Atrial Tachycardia in the Coronary Sinus Communicating With Circumflex Artery Aneurysm

Coronary artery fistula is a rare anomaly, and localized re-entrant atrial tachycardia (AT) in the coronary sinus (CS) has rarely been reported. We report a case in a patient with a left circumflex artery aneurysm associated with the CS fistula who underwent radiofrequency catheter ablation for localized re-entrant AT, which originated from the CS.

Automated prediction of isthmus areas in scar-related atrial tachycardias using artificial intelligence

INTRODUCTION

Ablation of scar-related reentrant atrial tachycardia (SRRAT) involves identification and ablation of a critical isthmus. A graph convolutional network (GCN) is a machine learning structure that is well-suited to analyze the irregularly-structured data obtained in mapping procedures and may be used to identify potential isthmuses.

METHODS

Electroanatomic maps from 29 SRRATs were collected, and custom electrogram features assessing key tissue and wavefront properties were calculated for each point. Isthmuses were labeled off-line. Training data was used to determine the optimal GCN parameters and train the final model. Putative isthmus points were predicted in the training and test populations and grouped into proposed isthmus areas based on density and distance thresholds. The primary outcome was the distance between the centroids of the true and closest proposed isthmus areas.

RESULTS

A total of 193 821 points were collected. Thirty isthmuses were detected in 29 tachycardias among 25 patients (median age 65.0, 5 women). The median (IQR) distance between true and the closest proposed isthmus area centroids was 8.2 (3.5, 14.4) mm in the training and 7.3 (2.8, 16.1) mm in the test group. The mean overlap in areas, measured by the Dice coefficient, was 11.5 ± 3.2% in the training group and 13.9 ± 4.6% in the test group.

CONCLUSION

A GCN can be trained to identify isthmus areas in SRRATs and may help identify critical ablation targets.

Ethanol infusion therapy for peri-mitral atrial tachycardia through the Marshall bundle with electrical irrelevance of left atrial appendage and mitral isthmus

A 62-year-old man with a history of catheter ablation for atrial fibrillation and atrial tachycardia (AT) received a line of block of the mitral isthmus (MI) and electrical isolation of the left atrial appendage (LAA). Upon entrainment pacing, AT recurred and was diagnosed as peri-mitral AT (PMAT) with electrical irrelevance of MI, LAA, and left pulmonary vein, having a critical isthmus identified as Marshall bundle (MB). MB was then infused with ethanol, leading to the successful treatment of the PMAT.

Atrial Tachycardia Facilitating Transcatheter Edge-to-Edge Repair for Severe Functional Mitral Regurgitation

An 89-year-old woman with paroxysmal atrial tachycardia (AT) was diagnosed with severe atrial functional mitral regurgitation. On transesophageal echocardiography, the mitral regurgitation jet appeared larger during sinus rhythm and smaller during AT. During transcatheter repair of the valve, chronotropic agents were given to induce AT, assisting with leaflet capture.

Atrial tachycardia ablation through the sub-pulmonary ventricle in a patient with multiple malformations associated with congenitally corrected transposition of the great arteries and double-sided slow-pathway

A 46-year-old woman with congenitally corrected transposition of the great arteries (ccTGA) associated with dextrocardia, situs viscerus inversus, and left superior vena cava persistence presented with an incessant supraventricular tachycardia. Electrophysiological study was not conclusive in differential diagnosis of atrial tachycardia versus atypical atrioventricular (AV) nodal reentrant tachycardia, also due to the unconventional anatomy of the coronary sinus. By a comprehensive mapping of cardiac chambers, a double side slow-pathway was localized in both atrial chambers and subsequently ablated by radiofrequency delivery without tachycardia changes. Aortic root and cusps were devoid of electrical activity. The muscular part of the sub-pulmonary ventricle at the level of interatrial septum showed an earliest activation signal of -90 ms and ablation of this site was effective in abolish the tachycardia. This is the first case to report technical concerns of septal atrial tachycardia ablation in ccTGA associated with multiple anatomical malformations. Moreover, some peculiarities have been reported for the first time including the presence of double-side AV nodal slow-pathway and atypical localization of the tachycardia origin into the muscular part of the sub-pulmonary ventricle instead of posterior pulmonary cusp.

Incidence of Atrial Fibrillation After Radiofrequency Catheter Ablation for Atrial Tachycardia in Congenital Heart Disease

BACKGROUND

Atrial tachycardia (AT) and atrial fibrillation (AF) coexist in 30% of congenital heart disease (CHD) patients. Successful atrial tachycardia catheter ablation (ATCA) might prevent AF. Data on new-onset AF after ATCA in CHD is scarce.

OBJECTIVES

This study aimed to evaluate the incidence of new-onset AF after ATCA and to assess clinical characteristics associated with new-onset AF after ATCA in CHD.

METHODS

CHD patients referred for ATCA to 3 European centers were included. New occurrence of AF was defined as electrocardiographic documentation of AF after any ATCA procedure in patients without history of AF.

RESULTS

In 277 CHD patients (median age 37 years [Q1, Q3: 23, 49 years], 58% men, 59 [21%] simple, 111 [40%] moderate, and 107 [39%] complex CHD), AF occurred in 25 patients (9%) a median of 8 months (Q1, Q3: 4, 27 months) after ATCA. New-onset AF was persistent in the majority of the patients (17 of 25 [63%]). Patients with new-onset AF were older (44 years [Q1, Q3: 29, 55 years] vs 36 years [Q1, Q3: 23, 49 years]; P = 0.009) and more frequently had simple CHD (13 of 25 [52%] vs 46 of 252 [18%], respectively; P < 0.0001). Acute ATCA success rates were similar in patients with and without AF (52% vs 48%; P = 0.429). Simple CHD was an independent predictor of new-onset AF during follow-up.

CONCLUSIONS

In our large cohort of patients with congenital heart disease, new-onset AF after ablation for AT occurred in only 9% of the patients. AF occurred without AT recurrence and was persistent in the majority of patients.

Posttransplant atrial fibrillation: Evidence of early posttransplant recipient-to-donor atrioatrial connections

INTRODUCTION

Atrial fibrillation and atrial flutter originating from the donor s heart is a commonly reported complication post heart transplant. Atrial tachyarrhythmia originating from the recipient s heart, propagated through recipient-to-donor connections, is rare with only few cases reported in the literature; most reported cases from our review occur years post-transplant.

CASE

A 47-year-old male presented with atrial tachycardia 6 months post heart transplant. Electrophysiologic study demonstrated atrial fibrillation originating from native heart and propagated through atrio-atrial connections to the donor heart. This arrhythmia was successfully terminated with radiofrequency ablation.

CONCLUSION

Atrio-atrial connection between recipient and donor can form as early as a few months post heart transplant. Radiofrequency ablation appears to be an effective treatment for atrial fibrillation propagated through donor-to-recipient connections.

Morphological evidence of a potential arrhythmogenic substrate in the caudal and cranial vena cava in horses

BACKGROUND

Three-dimensional electro-anatomical mapping, previously performed in horses with atrial arrhythmias, has demonstrated the medial region of the caudal vena cava (CaVC), 1-8 cm caudal to the fossa ovalis, as an anatomical predilection site for atrial tachycardia associated with areas of slow conduction and conduction block. Slow conduction has also been recorded in the cranial vena cava (CrVC).

OBJECTIVES

To investigate the morphological characteristics of the myocardial sleeves (MS) in the CaVC and CrVC, in order to identify a potential substrate of right sided atrial arrhythmias.

STUDY DESIGN

Cross sectional.

METHODS

Post-mortem dissection of 37 hearts from adult warmblood horses without known cardiovascular disease. Macroscopic examination of the myocardial distribution, evaluated the MS area, length, width, and shape in the CaVC and the CrVC. At least 2 samples from each vena cava MS were histologically examined using Masson's trichrome staining.

RESULTS

Myocardial sleeves into the medial CaVC and into the CrVC were observed in all horses and showed variations in distribution, shape, and size between horses. Their mean ± standard deviation length from the limbus into the CaVC reached 5.7 ± 1.0 cm (maximum 8.3 cm), and from the azygos vein into the CrVC 5.3 ± 1.6 cm (maximum 8.6 cm). Myocardium-free islands were observed in the CaVC and CrVC in 30% and 6% of horses, respectively. Histologically, MS showed a non-uniform myocardial fibre arrangement, with presence of fibroadipose tissue, features known to result in slow conduction and pro-arrhythmia.

MAIN LIMITATIONS

Study only included horses without history of atrial arrhythmia.

CONCLUSIONS

Myocardial sleeves are present in both CaVC and CrVC, showing anatomical variations between horses. Tissue characteristics known to favour re-entry were identified indicating that these venae cavae MS are a potential substrate for atrial tachyarrhythmias and a target for treatment by ablation.

A case of atrial tachycardia originating from the left atrial roof successfully ablated via the pulmonary artery approach

A 60-year-old male patient suffered from frequent episodes of atrial tachycardia (AT), after the index procedure of catheter ablation for paroxysmal atrial fibrillation. During the repeat procedure, the activation map showed that the earliest activation site was located at the roof of left atrium. Multiple ablations at the earliest activation site on the roof failed to terminate the AT; however, ablation within the pulmonary artery at an adjacent anatomical site successfully eliminated the AT, even without recording distinct near-field potential.

Catheter Ablation of Atrial Tachycardia after Pulmonary Vein Isolation in a Patient with Common Ostium of Inferior Pulmonary Veins: Case Report

Background and Objectives: Atrial fibrillation (AF), a prevalent cardiac arrhythmia, significantly impacts the quality of life of those affected. The preferred treatment for symptomatic AF, particularly when pharmacological methods fall short, is catheter ablation with pulmonary vein isolation (PVI). While common pulmonary vein (PV) anatomical variants, such as the right accessory pulmonary vein and the common ostium of left pulmonary veins (LCPV), have been studied extensively, their impact on the long-term outcome of PVI is known to be minimal. However, data on less common anomalies, like the common ostium of the left and right inferior pulmonary vein (CIPV), remain scarce in the medical literature. This report aims to shed light on the challenges and outcomes of catheter ablation in a patient with a rare CIPV anomaly. By presenting this case, we contribute to the limited knowledge about the management of such unique anatomical variations in AF treatment and discuss the importance of individualized treatment approaches. Case Presentation: We present a case involving a 56-year-old male diagnosed with AF in 2018. Initial PVI treatment was successful, but the patient experienced symptom recurrence after three years. A preprocedural CT scan before the second ablation revealed a CIPV anomaly. During the repeat procedure, a right superior pulmonary vein (RSPV) reisolation was performed due to identified gaps in the previous ablation line. Post-procedure, the patient maintained a sinus rhythm and reported no further symptoms. Conclusions: This case highlights the importance of recognizing rare PV anatomies like CIPV in the effective management of AF. Tailored ablation strategies, accounting for unique anatomical conditions, can lead to successful long-term outcomes, reinforcing the need for personalized approaches in AF treatment, especially in cases involving complex anatomical variations.

Localized Re-Entry Is a Frequent Mechanism of De Novo Atypical Flutter

BACKGROUND

Limited data exist about the origins and mechanisms of atypical atrial flutter that occurs in the absence of prior ablation or surgery.

OBJECTIVES

The aims of this study were to report a large cohort of patients who presented for catheter ablation of de novo atypical flutters, to identify the most common locations and mechanisms of arrhythmia, and to describe outcomes after ablation.

METHODS

Demographic, electrophysiological, and outcome data were collected for patients who underwent ablation of de novo atypical flutter.

RESULTS

The mechanisms of 85 atypical flutters were identified in 62 patients and localized to the left atrium (LA) in 58 and right atrium (RA) in 27. In the LA, mechanisms were classified as macro-re-entry in 29 (50%) and localized re-entry in 29 (50%), whereas in the RA, mechanisms were macro-re-entry in 8 (30%) and localized re-entry in 19 (70%) (proportion of localized re-entry in the LA vs. RA, P = 0.08). Nine patients had both localized and macro-re-entrant atypical flutters. In the LA, localized re-entry was commonly found in the anterior LA, followed by the pulmonary veins and septum. In the RA, localized re-entry was found at various sites, including the lateral or posterior RA, septum, and coronary sinus ostium. During 39.4 months (Q1-Q3: 18.2-65.8 months) of follow-up, atrial arrhythmias occurred in 66% of patients after a single ablation and in 50% after >1 ablation. Among patients who underwent repeat ablation, compared with the index arrhythmia, different tachycardia circuits or arrhythmias were documented in 13 of 18 cases (72%).

CONCLUSIONS

Atypical atrial flutters in patients without prior surgery or complex ablation are often due to localized re-entry (approximately 50% in the LA and a higher frequency in the RA). Other atrial tachycardias commonly occur during long-term follow-up following ablation, suggesting progressive atrial myopathy in these patients.

SuperMap algorithm: an efficient, safe and accurate modality for mapping and eliminating challenging cardiac arrhythmias

Even with the development of advanced catheter-based mapping systems, there remain several challenges in the electrophysiological evaluation and elimination of atrial arrhythmias. For instance, atrial tachycardias with irregular rates cannot be reliably mapped by systems that require stability in order to sequentially gather data points to be organized thereafter. Separately, these arrhythmias often arise following initial ablation for atrial fibrillation, posing logistic challenges. Here, we present the available literature summarizing the use of a non-contact mapping catheter, the AcQMap catheter, in conjunction with SuperMap, an algorithm that compiles a large number of non-contact data points from multiple catheter positions within the atria. These studies demonstrate the efficiency, safety and accuracy of this technology.

Efficacy and feasibility of vein of Marshall ethanol infusion during persistent atrial fibrillation ablation: A systematic review and meta-analysis

BACKGROUND

Catheter ablation (CA) is currently used to treat persistent atrial fibrillation (PeAF). However, its effectiveness is limited. This study aimed to estimate the effectiveness of the vein of Marshall absolute ethanol injection (VOM-EI) for PeAF ablation.

HYPOTHESIS

Adjunctive vein of Marshall ethanol injection (VOM-EI) strategies are more effective than conventional catheter ablation (CA) and have similar safety outcomes.

METHODS

We extensively searched the literature for studies evaluating the effectiveness and safety of VOM-EI + CA compared with CA alone. The primary endpoint was the rate of acute bidirectional block of the isthmus of the mitral annulus (MIBB). The secondary endpoints were atrial fibrillation (AF) or atrial tachycardia (AT) recurrence over 30 seconds after a 3-month blanking period. Weighted pooled risk ratios (RRs) and corresponding 95% confidence intervals (CIs) were calculated using a random effects model.

RESULTS

Based on the selection criteria, nine studies were included in this systematic review, including patients with AF (n = 2508), persistent AF (n = 1829), perimitral flutter (n = 103), and perimitral AT (n = 165). There were 1028 patients in the VOM-EI + CA group and 1605 in the CA alone group. The VOM-EI + CA group showed a lower rate of AF/AT relapse (RR = 0.70; 95% CI = 0.53-0.91; p = .008) and a higher rate of acute MIBB (RR = 1.29; 95% CI = 1.11-1.50; p = .0007) than the CA alone group.

CONCLUSION

Our meta-analysis revealed that adjunctive VOM-EI strategies are more effective than conventional CA and have similar safety outcomes.

Successful caudal vena cava and pulmonary vein isolation in healthy horses using 3D electro-anatomical mapping and a contact force-guided ablation system

BACKGROUND

Recently, treatment of equine atrial tachycardia by three-dimensional electro-anatomical mapping (3D EAM) and radiofrequency catheter ablation (RFCA) has been described. Myocardial sleeves in the caudal vena cava and pulmonary veins are a potential trigger for initiation and perpetuation of atrial tachycardia and atrial fibrillation in the horse. Isolation of these myocardial sleeves by RFCA may be an effective treatment for these arrhythmias.

OBJECTIVES

To describe the feasibility of 3D EAM and RFCA to isolate caudal vena cava and pulmonary veins in adult horses using 3D mapping and a contact force (CF)-guided ablation system.

STUDY DESIGN

In vivo experiments.

METHODS

3D EAM and RFCA was performed in five horses without cardiovascular disease under general anaesthesia, using the CF-guided system CARTO®3. Point-by-point RFCA aimed for isolation of caudal vena cava and pulmonary veins. Radiofrequency energy was delivered in power-controlled mode with a target power of 45 W, CF between 10 and 15 g and 30 mL/min irrigation rate, until an ablation-index of 450-500 was reached.

RESULTS

In the right atrium, myocardial sleeves of the caudal vena cava were isolated (n = 5). In the left atrium, isolation of ostium II (n = 3), ostium III (n = 1) and ostium I, II and III en bloc (n = 1) was performed. Successful isolation was confirmed by entrance and exit block.

MAIN LIMITATIONS

Horses were euthanised at the end of the procedure, so long term effects such as potential reconnection of isolated veins could not be studied.

CONCLUSIONS

This is the first description of 3D EAM and RFCA with CARTO®3 in horses, thereby showing the technical feasibility and successful caudal vena cava and pulmonary vein isolation. CF measurement allowed monitoring of catheter-tissue contact, resulting in efficient acute lesion creation as confirmed by entrance and exit block. This is a promising treatment for cardiac arrhythmias in horses.

Unidirectional conduction characterizing epicardial connections in patients with atrial tachyarrhythmias

INTRODUCTION

Electrophysiological characteristics of epicardial connections (ECs) in atria and pulmonary veins (PVs) are unclear despite their important contributions to atrial fibrillation (AF). Unidirectional conduction associated with source-sink mismatch can occur in ECs due to their fine fibers with abrupt changes in orientation. We detailed the prevalence and electrophysiological characteristics of unidirectional conduction in the atria and investigated its association with the clinical manifestation of AF.

METHODS

This study retrospectively reviewed electrophysiological studies and radiofrequency catheter ablation in 261 consecutive patients with AF.

RESULTS

Unidirectional conduction was observed during ablation encircling the PVs in eight (3.1%) patients, and all occurred in the suspected (N = 4) or definitively (N = 4) recognized ECs. These ECs included three intercaval bundles, four septopulmonary bundles, and one Marshall bundle, and were first manifested in a second procedure in 6 (75%) patients. The unidirectional property was from PV to atrium (exit conduction) in all intercaval bundles and three septopulmonary bundles, and from atrium to PV (entrance conduction) in the remaining two bundles. Intercaval bundles acted as a limb of bi-atrial macro-reentrant tachycardia (50%, three of the six including previous cases). Ablation of the exit outside the PVs, including the right atrium, eliminated ECs in three (38%) patients. All patients remain free from arrhythmia recurrence after a mean 13-month follow-up.

CONCLUSION

A unidirectional conduction property was closely associated with the EC, as estimated by histological findings. Recognition of this fact by electrophysiologists may help to clarify mechanisms for AF and atrial tachycardia and guide the creation of efficient and safe ablation lesion sets.

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

BACKGROUND

Substrate abnormalities can alter atrial activation during atrial tachycardias (ATs) thereby influencing AT-wave morphology on the surface electrocardiogram.

OBJECTIVES

This study sought to identify determinants of isoelectric intervals during ATs with complex atrial activation patterns.

METHODS

High-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).

RESULTS

ATs 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).

CONCLUSIONS

Reduced atrial activation area and voltage were associated with isoelectric intervals during ATs.

Bidirectional rotating biatrial tachycardia

A 72-year-old man was treated for recurrent atrial tachycardia (AT) and underwent ablation. The AT was diagnosed as bi-AT based on the activation map and the postpacing interval. Another AT appeared and was diagnosed as bi-AT by the same method. Surprisingly, the circuits of both ATs were perfectly matched and rotated in opposite directions. The left atrial anteroseptal wall was ablated during the AT. The AT was immediately stopped and was no longer induced.

Catheter ablation of left atrial tachycardia adjacent to a septal closure device: A multifaceted challenge?

Catheter ablation (CA) of left atrial tachycardia adjacent to implanted septal closure devices represents a multifaceted challenge. We describe the case of a 57-year-old patient with remote percutaneous closure of atrial septal defect who underwent successful CA of left atrial tachycardia adjacent to the septal device using a transaortic approach and RF energy. Besides the technical difficulties and associated risks, interference between the device and applied RF parameters may limit ablation efficiency. Further research is required to evaluate the safety, efficacy, and optimal energy type/parameters when ablating arrhythmias adjacent to these devices.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Antiplatelet and Anti-Coagulation Therapy for Left-Sided Catheter Ablations: What Is beyond Atrial Fibrillation?

Aim: International guidelines on the use of anti-thrombotic therapies in left-sided ablations other than atrial fibrillation (AF) are lacking. The data regarding antiplatelet or anticoagulation strategies after catheter ablation (CA) procedures mainly derive from AF, whereas for the other arrhythmic substrates, the anti-thrombotic approach remains unclear. This survey aims to explore the current practices regarding antithrombotic management before, during, and after left-sided endocardial ablation, not including atrial fibrillation (AF), in patients without other indications for anti-thrombotic therapy. Material and Methods: Electrophysiologists were asked to answer a questionnaire containing questions on antiplatelet (APT) and anticoagulation therapy for the following left-sided procedures: accessory pathway (AP), atrial (AT), and ventricular tachycardia (VT) with and without structural heart disease (SHD). Results: We obtained 41 answers from 41 centers in 15 countries. For AP, before ablation, only four respondents (9.7%) used antiplatelets and two (4.9%) used anticoagulants. At discharge, APT therapy was prescribed by 22 respondents (53.7%), and oral anticoagulant therapy (OAC) only by one (2.4%). In patients with atrial tachycardia (AT), before ablation, APT prophylaxis was prescribed by only four respondents (9.7%) and OAC by eleven (26.8%). At discharge, APT was recommended by 12 respondents (29.3%) and OAC by 24 (58.5%). For VT without SHD, before CA, only six respondents (14.6%) suggested APT and three (7.3%) suggested OAC prophylaxis. At discharge, APT was recommended by fifteen respondents (36.6%) and OAC by five (12.2%). Regarding VT in SHD, before the procedure, eight respondents (19.5%) prescribed APT and five (12.2%) prescribed OAC prophylaxis. At discharge, the administration of anti-thrombotic therapy depended on the LV ejection fraction for eleven respondents (26.8%), on the procedure time for ten (24.4%), and on the radiofrequency time for four (9.8%), with a cut-off value from 1 to 30 min. Conclusions: Our survey indicates that the management of anti-thrombotic therapy surrounding left-sided endocardial ablation of patients without other indications for anti-thrombotic therapy is highly variable. Further studies are necessary to evaluate the safest approach to these procedures.

Atrial echo beats as a novel mechanism of periodic fluctuation in cycle length of atrial tachycardia

Atrial echo beats due to a dual-atrioventricular nodal pathway are a possible cause of fluctuating tachycardia in cycle length (CL) but have not been reported so far. Here, we present a case of an 82-year-old man with symptomatic atrial tachycardia (AT), which was accompanied by periodic fluctuations in atrial sequence at the coronary sinus. Electrophysiological study (EPS) for atrioventricular conduction and three-dimensional (3D) electro-anatomical mapping system explained that the mechanism of periodic fluctuations was due to atrial echo beats through a dual-atrioventricular nodal pathway.

Focal atrial tachycardia arising from left superior pulmonary vein in a pediatric patient, safely treated by pulsed-field ablation

INTRODUCTION

We describe the first case of the use of pulsed-field ablation (PFA) to treat focal atrial tachycardia (FAT) in a pediatric patient.

METHODS

An 11-year-old girl with obesity was referred to our center for ablation of incessant atrial tachycardia. The earliest atrial activation was shown to be present in the left superior pulmonary vein. Radiofrequency ablation of FAT seems to be associated with a lower success rate and, especially, with a higher complication rate than in adult patients.

RESULTS

We performed ablation by means of a novel nonthermal energy source (PFA) that is able to reduce the risk of complications due to injury to anatomic structures surrounding the heart. After the first application, stable sinus rhythm was restored.

CONCLUSIONS

PFA can be used to treat FAT arising from pulmonary veins in young children as a good alternative to RFA ablation, thereby reducing the risk of potential procedure-related complications.

Visualization of the epicardial conduction through the Marshall bundle using the LUMIPOINT™ software

The LUMIPOINT™ software allows visualization of arrhythmia circuits through the MB. In cases where the full extent of the arrhythmia circuit cannot be identified and epicardial conduction is suspected, it is better to perform the analysis while adjusting the confidence slider in LUMIPOINT™.

Wide Complex Tachycardia in a Right-Sided Heart: Diagnostic and Therapeutic Challenges

Dextroposition is a rare cardiac malformation defined as heart shift to right of midline. ECG findings vary with degree of displacement within the chest cavity. We report the second known case of dextroposition with accessory pathway (posteroseptal in our patient), presenting as pre-excited atrial tachycardia. Abnormal anatomy complicates pathway localization/ablation. (Level of Difficulty: Intermediate.).

Hypomagnesemia Caused by Chronic Use of Over-the-Counter Proton Pump Inhibitor as a Possible Cause of Supraventricular Tachycardia

Magnesium is an important co-factor that helps regulates the movement of ions through voltage-mediated channels within myocardial tissues by the membrane sodium-potassium pump, and its deficiency can reduce the pump's activity, leading to partial depolarization and changes in the activity of many potential-dependent membrane channels leading to arrhythmias. In this case report, we are looking to establish the direct relationship between hypomagnesemia caused by proton pump inhibitors (PPIs), which could lead to cardiac arrhythmias. Here, we present a 45-year-old Hispanic female, with a known past medical history of supraventricular tachycardia (SVT), hiatal hernia on proton pump inhibitor (PPI), and chronic smoking, who presented to the emergency department complaining of dizziness and palpitations that started two hours prior arrival to the hospital. At triage, the patient was found to have a heart rate of 190 beats per minute (bpm), and an electrocardiogram (EKG) revealed supraventricular tachycardia with a heart rate of 185 bpm. During the review of this case, no other confounding factors besides hypomagnesemia were noted, leaving this one to be the most likely cause of the arrhythmia. Patients on long-term PPI therapy are at higher risk of developing hypomagnesemia, which could lead to cardiac arrhythmia.

Functional substrate mapping characteristics during sinus rhythm predicts critical isthmus of reentrant atrial tachycardia

BACKGROUND

Atrial tachycardia (AT) is a commonly encountered rhythm disorder in patients with underlying atrial scar. The role of atrial late activation mapping during sinus rhythm to predict the critical isthmus (CI) of AT has yet to be systematically evaluated. We aimed to investigate the relationship between the functional substrate mapping (FSM) characteristics and the CI of reentrant ATs in patients with underlying atrial low-voltage areas.

METHODS

Patients with history of left AT who underwent catheter ablation with 3D mapping using high-density mapping were enrolled. Voltage map and isochronal late activation mapping were created during sinus/paced rhythm to detect deceleration zones (DZ). Electrograms with continuous-fragmented morphology were also tagged. After induction of AT, 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

Among 35 patients [mean age: 62 ± 9, gender: 25 (71.5%) female] with left AT, a total of 42 reentrant ATs induced. Voltage mapping during sinus rhythm revealed low-voltage area of 37.1 ± 23.8% of the left atrium. The mean value of bipolar voltage, EGM duration, and conduction velocity during sinus rhythm corresponding to CI of ATs were 0.18 ± 0.12 mV, 133 ± 47 ms, and 0.12 ± 0.09 m/s, respectively. Total number of DZs per chamber was 1.5 ± 0.6, which were located in the low-voltage zone (<0.5 mV) detected by high-density mapping. All CIs of reentry were colocalized with DZs detected during FSM. The positive predictive value of DZs to detect CI of inducible ATs is 80.4%. Freedom from ATa after the index procedure was 74.3% during a mean follow-up of 12.2 ± 7.5 months.

CONCLUSION

Our findings demonstrated the utility of FSM during sinus rhythm to predict the CI of AT. DZs displayed continuous-fragmented signal morphology with slow conduction which may guide to tailor ablation strategy in case of underlying atrial scar.

Right Heart and Wrong Rhythm: Atrial Flutter in Dextrocardia

Atrial flutter is characterized by rapid atrial activity, causing an abnormal heart rhythm. Recognition and prompt management are of utmost importance since this cardiac arrhythmia could increase the risk of thromboembolic stroke and atrial fibrillation, which may lead to disability and death. Risk factors include myocardial infarction, surgery, medication, and structural heart abnormalities. One distinctive structural abnormality is dextrocardia. Herein, we present a case of a 47-year-old male who initially complains of difficulty in ambulation. Further workup showed atrial flutter with rapid ventricular response on electrocardiogram (ECG) and dextrocardia on imaging. This case tackles the possible association between dextrocardia and arrhythmias, which was an atrial flutter, its management, and treatment outcomes.

Pre-procedural imaging and atrial tachycardia ablation in a patient with complex congenital heart disease

Atrial tachycardias (AT) are common cardiac arrhythmia disorder for congenital heart disease (CHD). The anatomic substrate that surgical suture lines, scar tissue, or prosthetic material may cause pre-existing atrial conduction abnormalities which leads to the underlying mechanism of reentrant ATs. Radiofrequency Catheter ablation (RFCA) is used in the treatment of atrial tachycardia in CHD patients. However venous system abnormalities may complicate the procedure. We report that ablation of a case with atrial tachycardia with challenging anatomy (persistent left superior vena cava draining into the left atrium, coronary sinus agenesis, inferior vena cava (IVC) agenesis, azygos system drained to the superior vena cava, and repaired ventricular septal defect). This case report discusses the key points of access to cardiac chambers and mapping in very rare challenging anatomy.

Epicardial mapping and ablation of biatrial macroreentrant tachycardia via Bachmann's bundle

INTRODUCTION

Recent reports highlighted the role of epicardial connections in the development of biatrial tachycardia circuits.

METHODS

We reported a case of 60-year-old female patient who was admitted with recurrent atrial tachycardia (AT) after endocardial pulmonary vein isolation and anterior mitral line formation.

RESULTS

Epicardial activation map demonstrated fragmented continuous potentials at the Bachmann's bundle region with good entrainment response. Epicardial radiofrequency ablation terminated AT with complete block in the anterior mitral line.

CONCLUSIONS

This case corroborates the data relevant to the role of interatrial connections-specifically Bachmann's bundle-in biatrial macroreentrant ATs and demonstrates that epicardial mapping is an effective method to identify the entire reentrant circuit.

The Roles of Pre-P-wave Versus Peri-P-wave Fractionated Electrograms for Atrial Substrate Beyond Entrainment Response

Atrial tachycardia (AT) with alternating cycle lengths is sparsely reported, and, hence, the ideal mapping strategy has not been firmly established. Beyond the entrainment during tachycardia, some fragmentation characteristics might also give important clues for its possible participation in the macro-re-entrant circuit. We discuss a patient with prior atrial septal defect surgical closures who presented with dual macro-re-entrant ATs related to a fragmented area on the right atrial free wall (240 ms) and the cavotricuspid isthmus (260 ms), respectively. After ablation of the fastest AT on the lateral right atrial free wall, the cycle of the first AT changed to the second AT that was interrupted on cavotricuspid isthmus, proving the dual tachycardia mechanism. This case report addresses the utilization of electroanatomic mapping information as well as fractionated electrogram timing with respect to the surface P-wave as guides for ablation location.

Convergent Double Coronary Sinus Potentials During Atrial Tachycardia

The analysis of the patterns and timing of coronary sinus activation provides a rapid stratification of the most likely macro-re-entrant atrial tachycardias and points toward the likely origin of centrifugal ones by comparing the left atrial and coronary sinus activation sequence and morphology during sinus rhythm and atrial tachycardia. The analysis of both the near- and far-field electrogram morphology of atrial signals also gives important clues in determining the mechanism of the arrhythmia.

Emergent Zero-Fluoroscopy Mapping and Thoracoscopic Ectomy of Appendage in Pregnant Women with Life-Threatening Atrial Tachycardia: A Case Report and Literature Review

Background: Focal atrial tachycardia (AT) originating from the right atrial appendage (RAA), often persistent and refractory, is clinically rare in pregnant woman, and the therapy is much more challenging. We report that a pregnant woman presented with hypotension due to persistent and refractory atrial tachycardia and was successfully cured by a multidisciplinary treatment (MDT) approach, consisting of a combination of zero-fluoroscopy mapping and thoracoscopic atrial appendectomy. We also carried out a literature review of this topic. Methods and Results: A 26-year-old woman in pregnancy at 21 weeks presented with severe palpitation and hypotension due to persistent rapid supraventricular tachycardia (SVT). Since adenosine triphosphate could not terminate the tachycardia, a catheter ablation procedure was planned and finally canceled when the zero-fluoroscopy mapping using Carto 3^TM system revealed an atrial tachycardia originating from the RAA. Thoracoscopic RAA ectomy was recommended after multidisciplinary consultation and successfully performed without fluoroscopy. Ensite^TM velocity mapping system was used for accurately locating the origin of the arrhythmia during ectomy. The woman finally produced a healthy baby during follow-up. Conclusions: Focal AT originating from appendage in pregnant patients can be persistent, refractory, and life-threatening; traditional strategies, such as medicine or catheter ablation, are limited in this situation. MDT measures, using a thoracoscopic ectomy and zero-fluoroscopy three-dimensional electroanatomical mapping technique, is minimally invasive and a promising strategy.

Automatic identification of areas with low-voltage fragmented electrograms for the detection of the critical isthmus of atypical atrial flutters

INTRODUCTION

Critical isthmuses of atypical atrial flutters (AAFLs) are usually located at slow conduction areas that exhibit fractionated electrograms. We tested a novel software, intended for integration with a commercially available navigation system, that automatically detects fractionated electrograms, to identify the critical isthmus in patients with AAFL ablation.

METHODS AND RESULTS

All available patients were analyzed; 27 patients with 33 AAFLs were included. The PentaRay NAV catheter (Biosense Webster) was used for mapping. The novel software was retrospectively applied; fractionated points with duration ≥80 ms and bipolar voltage between 0.05 and 0.5 mV were highlighted on the surface of maps. In 10 randomly chosen AAFLs, an expert electrophysiologist evaluated the positive predictive value of the algorithm to detect true fractionation: 74.4%. We tested the capacity of the software to identify areas of fractionation (defined as clusters of ≥3 adjacent points with fractionation) at the critical isthmus of the AAFLs (defined using conventional mapping criteria). An area of fractionation was identified at the critical isthmus in 30 cases (91%). Globally, 144 areas of fractionation (median number per AAFL 4 [3-6]) were identified. Duration of the fractionation or the surface of the areas was not different between areas at critical isthmuses and the rest. Setting the fractionation score filter of the software in nine provided best performance.

CONCLUSIONS

The novel software detected areas of fractionation at the critical isthmus in most AAFLs, which may help identify the critical isthmus in clinical practice.

Novel findings of an old algorithm: PVC response "Atrial Pace'' initiates atrial arrhythmias in Abbott ICD and CRT-D devices

BACKGROUND

Many algorithms have been developed to ensure the safety and accuracy of cardiac implantable electric devices (CIED). A specific algorithm designed to prevent pacemaker induced tachycardia (PMT) after a premature ventricular complex (PVC response) is available in all Abbott (former St. Jude Medical) CIED. However, a few case reports suggest that this algorithm may be proarrhythmic when programmed to Atrial Pace (A-Pace on PVC).

METHODS

We analyzed the data of all (n = 333) Abbot implantable cardioverter defibrillator (ICD) and cardiac resynchronization defibrillator (CRT-D) devices followed remote using the Merlin.net Patient Care Network in our institute in 2020. Status of the PVC response algorithm A-Pace on PVC or Off was collected, and all atrial mode switch (AMS) episodes longer than 30 s were thoroughly evaluated. Data on clinical characteristics of the patients was collect from the electronic patient records.

RESULTS

A total of 173 patients had A-Pace on PVC and twenty-five of them (14%) had at least one atrial high rate episode (AHRE) >30 s (AHRE) triggered by the action of this algorithm. The median PVC count was higher in patients who had algorithm triggered AHRE than in those with no algorithm-triggered AHRE (1.7% [IQR 0-3.2] vs. 0% [IQR 0-1.1], p < .0001). The major clinical characteristics were comparable in the two groups.

CONCLUSION

The A-Pace on PVC setting was frequently used in our patients. Our study shows that a considerable number of patients had at least one AHRE triggered by the algorithm. The use of this algorithm should be carefully reconsidered.

Leptospirosis-Induced Myocarditis and Arrhythmias

Cardiac manifestations in leptospirosis usually involve atrial arrhythmias, conduction abnormalities, and nonspecific ST-T changes, while left ventricular dysfunction is rare. We present the case of a 45-year-old male without a pre-existing cardiovascular history who developed atrial fibrillation and atrial and ventricular tachycardia, in addition to new-onset cardiomyopathy in the setting of fulminant leptospirosis infection.

Reverse structural left atrial remodeling and atrial tachycardia in patients with repeat ablation for atrial fibrillation

BACKGROUND

Catheter ablation has been evolved to a cornerstone in the therapy of atrial fibrillation (AF); however, atrial tachycardias (AT) after AF ablation are still an important issue. Besides the electrical recurrence of atrial tachyarrhythmia after ablation, left atrial (LA) remodeling has received attention as a consequence of AF.

OBJECTIVE

The aim of this study is to evaluate predictors for AT recurrence and LA remodeling in patients with repeat AF ablation procedures.

METHODS AND RESULTS

One hundred thirteen patients who underwent repeat AF ablation with 3D electro-anatomical mapping system were evaluated. Mean age was 63.1 ± 9.3 years, and 2.3 ± 0.5 ablation procedures were performed during a time period of 22 [IQR 7;48] months. Reverse structural LA remodeling (LA volume decreased more than 15%) was observed in 25 (22.1%) patients. LA volume index (LAVI) during first procedure was the only predictor for positive reverse structural LA remodeling (hazard ratio (HR): 1.03, 95% CI: 1.00-1.07, p = .036) in multivariate analysis. Fifty-nine (52.2%) patients experienced only AF and 54 (47.8%) patients AT after first procedure. Female gender (HR: 5.21, 95% CI: 1.66-18.08, p = .006), LAVI (HR: 1.06, 95% CI: 1.02-1.11, p = .008) and LA scar percentage (HR: 1.08, 95% CI: 1.02-1.17, p = .019) were independent significant predictors for AT recurrence in multivariate analysis.

CONCLUSIONS

Reverse structural LA remodeling occurred in a quarter of patients with repeat ablation procedures for AF. Only larger LAVI during first procedure predicted reverse structural LA remodeling. Half of the patients experienced AT between first and last ablation procedure. Female gender, larger LAVI and larger scar area were significant predictors for AT after catheter ablation for AF.

A Case of Tachycardia-Induced Cardiomyopathy During Pregnancy: Clinical Presentation and Management

A 28-year-old G2P0010 woman with a history of COVID infection during her current pregnancy treated with monoclonal antibodies and benign gestational thrombocytopenia presented for routine prenatal care at 33 weeks' gestation. The patient was asymptomatic, but incidental tachycardia was noted on the physical exam with an irregular rhythm. An electrocardiogram (ECG) was performed and was consistent with multifocal atrial tachycardia at a rate of 144 beats per minute. The patient was started on labetalol 50 mg daily and was referred to cardiology for consultation. An echocardiogram was performed and showed dilated left ventricular cavity with a moderately reduced ejection fraction of 40%. No previous echocardiogram was available for comparison; the patient had no history of cardiac disease. The dose of labetalol was increased to 50 mg twice daily and she was admitted for digoxin loading and titration. Though fetal tolerance was excellent, her heart rate was not controlled. Digoxin was switched to flecainide and labetalol was switched to metoprolol which improved her heart rate and repeat echocardiogram showed an ejection fraction of 50%. The patient was admitted for induction of labor at 39 weeks of gestation and continued intrapartum flecainide. Metoprolol was continued intra and postpartum. Flecainide was resumed at three days postpartum due to the recurrence of atrial tachycardia and has been maintained. A repeat echocardiogram is scheduled six weeks postpartum to evaluate left ventricular function and wean off antiarrhythmics.

Pulsed field ablation in patients with complex consecutive atrial tachycardia in conjunction with ultra-high density mapping: Proof of concept

INTRODUCTION

Catheter-ablation (CA) of consecutive left atrial tachycardias (LAT) can be challenging. Pulsed field ablation (PFA) yields a novel nonthermal CA technology for treatment of atrial fibrillation (AF). There is no data regarding PFA of LAT. This study sought to investigate PFA of consecutive LAT following prior CA of AF.

METHODS

Consecutive patients with LAT underwent ultrahigh-density (UHDx) mapping. Subsequent to identification of the AT mechanism, PFA was performed at the assumed critical sites for LAT maintenance. Continuous ablation lines were performed if required and evaluated with pre- and post-PFA HDx-mapping.

RESULTS

Fifteen patients (age 70 ± 10, male 73%) who underwent 3.6 ± 2 prior AF-CA procedures were included. The total mean procedure and fluoroscopy times were 141 ± 43 and 18 ± 10 min, respectively. All 19 of 19 (100%) LAT were successfully ablated with PFA. Two AT located at the right atria required RF-ablation. LAT were identified as localized reentry (n = 1) and macro-reentry LAT (n = 18) and targeted with PFA. All LAT terminated with PFA either to sinus rhythm (9/15) or a secondary AT (6/15 and subsequently to SR); 63% (12/19) terminated with the first PFA-application. All lines (13 roof, 11 anterior, 1 mitral) were blocked. LA-posterior-wall isolation (LAPWI) was successfully achieved when performed (10/10). AF/AT free survival was 80% (12/15) after 153 [88-207] days of follow-up. No procedure-related complications occurred.

CONCLUSION

PFA of consecutive LAT is feasible and safe. Successful creation of ablation lines and LAPWI can be achieved in a short time. PFA may offer the opportunity for effective ablation of atrial arrhythmias beyond AF.

Narrow Complex Tachycardia With Intermittent 2:1 Atrioventricular Relationship

Narrow QRS complex tachycardia has a broad differential diagnosis. We present a series of rhythm strips with representative onset, transition from 2:1 AV conduction to 1:1 AV conduction, and offset of tachycardia. By analyzing these rhythm strips, we can identify the electrophysiologic mechanism and diagnosis. (Level of Difficulty: Intermediate.).

Case report: Efficacy analysis of radiofrequency catheter ablation combined with atrial appendage resection for atrial tachycardia originating from the atrial appendage in children

Objective

The aim of this study was to investigate the efficacy of radiofrequency catheter ablation (RFCA) combined with atrial appendage (AA) resection to treat atrial tachycardia (AT) originating from the AA in children.

Materials and methods

Using the Ensite three-dimensional electroanatomic mapping system, three children with AT originating from the AA were diagnosed. Clinical features and electrocardiographic (ECG) manifestations were analyzed. Ablations were performed using a cold saline-infused catheter at appendages targeting loci of AT origin under the guidance of the Ensite system. Atrial appendage resection was performed in combination with cardiac surgery, and the curative effect was evaluated.

Results

The ages of the three patients were 3.5, 5.75, and 12.9 years. Two cases originated from the right atrial appendage (RAA) and one originated from the left atrial appendage (LAA). The ECG characteristics of AT from the RAA were as follows: (1) negative P waves in lead V1; (2) positive P waves in leads II, III, and aVF; (3) positive P wave in lead I with varying shapes in lead aVL; and (4) prolonged PR interval with no QRS wave after some P waves. The ECG of the LAA was characterized by (1) positive P waves in lead V1 with a bimodal pattern; (2) positive P waves in leads II, III, and aVF; and (3) negative P waves in leads I and aVL. Preoperative echocardiography showed cardiac enlargement and a decreased left ventricular ejection fraction (LVEF) in all three cases. One case was cured after RFCA, and the remaining two cases required AA resection after RFCA. No recurrence was detected at 1-18 months of follow-up, and the left ventricular end-diastolic diameter and LVEF returned to normal.

Conclusion

Atrial tachycardia originating from the AA in children showed a characteristic P-wave presentation on ECG, and sustained episodes of AT resulted in tachycardia-induced cardiomyopathy. Children who are not successfully controlled by RFCA or who have a recurrence after RFCA could benefit from AA resection.