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Background: Identification of infrequent nonpulmonary vein trigger premature atrial contractions (PACs) is challenging. We hypothesized that pace mapping (PM) assessed by correlation scores calculated by an intracardiac pattern matching (ICPM) module was useful for locating PAC origins, and conducted a validation study to assess the accuracy of ICPM‐guided PM. Methods: Analyzed were 30 patients with atrial fibrillation. After pulmonary vein isolation, atrial pacing was performed at one or two of four sites on the anterior and posterior aspects of the left atrium (LA, n = 10/10), LA septum (n = 10), and lateral RA (n = 10), which was arbitrarily determined as PAC. The intracardiac activation obtained from each pacing was set as an ICPM reference consisting of six CS unipolar electrograms (CS group) or six CS unipolar electrograms and four RA electrograms (CS–RA group). Results: The PM was performed at 193 ± 107 sites for each reference pacing site. All reference pacing sites corresponded to sites where the maximal ICPM correlation score was obtained. Sites with a correlation score ≥98% were rarely obtained in the CS‐RA than CS group (33% vs. 55%, P =.04), but those ≥95% were similarly obtained between the two groups (93% vs. 88%, P =.71), and those ≥90% were obtained in all. The surface areas with correlation scores ≥98% (0[0,10] vs. 10[0,35] mm2, P =.02), ≥95% (10[10,30] vs. 50[10,180] mm2, P =.002) and ≥90% (60[30,100] vs. 170[100,560] mm2, P =.0002) were smaller in the CS‐RA than CS group. Conclusions: ICPM‐guided PM was useful for identifying the reference pacing sites. Combined use of RA and CS electrograms may improve the mapping quality. [ABSTRACT FROM AUTHOR]

Introduction: Endocardial pace mapping (PM) can identify conducting channels for ventricular tachycardia (VT) circuits in patients with structural heart disease (SHD). Recent findings show the temporal and spatial pattern of PM may aid identification of the surface harboring VT isthmii. The specific correlation of PM patterns to scar topography has not been examined. Objective: To correlate the pattern of endocardial PMs to underlying scar topography in SHD patients with VT. Methods: Data from patients undergoing VT ablation from August 2018 to February 2022 were reviewed. Results: Sixty‐three patients with SHD‐related VT (mean age 65 ± 14 years) with 83 endocardial PM correlation maps were analysed. Two main correlation patterns were identified, an "abrupt‐change correlation pattern (AC‐pattern)" and "centrifugal‐attenuation correlation pattern (CA‐pattern)." AC‐pattern had lower scar ratio (unipolar/bipolar % scar area; 1.1 vs. 1.5, p <.001), had longer maximal stimulus‐QRS intervals (97.5 vs. 68 ms, p =.002), and higher likelihood of endocardial dominant scar (11/21 [52%] vs. 3/38 [8%], p <.001) than CA‐pattern seen on intracardiac echocardiography (ICE). In contrast, CA‐pattern was more likely to have epicardial dominant scar or mid‐intramural scar on ICE (epicardial dominant scar; CA‐pattern: 12/38 [32%] vs. AC‐pattern: 1/21 [5%], p =.02, mid‐intramural scar; CA‐pattern: 15/38 [39%] vs. AC‐pattern: 1/21 [5%], p =.005). Conclusions: The spatial pattern of endocardial PM in SHD‐related VT directly correlates with scar topography. AC‐pattern is associated with endocardial dominant scar on ICE with lower scar ratio and longer stimulus‐QRS intervals, whereas CA‐pattern is strongly associated with epicardial dominant or mid‐intramural scar with higher scar ratio and shorter stimulus‐QRS intervals. [ABSTRACT FROM AUTHOR]

A 17-year-old patient presented with frequent palpitations, where the tachycardia was not sustained and could not be induced, making it impossible to pinpoint the earliest activation site using the activation map. However, by utilizing a dual-chamber electrogram-based pace mapping technique, we successfully identified the origin and achieved effective treatment., Competing Interests: The Section of Arrhythmia (from the Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan) is supported by an endowment from Medtronic JAPAN, Abbott JAPAN, and Boston Scientific JAPAN. K.I. and K.F. belong to the Section. However, all authors have reported that they have no relationships relevant to the contents of this paper to disclose., (© 2024 The Author(s). Journal of Arrhythmia published by John Wiley & Sons Australia, Ltd on behalf of Japanese Heart Rhythm Society.)

Background: There are limited data comparing ablation outcomes in patients with low intraprocedural burden of ventricular arrhythmias (VA) undergoing a pace mapping (PM)–guided strategy vs those with high burden guided by standard activation mapping strategy (non-PM). Objective: We sought to determine if catheter ablation–guided by PM of low-intraprocedural-burden idiopathic outflow tract VA would be noninferior compared to non-PM-guided ablation. Methods: Outcomes of catheter ablation of idiopathic outflow tract VA in 22 patients with a low burden of intraprocedural VA using PM-guided ablation were compared to 44 patients with a high burden of intraprocedural VA undergoing ablation using standard techniques. Results: Sixty-six patients were included (age 46.5 ± 14.8 years; 68% female, left ventricular ejection fraction 59% ± 5%). Within the PM group, 24-hour preprocedure premature ventricular complex (PVC) burden was 9.5% (interquartile range [IQR] 4%–13.8%), number of pace maps 33.6 ± 18.5, surface area of ≥95% pace map correlation 1.9 ± 1.2 cm2, with best pace map correlation 96% (IQR 92%–97%). Within the non-PM group, 24-hour preprocedure PVC burden was 13.5% (IQR 6.6%–30%), earliest activation time -33.7 ± 9.9 ms. Procedural duration, general anesthesia administration, fluoroscopy dose, and complications were all comparable. Following final procedure, 24-hour VA burden (PM 0% [IQR 0–2.4%] vs non-PM 0% [IQR 0–4.2%], P = .98), along with VA-free survival at 6-month follow-up (PM 77% vs non-PM 71%, P = .77), were both comparable. Conclusion: In patients with low intraprocedural burden of outflow tract VA, PM-guided catheter ablation can accurately identify the VA site of origin, leading to outcomes comparable to those achieved with standard ablation techniques.

We aim to describe the technical aspects of pace mapping (PM), as well as the two typical patterns of pacing correlation maps during ventricular tachycardia (VT) ablation. The first main pattern is focal, with a gradual and eccentric decrease of the QRS correlation from the area with the best PM correlation. This focal pattern may be associated with two clinical situations: (1) with some endocardial points showing a good correlation compared to VT morphology: true endocardial exit of VT or endocardial breakthrough of either an intramural or an epicardial circuit; (2) without any endocardial points showing a good correlation compared to VT morphology: the VT may originate from the other ventricle, but the presence of an intramural or an epicardial circuit should be considered in patients with a structural heart disease. The second pattern is the presence of PM points exhibiting a good correlation close to other PM points showing a poor correlation compared to VT morphology: this abrupt change in paced QRS morphology over a short distance indicates divergence of activation wavefronts between these sites and suggests the presence of a slow conduction channel: the VT isthmus. [ABSTRACT FROM AUTHOR]

Background: Ablation of infrequent premature ventricular complexes (PVC) is challenging., Objectives: A novel mapping strategy for patients with infrequent PVCs, called multielectrode catheter-induced ectopy mapping (MECIE mapping) is described, aiming at performing a hybrid activation/template matching map by taking advantage of multielectrode catheter-induced arrhythmogenicity., Methods: Patients referred to 3 tertiary centers for PVC ablation were prospectively enrolled if they had infrequent PVCs (less than 1 PVC per minute) at onset of procedure, preventing the realization of an accurate activation map. A detailed MECIE map was created using the arrhythmogenic property of multielectrode catheters, corresponding to a local activation time (LAT) map generated by annotating LAT from mechanical PVCs. Selecting mechanical PVCs with ≥99% concordance with the clinical PVC spotted the site of origin at which ablation was delivered. The primary endpoint was long-term success, defined as an >80% reduction in PVC burden during follow-up., Results: A total of 29 patients were included, with 25 (interquartile range [IQR] 7-30) PVCs in the initial 30 minutes of procedure. During MECIE mapping, 67 (IQR 1-332) points with ≥99% concordance were acquired. The best LAT was 34.0 ± 9.5 ms before QRS onset. Pace mapping was 97.4 ± 3.1% compared with the clinical PVC. Ablation was locally performed. After 13.2 ± 5.1 months of follow-up, 27 patients (93.1 %) had 80% reduction in PVC burden, and only 2 patients had symptomatic recurrences., Conclusion: A detailed MECIE map taking advantage of multielectrode catheter arrhythmogenicity may be generated to spot the origin of PVCs, a strategy resulting in a good procedural success rate., Competing Interests: Disclosures Prof Martins and Prof Cortez-Dias have received lecture fees from Biosense Webster. The other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Mapping and localizing presystolic Purkinje potentials are crucial for determining the optimal ablation site for fascicular premature ventricular contractions (PVCs). Here we present a case of PVCs originating from the distal left anterior fascicle (LAF). Activation mapping using a multipolar catheter with small electrodes demonstrated early presystolic Purkinje potentials during the PVCs. A moderately good pace-map match was also obtained near the successful ablation site. This case demonstrates the activation pattern of PVCs originating from the distal LAF and the usefulness of multipolar catheters with small electrodes for the mapping of fascicular PVCs. [ABSTRACT FROM AUTHOR]

Abstract Background Radiofrequency (RF) ablation is a well‐established approach to treat premature ventricular contractions (PVC) and is associated with good outcomes. Aim The present study sought to analyze the acute efficacy and 1‐year outcomes of PVC ablation using RF technology with an approach based on automated pace‐mapping and contact force (CF) information. Methods Sixty‐one consecutive patients (52.4% males, age 45.9 ± 12.5) underwent catheter ablation for symptomatic monomorphic PVC. All procedures were guided by a 3‐dimensional mapping system; site of ablation was selected based on PASO™ aided pace‐mapping; RF was started on the selected location when stable catheter position with >10 g of CF were obtained. The procedure was defined as acutely effective if the PVC was eliminated and it did not recur during within 30 minutes. Long‐term efficacy was defined as a decrease by more than 95% at 1 year of the initial PVC burden at ECG Holter monitoring. Results The PVC ablation was performed in the right ventricular outflow tract in 37 patients (60.7%), left ventricle in 15 patients (24.6%), coronary cusps in 6 patients (9.8%), right ventricle in 3 patients (4.9%); PVC ablation was acutely successful in 59 of patients (96.7%). At 1‐year efficacy was obtained in 57 patients (93.4%). No major complications occurred. Mean procedural and fluoroscopy time were 94.5 ± 20.9 and 4.3 ± 2.5 minutes respectively. Conclusion Premature ventricular contraction RF ablation mainly guided by PASO™ and CF showed high success rate in both acute and 1‐year follow‐up (96.7% and 93.4% respectively). The best efficacy cut‐off for RF ablation of PVCs has been identified in presence of both PASO™ ≥95% and CF >10 g.

The article comments on a study on high-density pace-mapping for myocardial scar-related ventricular tachycardia (VT) ablation. It points out the usefulness of pace-mapping during sinus rhythm to identifying the general location of focal arrhythmia sources. it reviews the use of pace-mapping technique in measuring the correlation between VT and paced QRS morphology and suggests its application in cases in which the critical isthmus is not located on the surface of being mapped.

Pace mapping is commonly used to locate the origin of ventricular arrhythmias, especially premature ventricular contraction (PVC). However, this technique relies on clinicians’ ability to rapidly interpret ECG data. To avoid time-consuming interpretation of ECG morphology, some automated algorithms or computational models have been explored to guide the ablation. Inspired by these studies, we propose a novel model based on spatial and morphological domains. The purpose of this study is to assess this model and compare it with three existing models. The data are available from the Experimental Data and Geometric Analysis Repository database in which three in vivo PVC patients are included. To measure the hit rate (A hit occurs when the predicted site is within 15 mm of the target) of different algorithms, 47 target sites are tested. Moreover, to evaluate the efficiency of different models in narrowing down the target range, 54 targets are verified. As a result, the proposed algorithm achieves the most hits (37/47) and fewest misses (9/47), and it narrows down the target range most, from 27.62 ± 3.47 mm to 10.72 ± 9.58 mm among 54 target sites. It is expected to be applied in the real-time prediction of the origin of ventricular activation to guide the clinician toward the target site.

Pace mapping is commonly used to locate the origin of ventricular arrhythmias, especially premature ventricular contraction (PVC). However, this technique relies on clinicians' ability to rapidly interpret ECG data. To avoid time-consuming interpretation of ECG morphology, some automated algorithms or computational models have been explored to guide the ablation. Inspired by these studies, we propose a novel model based on spatial and morphological domains. The purpose of this study is to assess this model and compare it with three existing models. The data are available from the Experimental Data and Geometric Analysis Repository database in which three in vivo PVC patients are included. To measure the hit rate (A hit occurs when the predicted site is within 15 mm of the target) of different algorithms, 47 target sites are tested. Moreover, to evaluate the efficiency of different models in narrowing down the target range, 54 targets are verified. As a result, the proposed algorithm achieves the most hits (37/47) and fewest misses (9/47), and it narrows down the target range most, from 27.62 ± 3.47 mm to 10.72 ± 9.58 mm among 54 target sites. It is expected to be applied in the real-time prediction of the origin of ventricular activation to guide the clinician toward the target site. [ABSTRACT FROM AUTHOR]

Ventricular arrhythmias arising from the left ventricular papillary muscles, having a right bundle branch block (RBBB) QRS morphology on the electrocardiogram, account for approximately 15% of arrhythmias in a structurally normal heart and have usually a benign prognosis. The mitral valve usually has two papillary muscles, anterolateral and posteromedial, with the latter one being always more arrhythmogenic. These arrhythmias are not typically inducible by programmed ventricular or atrial stimulation, suggesting a non-reentrant mechanism. Ventricular arrhythmias originated from the papillary muscles should be distinguished from other idiopathic left ventricular arrhythmias such as fascicular or mitral annular arrhythmias, which also have a RBBB pattern. Catheter ablation in these cases is always challenging and the recurrence risk is higher compared to other idiopathic ventricular arrhythmias. [ABSTRACT FROM AUTHOR]

Background: The moderator band (MB) is an endocavitary structure with only 2 exits to the bulk of the ventricular myocardium. Whether this may lead to specific electrophysiological characteristics remains unknown.Objective: The purpose of this study was to investigate electrocardiographic (ECG), activation, and pace mapping characteristics of MB-originated ventricular arrhythmias (VAs).Methods: Mapping and ablation of MB-VAs were performed in 12 patients under the guidance of a 3-dimensional electroanatomic mapping system and intracardiac echocardiography and ECG, and mapping data were analyzed. Of these patients, 11 underwent pace mapping study of 6 sites around the MB and the QRS morphology was compared.Results: The earliest activation site was free wall (FW) insertion in 8 patients (66.7%) and MB body in 4 patients (33.3%), preceding the QRS onset by 17.8±4.7 ms, and Purkinje-like potential was observed in 6 (50.0%). VAs were eliminated at the earliest activation site in the procedure, but recurrence was documented in 2 cases (16.7%) during a follow-up of 13.4±7.8 months. Pacing QRS complex from the MB was characterized by short QRS duration (P<.001), short intrinsicoid deflection time (P<.001), later precordial transition (P=.025), and notch on the descending limb of the inferior leads (P<.001) as compared with pacing from the adjacent anterior-lateral FW, and that notch could also differentiate MB from the anterior papillary muscle (P=.027). However, pacing QRS is identical between the MB body and the FW insertion in 11 of 11 patients and between the septal insertion and the MB body in 7 of 11 patients.Conclusion: Bidirectional conduction via the 2 exits during MB-VAs contributed to distinct ECG and electrophysiological characteristics, while pace mapping is of limited value in defining the ablation target. [ABSTRACT FROM AUTHOR]

Introduction: The voltage map during sinus rhythm (SR) is a cornerstone of substrate mapping (SM) in scar‐related ventricular tachycardia (VT) and frequently used with pace mapping (PM). Where to conduct PM is unclear in cases of an extensive or unidentified substrate. Conduction properties are another aspect incorporated by SM, and conduction slowing has gained interest as being related to successful ablation, although its mechanism has not been elucidated. We aimed to investigate the relationship between SR conduction properties and VT isthmuses. Methods: Nineteen patients (mean age, 62 years) who underwent VT ablation with voltage mapping and PM were reviewed. Isochronal late activation maps (ILAMs) with eight zones were reconstructed and sequentially named from one to eight according to the SR propagation. Good PM sites were superimposed on ILAMs, and the isthmus was defined using different pacing latencies. ILAM properties harboring isthmuses were investigated. Results: Twenty‐eight ILAMs (13 epicardium, 1 right ventricular [RV], and 14 left ventricular [LV] endocardium) were reviewed. Eighteen isthmuses of 24 target VTs were identified, in which the proximal ends were in a later zone than the distal ends (zone 6 vs 4; P <.001), suggesting a reverse isthmus vector to the SR. The conduction velocity of the zone involving the distal isthmus was significantly lower than that of the SR preceding zone (0.40 vs 1.30 m/s; P <.001). SR conduction velocity decelerated by 69.5% (range 59.7%‐74.5%) before propagating into the isthmus area. Conclusion: Conduction slowing area during SR were related with the exit portion of the VT isthmuses. [ABSTRACT FROM AUTHOR]

Background: Radiofrequency (RF) ablation is a well‐established approach to treat premature ventricular contractions (PVC) and is associated with good outcomes. Aim: The present study sought to analyze the acute efficacy and 1‐year outcomes of PVC ablation using RF technology with an approach based on automated pace‐mapping and contact force (CF) information. Methods: Sixty‐one consecutive patients (52.4% males, age 45.9 ± 12.5) underwent catheter ablation for symptomatic monomorphic PVC. All procedures were guided by a 3‐dimensional mapping system; site of ablation was selected based on PASO™ aided pace‐mapping; RF was started on the selected location when stable catheter position with >10 g of CF were obtained. The procedure was defined as acutely effective if the PVC was eliminated and it did not recur during within 30 minutes. Long‐term efficacy was defined as a decrease by more than 95% at 1 year of the initial PVC burden at ECG Holter monitoring. Results: The PVC ablation was performed in the right ventricular outflow tract in 37 patients (60.7%), left ventricle in 15 patients (24.6%), coronary cusps in 6 patients (9.8%), right ventricle in 3 patients (4.9%); PVC ablation was acutely successful in 59 of patients (96.7%). At 1‐year efficacy was obtained in 57 patients (93.4%). No major complications occurred. Mean procedural and fluoroscopy time were 94.5 ± 20.9 and 4.3 ± 2.5 minutes respectively. Conclusion: Premature ventricular contraction RF ablation mainly guided by PASO™ and CF showed high success rate in both acute and 1‐year follow‐up (96.7% and 93.4% respectively). The best efficacy cut‐off for RF ablation of PVCs has been identified in presence of both PASO™ ≥95% and CF >10 g. [ABSTRACT FROM AUTHOR]

The article presents the discussion on late activation mapping or abrupt transition in the QRS morphology. Topics include substrate mapping being performed in sinus or paced rhythm, and comprise of annotation of abnormal electrograms showing low voltage, fractionated, and late potential; and infering critical isthmus identification by means of effective elimination resulting in clinical VT non‐inducibility.

Background: Pace mapping is a useful tool but is of limited utility for the atrium because of poor spatial resolution. We investigated the use of bipolar electrograms recorded from widely spaced electrodes in order to improve the resolution of pace mapping. Methods: This prospective study included patients undergoing a clinical electrophysiology study. Unipolar pacing from either the superior or inferior lateral right atrium was performed to simulate atrial tachycardia. Twelve-lead electrocardiograms were recorded during pacing as a template. In addition, three intracardiac bipolar electrograms from a set of widely spaced electrodes were also recorded. Subsequently, unipolar pacing was performed from electrodes at known distances from the initial pacing site, and the morphology of P waves in the electrocardiogram and bipolar electrograms were compared with that of the template. Morphological comparison was performed by a cardiologist and by automated computerized matching. Spatial resolution was calculated as the minimum distance at which there was no match. Results: Fifteen patients participated in the study. Distance at which differences in morphology were noted was smaller in the bipolar electrograms compared to that indicated by P waves in the electrocardiogram, when matched by the cardiologist (6.1±3.8 mm vs. 9.9±5.2 mm, p=0.012) or by automated analysis (4±0 mm vs. 9.9±4 mm, p

Abstract: Introduction: Preferential conduction from an origin to breakout sites can occur during ventricular arrhythmias (VAs) originating from the left ventricular papillary muscles (LVPMs). The purpose of this study was to investigate the incidence, electrophysiological characteristics, and relevance to radiofrequency catheter ablation (RFCA) of such a preferential conduction demonstrated by pace mapping. Methods and results: We studied 34 consecutive patients undergoing RFCA of 40 LVPM VAs. Among 78 QRS morphologies during these VAs, pace mapping was performed for 67 QRS morphologies during 37 VAs, and revealed VA‐matched pace maps (M‐PMs) with a latency for 14 QRS morphologies during 11 VAs (30%). Among 47 QRS morphologies with activation mapping, RFCA at the earliest activation site (EAS) was successful in 39, but not successful in 8 despite M‐PMs with no latency. In these cases, RFCA was successful at remote sites of the M‐PMs with latency (n = 6) and a site located between the EAS and site of that with latency (n = 1). Among the remaining 31 QRS morphologies with pace mapping only, RFCA was successful at M‐PM sites with no latency in 17, and at M‐PMs sites with latency in 7. In 3 of those 7 QRS morphologies, M‐PMs were recorded at multiple remote sites, and RFCA was not successful at M‐PM sites with no latency (n = 2) or a shorter latency (n = 1). Conclusions: When an M‐PM with latency was recorded in LVPM VAs, RFCA at that site was highly successful. Attention should be paid to latency as well as the score during pace mapping of LVPM VAs. [ABSTRACT FROM AUTHOR]

Purpose: Catheter ablation is an effective treatment for premature ventricular complexes (PVCs). Activation mapping is accurate but requires PVCs at the time of the ablation. Pace-mapping correlation (PMC) is a supplemental tool recently developed as an integrated module for an electro-anatomical mapping platform. Our study sought to investigate whether pace-mapping technology provides similar ablation results in patients with low versus high idiopathic PVC burden at the time of ablation and the relationship between sites with the highest PMC and the earliest local activation time (LAT).Methods: A total of 59 consecutive patients undergoing catheter ablation for idiopathic PVCs were enrolled. Twelve out of 59 patients (20%) were classified in the low PVC burden group (defined as < 2 PVCs/min) and 47/59 (80%) in the high PVC burden group.Results: The most common origin of PVCs was the right ventricular outflow tract (RVOT) followed by aortic cusps, coronary sinus, parahisian region, and aorto-mitral continuity. Procedural and 1-month success rate were 95 and 87% respectively. PVC burden at the time of ablation did not influence the success rate. The median distance between the earliest LAT points and the highest PMC points was 6.4 (4.9-10.6) mm.Conclusions: Pace-mapping correlation is useful and accurate in localizing the origin of idiopathic PVCs irrespective of the initial PVC burden. It provides optimal ablation results when combined with LAT. Success rate at mid-term follow-up is higher when the origin of PVCs is located in the RVOT as compared to other locations. [ABSTRACT FROM AUTHOR]

Background Ablation of cardiac arrhythmias in children and teenagers often necessitates the use of anesthesia, which can suppress ventricular arrhythmias (VAs), making it difficult to map the site of origin using activation time (AT). Pace mapping, a technique employed to assist with VA origin localization, depends on subjective comparison of paced and targeted QRS morphology. We assessed the utility of a quantitative approach to paced QRS to VA morphology matching using the PaSo software (Carto 3, Biosense Webster), to localize the VA site of origin. Methods Twenty-four patients underwent 26 procedures for frequent VAs, 29 for targeted VA. If AT mapping was precluded due to infrequent VA, pace mapping was executed using the PaSo software, after regionalization based on targeted VA QRS morphology. Results Subjects were aged 1-32 (mean 14 ± 6) years; 10 were male. Heart disease was present in six patients. PVC frequency prior to onset of anesthesia was 15 ± 16/min, decreasing to 0-1 PVC/min in 17 cases prior to ablation. Arrhythmia localization was performed by AT mapping + PaSo (12) or PaSo only (17). Pace mapping exhibited an intraventricular gradient of percent QRS morphology match. Highest achieved QRS match averaged 96 ± 2%. Successful ablation (> 1-month follow-up) was achieved in 24/29 targeted VAs, 11/12 ablated using AT and pace mapping, and 13/17 VA ablated using pace mapping only, P = 0.29. Conclusions (1) Spontaneous VA frequency was markedly reduced following anesthesia, despite catecholamine administration. (2) Notwithstanding the ability to perform AT mapping, successful ablation can still be performed using pace mapping only, facilitated by the PaSo software. [ABSTRACT FROM AUTHOR]

Background: Focal atrial tachycardia (FAT) is extremely difficult to map and ablate when it is difficult to induce and nonsustained. The objective of this study is to evaluate the efficacy of pace mapping in identifying the FAT origin.Methods and Results: The study included 7 patients with drug-refractory FAT who experienced daily multiple episodes before ablation and presented with difficult-to-induce and nonsustained FAT and a distinct P wave morphology. Pace mapping was systematically performed in the areas of interest using 3-dimensional mapping to match the P wave morphology and paced intracardiac activation sequence recorded from multiple catheters. The anatomic origins of FAT were the right pulmonary vein (PV) in 3 patients, mitral annulus, crista terminalis, tricuspid annulus, and right-sided PV via a posterior conduction of previous PV isolation. In all patients, pace mapping obtained best-matched P wave morphology in ≥11/12 leads of surface ECG at the successful ablation site, and paced intracardiac activation sequence was identical to that of induced FAT. Focal ablation was delivered in 4 patients, including non-PV FAT in 3 and FAT in 1, via posterior gap along the previous right-sided PV isolation, and circumferential right-sided PV isolation was performed in the other 3 patients. No FAT was induced at the end of the procedure. All patients were free of arrhythmias without antiarrhythmic drugs during the 8.4±5.6-month follow-up.Conclusions: The combination of paced P wave morphology and intracardiac activation sequence can be used for the identification of FAT origin in patients with difficult-to-induce and nonsustained FAT. [ABSTRACT FROM AUTHOR]

Background In catheter ablation of idiopathic ventricular arrhythmia (VA), it is still unclear whether pace mapping or activation mapping is more useful for successful catheter ablation. The depth of origin in the ventricular wall especially affects the success rate of endocardial-approached catheter ablation. Thus, we examined the relationship between these tactics and QRS morphology. Methods We evaluated the relationship among pace mapping score, activation time, and peak deflection index (PDI) in 28 patients, with a total of 30 origins, who underwent successful catheter ablation of idiopathic VA. Results All origins were located in the ventricular outflow tract area, including three in the left coronary cusp (LCC). PDI, activation time, and pace mapping score at successful ablation sites were 0.60 ± 0.08, 26.3 ± 9.9 ms, and 19.1 ± 4.6, respectively. The pace mapping score inversely correlated with the PDI (R = −0.540, P = 0.0017), but the activation time did not correlate with the PDI. When excluding the three VAs originating from the LCC, in which perfect pace mapping was obtained from epicardial sites despite high PDI, this correlation coefficient became more intensive (R = −0.734, P < 0.0001). Conclusions Our study suggests that pace mapping with an endocardial approach could not reproduce the precise QRS morphology for VA originating from the intramural site of the ventricular wall. With such origins, we should rely on activation mapping to detect the optimal ablation site. [ABSTRACT FROM AUTHOR]

We successfully performed radiofrequency catheter ablation (RFCA) in 2 cases involving patients with idiopathic ventricular tachycardias (VTs) and premature ventricular contractions (PVCs) originating from the pulmonary artery (PA). The QRS morphology of the VTs and PVCs in the two cases exhibited a left bundle-branch block (LBBB) morphology with an inferior axis. Activation and pace mappings were performed in the right ventricular outflow tract (RVOT) and above the pulmonary valve to determine the origin of the VTs and PVCs. In both cases, the earliest ventricular activation was recorded in the PA above the pulmonary valve. Applications of radiofrequency current at those sites in the PA resulted in the elimination and noninducibility of the VT and PVC. During the follow-up, the VT or PVC did not recur without any antiarrhythmic drug administration.

Background: Pace mapping (PM) is used to identify the origin of ventricular arrhythmias (VAs). For intramural VAs, the site of origin often cannot be reached and therefore PM is less accurate.Objective: The purpose of this study was to assess the value of single- and dual-site pace maps to differentiate intramural from nonintramural VAs.Methods: In 18 consecutive patients with idiopathic intramural VAs, pace mapping was performed at 2 breakthrough sites in adjacent anatomic structures. Twelve-lead electrocardiograms of the 2 pace maps were averaged in MATLAB and compared (correlation coefficient [CC]) with the targeted VA. Dual-site pace mapping was performed in a control group of 18 patients with nonintramural VAs at the sites of earliest electrical activation and a breakthrough site in an adjacent anatomic location.Results: Dual-site pace maps had a higher CC than did best single-site pace maps (0.87 ± 0.1 vs 0.81 ± 0.16; P = .02) in patients with intramural VAs. At the site of origin, single-site pace maps had a higher CC than did dual-site pace maps obtained from adjacent anatomic locations (0.93 ± 0.04 vs 0.89 ± 0.05; P = .0004) in patients with nonintramural VAs. Sensitivity, specificity, positive predictive value, and negative predictive value of dual-site pace maps for identifying an intramural VA were 89%, 82%, 84%, 88%, and 86%, respectively. Furthermore, the receiver operating characteristic curve analysis revealed that a CC cutoff value of ≤0.86 for a single-site pace map best differentiated intramural from nonintramural VAs.Conclusion: A higher CC value for a dual-site pace map obtained from the earliest breakthrough site as well as a CC cutoff value of ≤0.86 for a single-site pace map obtained from the site of earliest electrical activation can best differentiate intramural from nonintramural VAs. [ABSTRACT FROM AUTHOR]

Background Pace mapping is a useful tool but is of limited utility for the atrium because of poor spatial resolution. We investigated the use of bipolar electrograms recorded from widely spaced electrodes in order to improve the resolution of pace mapping. Methods This prospective study included patients undergoing a clinical electrophysiology study. Unipolar pacing from either the superior or inferior lateral right atrium was performed to simulate atrial tachycardia. Twelve-lead electrocardiograms were recorded during pacing as a template. In addition, three intracardiac bipolar electrograms from a set of widely spaced electrodes were also recorded. Subsequently, unipolar pacing was performed from electrodes at known distances from the initial pacing site, and the morphology of P waves in the electrocardiogram and bipolar electrograms were compared with that of the template. Morphological comparison was performed by a cardiologist and by automated computerized matching. Spatial resolution was calculated as the minimum distance at which there was no match. Results Fifteen patients participated in the study. Distance at which differences in morphology were noted was smaller in the bipolar electrograms compared to that indicated by P waves in the electrocardiogram, when matched by the cardiologist (6.1±3.8 mm vs. 9.9±5.2 mm, p =0.012) or by automated analysis (4±0 mm vs. 9.9±4 mm, p <0.001). Conclusions Use of three bipolar electrograms recorded from a set of widely spaced electrodes in the right atrium improves the resolution of pace mapping compared to that using P waves from surface electrocardiograms alone. [ABSTRACT FROM AUTHOR]

Aims: One of the disadvantages of classic pace mapping (PM) is the operator's subjective interpretation. The aim of this single-centre retrospective study was to evaluate the value of automated template matching (AMT) in patients ablated due to ventricular outflow tract arrhythmias (OTAs).Methods and Results: From an overall group of 105 patients with OTA who were scheduled for transcatheter ablation (TA), AMT was accessible in 42 patients [21 right ventricular outflow tract (RVOT), 21 left ventricular outflow tract (LVOT), 28 women, aged 51.5 ± 12.7 years]. We used AMT to compare spontaneous arrhythmia ORS (spontQRS) with paced QRS complexes during PM in sites where radiofrequency (RF) applications were successful and in sites where RF applications were unsuccessful. The concordance was presented in per cents as objective matching scores (OMS). Then, at the successful ablation sites, we examined the relationship between OMS and the visual interpretation of PM was presented as electrophysiologists matching scores (EMS). The OMS of PM at sites of successful ablation varied from 78 to 99% (mean 94.1 ± 3.8) and from 47 to 95% (mean 80.2 ± 12.6%) at sites of unsuccessful ablation. Pace mapping in unsuccessful RF sites was significantly less similar to spontQRS morphologies than in successful RF sites (P = 0.0001). There was a significant correlation between OMS and EMS (r = 0.82; P < 0.0001). The OMS that indicated optimal ablation site was 89% (sensitivity = 95%; specificity = 80%). The mean OMS for successful sites at RVOT (95.1 ± 1.8%) and LVOT (93.1 ± 4.9%) were not different (P = 0.0551).Conclusion: This analysis revealed that AMT is a valuable technique for the interpretation of PM and for the identification of successful ablation sites in OTA. [ABSTRACT FROM AUTHOR]

Background: Evidence indicates that radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in patients with structural heart disease (SHD) is safe and effective. However, arrhythmia recurrence is still relatively high, and the optimal procedural strategy is unclear. In clinical practice, several combinations of mapping and ablation techniques are used to improve VT ablation efficacy., Aim: The study aimed to evaluate and provide evidence on the efficiency and safety of a systematized combination of VT ablation (mapping) techniques in patients with SHD., Methods: From 2016 to 2019, 47 patients (54 procedures) with SHD (89% heart failure, 94% ischemic heart disease, 37% VT storm) who underwent RFCA of VT were retrospectively analyzed from a group of 58 consecutive patients. During RFCA of VT, different combinations of three techniques, activation mapping (AM), pace mapping (PM), and substrate-based mapping (SbM), were used. The procedures were performed using the CARTO® 3 (Biosense Webster Inc., Diamond Bar, CA, US) electro-anatomical mapping system., Results: During a median (interquartile range [IQR]) follow-up of 25.5 months (11.75-52.25), VT-free survival after ablation was 68.5% (n = 37/54 procedures). Acute procedural success was achieved in 85% (n = 46/54 procedures). The number of induced VT morphologies, induction of non-clinical or non-sustained VT after ablation, and fewer VT mapping techniques used during the procedure were related to decreasing VT-free survival., Conclusions: VT ablation strategy based on systemic use of combined techniques is effective and safe in long-term follow-up of patients with SHD.

Background Analysis of implantable cardioverter-defibrillator electrograms (IEGMs) with pacing along the scar edge is often used to approximate distinct exit sites of scar-related ventricular tachycardia (VT). We evaluated the spatial resolution of IEGMs in identifying distinct exit sites of scar-related VT. Methods and Results Seventeen patients with scar-related VT were included. Threshold pacing (500-ms cycle length) was performed at sites spaced 10 mm apart along the scar border, as defined by high-density bipolar voltage mapping. Twelve-lead electrocardiogram and near-field and far-field IEGMs were recorded at each pacing site and assessed for morphology. The average scar size was 60 ± 30 cm2 and the scar border perimeter measured 28 ± 9 cm. A median of 18 pacing sites per patient were collected, spaced 14 ± 11 mm apart. The mean spatial resolution for the near-field, far-field, and combination of both was 82.7 ± 76 mm, 62.7 ± 53.6 mm, and 56.7 ± 50 mm (P for trend < 0.001). In all cases, IEGM analysis failed to identify distinct VT exit sites spaced <2 cm apart. Conclusions Analysis of IEGM morphology with pacing around the edge of the scar is unable to distinguish distinct VT exit sites spaced <2 cm apart, with an average spatial resolution of 5 cm. Given the wide range of values observed, detailed pace mapping over a perimeter of 10-15 cm along the scar edge appears crucial to define the boundaries of a linear ablation strategy to target the VT exit site based on IEGM pace match alone. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation of atrial fibrillation has been associated with left-sided phrenic nerve palsy. Knowledge of the individual left phrenic nerve course therefore is essential to prevent nerve injury. The aim of this study was to test the feasibility of an intraprocedural pace mapping and reconstruction of the left phrenic nerve course and to characterize which anatomical areas are affected. Methods: In patients undergoing left atrial catheter ablation, a three-dimensional map of the left atrial anatomical structures was created. The left-sided phrenic nerve course was determined by high-output pace mapping and reconstructed in the map. Results: In this study, 40 patients with atrial fibrillation or atrial tachycardias were included. Left phrenic nerve capture was observed in 23 (57.5%) patients. Phrenic nerve was captured in 22 (55%) patients inside the left atrial appendage, in 22 (55%) in distal parts, in 21 (53%) in medial parts, and in two (5%) in ostial parts of the appendage. In three (7.5%) patients, capture was found in the distal coronary sinus and in one (2.5%) patient in the left atrium near the left atrial appendage ostium. Ablation target was changed due to direct spatial relationship to the phrenic nerve in three (7.5%) patients. No phrenic nerve palsy was observed. Conclusions: Left-sided phrenic nerve capture was found inside and around the left atrial appendage in the majority of patients and additionally in the distal coronary sinus. Phrenic nerve mapping and reconstruction can easily be performed and should be considered prior catheter ablations in potential affected areas. [ABSTRACT FROM AUTHOR]