Acute and mid-term outcomes of ablation for atrial fibrillation with VISITAG SURPOINT: the Japan MIYABI registry

Role of Catheter-Tissue Contact in Pulsed Field Ablation

Pulsed electrical field energy is a highly customizable, minimally thermal energy source associated with a myriad of potential ablation recipes that would hypothetically limit the importance of catheter-tissue contact on lesion formation. However, recent preclinical studies conducted on ventricular swine models suggest that contact force is pivotal in achieving adequate lesion formation even during pulsed field ablation. Despite the accruing preclinical evidence, clinical data on ablation targets beyond pulmonary veins are lacking and vast, and prospective human studies are required to better explore the clinical outcome of patients undergoing contact-force-guided pulsed field ablation for cardiac arrhythmias.

Feasibility of unipolar signal-guided ablation in creating contiguous lines of conduction block: A proof-of-concept study

BACKGROUND

Modification of the atrial unipolar electrogram (Uni-EGM) with loss of the near-field negative component in response to radiofrequency (RF) ablation reflects transmural loss of tissue conductivity.

OBJECTIVE

This study sought to investigate the feasibility of Uni-EGM morphology-guided RF ablation in generating contiguous, transmural lesions that result in conduction block. This method was compared with ablation guided by standard ablation index parameters.

METHODS

In a beating heart swine model, linear transcaval ablation was performed using an irrigated ablation catheter with standard and high-power RF ablation. First, an optimal Uni-EGM endpoint for predicting a transmural lesion was determined by single RF applications in the smooth and trabeculated portions of the right atrium. We compared termination of RF energy immediately upon observing consistent loss of the negative component (S wave) on the local Uni-EGM vs extending RF delivery for an additional 3 seconds beyond (U+3). Next, linear ablation was achieved with either target ablation index of 400 or Uni-EGM (U+3)-based techniques. The latter method relied upon Uni-EGM morphology both to direct catheter positioning at sites of contiguous and viable tissue and to titrate RF delivery. Bidirectional block was demonstrated with standard EP pacing maneuvers, high-density activation mapping, and pathology.

RESULTS

Extending RF delivery for 3 additional seconds (U+3) after consistent loss of the negative component on the Uni-EGM proved an optimal endpoint, predicting a transmural lesion with 94% sensitivity and 100% specificity. It was observed that, with increasing distance from site of RF application, the near-field S wave on the Uni-EGM grows in magnitude whereas an acute current of injury pattern diminishes. Uni-EGM-based technique resulted in equal efficacy in producing ablation lines with complete bidirectional block compared with target AI-guided ablation. With standard power, Uni-EGM-guided ablation resulted in significantly less energy delivered per RF application.

CONCLUSION

We demonstrate that Uni-EGM can successfully guide ablation yielding conduction lines of block. Uni-EGM morphology reflects local tissue activation, and its modification in response to thermal injury can serve as an endpoint to ensure adequate yet avoid excess RF delivery. The near-field S wave on the Uni-EGM indicates viable tissue and, in conjunction with an acute current of injury, identified contiguous, conductive tissue for targeting. Characterization of Uni-EGM morphology with respect to myocardial electrical properties and understanding its modification in response to injury may lend to the continued pursuit of safer, more effective ablation strategies.

Low-voltage-area ablation for persistent atrial fibrillation: a randomized controlled trial

Low-voltage areas (LVAs) in the left atrium may promote atrial fibrillation (AF), but the efficacy of LVA ablation for preventing arrhythmia has not been determined. In the present study, we carried out a multicenter, randomized controlled trial (SUPPRESS-AF) to investigate the efficacy of LVA ablation in patients with persistent AF who had left atrial LVAs. Patients with persistent AF and left atrial LVAs that covered ≥5 cm2 of the left atrial surface on a voltage map after pulmonary vein isolation (PVI) were randomized to undergo LVA ablation (PVI + LVA-ABL group) or not (PVI-alone group) in a 1:1 fashion. Recurrence of AF or atrial tachycardia (AT) was monitored using 24-h Holter electrocardiography (ECG) and twice-daily portable ECG recordings. The primary endpoint was freedom from AF or AT recurrence without antiarrhythmic drug use during 1 year of follow-up. Of 1,347 patients (1,003 males and 344 females) who underwent initial ablation for AF, patients with left atrial LVAs were assigned to the PVI + LVA-ABL (n = 170) or the PVI-alone group (n = 171). Although the PVI + LVA-ABL group demonstrated a numerically higher rate of freedom from AF or AT recurrence compared with the PVI-alone group (61% (95% confidence interval (CI) = 53-68%) versus 50% (95% CI = 42-57%)), this difference did not reach statistical significance (P for log(rank) test = 0.127). There was no difference in the procedure-related serious adverse events between the two groups (1.7% versus 1.8%, P < 0.0001). In conclusion, LVA ablation in addition to PVI did not significantly reduce 1-year AF or AT recurrence in patients with persistent AF with left atrial LVAs. Future studies are needed to identify patients who may receive greater benefit from LVA ablation.

High-power short-duration setting prevents changes of periprocedural thrombotic markers and the onset of silent stroke in patients with atrial fibrillation

Background

It remains unclear whether the newly adopted high-power, short-duration (HP-SD) setting in ablation for atrial fibrillation (AF) impacts periprocedural thrombotic markers or silent stroke (SS) onset.

Objective

The aim of the present study was to investigate the clinical impact of HP-SD setting ablation on changes in periprocedural thrombotic markers and the onset of SS.

Methods

We enrolled 101 AF patients: the HP-SD group (n = 67) using 50 W and the conventional ablation group (n = 34) using 30 to 40 W. D-dimer, thrombin-antithrombin complex (TAT), and total plasminogen activator inhibitor-1 (tPAI-1) were analyzed the day before, immediately after, and 1 day after the procedure. Magnetic resonance imaging was performed within 48 hours after the procedure.

Results

Left atrial dwelling time was significantly shorter in the HP-SD group (P < .05). In the conventional ablation group, the D-dimer and tPAI-1 levels continued to increase until 1 day postprocedure, while the TAT peaked immediately after the ablation. On the other hand, the range of the variation of these thrombotic markers in the HP-SD group was smaller. SS occurred more frequently in the conventional ablation group than in the HP-SD group (26% vs 5%, P < .05). In the logistic regression analysis, the HP-SD setting and TAT difference (postprocedure - preprocedure) were independent predictors for SS (odds ratios 0.141 and 5.838, respectively; P < .05).

Conclusions

The HP-SD setting led to a shorter left atrial dwelling time and reduced change in thrombotic markers, resulting in lower prevalence of SS.

A negative relationship between first-pass pulmonary vein isolation and body mass index in ablation index-guided pulmonary vein isolation

Background

We previously reported the relationship between first-pass pulmonary vein isolation (FPI) and pulmonary vein isolation (PVI) durability in ablation index-guided atrial fibrillation ablation. Obesity is a worsening factor for atrial tachyarrhythmia (AT) recurrence. However, the impact of obesity on FPI has been scarcely reported. General anesthesia (GA) facilitates completing PVI by preventing airway obstruction caused by sedative drug use. However, the impact of GA on the relationship also has not been elucidated.

Objective

The study sought to evaluate the impact of obesity and its relationship with GA on FPI.

Methods

We retrospectively studied 2187 consecutive patients undergoing ablation index-guided first atrial fibrillation ablation (conscious sedation in 1969 and GA in 218). We divided them into 4 groups according to body mass index (BMI): underweight (BMI < 18.5 kg/m2) (n = 80), normal (18.5 kg/m2 ≤ BMI < 25 kg/m2) (n = 1,160), overweight (25 kg/m2 ≤ BMI < 30 kg/m2) (n = 763), and obesity (BMI ≥30 kg/m2) (n = 184).

Results

FPI rate decreased as BMI increased in both conscious sedation (68.1% in underweight, 61.5% in normal, 48.7% in overweight, and 39.0% in obesity; P < .001) and GA (87.5%, 67.1%, 61.3%, and 44.7%, respectively; P = .01). Multivariate analysis revealed overweight (odds ratio 0.65, 95% confidence interval [CI] 0.53-0.79, P < .001, vs normal) and obesity (OR 0.44, 95% CI 0.31-0.62 P < .001, vs normal) as independent predictors for FPI and obesity as an AT recurrence predictor (hazard ratio 1.35, 95% CI 1.01-1.81, P = .04).

Conclusion

BMI increase was negatively related to the FPI rate. Notably, the FPI rate in obese patients, even under GA, was low, which might be related to their high AT recurrence.

Dual energy for pulmonary vein isolation using dual-energy focal ablation technology integrated with a three-dimensional mapping system: SmartfIRE 3-month results

AIMS

Contact force (CF)-sensing radiofrequency (RF) catheters with an ablation index have shown reproducible outcomes for the treatment of atrial fibrillation (AF) in large multicentre studies. A dual-energy (DE) focal CF catheter to deliver RF and unipolar/biphasic pulsed field ablation (PFA), integrated with a three-dimensional (3D) mapping system, can provide operators with additional flexibility. The SmartfIRE study assessed the safety and efficacy of this novel technology for the treatment of drug-refractory, symptomatic paroxysmal AF. Results at 3 months post-ablation are presented here.

METHODS AND RESULTS

Pulmonary vein isolation (PVI) was performed using a DE focal, irrigated CF-sensing catheter with the recommendation of PFA at posterior/inferior and RF ablation at the anterior/ridge/carina segments. Irrespective of energy, a tag size of 3 mm; an inter-tag distance ≤6 mm; a target index of 550 for anterior, roof, ridge, and carina; and a target index of 400 for posterior and inferior were recommended. Cavotricuspid isthmus ablation was permitted in patients with documented typical atrial flutter. The primary effectiveness endpoint was acute procedural success. The primary safety endpoint was the rate of primary adverse events (PAEs) within 7 days of the procedure. A prespecified patient subset underwent oesophageal endoscopy (EE; 72 h post-procedure), neurological assessment (NA; pre-procedure and discharge), and cardiac computed tomography (CT)/magnetic resonance angiogram (MRA) imaging (pre-procedure and 3 months post-procedure) for additional safety evaluation, and a mandatory remapping procedure (Day 75 ± 15) for PVI durability assessment. Of 149 patients enrolled between February and June 2023, 140 had the study catheter inserted (safety analysis set) and 137 had ablation energy delivered (per-protocol analysis set). The median (Q1/Q3) total procedure and fluoroscopy times were 108.0 (91.0/126.0) and 4.2 (2.3/7.7) min (n = 137). The acute procedural success rate was 100%. First-pass isolation was achieved in 89.1% of patients and 96.8% of veins. Cavotricuspid isthmus ablations were successfully performed in 12 patients [pulsed field (PF) only: 6, RF only: 5, and RF/PF: 1]. The PAE rate was 4.4% [6/137 patients; 2 pulmonary vein (PV) stenoses, 2 cardiac tamponades/perforations, 1 stroke, and 1 pericarditis]. No coronary artery spasm was reported. No oesophageal lesion was seen in the EE subset (0/31, 0%). In the NA subset (n = 30), microemboli lesions were identified in 2 patients (2/30, 6.7%), both of which were resolved at follow-up; only 1 was symptomatic (silent cerebral lesion, 3.3%). In the CT/MRA subset (n = 30), severe PV narrowing (of >70%) was detected in 2 patients (2/30, 6.7%; vein level 2/128, 1.6%), of whom 1 underwent dilatation and stenting and 1 was asymptomatic; both were associated with high index values and a small inter-tag distance. In the PV durability subset (n = 30), 100/115 treated PVs (87%) were durably isolated and 18/30 patients (60.0%) had all PVs durably isolated.

CONCLUSION

A DE focal CF catheter with 3D mapping integration showed a 100% acute success rate with an acceptable safety profile in the treatment of paroxysmal AF. Prespecified 3-month remapping showed notable PVI durability.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05752487.

Predictors of pulmonary vein non-reconnection in the second procedure after ablation index-guided pulmonary vein isolation for atrial fibrillation and its impact on the outcome

INTRODUCTION

Although first-pass isolation (FPI) of the pulmonary vein (PV) has been suggested as a marker for PV isolation (PVI) durability, it has not been confirmed. Non-PV atrial fibrillation (AF) triggers were the main target in patients without PV reconnection in the second ablation procedure, but the outcome was unclear. We aimed to validate FPI as a marker of PVI durability and evaluate the outcome after the second procedure in patients without PV reconnection by comparing it to those with reconnection.

METHODS

Among the 2087 patients undergoing the first ablation index-guided radiofrequency AF ablation, 309 with atrial tachyarrhythmias (ATs) recurrence and undergoing the second procedure were studied. Clinical characteristics and outcomes were compared between the patients without PV reconnection (PV non-reconnection group, n = 142) and with reconnection (PV reconnection group, n = 167).

RESULTS

FPI in both PV sides in the first ablation procedure was significantly more frequent in the PV non-reconnection group (77.5%) than in the PV reconnection group (45.5%) (p < .001). Multivariate logistic regression analysis revealed that FPI (odds ratio, 3.71 [95% confidence interval, 2.23-6.19], p < .001) was the only predictor of PV non-reconnection. Radiofrequency applications for non-PV AF triggers were more frequently performed in the PV non-reconnection group (40.8% vs. 24.6%, respectively, p < .001). Kaplan-Meier analysis revealed that AT recurrence-free rate was significantly lower in the PV non-reconnection group (1-year recurrence-free rate, 62.7% vs. 75.4%, respectively; p = .01 by log-rank test).

CONCLUSION

FPI was the only independent predictor of PV non-reconnection. Despite aggressive ablation for non-PV triggers, AT recurrence was more frequent in patients with PV non-reconnection.