective study of all catheter ablations for atrial arrhythmias in ACHD patients between September 2014 and October 2021. Patients were identified using a field search through a centralised database. Pre-specified clinical and procedural data of interest, and time from ablation to recurrence, were determined. Cox regression analyses were used to determine potential predictors of acute procedural success and arrhythmia recurrence. ResultsCardiac ablation for supraventricular arrhythmia was undertaken in 142 cases across 100 unique patients (median age 41, interquartile range 31–52), with 70 (49%) cases treated for macro-reentrant atrial tachycardia, 16 (11%) for focal atrial tachycardia, 19 (13%) for multifocal atrial tachycardia, 17 (12%) for atrial fibrillation, 7 (5%) for atrioventricular nodal reentrant tachycardia, and 8 (6%) for atrioventricular reentrant tachycardia; and 68 cases (48%) had recurrent arrhythmia with a median time to recurrence of 800 days. Multivariable analysis identified acute procedural success as an independent predictor of freedom from arrhythmia, and ablation for persistent atrial fibrillation as an independent predictor for recurrence of arrhythmia. ConclusionCatheter ablation for supraventricular arrhythmia in ACHD patients is safe and effective, with most patients achieving multiple arrhythmia-free months. Procedural success and arrhythmia mechanism are important predictors of recurrence.

Electrophysiological characteristics of epicardial atrial tachycardias and endocardial breakthrough site targeting for ablation: a single center experience.

Despite being increasingly observed in daily practice, epicardial atrial tachycardias (Epi AT) have not been extensively characterized. In the present study, we retrospectively characterize electrophysiological properties, electroanatomic ablation targeting, and outcomes of this ablation strategy. Patients who underwent scar-based macro-reentrant left atrial tachycardia mapping and ablation patients with at least one Epi AT, which had a complete endocardial map, were selected for the inclusion. Based on current electroanatomical knowledge, Epi ATs were classified based by utilization of following epicardial structures: Bachmann's bundle, septopulmonary bundle, vein of Marshall. Endocardial breakthrough (EB) sites were analyzed as well as entrainment parameters. EB site was targeted for initial ablation. Among seventy-eight patients undergoing scar-based macro-reentrant left atrial tachycardia ablation, fourteen (17.8%) patients met the inclusion criteria for Epi AT and were included in the study. Sixteen Epi ATs were mapped, four utilizing Bachmann's bundle, five utilizing septopulmonary bundle, and seven utilizing vein of Marshall. Fractionated, low amplitude signals were present at EB sites. Rf terminated the tachycardia in ten patients; activation changed in five patients and in one patient atrial fibrillation ensued. During the follow-up, there were three recurrences. Epicardial left atrial tachycardias are a distinct type of macro-reentrant tachycardias that can be characterized by activation and entrainment mapping, without need for epicardial access. Endocardial breakthrough site ablation reliably terminates these tachycardias with good long-term success.

Atrial tachycardia occurring after a prior atrial fibrillation ablation procedure: Does non-inducibility matter?

Recurrent atrial tachycardia (AT) is a common phenomenon after catheter ablation for AF, particularly in the setting of additional substrate ablation, with many studies demonstrating gap-related macro re-entrant AT (predominantly mitral and roof dependent) to be the dominant mechanism. Although multiple inducible ATs after ablation of the clinical AT are commonly described at repeat procedures, the optimal ablation strategy, and procedural endpoints are unclear in this setting. A recent randomized study addressing the question of non-inducibility as a procedural endpoint demonstrated no additional benefits to the ablation of all induced, non-clinical ATs, but it was limited by small numbers and high rates of non-inducibility. Nevertheless, once ablation of the clinical AT has been successfully performed, ensuring durable linear block and PV isolation may be sufficient for the prevention of further AT. Durable linear block, particularly at the mitral isthmus, is difficult to achieve but may be facilitated by the real-time evaluation of lesion quality and contiguity and the novel technique of vein of Marshall ethanol infusion. Large-scale, randomized trials are needed, nonetheless, to fully assess the optimal ablation strategy in the setting of recurrent AT post-AF ablation.