Procedural efficiencies, lesion metrics, and 12-month clinical outcomes for Ablation Index-guided 50 W ablation for atrial fibrillation

CLOSE protocol versus lower ablation index value for paroxysmal atrial fibrillation: A randomized noninferior clinical trial

INTRODUCTION

The optimized ablation index (AI) value for catheter ablation of atrial fibrillation (AF) remains to be defined. We aimed to compare the efficacy and safety of CLOSE protocol and lower AI protocol in paroxysmal AF.

METHODS AND RESULTS

Patients with symptomatic, drug-resistant paroxysmal AF for first ablation were prospectively enrolled from September 2020 to January 2022. The patients were randomly divided into CLOSE group (AI ≥ 550 for anterior/roof segments and ≥400 for posterior/inferior segments) and lower AI group (AI ≥ 450 for anterior/roof segments and ≥350 for posterior/inferior segments). First-pass isolation, acute pulmonary vein (PV) reconnections, 1-year arrhythmia recurrence, and major complications were assessed. Of the 270 enrolled patients, 238 completed 1-year follow-up (118 in CLOSE group and 120 in lower AI group). First-pass isolation in left PVs was higher in CLOSE group (71.2% vs. 53.3%, p = .005). Acute PV reconnections were comparable between groups (9.3% vs. 14.2%, p = .246). At 1 year, 86.4% in CLOSE group versus 81.7% in lower AI group were free from atrial arrhythmia (log rank p = .334). The proportion difference was -4.8% (95% CI: -14.1% to 4.6%), and p = .475 for noninferiority. Stroke occurred in four patients of lower AI group, and no cardiac tamponade, atrioesophageal fistula, major bleeding or death occurred post procedure.

CONCLUSION

For patients with paroxysmal AF and treated by AI-guided PV ablation, lower AI is not noninferior to CLOSE protocol.

Comparison of very high-power short-duration, high-power short-duration, and low-power long-duration radiofrequency ablation for atrial fibrillation: A systematic review and network meta-analysis

BACKGROUND

The optimal power and duration settings for radiofrequency (RF) atrial fibrillation (AF) ablation to improve efficacy and safety is unclear. We compared low-power long-duration (LPLD), high-power short-duration (HPSD), and very HPSD (vHPSD) RF settings for AF ablation.

METHODS

This network meta-analysis (NMA) was structured according to the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. Medline, Scopus and Cochrane Central Register of Controlled Trials were systematically searched to identify relevant studies. Observational and randomized studies were included. Eligible studies compared outcomes in AF patients who underwent first-time RF ablation with the following settings: vHPSD (70-90 W, 3-10 s), HPSD (45-60 W, 5-10 s), or LPLD (20-40 W, 20-60 s).

RESULTS

Thirty-six studies comprising 10,375 patients were included (33% female). Frequentist NMA showed LPLD tended toward a lower odds of freedom from arrhythmia (FFA) versus HPSD (OR 0.93, 95% CI 0.86-1.00). There was no difference in FFA between vHPSD versus HPSD. Splitwise interval estimates showed a lower odds of FFA in LPLD versus vHPSD on direct (OR 0.78, 95% CI 0.65-0.93) and network estimates (OR 0.85, 95% CI 0.73-0.98). Frequentist NMA showed less total procedural (TP) time with HPSD versus LPLD (generic variance 1.06, 95% CI 0.83 to 1.29) and no difference between HPSD versus vHPSD.

CONCLUSION

This NMA shows improved procedural times in HPSD and vHPSD versus LPLD. Although HPSD tended toward improved odds of FFA compared to LPLD, the overall result was not statistically significant. The odds of FFA in LPLD was lower versus vHPSD on direct and network estimates on splitwise interval analysis. Large prospective head-to-head randomized trials are needed to validate HPSD and vHPSD settings.

Index-Guided High-Power Radiofrequency Catheter Ablation for Atrial Fibrillation: A Systematic Review and Meta-Analysis Study

PURPOSE OF REVIEW

Studies have suggested the superiority of high-power compared to standard-power radiofrequency ablation ablation (RFCA). This study aimed to assess the efficacy and safety of high-power compared to standard-power RFCA guided by ablation index (AI) or lesion index (LSI).

RECENT FINDINGS

A systematic review and meta-analysis study comparing IGHP and IGLP approaches for AF ablation was conducted. The relevant published studies comparing IGHP and IGSP methods for RFCA in AF patients until October 2022 were collected from Cochrane, ProQuest, PubMed, and ScienceDirect. A total of 2579 AF patients from 11 studies were included, 1682 received IGHP RFCA, and 897 received IGSP RFCA. To achieve successful pulmonary vein isolation (PVI), the IGHP RFCA group had a significantly shorter procedure time than the IGHP RFCA group (mean difference (MD) -19.91 min; 95% CI -25.23 to -14.59 min; p < 0.01), radiofrequency (RF) application time (MD -10.92 min; 95% CI -14.70 to -7.13 min; p < 0.01), and fewer number of lesions (MD -10.90; 95% CI -18.77 to -3.02; p < 0.01) than the IGSP RFCA. First-pass PVI was significantly greater in the IGHP RFCA group than in the IGSP RFCA group (risk ratio (RR) 1.17; 95% CI 1.07 to 1.28; p < 0.01). The IGHP RFCA is an effective and efficient strategy for AF ablation. The superiority of IGHP RFCA includes the shorter procedure time, shorter RF application time, fewer number of lesions for complete PVI, and more excellent first-pass PVI.

Progress in atrial fibrillation ablation during 25 years of Europace journal

The first edition of Europace journal in 1999 came right around the time of the landmark publication of the electrophysiologists from Bordeaux, establishing how elimination of ectopic activity from the pulmonary veins (PVs) resulted in a marked reduction of atrial fibrillation (AF). The past 25 years have seen an incredible surge in scientific interest to develop new catheters and energy sources to optimize durability and safety of ablation, as well as study the mechanisms for AF and devise ablation strategies. While ablation in the beginning was performed with classic 4 mm tip catheters that emitted radiofrequency (RF) energy to create tissue lesions, this evolved to using irrigation and contact force (CF) measurement while increasing power. Also, so-called single-shot devices were developed with balloons and arrays to create larger contiguous lesions, and energy sources changed from RF current to cryogenic ablation and more recently pulsed field ablation with electrical current. Although PV ablation has remained the basis for every AF ablation, it was soon recognized that this was not enough to cure all patients, especially those with non-paroxysmal AF. Standardized approaches for additional ablation targets have been used but have not been satisfactory in all patients so far. This led to highly technical mapping systems that are meant to unravel the drivers for the maintenance of AF. In the following sections, the development of energies, strategies, and tools is described with a focus on the contribution of Europace to publish the outcomes of studies that were done during the past 25 years.

Ostial vs. wide area circumferential ablation guided by the Ablation Index in paroxysmal atrial fibrillation

AIMS

Pulmonary vein isolation (PVI) guided by the Ablation Index (AI) has shown high acute and mid-term efficacy in the treatment of paroxysmal atrial fibrillation (AF). Previous data before the AI-era had suggested that wide-area circumferential ablation (WACA) was preferable to ostial ablation. However, with the use of AI, we hypothesize that ostial circumferential ablation is non-inferior to WACA and can improve outcomes in paroxysmal AF.

METHODS AND RESULTS

Prospective, multicentre, non-randomized, non-inferiority study of consecutive patients were referred for paroxysmal AF ablation from January 2020 to September 2021. All procedures were performed using the AI software, and patients were separated into two different groups: WACA vs. ostial circumferential ablation. Acute reconnection, procedural data, and 1-year arrhythmia recurrence were assessed. During the enrolment period, 162 patients (64% males, mean age of 60 ± 11 years) fulfilled the study inclusion criteria-81 patients [304 pulmonary vein (PV)] in the WACA group and 81 patients (301 PV) in the ostial group. Acute PV reconnection was identified in 7.9% [95% confidence interval (CI), 4.9-11.1%] of PVs in the WACA group compared with 3.3% (95% CI, 1.8-6.1%) of PVs in the ostial group [P < 0.001 for non-inferiority; adjusted odds ratio 0.51 (95% CI, 0.23-0.83), P = 0.05]. Patients in the WACA group had longer ablation (35 vs. 29 min, P = 0.001) and procedure (121 vs. 102 min, P < 0.001) times. No significant difference in arrhythmia recurrence was seen at 1-year of follow-up [11.1% in WACA vs. 9.9% in ostial, hazard ratio 1.13 (95% CI, 0.44-1.94), P = 0.80 for superiority].

CONCLUSION

In paroxysmal AF patients treated with tailored AI-guided PVI, ostial circumferential ablation is not inferior to WACA with regard to acute PV reconnection, while allowing quicker procedures with less ablation time.

Patient experience of very high power short duration radiofrequency ablation for atrial fibrillation under mild conscious sedation

BACKGROUND

Very high power short duration (vHPSD) radiofrequency ablation (RFA) may reduce ablation times and improve patient tolerability, permitting pulmonary vein isolation (PVI) under mild conscious sedation (mCS) and promoting same day discharge (SDD).

METHODS

First, a retrospective feasibility study was performed at 2 tertiary cardiac centres in the UK. Consecutive cases of first-time PVI using vHPSD ablation with 90 W lesions for up to 4 s were compared against cases performed using standard RF (sRF) and cryoballoon (Cryo) therapy. Subsequently, a prospective study of patients who had vHPSD or Cryo exclusively under mCS was undertaken. Questionnaires based on Likert and visual analogue scales (VAS) were used to measure anxiety, discomfort and pain.

RESULTS

In total, 182 patients (59 vHPSD, 62 sRF and 61 Cryo) were included in the retrospective study, with 53 (90%) of vHPSD cases successfully performed under mCS. PVI ablation time in the vHPSD group (5.8 ± 1.7 min) was shorter than for sRF (16.5 ± 6.3 min, p < 0.001) and Cryo (17.5 ± 5.9 min, p < 0.001). Fifty-one vHPSD and 52 Cryo patients were included in the prospective study. PVI ablation time in the vHPSD group was shorter than for the Cryo group (6.4 ± 2.9 min vs 17.9 ± 5.7 min, p < 0.001), but overall procedure duration was longer (121 ± 39 min vs 95 ± 20 min, p < 0.001). There were no differences in the patient experience of anxiety, discomfort or pain. SDD rates were the same in both groups (61% vs 67%, p = 0.49).

CONCLUSIONS

vHPSD RFA for PVI can be performed under mCS to achieve SDD rates comparable to cryoablation, without compromising patient experience.

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.

High-Power, Short-Duration Ablation under the Guidance of Relatively Low Ablation Index Values for Paroxysmal Atrial Fibrillation: Long-Term Outcomes and Characteristics of Recurrent Atrial Arrhythmias

OBJECTIVE

The purpose of this study was to evaluate the difference in effectiveness and safety of high-power, short-duration (HPSD) radiofrequency catheter ablation (RFA) guided by relatively low ablation index (AI) values and conventional RFA in paroxysmal atrial fibrillation (PAF) patients.

METHODS

The HPSD RFA strategy (40-50 W, AI 350-400 for anterior, 320-350 for posterior wall; n = 547) was compared with the conventional RFA strategy (25-40 W, without AI; n = 396) in PAF patients who underwent their first ablation. Propensity-score matching analyses were used to compare the outcomes of the two groups while controlling for confounders.

RESULTS

After using propensity-score matching analysis, the HPSD group showed a higher early recurrence rate (22.727% vs. 13.636%, p = 0.003), similar late recurrence rate, and comparable safety (p = 0.604) compared with the conventional group. For late recurrent atrial arrhythmia types, the rate of regular atrial tachycardia was significantly higher in the HPSD group (p = 0.013). Additionally, the rate of chronic pulmonary vein reconnection and non-pulmonary vein triggers during repeat procedures was similar in both groups.

CONCLUSIONS

For PAF patients, compared with the conventional RFA strategy, the HPSD RFA strategy at relatively low AI settings had a higher early recurrence rate, similar long-term success rate, and comparable safety.

Evolving Role of Catheter Ablation for Atrial Fibrillation: Early and Effective Rhythm Control

Catheter Ablation (CA) is an effective therapeutic option in treating atrial fibrillation (AF). Importantly, recent data show that CA as a rhythm control strategy not only significantly reduces AF burden, but also substantially improves clinical hard endpoints. Since AF is a progressive disease, the time of Diagnosis-to-Intervention appears crucial. Recent evidence shows that earlier rhythm control is associated with a lower risk of adverse cardiovascular outcomes in patients with early AF. Particularly, CA as an initial first line rhythm control strategy is associated with significant reduction of arrhythmia recurrence and rehospitalization in patients with paroxysmal AF. CA is shown to significantly lower the risk of progression from paroxysmal AF to persistent AF. When treating persistent AF, the overall clinical success after ablation remains unsatisfactory, however the ablation outcome in patients with "early" persistent AF appears better than those with "late" persistent AF. "Adjunctive" ablation on top of pulmonary vein isolation (PVI), e.g., ablation of atrial low voltage area, left atrial posterior wall, vein of Marshall, left atrial appendage, etc., may further reduce arrhythmia recurrence in selected patient group. New ablation concepts or new ablation technologies have been developing to optimize therapeutic effects or safety profile and may ultimately improve the clinical outcome.

Comparison of Effectiveness and Safety between High-Power Short-Duration Ablation and Conventional Ablation for Atrial Fibrillation: A Systematic Review and Meta-Analysis

Aim. We aimed to evaluate the effectiveness and safety between high-power short-duration (HPSD) radiofrequency ablation (RFA) and conventional RFA in patients with atrial fibrillation (AF). Methods. Studies comparing HPSD and traditional applications in patients undergoing initial catheter ablation for atrial fibrillation from inception through December 2021 were searched on Pubmed, Medline, Cochrane, and Clinicaltrials.gov. Results. The meta-analysis included seventeen studies with a total of 4934 patients. HPSD group decreased procedure duration (mean difference (MD) −38.28 min, $P<0.001$ ), RF duration (MD −20.51 min, $P<0.001$ ), fluoroscopy duration (MD −5.19 min, $P<0.001$ ), and acute pulmonary vein reconnection (Odds ratio (OR) 0.40, $P<0.001$ ), while improving the freedom from atrial arrhythmia at one year (OR 1.48, 95% confidence interval (CI) 1.12–1.94, $P=0.005$ ) and rates of first-pass isolation (OR 8.92, $P=0.001$ ). Compared with the conventional group, freedom from atrial arrhythmia at one-year follow-up was higher in the HPSD group without the guidance of AI/LSI (OR 1.66, $P=0.01$ ) and studies with a power setting of 40–50 W (OR 1.93, $P=0.002$ ). Nevertheless, the two groups had similar effectiveness with a power setting of 50 W in the HPSD RFA (OR 1.10, $P=0.52$ ). There was no difference in complications between the two groups ( $P=0.71$ ). Conclusion. HPSD RFA was associated with shorter procedure duration, higher freedom from atrial arrhythmia, and comparable safety compared to conventional RFA.

Ablation index-guided 50W radiofrequency ablation for left atrial posterior wall isolation in atrial fibrillation

Background

Ablation index (AI)-guided ablation for posterior wall isolation (PWI) using high-power, short-duration remains untested. We sought to evaluate the acute outcomes of AI-guided 50 W ablation vs. conventional ablation, and investigate the differences in relationship between contact force (CF), time and AI in both groups.

Methods

Consecutive patients undergoing first-time AI-guided ablation with PWI using either 50 W or 35–40 W ablation were enrolled. Acute procedural metrics and individual lesion level ablation data were compared between groups.

Results

40 patients (50 W: n = 20, 35–40 W: n = 20) with atrial fibrillation were included. Total procedure time was significantly reduced with 50 W (120 vs. 143 mins, p = 0.004) and there was a trend toward decreased ablation time (22 vs. 28 mins, p = 0.052). First pass and acute success of PWI were comparable between the 50 W and 35–40 W groups (10 vs. 8 patients, p = 0.525 and 20 vs. 19 patients, p = 1.000, respectively). Individual lesion analysis of all 959 RF applications (50 W: n = 458, 35–40 W: n = 501) demonstrated that 50 W ablation led to lower ablation time per lesion (10.4 vs. 13.0s, p < 0.001), and increased AI (471 vs. 461, p < 0.001) and impedance drop (7.4 vs. 6.9ohms, p = 0.007). Excessive ablations (AI>600 for roof line; AI>500 elsewhere) were more frequently observed in the 50 W group (9.0% vs. 4.6%, p = 0.007). CF had very good discriminative capability for excessive ablation in both groups. At 50 W, limiting the CF to <10 g reduced the number of excessive ablations on the floor line and within the posterior box to 12% and 4%,respectively. Recurrence of atrial arrhythmias at 12 months were comparable between the groups.

Conclusion

AI-guided 50 W RF ablation reduces the ablation time of individual lesions and total procedure time without compromising first pass and acute success rates of PWI or 12-month outcomes compared to conventional powers.

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

Background

Although both high-power (HP) ablation and lesion size index (LSI) are novel approaches to make effective lesions during pulmonary vein isolation (PVI) for atrial fibrillation (AF), the optimal LSI in HP ablation for PVI is still unclear. Our study sought to explore the association between LSI and acute conduction gap formation and investigate the optimal LSI in HP ablation for PVI.

Methods

A total of 105 consecutive patients with AF who underwent HP ablation guided by LSI (LSI-guided HP) for PVI in our institute between June 2019 and July 2020 were retrospectively enrolled. Each ipsilateral PV circle was subdivided into four segments, and ablation power was set to 50 W with target LSI values at 5.0 and 4.0 for anterior and posterior walls, respectively. We compared the LSI values with and without acute conduction gaps after the initial first-pass PVI.

Results

PVI was achieved in all patients, and the incidence of first-pass PVI was 78.1% (82/105). A total of 6,842 lesion sites were analyzed, and the acute conduction gaps were observed in 23 patients (21.9%) with 45 (0.7%) lesion points. The gap formation was significantly associated with lower LSI (3.9 ± 0.4 vs. 4.6 ± 0.4, p < 0.001), lower force-time integral (82.6 ± 24.6 vs. 120.9 ± 40.4 gs, p < 0.001), lower mean contact force (5.7 ± 2.4 vs. 8.5 ± 2.8 g, p < 0.001), shorter ablation duration (10.5 ± 3.6 vs. 15.4 ± 6.4 s, p < 0.001), lower mean temperature (34.4 ± 1.4 vs. 35.6 ± 2.6°C, p < 0.001), and longer interlesion distance (4.4 ± 0.3 vs. 4.3 ± 0.4 mm, p = 0.031). As per the receiver operating characteristic analysis, the LSI had the highest predictive value for gap formation in all PVs segments, with a cutoff of 4.35 for effective ablation (sensitivity 80.0%; specificity 75.4%, areas under the curve: 0.87). The LSI of 4.55 and 3.95 had the highest predictive value for gap formation for the anterior and posterior segments of PVs, respectively.

Conclusion

Using LSI-guided HP ablation for PVI, more than 4.35 of LSI for all PVs segments showed the best predictive value to avoid gap formation for achieving effective first-pass PVI. The LSI of 4.55 for the anterior wall and 3.95 for the posterior wall were the best cutoff values for predicting gap formation, respectively.

Ablation Index-Guided High-Power Radiofrequency Application Shortens the Procedure Time With Similar Outcomes to Conventional Power Application in Atrial Fibrillation Ablation

Background: The impact of high-power radiofrequency (RF) application in ablation index (AI)-guided atrial fibrillation (AF) ablation has not been elucidated.

Methods and Results: We investigated 1,333 patients undergoing first AF ablation (median age 68 years; interquartile range [IQR] 61–73 years). The first 301 patients underwent AI-guided conventional power RF application (CP group), whereas the following 1,032 patients underwent high-power RF application (HP group). The minimum AI target values were 400, 360, and 260 at the left atrial anterior wall, posterior wall, and esophagus, respectively. RF power in the CP group was 30–40, 20–25, and 20 W at the anterior wall, posterior wall, and esophagus, respectively, compared with 50, 40, and 25, respectively, in the HP group. Procedure time was shorter in the HP than CP group (median 153 [IQR 129–190] vs. 180 (IQR 152–229) min; P<0.0001). The percentage of first-pass pulmonary vein isolation (69% vs. 73%; P=0.07) and all procedure-related complications (2.0% vs. 3.4%; P=0.19) was similar. Kaplan-Meier analysis showed similar recurrence-free survival (RFS) for all AF types. Respective 1-year RFS in the CP and HP groups was 82% and 87% in paroxysmal AF, 78% and 82% in persistent AF, and 59% and 58% in long-standing persistent AF.

Conclusions: In AI-guided AF ablation, high-power RF application shortens the procedure time without increasing complications and with similar outcomes.