How to ablate the septo-pulmonary bundle: a case-based review of percutaneous ablation strategies to achieve roof line block

Steps to improve the outcome of a single ablation procedure for paroxysmal atrial fibrillation: Significance of a burst stimulation-guided ablation strategy

BACKGROUND

The outcome of a single ablation procedure for paroxysmal atrial fibrillation (PAF) is suboptimal. The value of burst stimulation and additional ablation following the isolation of pulmonary vein (PV) and superior vena cava (SVC) remains unclear.

OBJECTIVE

The aim of this study was to optimize the ablation strategy and improve the outcome of a single procedure for PAF.

METHODS

This retrospective study involved 404 PAF patients who underwent radiofrequency ablation, and were divided into Group 1 (PV + SVC isolation, n = 81) and Group 2 (PV + SVC isolation + burst stimulation-guided ablation, n = 323). In Group 2, additional linear ablation was performed if atrial fibrillation (AF) or atrial flutter (AFL) persisted or was induced by burst stimulation after PV and SVC isolation.

RESULTS

In Group 1, 20 (24.69 %) patients experienced recurrences of AF (n = 16) and AFL (n = 4) during an average follow-up period of 733.60 days. In Group 2, 76 (23.53 %) patients experienced persistent arrhythmias (n = 25) or arrhythmias induced by burst stimulation (n = 51) after PV and SVC isolation, including AF (n = 27) and AFL (n = 49). Ablation along the left atrial roofline, mitral isthmus, and tricuspid isthmus was performed in 37, 34, and 49 patients, respectively. During the average follow-up duration of 660.80 days, the recurrence rate (29/323, 8.98 %) of AF/AFL was significantly lower in Group 2 than that in Group 1 (p < 0.001).

CONCLUSION

Additional stepwise linear ablation guided by burst stimulation significantly improved the outcome of a single ablation procedure for PAF.

Efficacy of the peak frequency map for left atrial posterior wall isolation

INTRODUCTION

Complete isolation of the left atrial posterior wall (LAPW) is challenging owing to overlapping epicardial conduction. Peak frequency (PF) is a novel parameter that focuses on near- and far-field electrogram components. In this study, we aimed to determine whether transmural block completion is related to the ablation site PF.

METHODS

We analyzed 44 consecutive patients undergoing initial LAPW isolation (LAPWI) between June 2023 and February 2024. Pre-LAPWI and PF maps were obtained using an HD-Grid catheter. In 17 of the 44 patients (Group-1), LAPWI was performed conventionally. In the remaining 27 patients (Group-2), PF-guided LAPWI was applied based on Group-1 results.

RESULTS

In Group-1, the left atrial (LA) roof and floor line success rates were 58.8% and 76.5%, respectively. The average PF value in the roof lines of patients with a completed block line was significantly higher than that of the remaining patients (286.6 ± 29.3 Hz vs. 236.1 ± 40.9 Hz, p = .012), but the floor lines were similar. In Group-2, relatively high PF values were targeted to achieve complete block of the LA roof and floor lines, following the results obtained in Group-1. The LA roof line success rates (92.6% vs. 58.8%, p = .007), total number of radiofrequency (RF) applications (22.7 ± 5.6 vs. 27.6 ± 8.5, p = .03), and procedural time (32.6 ± 18.3 vs. 47.9 ± 25.6 min, p = .03) differed between Group-1 and Group-2.

CONCLUSION

Using a PF map for determining the optimal ablation line for LAPWI by RF catheter ablation is feasible.

Catheter ablation for atrial fibrillation: indications and future perspective

Recent advances in techniques, technologies and proven superiority over anti-arrhythmic drugs have made catheter ablation the cornerstone of management for atrial fibrillation (AF), which has shown a steady increase in prevalence in the ageing population worldwide. The aim of therapeutic interventions is to achieve stable sinus rhythm that would improve the quality of life and reduce the risk of AF-associated complications. Pulmonary veins (PVs) were first described as the source of initiation of ectopic triggers driving AF, which led to the establishment of PV isolation (PVI) as the most widely practiced procedure to treat AF. Antral PVI is still recognized as the stand-alone ablation strategy for newly diagnosed paroxysmal AF (PAF). However, in non-PAF patients, PVI seems to be inadequate and several adjunctive strategies, including ablation of left atrial posterior wall and non-PV triggers, AF mapping and ablation of rotors and drivers, ethanol infusion of vein of Marshall and renal denervation, etc. have been reported with mixed results. Recent trials have also documented the benefits of early rhythm control in preventing cardiovascular events in addition to slowing the progression of PAF to more persistent forms. Similarly, very late relapse of the arrhythmia after successful PVI has drawn attention to the critical role of non-PV triggers and highlighted their relevance as potential ablation targets during repeat procedures. Ablation technology is also under constant evolution with the introduction of non-thermal energy sources and new tools to create durable lesions. This review summarizes the indications, advancements, and future perspective of AF ablation.

A novel approach to terminate roof-dependent atrial flutter with epicardial conduction through septopulmonary bundle

Atrial flutter, a prevalent cardiac arrhythmia, is primarily characterized by reentrant circuits in the right atrium. However, atypical forms of atrial flutter present distinct challenges in terms of diagnosis and treatment. In this study, we examine three noteworthy clinical cases of atypical atrial flutter, which offer compelling evidence indicating the implication of the lesser-known Septopulmonary Bundle (SPB). This inference is based on the identification of distinct electrocardiographic patterns observed in these patients and their favorable response to catheter ablation, which is a standard treatment for atrial flutter. Remarkably, in each case, targeted ablation at the anterior portion of the left atrial roof effectively terminated the arrhythmia, thus providing further support for the hypothesis of SPB involvement. These insightful observations shed light on the potential significance of the SPB in the etiology of atypical atrial flutter and introduce a promising therapeutic target. We anticipate that this paper will stimulate further exploration into the role of the SPB in atrial flutter and pave the way for the development of targeted ablation strategies.

Detection of Epicardial Connection Through Intercaval Bundle Involving Right Pulmonary Veins After Ipsilateral Circumferential Ablation by Intra-Atrial Activation Sequence Pacing From the Right Pulmonary Vein

BACKGROUND

An epicardial connection (EC) through the intercaval bundle (EC-ICB) between the right pulmonary vein (RPV) and right atrium (RA) is one of the reasons for the need for carina ablation for PV isolation and may reduce the acute and chronic success of PV isolation. We evaluated the intra-atrial activation sequence during RPV pacing after failure of ipsilateral RPV isolation and sought to identify specific conduction patterns in the presence of EC-ICB.

METHODS AND RESULTS

This study included 223 consecutive patients who underwent initial catheter ablation of atrial fibrillation. If the RPV was not isolated using circumferential ablation or reconnected during the waiting period, an exit map was created during mid-RPV carina pacing. If the earliest site on the exit map was the RA, the patient was classified into the EC-ICB group. The exit map, intra-atrial activation sequence, and RPV-high RA time were evaluated. First-pass isolation of the RPV was not achieved in 36 patients (16.1%), and 22 patients (9.9%) showed reconnection. Twelve and 28 patients were classified into the EC-ICB and non-EC-ICB groups, respectively, after excluding those with multiple ablation lesion sets or incomplete mapping. The intra-atrial activation sequence showed different patterns between the 2 groups. The RPV-high RA time was significantly shorter in the EC-ICB than in the non-EC-ICB group (69.2±15.2 versus 148.6±51.2 ms; P<0.001), and RPV-high RA time<89.0 ms was highly predictive of the existence of an EC-ICB (sensitivity, 91.7%; specificity, 89.3%).

CONCLUSIONS

An EC-ICB can be effectively detected by intra-atrial sequencing during RPV pacing, and an RPV-high RA time of <89.0 ms was highly predictive.