An Epicardial Connection With a Unidirectional Conduction Property From the Left Atrium to Pulmonary Vein

Role of Sleep-Disordered Breathing and Epicardial Connections in the Recurrence of Atrial Fibrillation

The presence of epicardial connections (ECs) between the pulmonary veins (PVs) and atrium may contribute to atrial fibrillation (AF) recurrence. This study aimed to determine the impact of sleep-disordered breathing (SDB) on the presence of ECs and the interplay between SDB and ECs on AF recurrence.We retrospectively reviewed 400 consecutive non-valvular AF patients. Among them, 235 patients exhibiting a 3% oxygen desaturation index (ODI) of ≥ 10 events/hour underwent polysomnography to evaluate the SDB severity, measured by the apnea-hypopnea index (AHI). To facilitate the ablation of AF and ECs, a high-density mapping catheter (HDMC) was employed. AF recurrence was evaluated over a 12-month period post-AF ablation.The key findings included: 1) 63% of AF patients with ECs had SDB with an AHI ≥ 20 events/hour. 2) Despite achieving complete PV isolations and precise EC ablation using an HDMC, SDB presence was associated with an increased AF recurrence. 3) Continuous positive airway pressure therapy for SDB improved AF recurrence among the AF patients with both ECs and SDB (57% versus 73%; P = 0.016). 4) AHI (odds ratio [OR] = 1.91, ≥ 28.4 events/hour) and left atrial volume (LAV) (OR = 1.42, ≥ 128.3 mL) were independent predictors of the presence of ECs, and AHI (OR = 1.44, ≥ 27.8 events/hour) was an independent predictor of the presence of AF recurrence.It is essential for physicians to recognise the potential complexity of ECs and SDB in AF patients. Thus, screening and treating SDB in AF patients presenting with ECs might play a pivotal role in suppressing AF recurrence.

Identification of epicardial connections can improve the success rate of first-pass right pulmonary vein isolation

Background

Epicardial connections between the right pulmonary vein (PV) and the right atrium have been reported.

Objective

The purpose of this study was to evaluate the usefulness of our new pulmonary vein isolation (PVI) strategy with identification of these epicardial connections.

Methods

Overall, 235 patients with atrial fibrillation were included. High-density mapping of the left atrium was performed to identify the earliest activation sites (EASs) before PVI in all patients. With our new strategy, if EASs around the right PV carina were identified, we ablated these sites and performed usual first-pass circumferential PVI. The patients were divided into 2 groups according to the ablation strategy. One hundred fifteen patients underwent first-pass PVI without information on EASs (nonanalyzed group), and 78 patients underwent ablation at EASs around the right PV carina in addition to PVI (analyzed group). After first-pass ablation around the PV antrum, remapping was performed.

Results

High-density mapping before PVI showed that the prevalence of EASs around the right PV carina was 10.9% in all patients (9.6% in the nonanalyzed group, 12.8% in the analyzed group; P = .74. The first-pass right PVI success rate was higher in the analyzed group than in the nonanalyzed group (93.6% vs 82.6%; P = .04). The radiofrequency application time for PVI was significantly shorter in the analyzed group than in the nonanalyzed group (45.6 ± 1.0 minutes vs 51.2 ± 0.9 minutes; P <.05).

Conclusion

Identification of epicardial connections before ablation could improve the success rate of first-pass right PVI.

Characteristics of right pulmonary vein with an epicardial connection needing additional carina ablation for isolation

Background

This study thought to elucidate the anatomical features that can predict an epicardial connection (EC) between the right pulmonary vein (RPV) and right atrium.

Methods

We retrospectively analyzed 251 consecutive patients undergoing initial radiofrequency pulmonary vein isolation. We defined EC as present when RPV could not be isolated with circumferential ablation and additional ablation for the conduction gap if needed, and RPV isolation could be achieved by ablation for the earliest activation site >10 mm inside the initial ablation line. Using computed tomography data, we evaluated the RPV bifurcation angle, and the area occupation ratio of the carina region to the RPV antrum (ARC) for predicting EC. In subjects with EC undergoing RPV activation mapping after circumferential ablation, the correlation between conduction delay and bipolar/unipolar potential voltage in the carina region was investigated.

Results

There were ECs in 45 out of 251 patients (17.9%). The RPV bifurcation angle (47.7° vs. 38.8°, p < .001) and ARC (37.2% vs. 29.7%, p < .001) were significantly greater in the EC (+) group. Multivariate logistic regression analysis revealed that RPV bifurcation angle (odds ratio [OR]: 1.994, p = .002) and ARC (OR: 3.490, p = .013) were independent predictors of EC. In nine patients with EC undergoing carina region mapping, the unipolar potential voltage was correlated with conduction delay in RPV with EC (R = -0.401, p < .001).

Conclusion

Anatomical features suggesting a wider RPV carina region could predict the presence of EC, and potential with high voltage could be helpful for detecting EC connection sites.

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.

Impact of Interatrial Epicardial Connections on the Dominant Frequency of Atrial Fibrillation

BACKGROUND

An epicardial connection (EC) between the right-sided pulmonary venous (RtPV) carina and right atrium (RA) may preclude PV isolation, but its electrophysiological role during atrial fibrillation (AF) remains unknown.

METHODS AND RESULTS

This prospective observational study included 98 consecutive patients undergoing catheter ablation for AF, subdivided into the EC group (n=17) and non-EC group (n=80) based on observation of RA posterior wall breakthrough during RtPV pacing. Mean left atrial (LA) dominant frequency (mean DFLA) was defined as the averaged DFs at the right and left PVs and LA appendage. The regional DF was higher in the EC group vs. the non-EC group except at the left PV antrum. The DF at the RA appendage (RAA) and mean DFLAwere equivocal (6.5±0.7 vs. 6.6±0.7 Hz) in the EC group, but the mean DFLAwas significantly higher than that at the RAA (5.8±0.6 vs. 6.1±0.5 Hz, P=0.001) in the non-EC group, suggesting an LA-to-RA DF gradient. A significant correlation of DF between the RtPV antrum and RAA was observed in the EC group (P<0.001, r=0.84) but not in the non-EC group.

CONCLUSIONS

An electrophysiological link via interatrial ECs might attenuate the hierarchical nature of activation frequencies of AF, leading to advanced electrical remodeling of the atria.

Epicardial Connections After a Conventional Pulmonary Vein Antrum Isolation in Patients With Atrial Fibrillation

BACKGROUND

The existence of epicardial connection(s) (ECs) between the pulmonary veins (PVs) and atrium may hinder establishing a complete PV antrum isolation (AI) (PVAI) in patients with atrial fibrillation (AF). Thus, the purpose of this study was to determine the prevalence and location of ECs inside the conventional PVAI lines.

METHODS AND RESULTS

Three-hundred consecutive patients with non-valvular AF were evaluated. This study revealed that: (1) the prevalence of patients with ECs and the number of ECs per patient between the PVs and atrium became significantly greater, respectively, in accordance with the progression of paroxysmal to long-lasting AF and left atrial enlargement; (2) some ECs were located at sites far distal to the PVAI lines; (3) 25% of ECs could be detected only by high-density mapping catheters, but not by conventional circular mapping catheters; (4) a B-type natriuretic peptide (BNP) level of 176.6pg/mL and left atrial volume (LAV) of 129.0 mL may be important predictors of the presence of ECs; and (5) the rate of conduction of ECs from the right PVs was dominantly to the atrium and His-bundle, and that from the left PVs to the coronary sinus was most dominant.

CONCLUSIONS

The PVAI may not be completed by using only a conventional PVAI method, and additional EC ablation inside the PVAI lines detected using high-density mapping may be able to achieve a more complete PVAI.