Optimal Lesion Size Index for Pulmonary Vein Isolation in High-Power Radiofrequency Catheter Ablation of Atrial Fibrillation

Voltage-guided pulmonary vein isolation for atrial fibrillation

BACKGROUND

Bipolar voltage amplitude is capable of helping determine the ideal lesion size index (LSI) setting during radiofrequency ablation for atrial fibrillation (AF).

OBJECTIVE

We aimed to determine whether voltage-guided pulmonary vein isolation (PVI) is noninferior to conventional LSI-guided PVI in patients with nonvalvular AF.

METHODS

This was a multicenter randomized trial conducted during a period of 12 months. The primary efficacy end points of the study were AF recurrence, atrial flutter, and atrial tachycardia, and the noninferiority margin was set at a hazard ratio of 1.4. The primary safety end point was a composite of procedure-related complications.

RESULTS

A total of 370 patients underwent randomization; 189 and 181 were assigned to the voltage (underwent voltage-guided PVI) and control (underwent conventional LSI-guided PVI) groups, respectively. The primary efficacy end point occurred in 22 patients (12.0%) in the voltage group and 23 patients (12.9%) in the control group (1-year Kaplan-Meier event-free rate estimates, 88.0% and 87.1%, respectively; hazard ratio, 1.00; 95% confidence interval, 0.80-1.25). The primary safety end points were 4.8% in the voltage group and 6.6% in the control group (P = .2791). PVI time was significantly shorter in the voltage group (35.7 ± 14.5 minutes vs 39.7 ± 14.7 minutes; P < .001).

CONCLUSION

Voltage-guided PVI was noninferior to conventional LSI-guided PVI with respect to efficacy in the treatment of patients with AF, and its use significantly reduced procedure time. UMIN Clinical Trials Registry: UMIN000042325.

Radiofrequency lesion formation prediction with contact force versus local impedance

PURPOSE OF REVIEW

Safe and effective radiofrequency (RF) myocardial ablation requires real-time monitoring of lesion formation. Here, we review conventional and novel approaches proposed to guide titration of RF energy application.

RECENT FINDINGS

Conventional monitoring modalities, such as ablation electrode temperature, generator impedance, and tissue electrophysiological properties have been of limited value in predicting efficacy and safety of ablation. Therefore, several input-driven indices have been proposed to improve the quality and durability of RF ablation lesion while maintaining safety. These metrics predominantly incorporate RF power output, duration of RF application, and firmness and stability of electrode-tissue contact. More recently, novel catheters have enabled measuring local impedance at the catheter-tissue interface, which has been found valuable for real-time monitoring of RF lesion formation.

SUMMARY

It is likely that using the combination of multiple metrics would be required to improve the quality and safety of RF lesions, but further investigation is still required.

Clinical outcome of lesion size index-guided high-power radiofrequency catheter ablation for pulmonary vein isolation in patients with atrial fibrillation: 2-year follow-up

INTRODUCTION

The long-term efficacy of high-power (50 W) ablation guided by lesion size index (LSI-guided HP) for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) remains undetermined. Our study sought to assess the clinical efficacy of LSI-guided HP ablation for PVI in patients with AF and explore the potential predictors associated with clinical outcomes.

METHODS

We consecutively included 186 patients with AF who underwent LSI-guided HP (50 W) ablation at Fuwai Hospital from June 2019 to October 2021. The target LSI values of 4.5-5.5 and 4.0-4.5 at the anterior and posterior walls, respectively, were used in our study. The baseline clinical characteristics, procedural and ablation data, and clinical outcomes were evaluated. The independent potential predictors associated with AF recurrence were further evaluated.

RESULTS

The incidence rate of first-pass PVI was 83.9% (156/186). A total of 11 883 lesions were analyzed, and compared with posterior walls of pulmonary veins, anterior walls had significantly lower mean contact force (8.2 ± 3.0 vs. 8.3 ± 2.3 g, p = .015), longer mean radiofrequency duration (16.9 ± 7.2 vs. 12.9 ± 4.5 s, p < .001) and higher mean LSI (4.8 ± 0.2 vs. 4.4 ± 0.2, p < .001). The overall incidence of periprocedural complications was 3.7%, and steam pops without pericardial effusion occurred in three patients (1.6%). During a mean follow-up of 24.0 ± 8.4 months, the overall AF recurrence-free survival was 87.1% after a single procedure. Patients with paroxysmal AF had a higher incidence of freedom from AF recurrence than those with persistent AF (91.2% vs. 80.8%, log-rank p = .034). Higher LSI (HR 0.50, p < .001) and paroxysmal AF (HR 0.39, p = .029) were significantly associated with decreased AF recurrence. By receiver operating characteristic analysis, the LSI of 4.7 and 4.3 for the anterior and posterior walls of the PVs had the highest predictive value for AF recurrence, respectively.

CONCLUSION

LSI-guided HP (50 W) ablation for PVI was an efficient and safe strategy and led to favorable single-procedure 2-year AF recurrence-free survival in patients with AF. Higher LSI and paroxysmal AF were independent predictors of decreased 2-year AF recurrence. The LSI of 4.7 for the anterior wall and 4.3 for the posterior wall of the PVs were the best cutoff values for predicting AF recurrence after LSI-guided HP ablation.

Unipolar Electrogram-Guided versus Lesion Size Index-Guided Catheter Ablation in Patients with Paroxysmal Atrial Fibrillation

Background: This research explores the relationship between the unipolar electrogram (UP-EGM) and lesion size index (LSI) in different regions of continuous circular lesions (CCLs) and to assess the safety and efficacy of UP-EGM-guided versus LSI-guided radiofrequency catheter ablation (RFCA) in patients with paroxysmal atrial fibrillation (PAF). Methods: A total of 120 patients with drug-refractory PAF who underwent index RFCA were scheduled to be consecutively included from March 2020 to April 2021. All the patients were randomly divided 1:1 into two groups: the UP-EGM group and the LSI group. The first-pass PVI rate, acute PVI rate, and the sinus rhythm maintenance rate were compared. Results: A total of 120 patients with PAF were included in the study: the UP-EGM group (n = 60) and the LSI group (n = 60). All the LSI values in the UP-EGM group were less than those in the corresponding regions in the LSI group (all p < 0.001). There were no significant differences in the first-pass PVI rate and acute PVI rate between the two groups. After a mean follow-up period of 11.31 ± 1.70 months, the sinus rhythm maintenance rate in the UP-EGM group was comparable to that in the LSI group (90% vs. 91.7%, p = 0.752). Conclusion: UP-EGM-guided and LSI-guided RFCA are both effective and safe in patients with PAF. However, UP-EGM may be more suitable than LSI for guiding individual RFCA.