Prospective use of Ablation Index targets improves clinical outcomes following ablation for atrial fibrillation

Comparison of Second-Generation Cryoballoon Ablation and Quantitative Radiofrequency Ablation Guided by Ablation Index for Atrial Fibrillation

We compared the efficacy and complication rates of quantitative radiofrequency ablation guided by ablation index (RFCA-AI) with those of second-generation cryoballoon ablation (CBA-2). Consecutive patients (n = 230) with symptomatic atrial fibrillation (AF) undergoing a first ablation CBA-2 (92 patients) or RFCA-AI (138 patients) procedure were enrolled in this study. The late recurrence rate in the CBA-2 group was higher than that in the RFCA-AI group (P = .012). Subgroup analysis showed the same result in patients with paroxysmal AF (PAF) (P = .039), but no difference was found in patients with persistent AF (P = .21). The average operation duration in the CBA-2 group (85 [75-99.5] minutes) was shorter than that in the RFCA-AI group (100 [84.5-120] minutes) (P < .0001), but the average exposure time (17.36(13.87-22.49) vs 5.49(4.00-8.24) minutes) in the CBA-2 group and X-ray dose (223.25(149.15-336.95) vs 109.15(80.75-168.7) mGym) were significantly longer than those in RFCA-AI group (P < .0001). Multivariate logistic regression analysis showed that left atrial diameter (LAD), early recurrence, and methods of ablation (cryoballoon ablation) were independent risk factors for late recurrence after AF ablation. Early recurrence of AF and LAD were independent risk factors for predicting late recurrence after AF ablation.

Impedance-guided modified CLOSE protocol ablation can reduce ablation index necessary for pulmonary vein isolation in patients with atrial fibrillation

BACKGROUND

Real-time monitoring of generator impedance drop is not considered in CLOSE protocol pulmonary vein (PV) isolation (PVI) in patients with atrial fibrillation (AF). We verified whether additional information of impedance drop could minimize ablation index required for PVI using modified CLOSE protocol (target ablation index ≥ 500 on anterior wall and ≥400 on posterior wall along with inter-lesion distance of 3-6 mm and maximum power of 35 W) without any adverse effect of procedural data and efficacy.

METHODS

Sixty consecutive Japanese AF patients [paroxysmal AF: 43 (72 %) patients] underwent first-time PVI with modified CLOSE protocol with real-time monitoring of impedance drop (impedance-guided modified CLOSE protocol). Ablation tags were colored according to impedance drop and ablation was immediately terminated before reaching target ablation index if impedance drop of ≥10 Ω was confirmed. Ablation index needed for PVI, first-pass PVI rate, other procedural data, and atrial tachyarrhythmia recurrence were evaluated.

RESULTS

Mean ablation index and impedance drop on anterior and posterior walls were 437.6 ± 43.5 Ω and 10.2 ± 2.6 Ω and 393.3 ± 27.4 Ω and 9.3 ± 2.2 Ω, respectively. First-pass PVI per PV pair was accomplished in 90/120 (75 %). No complications occurred. PV gaps after first-pass ablation were locationally most often found on right posterior wall than on the other parts (p < 0.001). There were no differences in mean contact force, impedance drop, and ablation index between walls with and without PV gaps after first-pass PV ablation. During a mean follow-up of 24 ± 9 months, survival from atrial tachyarrhythmia recurrence was 51/60 (85 %) patients.

CONCLUSIONS

Using additional generator impedance drop information may be useful to minimize radiofrequency current application to accomplish PVI with modified CLOSE protocol while maintaining efficacy and safety in Japanese AF population.

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.

Very high-power short-duration catheter ablation for treatment of cardiac arrhythmias: Insights from the FAST and FURIOUS study series

The QDOT MICRO™ Catheter is a novel open-irrigated contact force-sensing radiofrequency ablation catheter. It offers very high-power short-duration (vHPSD) ablation with 90 W for 4 s to improve safety and efficacy of catheter ablation procedures. Although the QDOT MICRO™ Catheter was mainly designed for pulmonary vein isolation (PVI) its versatility to treat atrial fibrillation (AF) and other types of arrhythmias was recently evaluated by the FAST and FURIOUS study series and other studies and will be presented in this article. Available study and registry data as well as case reports concerning utilization of the QDOT MICRO™ Catheter for the treatment of cardiac arrhythmias including AF, focal and macroreentry atrial tachycardia, typical atrial flutter by cavotricuspid isthmus block, premature ventricular contractions, and accessory pathways were reviewed and summarized. In summary, the QDOT MICRO™ Catheter showed safety and efficacy for PVI and is able to treat also other types of arrhythmias as is was recently evaluated by case reports and the FAST and FURIOUS studies.

Pulmonary vein isolation durability after very high-power short-duration ablation utilizing a very-close protocol - The FAST AND FURIOUS redo study

Background

Very high-power short-duration (vHP-SD) radiofrequency (RF) ablation of atrial fibrillation (AF) treatment by pulmonary vein isolation (PVI) aims for safer, more effective and faster procedures. Although acute efficacy and safety for PVI was recently shown data on chronic PVI durability is limited. Here chronic PVI durability was evaluated during repeat electrophysiological procedures in patients after initial vHP-SD and conventional RF based PVI.

Methods

A total of 25 consecutive patients with repeat left atrial procedures after initial vHP-SD based PVI were included in this study. Twenty-five patients with previous conventional RF based PVI and repeat left atrial procedures served as control (control group).

Results

For index procedures the median RF time was 328 (277, 392) seconds (vHP-SD) and 1470 (1310, 1742) seconds (control); p < 0.001, the median procedure time was 55 (53, 68) minutes (vHP-SD) and 110 (94, 119) (control); p < 0.001). First pass isolation rate was 84 % (vHP-SD) and 88 % (control, p = 0.888). No differences for severe adverse events (vHP-SD: 1/25, 4 % vs. control: 0/25, 0 %; p = 0.676 were detected.Chronic durability of all PVs was assessed in vHP-SD: 16/25 (64 %) and control: 8/25 (32 %) patients (p = 0.023) and vHP-SD: 81 % and control: 62 % of PVs were found to be isolated (p = 0.003). For right PVs vHP-SD: 84 % vs. control: 60 % of PVs (p < 0.001) and for left PVs vHP-SD: 78 % vs. control: 64 % (p = 0.123) were found to be isolated.

Conclusions

PVI solely utilizing vHP-SD via a very close-protocol provides fast, safe and effective acute PVI. High rates of chronically isolated pulmonary veins have been detected.

Lower contact force predicts right pulmonary vein carina breakthrough after ablation index-guided pulmonary vein isolation using high-power short-duration

INTRODUCTION

Carina breakthrough (CB) at the right pulmonary vein (RPV) can occur after circumferential pulmonary vein isolation (PVI) due to epicardial bridging or transient tissue edema. High-power short-duration (HPSD) ablation may increase the incidence of RPV CB. Currently, the surrogate of ablation parameters to predict RPV CB is not well established. This study investigated predictors of RPV CB in patients undergoing ablation index (AI)-guided PVI with HPSD.

METHODS

The study included 62 patients with symptomatic atrial fibrillation (AF) who underwent AI-guided PVI using HPSD. Patients were categorized into two groups based on the presence or absence of RPV CB. Lesions adjacent to the RPV carina were assessed, and CB was confirmed through residual voltage, low voltage along the ablation lesions, and activation wavefront propagation.

RESULTS

Out of the 62 patients, 21 (33.87%) experienced RPV CB (Group 1), while 41 (66.13%) achieved first-pass RPV isolation (Group 2). Despite similar AI and HPSD, patients with RPV CB had lower contact force (CF) at lesions adjacent to the RPV carina. Receiver operating characteristic (ROC) curve analysis identified CF < 10.5 g as a predictor of RPV CB, with 75.7% sensitivity and 56.2% specificity (area under the curve: 0.714).

CONCLUSION

In patients undergoing AI-guided PVI with HPSD, lower CF adjacent to the carina was associated with a higher risk of RPV CB. These findings suggest that maintaining higher CF during ablation in this region may reduce the occurrence of RPV CB.

Successful caudal vena cava and pulmonary vein isolation in healthy horses using 3D electro-anatomical mapping and a contact force-guided ablation system

BACKGROUND

Recently, treatment of equine atrial tachycardia by three-dimensional electro-anatomical mapping (3D EAM) and radiofrequency catheter ablation (RFCA) has been described. Myocardial sleeves in the caudal vena cava and pulmonary veins are a potential trigger for initiation and perpetuation of atrial tachycardia and atrial fibrillation in the horse. Isolation of these myocardial sleeves by RFCA may be an effective treatment for these arrhythmias.

OBJECTIVES

To describe the feasibility of 3D EAM and RFCA to isolate caudal vena cava and pulmonary veins in adult horses using 3D mapping and a contact force (CF)-guided ablation system.

STUDY DESIGN

In vivo experiments.

METHODS

3D EAM and RFCA was performed in five horses without cardiovascular disease under general anaesthesia, using the CF-guided system CARTO®3. Point-by-point RFCA aimed for isolation of caudal vena cava and pulmonary veins. Radiofrequency energy was delivered in power-controlled mode with a target power of 45 W, CF between 10 and 15 g and 30 mL/min irrigation rate, until an ablation-index of 450-500 was reached.

RESULTS

In the right atrium, myocardial sleeves of the caudal vena cava were isolated (n = 5). In the left atrium, isolation of ostium II (n = 3), ostium III (n = 1) and ostium I, II and III en bloc (n = 1) was performed. Successful isolation was confirmed by entrance and exit block.

MAIN LIMITATIONS

Horses were euthanised at the end of the procedure, so long term effects such as potential reconnection of isolated veins could not be studied.

CONCLUSIONS

This is the first description of 3D EAM and RFCA with CARTO®3 in horses, thereby showing the technical feasibility and successful caudal vena cava and pulmonary vein isolation. CF measurement allowed monitoring of catheter-tissue contact, resulting in efficient acute lesion creation as confirmed by entrance and exit block. This is a promising treatment for cardiac arrhythmias in horses.

Comparison of myocardial injury and inflammation between ablation index-guided and conventional contact force-guided ablation in atrial fibrillation patients

PURPOSE

Ablation index (AI)-guided ablation improves the incidence of arrhythmia recurrence as compared to conventional contact force (CF)-guided ablation. The aim of this study was to elucidate the differences in the biomarkers associated with myocardial injury and inflammation between conventional CF-guided and AI-guided ablation.

METHODS

Atrial fibrillation (AF) patients who underwent pulmonary vein isolation (PVI) from the Osaka Rosai Atrial Fibrillation ablation (ORAF) registry were enrolled. We divided the patients into two groups: conventional CF-guided PVI (CF group) and AI-guided PVI (AI group). The differences in biomarkers associated with myocardial injury and inflammation, and long-term durability of PVI between the two groups were evaluated.

RESULTS

This study population included a total of 794 patients (CF-guided, 241 patients; AI-guided, 553 patients). Total application time was significantly shorter, and total application number was significantly smaller in AI than CF group. High-sensitive troponin I (hs-TnI) post-ablation was significantly higher in AI than CF group (p < 0.001), even after taking the total application number and total application time into consideration. No significant differences in inflammatory markers changes from pre- to post-ablation were observed between the two groups. AI-guided ablation was significantly associated with the hs-TnI post-ablation by multiple regression analysis. The PV reconnection ratio was significantly smaller in AI than CF group (p = 0.037).

CONCLUSIONS

AI-guided ablation had the ability to create larger lesions than CF-guided ablation despite no increase in inflammation and achieved the better PVI durability than that of CF-guided.

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.

The Impact of Regional Maximum Tolerated Interlesion Distance on the Long-Term Ablation Outcomes in Ablation Index Guided Pulmonary Vein Isolation for Atrial Fibrillation

BACKGROUND

An adequate interlesion distance (ILD) applied during point-by-point pulmonary vein (PV) isolation for atrial fibrillation (AF) has never been established. We hypothesized that maximum tolerated ILD may differ between PV regions and may influence long-term ablation outcomes.

METHODS

A total of 260 AF patients underwent PV isolation with 3D electroanatomical platform. Postablation, ILD values were classified into 5 groups (6-5.5 mm, 5.5-5.0 mm, 5.0-4.5 mm, 4.5-4.0 mm and <4.0 mm); the number of tags in each group was calculated and correlated with postablation AF recurrence (AFR). All measurements were performed globally for the entire encirclement around each individual PV and regionally for designated PV anatomic segments.

RESULTS

Single-procedure freedom from AF was 81% for paroxysmal and 66% for persistent AF at 12 months. Global analysis showed that AFR was not related to median ILD nor the number of lesions within each ILD tag group for any PV. Segmental analysis showed that AFR was not related to median ILD. However, the presence of tags from the 5.5-6.0 mm ILD group located on the posterior aspect of right upper PV (RUPV) correlated with AFR. This was confirmed in a multivariable logistic regression model.

CONCLUSIONS

Maximum tolerated ILD of 6.0 mm translated into well-accepted ablation results. However, the study suggests that it may be inadequate at the posterior aspect of RUPV.

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.

Very high-power short-duration ablation for pulmonary vein isolation utilizing a very-close protocol-the FAST AND FURIOUS PVI study

AIMS

The very high-power short-duration (vHP-SD) radiofrequency (RF) ablation concept of atrial fibrillation (AF) treatment by pulmonary vein isolation (PVI) aims for safer, more effective, and faster procedures. Utilizing conventional ablation, the 'close protocol' has been verified. Since lesion formation of vHP-SD ablation creates wider but shallower lesions we adapted the close protocol to an individualized and tighter 'very-close protocol' of 3-4 mm of inter-lesion distance (ILD) at the anterior and 5-6 mm at the posterior aspect of the left atrium using vHP-SD only. Here, we evaluated the safety and efficacy of vHP-SD ablation for PVI utilizing a very-close protocol in comparison with standard ablation.

METHODS AND RESULTS

A total of 50 consecutive patients with symptomatic AF were treated with a very-close protocol utilizing vHP-SD (vHP-SD group). The data were compared with 50 consecutive patients treated by the ablation-index-guided strategy (control group). The mean RF time was 352 ± 81 s (vHP-SD) and 1657 ± 570 s (control, P < 0.0001), and the mean procedure duration was 59 ± 13 (vHP-SD) and 101 ± 38 (control, P < 0.0001). The first-pass isolation rate was 74% (vHP-SD) and 76% (control, P = 0.817). Severe adverse events were reported in 1 (2%, vHP-SD) and 3 (6%, control) patients (P = 0.307). A 12-month recurrence-free survival was 78% (vHP-SD) and 64% (control, P = 0.142). PVI durability assessed during redo-procedures was 75% (vHP-SD) vs. 33% (control, P < 0.001).

CONCLUSIONS

PVI solely utilizing vHP-SD via a very-close protocol provides safe and effective procedures with a high rate of first-pass isolations. The procedure duration and ablation time were remarkably low. A 12-month follow-up and PVI durability are promising.

The Importance of a Distance between the Lines Encircling Pulmonary Veins in Atrial Fibrillation Ablation on First-Pass Isolation Ratio and Clinical Outcomes

INTRODUCTION

How wide the encircling line is made may influence the outcomes of pulmonary vein isolation (PVI). In the present study we hypothesised that the distance between the lines encircling the pulmonary veins may correspond with the extent of wide antral circumferential ablation (WACA). The aim of the study was to assess the impact of the distance and the area between the lines on the posterior wall of the left atrium on first-pass isolation rate and 12-month freedom from atrial arrhythmia in patients undergoing PVI ablation.

METHODS AND RESULTS

One hundred sixteen patients underwent circumferential ablation index (AI)-guided PVI. The distance between the encircling ablation lines was measured off-line between the uppermost points (right and left) and the lowest points and as the area between the encircling lines on the posterior wall. The first-pass isolation rate and 12-month freedom from atrial arrhythmia were 59% and 73%, respectively. Distance between the encircling lines measured linearly or as the area of the posterior wall, assessed as direct values or indexed to left atrial dimensions, did not differ between patients with and without first-pass isolation or between patients with and without recurrences of atrial arrhythmia.

CONCLUSIONS

The distance between the ablation lines did not influence the rate of first-pass isolation and arrhythmia recurrence in the long-term follow-up after PVI procedures incorporating the ablation index protocol.

Validation of the accuracy of contact force measurement by contemporary force-sensing ablation catheters

INTRODUCTION

Contact force sensing catheters are widely used for ablation of cardiac arrhythmias. They allow quantification of catheter-to-tissue contact, which is an important determinant for lesion formation and may reduce the risk of complications. The accuracy of these sensors may vary across the measurement range, catheter-to-tissue angle, and amongst manufacturers. We aim to compare the accuracy and reproducibility of four different force sensing ablation catheters.

METHODS

A measurement setup containing a heated saline water bath with an integrated force measurement unit was constructed and validated. Subsequently, we investigated four different catheter models, each equipped with a unique measurement technology: Tacticath Quartz (Abbott), AcQBlate Force (Biotronik/Acutus), Stablepoint (Boston Scientific), and Smarttouch SF (Biosense Webster). For each model, the accuracy of three different catheters was measured within the range of 0-60 g and at contact angles of 0°, 30°, 45°, 60°, and 90°.

RESULTS

In total, 6685 measurements were performed using 4 × 3 catheters (median of 568, interquartile range: 511-606 measurements per catheter). Over the entire measurement-range, the force measured by the catheters deviated from the real force by the following absolute mean values: Tacticath 1.29 ± 0.99 g, AcQBlate Force 2.87 ± 2.37 g, Stablepoint 1.38 ± 1.29 g, and Smarttouch 2.26 ± 2.70 g. For some models, significant under- and overestimation of >10 g were observed at higher forces. Mean absolute errors of all models across the range of 10-40 g were <3 g.

CONCLUSION

Contact measured by force-sensing catheters is accurate with 1-3 g deviation within the range of 10-40 g. Significant errors can occur at higher forces with potential clinical consequences.

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.

Ablation index-guided high-power vs. moderate-power cavotricuspid isthmus ablation

Ablation index (AI)-guided ablation is useful for pulmonary vein isolation (PVI) and cavotricuspid isthmus (CTI) ablation. However, the impact of radiofrequency (RF) application power on CTI ablation with a fixed target AI remains unclear. One-hundred-thirty drug-refractory atrial fibrillation and/or atrial flutter patients who underwent AI-guided CTI ablation with or without PVI between July 2020 and August 2021 were randomly assigned to high-power (45 W) and moderate-power (35 W) groups. We performed CTI ablation with the same target AI value in both groups: 500 for the anterior 1/3 segments and 450 for the posterior 2/3 segments. In total, first-pass conduction block of the CTI was obtained in 111 patients (85.4%), with 7 patients (5.4%) showing CTI reconnection. The rate of first-pass conduction block was significantly higher in the 45 W group (61/65, 93.8%) than in the 35 W group (50/65, 76.9%, P = 0.01). CTI ablation and CTI fluoroscopy time were significantly shorter in the 45 W group than in the 35 W group (CTI ablation time: 192.3 ± 84.8 vs. 319.8 ± 171.4 s, P < 0.0001; CTI fluoroscopy time: 125.2 ± 122.4 vs. 171.2 ± 124.0 s, P = 0.039). Although there was no significant difference, steam pops were identified in two patients from the 45 W group at the anterior segment of the CTI. The 45 W ablation strategy was faster and provided a higher probability of first-pass conduction block than the 35 W ablation strategy for CTI ablation with a fixed AI target.

High-power short-duration versus low-power long-duration ablation guided by the ablation index

AIMS

To compare the two different ablation strategies, both guided by the Ablation Index (AI), in the setting of atrial fibrillation (AF) ablation: high-power short-duration (HPSD) ablation using 40 W on the posterior wall and 50 W elsewhere versus low-power long-duration (LPLD) using 25 W posteriorly and 35 W elsewhere.

METHODS

Prospective, multicenter nonrandomized, noninferiority study of consecutive patients referred for paroxysmal AF ablation from January 2018 to July 2019. Ablation was guided by the AI (≥500 for anterior segments, ≥450 for the roof and inferior segments and 400 posteriorly) and an interlesion distance (ILD) ≤ 6 mm. Patients were separated into two groups: HPSD vs LPLD. Acute reconnection (after adenosine trial) and 2-year outcomes were assessed.

RESULTS

160 patients (61% males, median age of 62 [IQR 51-69] years), fulfilled the study inclusion criteria - 80 patients (316 pulmonary veins [PV]) in the HPSD group and 80 patients (314 PV) in the LPLD. The probability of acute PV reconnection was similar between both groups: 2.2% in HPSD, 95%CI 0.6% to 3.8% vs. 3.4% in LPLD, 95%CI 1.4% to 5.4%; p < 0.001 for noninferiority. Median PV ablation time (20 min vs 30 min, p < 0.01) and procedure duration (80 min vs 100 min, p < 0.001) were shorter in the HPSD group. After a median follow-up of 26 months, arrhythmia recurrence was similar between groups (17.5% in HPSD group vs. 18.8% in LPLD group, p = 0.79).

CONCLUSIONS

In paroxysmal AF patients treated with the Ablation Index, a HPSD strategy is noninferior to the more standard LPLD ablation, while allowing for quicker procedures with shorter ablation times.

Posterior wall substrate modification using optimized and contiguous lesions in patients with atrial fibrillation

BACKGROUND

Radiofrequency (RF) linear ablation at the left atrial (LA) roof and bottom to isolate the LA posterior wall using contiguous and optimized RF lesions was evaluated. Achieving isolation of the LA posterior wall is challenging as two continuous linear lesion sets are necessary.

METHODS

Forty consecutive patients with symptomatic atrial fibrillation (AF) and arrhythmia substrates affecting the LA posterior wall underwent posterior wall isolation by linear lesions across the roof and bottom. The cohort was divided into two groups: group 1 (20 patients) linear ablation guided by contact force (CF) only; group 2 (20 patients) guided by ablation index (AI) and interlesion distance.

RESULTS

Bidirectional block across the LA roof and bottom was achieved in 40/40 patients. Additional endocardial RF applications in 5 patients from group 1 vs. 3 patients from group 2 resulted in posterior wall isolation in all patients. Procedure duration was almost equal in both groups. CF and AI were significantly higher in group 2 for the roof line, whereas no statistical difference was found for the bottom line. AI-guided LA posterior wall isolation led to a significantly lower maximum temperature increase. The mean AI value as well as the mean value for catheter-to-tissue CF for the roof line were significantly higher when AI-guided ablation was performed. Standard deviation in group 2 showed a remarkably lower dispersion.

CONCLUSIONS

Ablation index guided posterior wall isolation for substrate modification is safe and effective. AI guided application of the posterior box lesion allows improved lesion formation.

Oesophageal safety in voltage-guided atrial fibrillation ablation using ablation index or contact force only: a prospective comparison

AIMS

Left atrial ablation using radiofrequency (RF) is associated with endoscopically detected thermal oesophageal lesions (EDELs). The aim of this study was to compare EDEL occurrence after conventional contact force-guided (CFG) RF ablation vs. an ablation index-guided (AIG) approach in clinical routine of voltage-guided ablation (VGA). Predictors of EDEL were also assessed.

METHODS AND RESULTS

This study compared CFG (n = 100) with AIG (n = 100) in consecutive atrial fibrillation ablation procedures, in which both pulmonary vein isolation and VGA were performed. In the AIG group, AI targets were ≥500 anteriorly and ≥350-400 posteriorly. Upper endoscopy was performed after ablation.The CFG and AIG groups had comparable baseline characteristics. The EDEL occurred in 6 and 5% (P = 0.86) in the CFG and AIG groups, respectively. Category 2 lesions occurred in 4 and 2% (P = 0.68), respectively. All EDEL healed under proton pump inhibitor therapy. The AI > 520 was the only predictor of EDEL [odds ratio (OR) 3.84; P = 0.039]. The more extensive Category 2 lesions were predicted by: AI max > 520 during posterior ablation (OR 7.05; P = 0.042), application of posterior or roof lines (OR 5.19; P = 0.039), existence of cardiomyopathy (OR 4.93; P = 0.047), and CHA2DS2-VASc score (OR 1.71; P = 0.044). The only Category 2 lesion with AI max < 520 (467) occurred in a patient with low body mass index.

CONCLUSIONS

Both methods were comparable with respect to clinical complications and EDEL. In consideration of previous reconnection data and our study results regarding oesophageal safety, optimal AI target range might be between 400 and 450.

Effectiveness and Safety of High-Power Radiofrequency Ablation Guided by Ablation Index for the Treatment of Atrial Fibrillation

Background

To investigate the efficacy and safety of ablation index- (AI-) guided high-power radiofrequency ablation in the treatment of atrial fibrillation (AF).

Methods

Outcomes of radiofrequency (RF) applications were compared in a swine ventricular endocardial model (n = 10 each for 50 W, 40 W, and 30 W; AI = 500). And a total of 100 consecutive patients with paroxysmal AF undergoing pulmonary vein isolation (PVI) were included. The patients were divided into two groups (n = 50 for each) as follows: control group, treated with conventional power (30 W) ablation mode; and study group, treated with high power (40 W) radiofrequency ablation mode. All groups were treated with the same AI value guided the ablation (target AI = 400/500 on posterior/anterior wall, respectively). Acute pulmonary vein (PV) reconnection was assessed post adenosine administration 20 minutes after ablation. Subsequently, pathological observation of porcine heart lesions and necrotic tissue was performed. Additionally, statistical analyses were carried out on patients' baseline clinical characteristics, surgical data, and total RF energy.

Results

In swine ventricular endocardial RF applications, compared with 40 W and 30 W, the use of 50 W was associated with shallower tissue lesion depth (p < 0.001) and greater lesion maximum diameter (p < 0.001). Compared with 40 W and 30 W, tissue necrosis caused by 50 W was the deepest and largest (p < 0.001). In pulmonary vein isolation (PVI), there was no significant difference in baseline data between the study group and control group (p > 0.05). In patients with paroxysmal atrial fibrillation, the procedure time in the high-power group was significantly shortened (p < 0.001). The ablation time was significantly shorter (p < 0.001). Compared with control group, RF energy per point and acute pulmonary vein (PV) reconnection were lower (p < 0.001), and first-pass PVI was higher (p < 0.01) in study group. There were no significant differences in complications and sinus rhythm maintenance at 12 months between the two groups (p > 0.05).

Conclusions

Compared with conventional (30 W) PVI, AI-guided high-power (40 W) was safe and associated with shorter procedure time and reduced acute PV reconnection.

Efficacy of ablation index-guided pulmonary vein isolation in patients with paroxysmal atrial fibrillation

BACKGROUND

Ablation index (AI) is a novel technology of ablation lesion quality to help improve homogeneity of lesion size and continuity. In this study, we aim to evaluate whether AI-guided PVI improves clinical outcomes compared to CF-guided PVI in patients with paroxysmal AF (PAF).

METHODS

Patients undergoing first-time radiofrequency ablation for PAF were randomized in a 2:1 ratio to two groups: AI-guided PVI and CF-guided PVI. In the AI group, AI ≥500 was recommended at the anterior/superior/inferior walls, 350-400 at the posterior wall, and inter-lesion distance ≤4 mm. The primary endpoint is the freedom from atrial arrhythmia recurrence during 12 months follow-up, without antiarrhythmic drug therapy (ADT). The key secondary endpoints include intra-procedural efficiency and peri-procedural complications.

RESULTS

225 patients were randomized (AI group (n = 149) and CF group(n = 76)). First-pass isolation rate in AI group was significantly higher than that in CF group (58.3% vs. 43.4%, p = 0.035). After a median follow-up of 12.2 months, 154/225(68.4%) of patients were free from atrial arrhythmia recurrence without ADT, which was higher in AI group compared with CF group, but without significant difference (71.1% vs. 63.2%, p = 0.253). The incidence of peri-procedural complications is low and without difference between two groups.

CONCLUSIONS

AI-guided ablation provided higher acute efficacy than CF-guided ablation in PV isolation for patients with paroxysmal AF. The long-term success rate in AI group was higher than CF group, but did not reach statistical significance. This article is protected by copyright. All rights reserved.

Ablation Index Guided Left Atrial Posterior Wall Isolation

Ablation index (AI)-guided linear ablation is reported to be feasible.We assessed the feasibility of AI-guided left atrial (LA) posterior wall isolations (PWIs) using different target AI values.Seventy-one persistent atrial fibrillation patients who underwent AI-guided PWIs following pulmonary vein isolation were included. LA linear lesions were created with strict contiguity (inter-lesion distance < 4 mm) and different predetermined AI target values (Group-1: 430, Group-2: 450). The data was analyzed retrospectively.The total radiofrequency application time of the roof and bottom-line ablation was a median of 2.8 (2.0, 3.8) and 3.6 (2.8, 4.3) minutes. The first-pass PWI success rate (26/35 [74.3%] versus 16/36 [44.4%], P = 0.011) and a first-pass roof line block (28/35 [80.0%] versus 21/36 [58.3%], P = 0.048) were significantly higher in Group-2 than Group-1, but that for the first-pass bottom line block was similar between Group-1 and Group-2 (29/36 [80.6%] versus 29/35 [82.9%], P = 0.80). Successful PWIs were achieved by additional applications in all. The significant parameter associated with a successful first-pass LA roof line block was a greater RF power, and that for the LA bottom were a higher radiofrequency power and shorter inter-lesion distance. Conduction gaps were mostly located at the middle of both lines. Among 22 roof line gaps, 12 were closed on the line whereas 10 (45.4%) required ablation inside the posterior wall for PWIs. On the contrary, all 11 gaps on bottom lines were closed on the line.Successful first-pass PWIs were obtained in 74% of patients using a target AI value of 450 and strict criteria for the lesion contiguity.

Tailored Target Ablation Index Guided Pulmonary Vein Isolation in Treating Paroxysmal Atrial Fibrillation: A Single Center Randomized Study in Asian Population (AI-Asian-I)

Objective

To evaluate the efficacy and safety of lower ablation indexes (AI) guided pulmonary vein isolation (PVI) in treating paroxysmal atrial fibrillation (AF).

Methods

Ninety patients with paroxysmal AF scheduled for radiofrequency ablation were randomly divided into three groups. The AI targets for PVI were as follows: In group A/B/C, 550/500/450 for roof and anterior wall, and 400/350/300 for posterior/inferior wall. The first-pass PVI rate, ablation time, complications and recurrence of atrial tachyarrhythmia (ATa) were compared.

Results

The mean age was 62.5 years (male: 63.0%), mean body mass index (BMI): 24.35 ± 3.66 kg/m². The baseline characteristics were comparable. There was no significant difference in the first-pass PVI rate among the three groups (left-sided-PV: 66.7% vs. 80% vs. 73.3%, P = 0.51; right-sided-PV: 70% vs. 83.3% vs. 73.3%, P = 0.64), also with similar gap rate during the procedural waiting time. At 1-year follow-up there was no significant difference in the recurrence rate of ATa among the three groups (10% vs. 13.3% vs. 13.3%, P = 1.00). The ablation time in the Group C was significantly less than that in the other two groups (47.8 min. vs. 47.0 min. vs. 36.6 min, P < 0.001). Higher AI seemed to link a non-significant trend toward higher rate of pericardial effusion (group A + B vs. group C:6.7% vs. 0%, P = 0.30), although the rate of overall complications was not different among the three groups.

Conclusion

This randomized study shows that, a relatively lower target AI guided ablation may be similarly effective to achieve PVI with significantly reduced ablation time and obtain similar clinical outcome in treating paroxysmal AF in Asian population.

Clinical Trial Registration

[www.ClinicalTrials.gov], identifier [NCT:04549714].

Augmented wide area circumferential catheter ablation for reduction of atrial fibrillation recurrence (AWARE) trial: Design and rationale

BACKGROUND

Recurrence of atrial fibrillation (AF) after a pulmonary vein isolation procedure is often due to electrical reconnection of the pulmonary veins. Repeat ablation procedures may improve freedom from AF but are associated with increased risks and health care costs. A novel ablation strategy in which patients receive "augmented" ablation lesions has the potential to reduce the risk of AF recurrence.

OBJECTIVE

The Augmented Wide Area Circumferential Catheter Ablation for Reduction of Atrial Fibrillation Recurrence (AWARE) Trial was designed to evaluate whether an augmented wide-area circumferential antral (WACA) ablation strategy will result in fewer atrial arrhythmia recurrences in patients with symptomatic paroxysmal AF, compared with a conventional WACA strategy.

METHODS/DESIGN

The AWARE trial was a multicenter, prospective, randomized, open, blinded endpoint trial that has completed recruitment (ClinicalTrials.gov NCT02150902). Patients were randomly assigned (1:1) to either the control arm (single WACAlesion set) or the interventional arm (augmented- double WACA lesion set performed after the initial WACA). The primary outcome was atrial tachyarrhythmia (AA; atrial tachycardia [AT], atrial flutter [AFl] or AF) recurrence between days 91 and 365 post catheter ablation. Patient follow-up included 14-day continuous ambulatory ECG monitoring at 3, 6, and 12 months after catheter ablation. Three questionnaires were administered during the trial- the EuroQuol-5D (EQ-5D) quality of life scale, the Canadian Cardiovascular Society Severity of Atrial Fibrillation scale, and a patient satisfaction scale.

DISCUSSION

The AWARE trial was designed to evaluate whether a novel approach to catheter ablation reduced the risk of AA recurrence in patients with symptomatic paroxysmal AF.

Assessment of the Need of a Waiting Period after Pulmonary Vein Isolation with the Ablation Index Software

PURPOSE

Since the widespread availability of contact-force sensing catheters, the need of a waiting period after pulmonary vein isolation (PVI) has not been reassessed. We aim to evaluate whether a waiting period is still necessary after PVI guided by the Ablation Index (AI).

METHODS

Prospective, multicenter, randomized study of consecutive patients referred for paroxysmal atrial fibrillation (AF) ablation from May 2019 to February 2020. Patients were randomized in a 1:1 ratio to PVI with versus without a waiting period of 20 minutes. Acute pulmonary vein (PV) reconnection after adenosine challenge was the primary endpoint. A per-protocol analysis was designed to determine whether a strategy of dismissing the waiting period after PVI was noninferior to waiting 20minutes for identifying acute PV reconnection. PVI was guided by tailored AI values and an inter-lesion distance ≤6mm.

RESULTS

During the enrollment period, 167 patients (56% males, mean age of 57±14 years) fulfilled the study inclusion criteria - 84 patients (308 PV) in the waiting period group (group A) and 83 patients (314 PV) in the group without a waiting period (group B). Acute PV reconnection was identified in 3.8% (95% CI, 1.7% to 5.9%) of PVs in the study group B compared to 2.9% (95% CI, 1.0% to 4.8%) of PVs in the group A (p=0.002 for non-inferiority). At 1-year follow-up there was no significant difference in arrhythmia recurrence between groups (9.5% in group A vs. 9.6% in group B, HR 1.03 [95% CI, 0.39-2.73], p=0.98).

CONCLUSIONS

In paroxysmal AF patients submitted to ablation, a tailored PVI guided by the Ablation Index rendered a 20-minute waiting period unnecessary. This article is protected by copyright. All rights reserved.

Improved procedural workflow for catheter ablation of paroxysmal AF with high-density mapping system and advanced technology: Rationale and study design of a multicenter international study

BACKGROUND

The antral region of pulmonary veins (PV)s seems to play a key role in a strategy aimed at preventing atrial fibrillation (AF) recurrence. Particularly, low-voltage activity in tissue such as the PV antra and residual potential within the antral scar likely represent vulnerabilities in antral lesion sets, and ablation of these targets seems to improve freedom from AF. The aim of this study is to validate a structured application of an approach that includes the complete abolition of any antral potential achieving electrical quiescence in antral regions.

METHODS

The improveD procEdural workfLow for cathETEr ablation of paroxysmal AF with high density mapping system and advanced technology (DELETE AF) study is a prospective, single-arm, international post-market cohort study designed to demonstrate a low rate of clinical atrial arrhythmias recurrence with an improved procedural workflow for catheter ablation of paroxysmal AF, using the most advanced point-by-point RF ablation technology in a multicenter setting. About 300 consecutive patients with standard indications for AF ablation will be enrolled in this study. Post-ablation, all patients will be monitored with ambulatory event monitoring, starting within 30 days post-ablation to proactively detect and manage any recurrences within the 90-day blanking period, as well as Holter monitoring at 3, 6, 9, and 12 months post-ablation. Healthcare resource utilization, clinical data, complications, patients' medical complaints related to the ablation procedure and patient's reported outcome measures will be prospectively traced and evaluated.

DISCUSSION

The DELETE AF trial will provide additional knowledge on long-term outcome following a structured ablation workflow, with high density mapping, advanced algorithms and local impedance technology, in an international multicentric fashion. DELETE AF is registered at ClinicalTrials.gov (NCT05005143).

Impact of baseline impedance of pulmonary vein antrum on success of catheter ablation for paroxysmal atrial fibrillation guided by ablation index

Objective

Ablation index (AI) is an effective ablation quality marker. Impedance is also an important factor for lesion formation. The present study evaluated the influence of the baseline impedance in the effect of ablation for atrial fibrillation (AF) guided by AI.

Methods

This was a retrospective study. 101 patients with paroxysmal AF (PAF) were enrolled. All patients underwent radiofrequency ablation guided by the same AI strategy. The ablation strategy was pulmonary vein (PV) isolation with non-PV triggers ablation. The baseline impedance of the ablation points was recorded. The patients were followed up every 3 months or so.

Results

During a median follow-up of 12 (4–14) months, freedom from AF/atrial tachycardia recurrence were 82.2%. No difference existed in baseline characteristics between the success group and the recurrence group. The average baseline impedance was 124.3 ± 9.7 Ω. The baseline impedance of the ablation points in success group was lower compared to the recurrence group (122.9 ± 9.4 vs. 130.5 ± 8.8 Ω, P < 0.01). The ratio of impedance drop in the success group was higher than the recurrence group ([8.8 ± 1.4]% vs. [8.1 ± 1.2]%, P = 0.03). Multivariate analysis revealed that baseline impedance, PAF duration and AI were the independent predictors of AF recurrence. The cumulative free of recurrence rate of low-impedance group (≤ 124 Ω, n = 54) was higher than that of high-impedance group.

Conclusion

Baseline impedance correlates with clinical outcome of radiofrequency ablation for PAF guided by AI. Higher impedance in the same AI strategy may result in an ineffective lesion which probably causes recurrence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02530-y.

Procedural characteristics of pulmonary vein isolation with high-power short-duration setting compared to conventional setting

Purpose

The purpose of this study was to investigate the safety and efficacy of high-power short-duration (HP-SD) ablation compared to conventional ablation in patients with atrial fibrillation (AF).

Methods

We enrolled consecutive 158 drug-refractory symptomatic AF patients (119 males, mean age 63 ± 10 years) who had undergone first radiofrequency pulmonary vein isolation (PVI). PVI was performed using the conventional setting (20–35 W) in 73 patients (Conventional group) and using the HP-SD setting (45–50 W) in 85 patients (HP-SD group). The rate of first pass isolation, remaining gaps after circumferential ablation, dormant conduction, and the radiofrequency application time in each pulmonary vein (PV) were compared between the groups.

Results

The first pass isolation ratio was significantly higher in the HP-SD group than in the Conventional group (81% vs. 65%, P = 0.027) in the right PV, but did not differ in the left PV. The remaining gaps were fewer in the right superior PV (4% vs. 21%, P = 0.001) and left inferior PV (1% vs. 8%, P = 0.032) areas, and the radiofrequency application time in each PV was shorter (right PV, 12.0 ± 8.9 min vs. 34.0 ± 31.7 min, P < 0.001; left PV, 10.6 ± 3.6 min vs. 25.7 ± 22.3 min, P < 0.001) in the HP-SD group than in the Conventional group.

Conclusion

The use of the HP-SD setting might contribute to improve the first pass isolation rate and to shorten the radiofrequency application time in each PV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02459-2.

Catheter contact angle influences local impedance drop during radiofrequency catheter ablation: Insight from a porcine experimental study with 2 different LI-sensing catheters

BACKGROUND

Local impedance (LI) can indirectly measure catheter contact and tissue temperature during radiofrequency catheter ablation (RFCA). However, data on the effects of catheter contact angle on LI parameters are scarce. This study aimed to evaluate the influence of catheter contact angle on LI changes and lesion size with 2 different LI-sensing catheters in a porcine experimental study.

METHODS

Lesions were created by the INTELLANAV MiFi™ OI (MiFi) and the INTELLANAV STABLEPOINT™ (STABLEPOINT). RFCA was performed with 30 watts and a duration of 30 seconds. The CF (0, 5, 10, 20, and 30 g) and catheter contact angle (30°, 45°, and 90°) were changed in each set (n=8 each). The LI rise, LI drop, and lesion size were evaluated.

RESULTS

The LI rise increased as CF increased. There was no angular dependence with the LI rise under all CFs in the MiFi. On the other hand, the LI rise at 90° was lower than at 30° under 5 and 10 g of CF in STABLEPOINT. The LI drop increased as CF increased. Regarding the difference in catheter contact angles, the LI drop at 90° was lower than that at 30° for both catheters. The maximum lesion widths and surface widths were smaller at 90° than at 30°, whereas there were no differences in lesion depths.

CONCLUSION

The LI drop and lesion widths at 90° were significantly smaller than those at 30°, although the lesion depths were not different among the 3 angles for the MiFi and STABLEPOINT. This article is protected by copyright. All rights reserved.

Differences in the durability of left atrial posterior wall isolation based on the isolation process

PURPOSE

The best strategy for durable left atrial posterior wall isolation (PWI) after completion of pulmonary vein isolation (PVI) is not yet determined. This study aimed to examine the differences in the durability of PWI based on the isolation process and the predictors of the reconduction of PWI.

METHODS

Among the 221 patients (mean age, 65 ± 11 years) with consecutive non-paroxysmal atrial fibrillation (AF) who completed PVI and PWI, 50 patients undergoing repeat AF ablation were enrolled and divided into the following groups based on how PWI was achieved at the initial procedure: by only the first line on the roof and floor line (group A), by additional gap ablation to the first line or second liner ablation next to the first line (group B), and by adjunct ablation inside the PW revealing the earliest activation (group C).

RESULTS

Reconduction of PWI occurred in 24 of the 50 patients (48%). The durability of PWI in groups A, B, and C was 81% (17 of 21 patients), 75% (6 of 8 patients), and 14% (3 of 21 patients), respectively (p < 0.01). In a multivariate analysis, the ablation inside the PW for PWI was the independent predictor of the reconduction of PWI (p < 0.001).

CONCLUSION

PWI achieved by the ablation inside the PW resulted in a high rate of reconduction. It may be necessary to aim to achieve the PWI without ablating the inside of the PW to prevent reconduction.

Radiofrequency ablation to achieve durable pulmonary vein isolation

Pulmonary vein isolation (PVI) by radiofrequency (RF) ablation is an important alternative to antiarrhythmic drugs in the treatment of symptomatic atrial fibrillation. However, the inability to consistently achieve durable isolation of the pulmonary veins hampers the long-term efficacy of PVI procedures. The large number of factors involved in RF lesion formation and the complex interplay of these factors complicate reliable creation of durable and transmural ablation lesions. Various surrogate markers of ablation lesion formation have been proposed that may provide information on RF lesion completeness. Real-time assessment of these surrogates may aid in the creation of transmural ablation lesions, and therefore, holds potential to decrease the risk of PV reconnection and consequent post-PVI arrhythmia recurrence. Moreover, titration of energy delivery until lesions is transmural may prevent unnecessary ablation and subsequent adverse events. Whereas several surrogate markers of ablation lesion formation have been described over the past decades, a 'gold standard' is currently lacking. This review provides a state-of-the-art overview of ablation strategies that aim to enhance durability of RF-PVI, with special focus on real-time available surrogates of RF lesion formation in light of the biophysical basis of RF ablation.

Esophageal thermal injury in catheter ablation of atrial fibrillation

Pulmonary vein isolation is an established method for the catheter ablation of atrial fibrillation. Esophageal thermal injuries, such as esophageal erosion, ulceration and periesophageal nerve injury leading to gastric hypomotility, are important complications associated with pulmonary vein isolation. In this review article, we describe the mechanisms, characteristics and the predictors of esophageal thermal injury associated with pulmonary vein isolation.

Relationship between Surpoint Tag Index, a Radiofrequency Ablation lesion quality indicator, and Atrial wall thickness in Cavotricuspid isthmus Ablations exhibiting bidirectional block

Background

An RFA lesion quality indicator, Surpoint Tag Index^® (TI) incorporates key factors: power, time, and contact force, impacting lesion quality. TI accurately estimates lesion depth in animal studies. However, the relationship between TI and in‐vivo atrial wall thickness in patients exhibiting bidirectional block remains unknown.

Objective

To describe the relationship between atrial wall thickness and TI in CTI exhibiting bidirectional block.

Methods

Data from 492 RFA lesions from 25 patients undergoing PVI and CTI ablations in SR with point‐by‐point RF lesions (<45 W) utilizing a Thermocool Smarttouch^® SF ablation catheter and CARTO‐3 mapping were retrospectively analyzed. Operators were blinded to TI data and CTI thickness. CTI thickness was obtained using ICE images on Cartosound pre‐ablation. Durable lesions were defined as part of a lesion set exhibiting bidirectional block of >30 min.

Results

In lesions exhibiting bidirectional block, the thinnest (1–2 mm; 5% lesions) and thickest (8–10 mm; 6% lesions) portions of the CTI correlated with the lowest (429 ± 75) and highest (516 ± 64) TI. The bulk of thickness (2–6 mm; 80%) correlated with a TI of 455 ± 72 (p = 0.001). There was a weak but positive correlation between TI and CTI thickness (r = 0.2; p ≤ 0.01). Examined in sectors, the anterior 1/3^rd CTI was the thickest (4.8 ± 1.9 mm) but correlated with a similar TI value (479 ± 75 vs. 471 ± 70; p = 0.34) as the thinner middle 1/3^rd (3.8 ± 1.7 mm; p ≤ 0.0001).

Conclusion

A mean TI value of 455 correlates with bidirectional block across the bulk of CTI with lower and higher values needed for the thinner and thicker portions, respectively. Tissue composition, aside from wall thickness, influences TI values for the creation of the bidirectional block.

Relationship between ablation index and myocardial biomarkers after radiofrequency catheter ablation for atrial fibrillation

Background

Further in-vivo evidence is needed to support the usefulness of ablation index (AI) in guiding atrial fibrillation (AF) ablation. We aimed at evaluating the relationship between AI and other lesion indicators and the release of myocardial-specific biomarkers following radiofrequency AF ablation.

Methods

Forty-six patients underwent a first-time radiofrequency AF ablation and were prospectively enrolled in this study. Pulmonary vein isolation was performed by six experienced electrophysiologists with a point-by-point approach, guided by strict Visitag criteria and consistent AI target values. Myocardial-specific biomarkers troponin T and creatine kinase myocardial band were measured after 6 (TnT6 and CKMB6) and 20 h (TnT20 and CKMB20) following sheath removal. Ablation duration, impedance drop (ID), force-time integral (FTI) and AI were registered automatically and analyzed offline.

Results

TnT release was 985 ± 495 ng/L and 1038 ± 461 ng/L (p = ns) while CKMB release was 7.3 ± 2.7 μg/L and 6.5 ± 2.1 μg/L (p < 0.001) at 6 and 20 h respectively. Ablation duration, ID, FTI and AI were all significantly correlated with the release of myocardial-specific biomarkers both at 6 and 20 h. Ablation index showed the highest degree of correlation with TnT6, TnT20, CKMB6 and CKMB20 (Pearson's R 0.69, 0.69, 0.61, 0.64 respectively, p < 0.001). Multiple regression analysis demonstrated that AI had the strongest association with TnT6, TnT20, CKMB6 and CKMB20 (β 0.43, β 0.71, β 0.44 and β 0.43 respectively).

Conclusion

Ablation index appears as the strongest lesion indicator as measured by the release of myocardial-specific biomarkers following radiofrequency catheter ablation for AF.

Ablation Index-guided point-by-point ablation versus Grid annotation-guided dragging for pulmonary vein isolation: A randomized controlled trial

Introduction

Radiofrequency (RF) atrial fibrillation (AF) ablation using a catheter dragging technique may shorten procedural duration and improve durability of pulmonary vein isolation (PVI) by creating uninterrupted linear ablation lesions. We compared a novel AF ablation approach guided by Grid annotation allowing for “drag lesions” with a standard point‐by‐point ablation approach in a single‐center randomized study.

Methods

Eighty‐eight paroxysmal or persistent AF patients were randomized 1:1 to undergo RF‐PVI with either a catheter dragging ablation technique guided by Grid annotation or point‐by‐point ablation guided by Ablation Index (AI) annotation. In the Grid annotation arm, ablation was visualized using 1 mm³ grid points coloring red after meeting predefined stability and contact force criteria. In the AI annotation arm, ablation lesions were created in a point‐by‐point fashion with AI target values set at 380 and 500 for posterior/inferior and anterior/roof segments, respectively. Patients were followed up for 12 months after PVI using ECGs, 24‐h Holter monitoring and a mobile‐based one‐lead ECG device.

Results

Procedure time was not different between the two randomization arms (Grid annotation 71 ± 19 min, AI annotation 72 ± 26 min, p = .765). RF time was significantly longer in the Grid annotation arm compared with the AI annotation arm (49 ± 8 min vs. 37 ± 8 min, respectively, p < .001). Atrial tachyarrhythmia recurrence was documented in 10 patients (23%) in the Grid annotation arm compared with 19 patients (42%) in the AI annotation arm with time to recurrence not reaching statistical significance (p = .074).

Conclusions

This study shows that a Grid annotation‐guided dragging approach provides an alternative to point‐by‐point RF‐PVI using AI annotation.

Ablation index-guided pulmonary vein isolation can reduce early recurrences of atrial tachyarrhythmias: a propensity score-matched analysis

PURPOSE

Early recurrence of atrial tachyarrhythmias (ERAT) cause various symptoms and predict worse outcomes after pulmonary vein isolation (PVI). This study aimed to clarify whether ablation index (AI)-guided PVI, which is a novel technology of radiofrequency ablation, could reduce ERAT as compared to conventional contact force (CF)-guided PVI.

METHODS

Consecutive atrial fibrillation (AF) patients who underwent initial PVI from September 2014 to August 2019 were enrolled. We divided the patients into two groups: patients who underwent AI-guided PVI (AI group) and those who underwent CF-guided PVI (CF group). Using propensity score matching (PSM), we adjusted for the patient backgrounds. We compared the incidence of ERAT and late reconnection rate of isolated pulmonary veins (PVs) during second session between the two groups. ERAT was defined as any atrial tachyarrhythmias ≥ 30 s during a 90-day blanking period.

RESULTS

A total of 697 AF patients (paroxysmal 51%) were enrolled. After the PSM, both groups included 229 patients. The incidence of ERAT was significantly lower in the AI group than that in the CF group (21.5% vs. 36.1%, P < 0.001). Total 118 patients (25.7%) experienced late recurrence of atrial tachyarrhythmias (LRAT) after blanking period. LRAT free survival rate was significantly higher in patients without ERAT than those with ERAT (88.1% vs. 42.0%, P < 0.001). The rate of PV reconnection was lower in the AI group than that in the CF group (45.8% vs. 71.4%, P = 0.028). Multivariate analysis demonstrated that AI-guided PVI was independently correlated with ERAT (OR = 0.415, 95%CI = 0.269-0.639, P < 0.001).

CONCLUSIONS

AI-guided PVI can reduce ERAT as compared to conventional CF-guided PVI.

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.

Personalized paroxysmal atrial fibrillation ablation by tailoring ablation index to the left atrial wall thickness: the 'Ablate by-LAW' single-centre study-a pilot study

AIMS

To determine if adapting the ablation index (AI) to the left atrial wall thickness (LAWT), which is a determinant of lesion transmurality, is feasible, effective, and safe during paroxysmal atrial fibrillation (PAF) ablation.

METHODS AND RESULTS

Consecutive patients referred for PAF first ablation. Left atrial wall thickness three-dimensional maps were obtained from multidetector computed tomography and integrated into the CARTO navigation system. Left atrial wall thickness was categorized into 1 mm layers and AI was titrated to the LAWT. The ablation line was personalized to avoid thicker regions. Primary endpoints were acute efficacy and safety, and freedom from atrial fibrillation (AF) recurrences. Follow-up (FU) was scheduled at 1, 3, 6, and every 6 months thereafter. Ninety patients [60 (67%) male, age 58 ± 13 years] were included. Mean LAWT was 1.25 ± 0.62 mm. Mean AI was 366 ± 26 on the right pulmonary veins with a first-pass isolation in 84 (93%) patients and 380 ± 42 on the left pulmonary veins with first-pass in 87 (97%). Procedure time was 59 min (49-66); radiofrequency (RF) time 14 min (12.5-16); and fluoroscopy time 0.7 min (0.5-1.4). No major complication occurred. Eighty-four out of 90 (93.3%) patients were free of recurrence after a mean FU of 16 ± 4 months.

CONCLUSION

Personalized AF ablation, adapting the AI to LAWT allowed pulmonary vein isolation with low RF delivery, fluoroscopy, and procedure time while obtaining a high rate of first-pass isolation, in this patient population. Freedom from AF recurrences was as high as in more demanding ablation protocols. A multicentre trial is ongoing to evaluate reproducibility of these results.

Influence of power setting on superior vena cava potential during right pulmonary vein isolation

PURPOSE

High-power short-duration (HP-SD) ablation could reduce collateral tissue damage by shortening the conductive heating phase. However, it is difficult to evaluate the transmural effect of ablation lesions during pulmonary vein isolation (PVI) procedures. The present study aimed to evaluate the change in superior vena cava (SVC) potential delay as a surrogate marker of collateral tissue damage during right PVI, which is adjacent to SVC.

METHODS

Out of 250 consecutive patients who underwent PVI, 86 patients in whom SVC potential during sinus rhythm was recorded both before and after right PVI were analyzed. In 46 of the patients, an HP-SD setting of 45-50 W was used (HP-SD group). In the remaining 40 patients, a conventional power setting of 20-30 W was used (conventional group). We compared the change in SVC potential delay after right PVI, radiofrequency energy, and mean contact force in the anterior-superior right PVI line, which was close to the posterior aspect of SVC, between the two groups.

RESULTS

Although the total delivered radiofrequency energy (2,924 J vs. 2,604 J) and the mean contact force (18.5 g vs. 16.0 g) in the SVC overlapping area did not differ, the change in SVC potential delay after right PVI was significantly longer in the conventional group compared to the HP-SD group (5.0 ms vs. 0.0 ms, p < 0.001).

CONCLUSIONS

The changes in SVC potential delay after right PVI might be a surrogate marker of collateral tissue damage according to the used energy settings.

Safety, efficacy, and reproducibility of cavotricuspid isthmus ablation guided by the ablation index: acute results of the FLAI study

AIMS

Ablation index (AI) is a marker of lesion quality during catheter ablation that incorporates contact force, time, and power in a weighted formula. This index was originally developed for pulmonary vein isolation as well as other left atrial procedures. The aim of our study is to evaluate the feasibility and efficacy of the AI for the ablation of the cavotricuspid isthmus (CTI) in patients presenting with typical atrial flutter (AFL).

METHODS AND RESULTS

This prospective multicentre non-randomized study enrolled 412 consecutive patients with typical AFL undergoing AI-guided cavotricuspid isthmus ablation. The procedure was performed targeting an AI of 500 and an inter-lesion distance measurement of ≤6 mm. The primary endpoints were CTI 'first-pass' block and persistent block after a 20-min waiting time. Secondary endpoints included procedural and radiofrequency duration and fluoroscopic time. A total of 412 consecutive patients were enrolled in 31 centres (mean age 64.9 ± 9.8; 72.1% males and 27.7% with structural heart disease). The CTI bidirectional 'first-pass' block was reached in 355 patients (88.3%), whereas CTI block at the end of the waiting time was achieved in 405 patients (98.3%). Mean procedural, radiofrequency, and fluoroscopic time were 56.5 ± 28.1, 7.8 ± 4.8, and 1.9 ± 4.8 min, respectively. There were no major procedural complications. There was no significant inter-operator variability in the ability to achieve any of the primary endpoints.

CONCLUSION

AI-guided ablation with an inter-lesion distance ≤6 mm represents an effective, safe, and highly reproducible strategy to achieve bidirectional block in the treatment of typical AFL.

Effectiveness of Radiofrequency Catheter Ablation Using Ablation Index Versus Second Generation Cryoballoon in the Treatment of Persistent Atrial Fibrillation: A Matching-Adjusted Indirect Comparison

Introduction

Both radiofrequency (RF) and cryoballoon (CB) ablation are treatment options for persistent atrial fibrillation (PsAF). An important recent innovation in RF ablation is Ablation Index (AI), known also as the VISITAG SURPOINT™ Module, a composite lesion quality marker whose use has been shown to significantly reduce the incidence of acute and late pulmonary vein (PV) reconnection and the recurrence of atrial arrhythmias in PsAF. Due to a lack of direct comparative evidence between the latest generations of technologies, there is uncertainty regarding the best treatment option in PsAF. The objective of the present study was to conduct a matching-adjusted indirect treatment comparison (MAIC) using individual patient-level data (IPD) to assess the comparative effectiveness of the THERMOCOOL SMARTTOUCH™ Catheter or the THERMOCOOL SMARTTOUCH™ SF Catheter with AI/VISITAG SURPOINT™ Module (STAI) versus the second-generation CB catheter (Arctic Front Advance™; herein referred to as CB) with respect to 12-month atrial arrhythmia recurrence, fluoroscopy time, and procedural efficiency.

Methods

IPD for STAI were obtained from four investigator-initiated studies and were pooled. Comparable CB studies identified from a systematic literature review were also pooled. In the absence of a common treatment arm between STAI and CB studies, an unanchored MAIC was conducted. The primary analysis compared the pooled STAI IPD to the pooled CB cohort, with corrections for differences across trials, including eligibility criteria and patient baseline characteristics. Scenario and sensitivity analyses were conducted to assess the robustness of the primary analysis.

Results

In the primary analysis, which was adjusted for left atrial diameter (LAD), age, diabetes, and sex, STAI was associated with a statistically significant 65% relative reduction in the rate of arrhythmia recurrence compared to CB at 12-month follow-up (HR 0.35; 95% CI 0.23, 0.52). STAI was associated with shorter total fluoroscopy time than CB but longer procedure time. Results were consistent across scenario and sensitivity analyses.

Conclusion

Radiofrequency ablation with AI significantly reduced atrial arrhythmia recurrence at 12-month follow-up and fluoroscopy time compared to CB, with longer procedure times.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01846-z.

Prospective use of ablation index for the ablation of right ventricle outflow tract premature ventricular contractions: a proof of concept study

AIMS

Radiofrequency catheter ablation (RFCA) represents an effective option for idiopathic premature ventricular contractions (PVCs) treatment. Ablation Index (AI) is a novel ablation marker incorporating RF power, contact force, and time of delivery into a single weighted formula. Data regarding AI-guided PVCs RFCA are currently lacking. Aim of the study was to compare AI-guided and standard RFCA outcomes in patients with PVCs originating from the right ventricle outflow tract (RVOT).

METHODS AND RESULTS

Consecutive patients undergoing AI-guided RFCA of RVOT idiopathic PVCs were prospectively enrolled. Radiofrequency catheter ablation was performed following per-protocol target cut-offs of AI, depending on targeted area (RVOT free wall AI cut-off: 590; RVOT septum AI cut-off: 610). A multi-centre cohort of propensity-matched (age, sex, ejection fraction, and PVC site) patients undergoing standard PVCs RFCA was used as a comparator. Sixty AI-guided patients (44.2 ± 18.0 years old, 58% male, left ventricular ejection fraction 56.2 ± 3.8%) were enrolled; 34 (57%) were ablated in RVOT septum and 26 (43%) patients in the RVOT free wall area. Propensity match with 60 non-AI-guided patients was performed. Acute outcomes and complications resulted comparable. At 6 months, arrhythmic recurrence was more common in non-AI-guided patients whether in general (28% vs. 7% P = 0.003) or by ablated area (RVOT free wall: 27% vs. 4%, P = 0.06; RVOT septum 29% vs. 9% P = 0.05). Ablation Index guidance was associated with improved survival from arrhythmic recurrence [overall odds ratio 6.61 (1.95-22.35), P = 0.001; RVOT septum 5.99 (1.21-29.65), P = 0.028; RVOT free wall 11.86 (1.12-124.78), P = 0.039].

CONCLUSION

Ablation Index-guidance in idiopathic PVCs ablation was associated with better arrhythmic outcomes at 6 months of follow-up.

Very high-power short-duration temperature-controlled ablation versus conventional power-controlled ablation for pulmonary vein isolation: The fast and furious - AF study

Background

Catheter ablation for atrial fibrillation (AF) treatment provides effective and durable pulmonary vein isolation (PVI) and is associated with encouraging clinical outcome. A novel CF sensing temperature-controlled radiofrequency (RF) ablation catheter allows for very high-power short-duration (vHP-SD, 90 W/4 s) ablation aiming a potentially safer, more effective and faster ablation. We thought to evaluate preliminary safety and efficacy of vHP-SD ablation for PVI utilizing a novel vHP-SD catheter. The data was compared to conventional power-controlled ablation index (AI) guided PVI utilizing conventional contact force (CF) sensing catheters.

Methods and Results

Fifty-six patients with paroxysmal or persistent AF were prospectively enrolled in this study. Twenty-eight consecutive patients underwent vHP-SD based PVI (vHP-SD group) and were compared to 28 consecutive patients treated with conventional CF-sensing catheters utilizing the AI (control group). All PVs were successfully isolated using vHP-SD. The median RF ablation time for vHP-SD was 338 (IQR 286, 367) seconds vs control 1580 (IQR 1350, 1848) seconds (p < 0.0001), the median procedure duration was vHP-SD 55 (IQR 48–60) minutes vs. control 105 (IQR 92–120) minutes (p < 0.0001). No differences in periprocedural complications were observed.

Conclusions

This preliminary data of the novel vHP-SD ablation mode provides safe and effective PVI. Procedure duration and RF ablation time were substantially shorter in the vHP-SD group in comparison to the control group.

Standard versus strict stability criteria in radiofrequency paroxysmal atrial fibrillation ablation using ablation index

PURPOSE

To compare the outcome of paroxysmal atrial fibrillation (AF) ablation via pulmonary vein isolation using Ablation Index (AI) with strict or standard stability criteria.

METHODS

We enrolled 130 consecutive naive patients affected by paroxysmal AF who underwent PVI at two high-volume centers. AI target was ≥380 at the posterior wall and ≥500 at the anterior wall. Strict versus standard stability criteria were set for Group 1 (65 patients) and Group 2 (65 patients), respectively. We compared those strategies with a historical cohort of 72 consecutive patients treated at same centers in the VISITALY study, using average force ≥10 g and strict stability criteria as target parameters. Interlesion distance target was <6 mm. Recurrence was defined as any AF, atrial tachycardia (AT) or atrial flutter (AFL) during the 12 months after ablation, excluding a 90-days blanking period.

RESULTS

Procedure duration (224.05 ± 47.21 vs. 175.61 ± 51.29 min; p < .001), fluoroscopy time (11.85 ± 4.38 vs. 10.46 ± 6.49 min; p = .019) and pericardial effusion rate (9.23% vs. 0%; p = .01) were higher in Group 1 than in Group 2. Freedom from AF/AT/AFL at 12 months was not significantly different (Group 1: 86.15%; Group 2: 90.77%; p = .42). Compared to VISITALY study, there were not significant differences in terms of recurrences.

CONCLUSION

A strategy of PVI using AI with standard stability criteria performed the best in terms of procedure efficiency and safety. Twelve-months arrhythmia-free survival rate was comparable with other strategies pursuing an interlesion distance target <6 mm, regardless of the use of AI.

Predicting early reconnection after cryoballoon ablation with procedural and biophysical parameters

BACKGROUND

Predicting early reconnection/dormant conduction (ERC) immediately after pulmonary vein isolation (PVI) can avoid a waiting period with adenosine testing.

OBJECTIVE

To identify procedural and biophysical parameters predicting ERC.

METHODS

Consecutive atrial fibrillation (AF) patients undergoing a first cryoballoon ablation (Arctic Front Advance) between 2014 and 2017 were included. ERC was defined as manifest or dormant pulmonary vein (PV) reconnection with adenosine 30 minutes after PVI. Time to isolation (TTI), balloon temperatures (BT), and thawing times were evaluated as potential predictors for ERC. Based on a multivariable model, cut-off-values were defined and a formula was constructed to be used in clinical practice.

RESULTS

A total of 136 patients (60 ± 10 years, 96 male, 95% paroxysmal AF) were included. ERC was found in 40 (29%) patients (ERC group) and in 53 of 575 (9%) veins. Procedural and total ablation time and the number of unsuccessful freezes were significantly longer/higher in the ERC group compared to the non-ERC group (150 ± 40 vs 125 ± 34 minutes; 24 ± 5 vs 17 ± 4 minutes, and 38% vs 24%, respectively (P = .028). Multivariable analysis showed that a higher nadir balloon temperature (hazard ratio [HR] 1.17 [1.09-1.23, P < .001), a higher number of unsuccessful freezes (HR 1.69 [1.15-2.49], P = .008) and a longer TTI (HR 1.02 [1.01-1.03], P < .001) were independently associated with ERC, leading to the following formula: 0.02 × TTI + 0.5 × number of unsuccessful freezes + 0.2 × nadir BT with a cut-off value of ≤-6.7 to refrain from a waiting period with adenosine testing.

CONCLUSION

Three easily available parameters were associated with ERC. Using these parameters during ablation can help to avoid a 30-minute waiting period and adenosine testing.

Pulmonary vein isolation guided by moderate ablation index targets combined with strict procedural endpoints for patients with paroxysmal atrial fibrillation

INTRODUCTION

Ablation index (AI)-guided radiofrequency ablation has been increasingly used for the treatment of drug-resistant paroxysmal atrial fibrillation (AF)，but the optimal AI targets remain to be determined. We aimed to examine the efficacy and safety of catheter ablation guided by moderate AI values but more strict procedural endpoints in patients with paroxysmal AF.

METHODS

We conducted a retrospective review of a consecutive series of patients who received their first AI-guided ablation for paroxysmal AF from 2017 to 2018. The standard procedural protocol recommends AI targets as follows: anterior: 400-450; posterior: 280-330; and roof/inferior wall: 380-430. After circumferential pulmonary vein isolation (PVI), we performed bipolar pacing along the ablation line, adenosine triphosphate (ATP)-provocation, and waited for 30 min to verify PVI. The primary clinical outcome was the rate of freedom from AF recurrence at 12 months.

RESULTS

A total of 140 consecutive patients were included. The mean procedure and ablation times were 132.2 ± 30.2 min and 24.2 ± 7.9 min, respectively. The first-pass isolation and final isolation rates were documented in 49.3% and in 100% of the patients, respectively. At 12 months, single-procedure freedom from atrial tachyarrhythmias was observed in 92.1% of patients. No major procedure-related complications were encountered.

CONCLUSIONS

Moderate AI-guided catheter ablation is highly effective for the treatment of drug-refractory paroxysmal AF in real-world settings. Over 90% of patients achieved single-procedure arrhythmia-free survival at 1 year. The outcome was obtained without major complications and the procedure involved relatively short procedure and ablation times.