Detailed investigation of the lesion formation with a novel contact force sensing catheter with a mesh-shaped irrigation tip

Cerebral Safety Comparison: High-Power vs. Low-Power Ablation in AF Pulmonary Vein Isolation

BACKGROUND

The use of high-power short-duration radiofrequency ablation techniques for atrial fibrillation (AF) treatment has gained popularity; however, the implications for cerebral safety, particularly regarding the risk of silent cerebral embolism (SCE), remain unclear. This study aims to assess procedural complications, focusing on cerebral safety, between HPSD and LPLD ablation techniques in patients who are receiving pulmonary vein isolation for AF.

METHODS

This study comprised 74 patients who were randomly allocated into two equal groups at a 1:1 ratio. The HPSD group utilized a 70 W, whereas the LPLD group employed a 40 W. The study evaluated safety (asymptomatic cerebral embolism, bleeding, and steam pop incidence) and efficacy (ablation time and success rates) between the groups.

RESULTS

In the HPSD group, 9 (26%) patients experienced SCE, compared to 12 (33%) patients in the LPLD group. The two groups did not differ significantly (p = 0.482). There were no clinically evident cerebrovascular events (stroke or TIA) in any patients. The incidence of steam pops was comparable (5% vs. 3%, p = 0.556). Significant differences were observed in ablation times for the left (218.70 ± 96.48 vs. 600.27 ± 249.83 s, p < 0.001) and right pulmonary veins (224.05 ± 77.89 vs. 658.38 ± 168.84 s, p < 0.001). A single case of hematoma was reported in the LPLD group.

CONCLUSIONS

The incidence of SCE during PVI ablation is similar between HPSD and LPLD techniques. HPSD ablation is a safe and effective technique that significantly reduces ablation time without elevating perioperative complications.

Feasibility and efficacy of 50 W ablation with the TactiFlex catheter for the initial pulmonary vein isolation of atrial fibrillation

Background

A novel contact force (CF) sensing catheter with a mesh-shaped irrigation tip (TactiFlexTM SE, Abbott), is expected to provide safe and effective radiofrequency ablation. Our previous study revealed that the TactiFlex catheter needs a higher power for pulmonary vein isolation (PVI) due to the long tip length. This study aimed to examine the feasibility and safety of a 50 W ablation with the TactiFlex for PVI of atrial fibrillation (AF).

Methods

A PVI was performed in 100 AF patients using TactiFlex catheters with a 50 W setting, 5-20 g CF, and 15-20 s ablation time. The primary outcomes included a successful PVI, the incidence of first-pass isolations (FPIs), the presence of PV conduction gaps, and the incidence of complications.

Results

FPIs were achieved for 82/100 (82%) right pulmonary veins (RPVs) and 87/100 (87%) left PVs (LPVs). Among the unsuccessful RPV FPIs, residual carina potentials were observed in 16/18 cases (89%), PV gaps in 1/18 cases (5.5%), and both carina and PV gaps in 1/18 cases (5.5%). Similarly, among the unsuccessful LPV FPIs, residual carina potentials were observed in 11/13 cases (84.6%), PV gaps in 1/13 cases (7.7%), and both carina and PV gaps in 1/13 cases (7.7%). Periesophageal nerve injury occurred in 1/100 cases (1%), and no cardiac tamponade occurred. The overall AF-free rate at one-year was 81.7%.

Conclusions

The 50 W ablation with the TactiFlex demonstrated a high rate of an FPI, low incidence of PV gaps, and proved to be a safe and effective approach for the initial PVI of AF.

In Vivo Tissue Temperature Characteristics of Contact Force Catheter With a Mesh-Shaped Irrigation Tip: A Porcine Study

BACKGROUND

Neither the actual in vivo tissue temperatures reached with a novel contact force sensing catheter with a mesh-shaped irrigation tip (TactiFlex SE, Abbott) nor the safety profile has been elucidated.

METHODS

In a porcine model (n = 8), thermocouples were implanted epicardially in the superior vena cava, right pulmonary vein, and esophagus close to the inferior vena cava following a right thoracotomy. After chest closure, endocardial ablation was conducted near the thermocouples under fluoroscopic guidance. We compared tissue temperatures during 50 W/13-s high-power short-duration (HPSD) and 30 W/30-s standard ablation.

RESULTS

No steam pops were observed in 34 HPSD and 35 standard ablation applications. Tmax (maximum tissue temperature when the thermocouple was located ≤5 mm from the catheter tip) was modestly higher in HPSD compared to standard ablation (60.1°C ± 12.4°C vs. 57.8°C ± 12.9°C; p = 0.46). The peak tissue temperature correlated inversely with the catheter tip-to-thermocouple distance (HPSD: r = -0.40; standard: r = -0.57). Lethal temperatures (≥50°C) were reached faster with HPSD (6.5 ± 3.2 s vs. 10.3 ± 8.6 s; p = 0.04) and the distance from the catheter tip achieving a lethal tissue temperature ≥50°C (indicative of the lesion depth) was slightly shallower with HPSD (4.2 and 4.8 mm, respectively). The esophageal injury occurred superficially in both settings (0.98 ± 0.22 mm vs. 1.16 ± 0.18 mm; p = 0.29).

CONCLUSIONS

HPSD ablation produced a modestly higher and more rapid increase in the tissue temperature around the veno-atrial junction with a shorter catheter tip-to-thermocouple distance required to reach lethal temperatures. This data contributes to understanding effective lesion creation and collateral injury prevention with the TactiFlex catheter.

Optimal ablation settings of TactiFlex SE laser-cut irrigated-tip catheter: comparison with ThermoCool SmartTouch SurroundFlow porous irrigated-tip catheter

BACKGROUND

The TactiFlex SE catheter (TFSE, Abbott) with a contact force (CF) sensor and a laser-cut irrigated-tip has recently become available but lacks a lesion quality marker. This study aimed to explore distinctions in lesion characteristics between the TFSE and the ThermoCool SmartTouch SurroundFlow catheter (STSF, Biosense Webster), which utilizes a porous irrigated tip, and to assess the most effective application settings for the TFSE.

METHODS

Lesions were generated using varying settings of radiofrequency power (30-50 W), CF (10-20 g), application duration (10-40 s), and catheter orientation (perpendicular or parallel) in an ex vivo porcine model. Comparative analysis between the TFSE and STSF was conducted for lesion characteristics and incidence of steam pops using predictive models in regression analyses.

RESULTS

Among 720 applications, the TFSE exhibited a significantly lower incidence of steam pops compared to the STSF (0.6% vs. 36.8%, P < 0.001). Moreover, coefficients of determination (R2) for the TFSE were higher than those for the STSF concerning lesion depth (0.710 vs. 0.541) and volume (0.723 vs. 0.618). The lesion size generated with the TFSE was notably smaller than that with the STSF under identical application settings. Additionally, to achieve a lesion depth ≥ 4.0 mm, the TFSE required an application duration 8-12 s longer than the STSF under similar settings.

CONCLUSIONS

The TFSE demonstrated a lower incidence of steam pops and superior predictability in lesion size compared to the STSF. However, the TFSE necessitated a longer application duration than the STSF to achieve an adequate lesion size.

Acute procedural safety of the latest radiofrequency ablation catheters in atrial fibrillation ablation: Data from a large prospective ablation registry

BACKGROUND

Safety data of the latest radiofrequency (RF) technologies during atrial fibrillation (AF) ablation in real-world clinical practice are limited.

OBJECTIVES

We sought to evaluate the acute procedural safety of the four latest ablation catheters commonly used for AF ablation.

METHODS

A total of 3957 AF ablation procedures performed between January 2022 and December 2023 at 20 centers with either the THERMOCOOL SMARTTOUCH SF (STSF), TactiCath (TC), QDOT Micro (QDM), or TactiFlex (TF) were retrospectively analyzed.

RESULTS

In total, QDM, STSF, TF, and TC were used in 343 (8.7%), 1793 (45.3%), 1121 (28.4%), and 700(17.7%) procedures. Among 2406 index procedures, electrical pulmonary vein isolations were successfully achieved in 99.5%. Despite similar total procedure times in the four groups, the total fluoroscopic time was significantly shorter for QDM/STSF with CARTO than TF/TC with EnSite (18.7 ± 14 vs. 27.6 ± 20.6 min, p < .001) and longest in the TF group. The incidence of cardiac tamponade was 0.7% (0.5% and 0.9% during index and redo procedures, 0.8% and 0.3% for paroxysmal and non-paroxysmal AF) and was significantly lower for QDM/STSF than TF/TC (0.2% vs. 1.1%, p = .008) and highest in the TF group. The incidence of cardiac tamponade was higher for TF than TC and STSF than QDM. In the multivariate analysis, TF/TC with EnSite was a significant independent predictor of cardiac tamponade during both the index (odds ratio [OR] = 4.8, 95% confidence interval [CI] = 1.3-17.5, p = .02) and all procedures (OR = 3.0, 95% CI = 1.3-7.2, p = .01).

CONCLUSIONS

The incidence of cardiac tamponade and the fluoroscopic time during AF ablation significantly differed among the latest RF catheters and mapping systems in real-world clinical practice.

Radiofrequency ablation-Real-time visualization of lesions and their correlation with underlying parameters

BACKGROUND

Lesion durability and transmurality are crucial for successful radiofrequency (RF) ablation. This study provides a model of real-time RF lesion visualization and insights into the role of underlying parameters, as local impedance (LI).

METHODS

A force-sensing, LI-sensing catheter was used for lesion creation in an ex vivo model involving cross-sections of porcine cardiac preparations. During 60 s of RF application, one measurement per second was performed regarding lesion size and available ablation parameters. In total, 1847 measurements from n = 36 lesions were performed. Power (20-50 W) and contact force (1-5 g, 10-15 g, 20-25 g) were systematically alternated.

RESULTS

Lesion formation was most prominent in the first seconds of RF application during which nonlinear lesion growth was observed (max. 1.08 mm/s for lesion depth and 2.71 mm/s for lesion diameter). Power levels determined the extent of lesion formation in the early phase. After 20 s, lesion size growth velocity approaches 0.1 mm/s at all power levels. LI changes were also highest in the first seconds (up to - 12 Ω/s) and decreased to less than - 0.1Ω/s after prolonged application.

CONCLUSION

Lesion formation in irrigated RF ablation is a nonlinear process. Final lesion size resulting from an RF application is mainly influenced by high rates of lesion growth in the first seconds of ablation. LI seems to be a good surrogate for differentiating changes in lesion formation.

Ablation of Paroxysmal Atrial Fibrillation: between Present and Future

Pulmonary vein isolation (PVI) is the established cornerstone for atrial fibrillation (AF) ablation, indeed current guidelines recognize PVI as the gold standard for first-time AF ablation, regardless of if it is paroxysmal or persistent. Since 1998 when Haïssaguerre pioneered AF ablation demonstrating a burden reduction after segmental pulmonary vein (PV) ablation, our approach to PVI was superior in terms of methodology and technology. This review aims to describe how paroxysmal atrial fibrillation ablation has evolved over the last twenty years. We will focus on available techniques, a mechanistic understanding of paroxysmal AF genesis and the possibility of a tailored approach for the treatment of AF, before concluding with a future perspective.

Safety and effectiveness of the first contact force ablation catheter with a flexible tip

Background

Catheter ablation is an established therapy for paroxysmal atrial fibrillation (PAF). The TactiFlex Ablation Catheter, Sensor Enabled (TactiFlex SE) is a next-generation radiofrequency ablation catheter incorporating fiber optics-based contact force-sensing technology with a flexible, laser-cut tip.

Objective

The study sought to evaluate the safety and effectiveness of the TactiFlex SE ablation catheter for treatment of drug-refractory PAF.

Methods

The TactiFlex AF investigational device exemption was a prospective, nonrandomized, multicenter clinical study. Enrollment began on June 26, 2020 and completed June 18, 2021. Subjects with PAF underwent de novo pulmonary vein isolation and, if indicated, ablation for typical atrial flutter. Subjects were followed for 12 months.

Results

Of the 355 subjects enrolled at 37 sites worldwide, 334 underwent ablation with the TactiFlex SE catheter. The Kaplan-Meier estimate of 12-month freedom from AF/atrial flutter (AFL)/atrial tachycardia recurrence was 72.9% (95% confidence interval [CI] 95% CI 67.2%-77.8%) and clinical success was 83.6% (95% CI 95% CI 78.1%-87.2%). As-treated analyses compared subjects treated at high power (left atrium time-averaged power setting 40-50 W; n = 222) vs low power (<40 W; n = 97). The Kaplan-Meier estimate of 12-month freedom from AF/AFL/atrial tachycardia recurrence was 76.4% (95% CI 69.3%-82.0%) and clinical success was 83.9% (95% CI 77.5%-88.6%) in the high-power group compared with 66.8% (95% CI 56.1%-75.5%) and 80.7% (95% CI 70.8%- 87.5%), respectively, in the low-power group. The primary safety event rate in all treated subjects was 4.3%; 4.1% in the HP group and 5.2% in the LP group (P = .7671).

Conclusion

TactiFlex SE is safe and effective for treatment of drug-refractory PAF and concomitant AFL and enables more efficient procedures than previous generation catheters.