Achievement of successful pulmonary vein isolation: methods of adenosine testing and incremental benefit of exit block

Revisiting exit block after entrance block: Investigation of ablation index-guided pulmonary vein isolation

INTRODUCTION

Unidirectional block, left atrium to pulmonary vein (LA-PV) entrance block without PV-LA exit block, has not been fully investigated in the setting of ablation index (AI)-guided pulmonary vein (PV) isolation (PVI). The aim of this study was to investigate unidirectional blocks during AI-guided PVI.

METHODS

After achieving entrance block, exit block was evaluated by pacing from the catheter placed in the PV. Local PV musculature capture without conduction to the LA was necessary to prove exit block.

RESULTS

In total, 441 PVs (including nine left common PVs) from 113 consecutive patients (mean age: 71 ± 12 years, 77 men, 61 paroxysmal atrial fibrillation cases) who underwent initial AI-guided PVI for atrial fibrillation were studied. Entrance block was achieved in all PVs. of the 247/441 (56%) PVs showing local PV musculature capture, 5/247 (2.0%) showed unidirectional blocks. Three of the five PVs (left superior and inferior PVs in one patient; right superior PV in another patient) showed LA-PV reconnection, requiring additional ablation to achieve bidirectional block during the procedure. Two of the five PVs (left superior and inferior PVs in one patient) showed LA-PV reconnection, and thereafter, LA-PV conduction became blocked again spontaneously, leading to bidirectional block without further ablation during the procedure.

CONCLUSION

AI-guided PVI presented a low prevalence of unidirectional block (2%), using entrance block alone as the endpoint of PVI could therefore be justified.

High-resolution mapping as an alternative for exit block testing in the presence of entrance block after high-power short-duration pulmonary vein isolation

BACKGROUND

After pulmonary vein isolation (PVI) for atrial fibrillation (AF), it is common as an endpoint to demonstrate an exit block from the pulmonary veins (PVs) in addition to an entrance block into them. By using high-resolution mapping catheters, even very small signals can be detected.

OBJECTIVES

We investigated whether additional exit block testing is still necessary when using high-resolution mapping catheters after ablation in high-power short-duration (HPSD) techniques.

MATERIALS AND METHODS

Overall, 114 patients with AF (average age, 65.14 ± 11.3 years; 65.8% male) undergoing radiofrequency PVI were included in the study. Ablation was performed with the HPSD technique using a fixed protocol for energy delivery of 50 W (contact force 3-20 g). Entrance and exit block were tested with a high-resolution mapping catheter. Isolation of the PVs was achieved in all patients.

RESULTS

Capture of local PV tissue was demonstrated in all patients after PVI and exit block was present in all patients after entrance block was detected using a high-resolution mapping catheter.

CONCLUSION

Exit block testing in addition to the demonstration of an entrance block as an endpoint of PVI seems to have no additional benefit and might no longer be necessary when a high-resolution mapping catheter is used in HPSD ablation for PVI of AF.

Effect of electrophysiological mapping on non-transmural annulus ablation and atrial fibrillation recurrence prediction after 6 months of Cox-Maze IV procedure

Objective

The objective of this study was to observe the safety and efficacy of electrophysiological mapping following the Cox-Maze IV procedure and to investigate whether a correlation exists between recurrence of atrial fibrillation (AF) with the completeness of bidirectional electrical isolation and the inducibility of AF immediately after the Cox-Maze IV procedure.

Methods

Totally, 80 consecutive patients who suffered from aortic valve or mitral valve disease and persistent AF were randomly enrolled into the control group and electrophysiological mapping following the Cox-Maze IV group (Electrophysio-Maze group). In the Electrophysio-Maze group, patients underwent concomitant Cox-Maze procedure and following electrophysiological mapping of ablation lines in mitral isthmus, left atrial “box,” and tricuspid annulus. If the bidirectional electrical isolation of tricuspid annulus ablation line is incomplete, whether to implement supplementary ablation will be independently decided by the operator. Before and after the Cox-Maze IV procedure, AF induction was performed. All patients in both groups were continuously followed-up and underwent electrocardiogram Holter monitoring after 6 months.

Results

In total, 42 Electrophysio-Maze patients and 38 controls were enrolled. Compared with patients in the control group, there were shorter hospital stay, better cardiac remodeling changes, and higher relief from AF during the follow-up period of 6 months in the Electrophysio-Maze group. Within the Electrophysio-Maze group, the rate of incomplete the bidirectional electrical isolation of “box” ablation lines was zero, and the rate of incomplete bidirectional electrical isolation of mitral isthmus ablation line or tricuspid annulus ablation line was 23.8%. After two cases of successful complementary ablation on the tricuspid annulus ablation line, the final incomplete bidirectional electrical isolation of annulus ablation lines was 19.0%. There were correlations between late AF recurrence after 6 months with incomplete bidirectional electrical isolation of annulus ablation lines and AF induction immediately after the Cox-Maze IV procedure.

Conclusion

Electrophysiological mapping following the Cox-Maze procedure is safe and effective. Electrophysiological mapping in the Cox-Maze procedure can find out the non-transmural annulus ablation lines by assessing the completeness of bidirectional electrical isolation of ablation lines, guide supplementary ablation, and predict AF recurrence after 6 months.

A deep learning model to predict recurrence of atrial fibrillation after pulmonary vein isolation

Background and Objectives

The efficacy of radiofrequency catheter ablation (RFCA) in atrial fibrillation (AF) is well established. The standard approach to RFCA in AF is pulmonary vein isolation (PVI). However, a large proportion of patients experiences recurrence of atrial tachyarrhythmia. The purpose of this study is to find out whether the AI model can assess AF recurrence in patients who underwent PVI.

Materials and methods

This study was a retrospective cohort study that enrolled consecutive patients who underwent catheter ablation for symptomatic, drug-refractory AF and PVI. We developed an AI algorithm to predict recurrence of AF after PVI using patient demographics and three-dimensional (3D) reconstructed left atrium (LA) images.

Results

We included 527 consecutive patients in the study. The overall mean LA diameter was 42.0 ± 6.8 mm, and the mean LA volume calculated using 3D reconstructed images was 151.1 ± 46.7 ml. During the follow-up period, atrial tachyarrhythmia recurred in 158 patients. The area under the curve (AUC) of the AI model based on a convolutional neural network (including 3D reconstruction images) was 0.61 (95% confidence interval [CI] 0.53–0.74) using the test dataset. The total test accuracy was 66.3% (57.0–75.6), and the sensitivity was 53.3% (34.8–71.9). The specificity was 73.2% (51.8–75.0), and the F1 score was 52.5% 34.5–66.7).

Conclusion

In this study, we developed an AI algorithm to predict recurrence of AF after catheter ablation of PVI using individual reconstructed LA images. This AI model was unable to predict recurrence of AF overwhelmingly; therefore, further large-scale study is needed.

Epicardial and Endocardial Validation of Conduction Block After Thoracoscopic Epicardial Ablation of Atrial Fibrillation

Objective

It is unknown whether epicardial and endocardial validation of bidirectional block after thoracoscopic surgical ablation for atrial fibrillation is comparable. Epicardial validation may lead to false-positive results due to epicardial tissue edema, and thus could leave gaps with subsequent arrhythmia recurrence. It is the aim of the present study to answer this question in patients who underwent hybrid atrial fibrillation ablation (combined thoracoscopic epicardial and endocardial catheter ablation).

Methods

After epicardial ablation of the pulmonary veins (PVs) and connecting inferior and roof lines (box lesion), exit and entrance block were epicardially and endocardially evaluated using an endocardial His Bundle catheter and electrophysiological workstation. If incomplete lesions were found, endocardial touch-up ablation was performed. Validation results were also compared to predictions about conduction block based on tissue conductance measurements of the epicardial ablation device.

Results

Twenty-five patients were included. Epicardial validation results were 100% equal to the endocardial results for the left superior, left inferior, and right inferior PVs and box lesion. For the right superior PV, 85% similarity was found. Based on tissue conductance measurements, 139 lesions were expected to be complete; however, in 5 (3.6%) a gap was present.

Conclusions

Epicardial bidirectional conduction block in the PVs and the box lesion corresponded well with endocardial bidirectional conduction block. Conduction block predictions by changes in tissue conductance failed in few cases compared to block confirmation. This emphasizes that tissue conduction measurements can provide a rough indication of lesion effectiveness but needs endpoint confirmation by either epicardial or endocardial block testing.

Revaluation of the Significance of Demonstrable Exit Block After Radiofrequency Pulmonary Vein Isolation

Background: Demonstration of exit block from the pulmonary vein (PV) to the left atrium after PV isolation (PVI) is not always possible after demonstration of entrance block. We examined factors associated with demonstrable exit block and the relationship between demonstrable exit block and subsequent PV reconnection. Methods and Results: The subjects consisted of 227 patients (908 PV; mean patient age, 59.2±10.8 years; 72.2% male) who underwent radiofrequency PVI, 49 of whom proceeded to the second session after a mean duration of 563.4±456.3 days after the first session. In the first session, exit block was demonstrated in 73.1% of PV, and the predictors were superior PV, longitudinal diameter of the PV, and spontaneous activity in the PV. In the second session (n=49), exit block was demonstrated in 51.0% (33.1% in PV without reconnection vs. 79.7% in PV with reconnection, P<0.0001). Spontaneous activity (OR, 2.74; 95% CI: 1.12-7.03, P=0.0272) and use of a contact force-sensing catheter (OR, 0.42, 95% CI: 0.20-0.85, P=0.0151) were independent predictors of PV reconnection, but demonstrable exit block was not (OR, 1.58; 95% CI: 0.74-3.46, P=0.2377). Conclusions: Inability to demonstrate exit block was not associated with increased risk of future PV reconnection.

Clinical Implications of Unmasking Dormant Conduction After Circumferential Pulmonary Vein Isolation in Atrial Fibrillation Using Adenosine: A Systematic Review and Meta-Analysis

Purpose: Circumferential pulmonary vein isolation (CPVI) is a routine ablation strategy of atrial fibrillation (AF). The adenosine test can be used to unmask dormant conduction (DC) of pulmonary veins after CPVI, thereby demonstrating possible pulmonary vein re-connection and the need for further ablation. However, whether adenosine test could help improve the long term successful rate of CPVI is still controversial. This systemic review and meta-analysis was to determine the clinical utility of the adenosine test.

Methods: PubMed, EMBASE, Web of Science and Cochrane Library database were searched through July 2016 to identify relevant studies using the keywords “dormant pulmonary vein conduction,” “adenosine test,” “circumferential pulmonary vein isolation,” and “atrial fibrillation.” A random-effects model was used to compare pooled outcomes and tested for heterogeneity.

Results: A total of 17 studies including 5,169 participants were included in the final meta-analysis. Two groups of comparisons were classified: (1) Long-term successful rate in those AF patients underwent CPVI with and without adenosine test [Group A (+) and Group A (−)]; (2) Long-term successful rate in those patients who had adenosine test with and without dormant conduction [Group DC (+) and Group DC (−)]. The overall meta-analysis showed that no significant difference can be observed between Group A (+) and Group A (−) (RR 1.08; 95% CI 0.97–1.19; P = 0.16; I² = 66%) and between Group DC (+) and Group DC (−) (RR 1.01; 95% CI 0.91–1.12; P = 0.88; I² = 60%).

Conclusion: Pooled meta-analysis suggested adenosine test may not improve long-term successful rate in AF patients underwent CPVI. Furthermore, AF recurrence may not be decreased by eliminating DC provoked by adenosine, even though adenosine test was applied after CPVI.