Insight into contact force local impedance technology for predicting effective pulmonary vein isolation

Ultra High-Density Mapping and Ablation of Localized Micro-Reentrant Tachycardias: Insight From the CHARISMA Registry

BACKGROUND

Recent advancements in ultra-high-density mapping (UHDM) featuring automated functionalities have enhanced our understanding of micro-reentrant atrial tachycardias (mAT) circuits and the precise localization of the origin.

PURPOSE

To evaluate the diagnostic support provided by an automated UHDM algorithm in guiding the ablation of mATs.

METHODS

Consecutive patients eligible for AT ablation in 22 Italian centers were prospectively enrolled. All ATs were comprehensively mapped in either the left or right atrium utilizing the RHYTHMIA mapping system. The LUMIPOINT tool was systematically employed to confirm electrogram fragmentation within this defined area.

RESULTS

Among 159 ATs analyzed, 97 (61.0%) were identified as macro-reentrant ATs, 50 (31.4%) as focal ATs and 12 (7.5%) as mATs. Concerning the mAT group, the targeted activity was localized in the anterior wall in 4 cases (33.3%), in proximity to PVs in 3 cases (25%), along the left ridge in 2 cases (16.6%), and at the roof, in the free wall and along the CTI in 1 case (8.3%), respectively. Low voltage areas (< 0.1 mV) were detected in all mAT cases and colocalized with the origin site. Over a median of 288 [248-349] days of follow-up, 5 (3.1%) patients suffered from an AT/AF arrhythmia recurrence: 3 (3.1%) were in the MAT group, 1 (2%) in the focal AT and 1 (8.3%) in the mAT group.

CONCLUSION

A novel automated algorithm for mAT identification, coupled with ORION catheter, enables mAT description and transcatheter ablation of the localized origin of this rare form of AT results in a satisfactory procedural success rate.

TRIAL REGISTRATION

Catheter Ablation of Arrhythmias With High-Density Mapping System in the Real World Practice (CHARISMA). http://clinicaltrials.gov/ Identifier: NCT03793998.

Local epicardial robotic-enhanced hybrid ablation efficacy predictors for persistent atrial fibrillation

Background

Hybrid ablation can manage persistent atrial fibrillation (PsAF) and long-standing persistent atrial fibrillation (LSPAF). Robotic-enhanced hybrid ablation (RE-HA) offers greater precision and stability. However, biophysical predictors of effective local epicardial radiofrequency ablation (ELRF) during epicardial ablation are unknown.

Objective

The purpose of this study was to compare the time course of biophysical predictors of ELRF and no-ELRF during the first stage of RE-HA in patients with PsAF and LSPAF.

Methods

We conducted a dual-center retrospective cohort study involving 92 consecutive patients with PsAF or LSPAF who underwent RE-HA between January 2021 and May 2024. Epicardial electrogram disappearance, defined as a reduction of bipolar voltages to <0.05 mV, baseline impedance (BI), and impedance drop (ID), were compared between ELRF and no-ELRF cases. Univariate and multivariate logistic regression models were used to identify predictive variables. Optimal cutoff values were determined using receiver operating characteristic curves.

Results

Among 2474 radiofrequency (RF) applications, significant predictors of ELRF included BI and ID at 1 and 8 seconds, with optimal cutoff values of <107, 0-7, and 5-17 Ω. The composite predictive model had an area under the receiver operating characteristic of 0.775, with 94% sensitivity, 53% specificity, and 65% accuracy. Our predictive ELRF score ranged from 0-4, and the Youden J test identifying a cutoff value of 3 as optimal.

Conclusion

BI and progressive ID were strong predictors of local epicardial RE-HA efficacy. The composite model was a reliable tool for early identification of ELRF, potentially reducing RF delivery and enhancing procedural efficiency. Larger prospective studies are needed to validate these findings.

Case Report: Fatal atrioesophageal fistula following atrial fibrillation ablation-critical reflections on prevention

Radiofrequency ablation (RFA) is an important therapeutic modality for atrial fibrillation (AF), widely utilized in clinical practice due to its safety and significant efficacy. However, post-procedural complications may arise, influenced by anatomical positioning and the intensity of ablation energy, with atrioesophageal fistula (AEF) being particularly rare yet severe. This case report describes a unique instance of a patient developing AEF following AF ablation, accompanied by ischemic stroke and myocardial infarction. A 71-year-old male admitted to the emergency department on July 19, 2024, with acute loss of consciousness and convulsions. Upon admission, physical examination and laboratory tests revealed vital signs within abnormal ranges and indicators suggesting inflammation and potential myocardial injury. Head CT scans showed hypoattenuating areas indicative of cerebral infarction, chest CT suggested possible air accumulation in the left atrial region. ECG findings were consistent with atrial flutter, myocardial infarction, and incomplete right bundle branch block. Given his history of atrial fibrillation and RFA, alongside clinical manifestations, the patient was diagnosed with cardio-cerebral syndrome, suspected to be complicated by an AEF due to the presence of air in the left atrium. AEF diagnosis was confirmed via cardiac CTA, leading to conservative management decisions. Despite initiating thrombolysis for cerebral infarction and supportive treatments for heart failure, including VA-ECMO, the patient's condition continued to decline, evidenced by cardiogenic shock, heart failure, and progressive neurological deficits including coma and dilated non-reactive pupils. Ultimately resulting in family-elected discharge against medical advice on the fourth day of hospitalization.

Electrographic Flow Mapping Provides Prognosis for AF Ablation Outcomes Across Two Independent Prospective Patient Cohorts

Background/Objectives: Electrographic flow (EGF) mapping allows for the visualization and quantification of atrial fibrillation (AF) wavefront propagation patterns. EGF-identified sources were shown in the randomized controlled FLOW-AF trial to significantly increase the likelihood of AF recurrence within 1 year if left unablated. Electrographic flow consistency (EGFC) additionally measures the stability of observed wavefront patterns, such that patients with more organization have a healthier substrate and lower recurrence. Source presence and EGFC can be used collectively to assign mechanistic phenotypes to AF patients. Methods: The patient phenotypes, treatment modalities, and outcomes in FLOW-AF were compared with those of patients in the ensuing AF-FLOW Global Registry, which was conducted by separate physicians at discrete clinical centers. Results: Patients with low EGFC (≤0.62) had a 12-month freedom from AF (FFAF) of 46%, while those with a high mean EGFC (>0.62) had a FFAF of 81%. Right atrial EGFC was correlated with left atrial EGFC, and the highest recurrence occurred in those with biatrial low EGFC. Source presence also affected the recurrence rates in both trials, such that the presence of EGF-identified sources in PVI-only patients lowered the FFAF from 65% to 36%, but the elimination of sources produced a 30% absolute increase in FFAF from 36% to 66%. Conclusions: Patient outcomes by EGF-based AF phenotype were consistent across two cohorts of patients from separate clinical trials at distinct centers. Patients with a high EGFC and no sources post-procedure had the best outcomes. EGF mapping provides insights into underlying disease pathophysiology and may be employed prospectively to predict recurrence.

Correlation Between Voltage and Impedance Mapping in Patients with Atrial Fibrillation

Background. Pulmonary vein isolation (PVI) represents the cornerstone of paroxysmal (PAF) and persistent atrial fibrillation (PsAF) ablation. Impedance values provide insights on tissue conductive properties. Methods. Consecutive patients undergoing PAF and PsAF ablation were prospectively enrolled. All the patients underwent a preprocedural multidetector computed tomography (MDCT) to evaluate left atrial wall thickness (LAWT). Electroanatomic maps were acquired with the ablation catheter, and impedance values (Ω) and voltage amplitude (mV) of bipolar electrograms were collected. Results. A total of 60 patients (40 with PAF and 20 with PsAF) were included in the study. In all PAF cases, no voltage value lower than 0.5 mV was found at LA mapping; the corresponding mean impedance value was 151.5 ± 5.4 Ω. In PsAF cases, voltage values inferior to 0.05 mV have been reported in 19/20 patients. PsAF patients showed a mean impedance value of 129.1 ± 3.8 Ω. The correlation analysis between bipolar voltage and impedance reported an rs value of 0.4166 (p < 0.001), showing a positive correlation between the two variables. On the contrary, no direct correlation was found between voltage and LAWT and between impedance and LAWT (rsv-t = 0.1838; rsi-t = 0.1133, respectively). Conclusions. This research study suggests a correlation between voltage amplitude and impedance values, so that impedance might be used for arrhythmogenic substrate characterization.

Contact-force local impedance algorithm to guide effective pulmonary vein isolation in AF patients: 1-year outcome from an international multicenter clinical setting

BACKGROUND

The combination of highly localized impedance (LI) and contact force (CF) may improve tissue characterization and lesion prediction during radiofrequency (RF) pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF).

OBJECTIVE

We report the outcomes of our acute and long-term clinical evaluation of CF-LI-guided PVI in consecutive AF ablation cases from an international multicenter clinical setting.

METHODS

Three hundred twenty-four consecutive patients from 20 European centers undergoing RF catheter ablation with the Stablepoint™ catheter were enrolled in the CHARISMA registry. Of these, 275 had a minimum follow-up of 1 year and were included in the primary analysis.

RESULTS

The mean procedure duration was 115 ± 47 min, and the mean fluoroscopy time was 9.9 ± 6 min. At the end of the procedures, all PVs had been successfully isolated in all study patients. Minor complications were reported in 12 patients (4.4%). At 1 year, 36 (13.1%) patients had had an AF recurrence, and freedom from antiarrhythmic drugs and AF recurrence was achieved in 228 (82.9%) patients. The recurrence rate was higher in patients with persistent AF (21/116, 18.1%) than in those with paroxysmal AF (15/159, 9.4%; p = 0.0459). On multivariate logistic analysis adjusted for baseline confounders, only time > 6 months from first diagnosis of AF to ablation (HR = 2.93, 95%CI 1.03 to 8.36, p = 0.0459) was independently associated with recurrences.

CONCLUSION

An ablation strategy for PVI guided by CF-LI technology proved safe and effective and resulted in a low recurrence rate of AF over 1-year follow-up, irrespective of the underlying AF type.

CLINICAL TRIAL REGISTRATION

Catheter Ablation of Arrhythmias with a High-Density Mapping System in Real-World Practice. (CHARISMA). URL: http://clinicaltrials.gov/ Identifier: NCT03793998.

Pulsed field ablation technology for pulmonary vein and left atrial posterior wall isolation in patients with persistent atrial fibrillation

INTRODUCTION

Limited data exist on pulsed-field ablation (PFA) in patients with persistent atrial fibrillation (PeAF) undergoing left atrial posterior wall isolation (LAPWI).

METHODS

The Advanced TecHnologies For SuccEssful AblatioN of AF in Clinical Practice (ATHENA) prospective registry included consecutive patients referred for PeAF catheter ablation at 9 Italian centers, treated with the FARAPULSETM-PFA system. The primary efficacy and safety study endpoints were the acute LAPWI rate, freedom from arrhythmic recurrences and the incidence of major periprocedural complications. Patients undergoing pulmonary vein isolation (PVI) alone, PWI + LAPWI and redo procedures were compared.

RESULTS

Among 249 patients, 21.7% had long-standing PeAF, 79.5% were male; mean age was 63 ± 9 years. LAPWI was performed in 57.6% of cases, with 15.3% being redo procedures. Median skin-to-skin times (PVI-only 68 [60-90] vs. PVI + LAPWI 70 [59-88] mins) did not differ between groups. 45.8% LAPWI cases were approached with a 3D-mapping system, and 37.3% with intracardiac echocardiography. LAPWI was achieved in all patients by means of PFA alone, in 88.8% cases at first pass. LAPWI was validated either by an Ultrahigh-density mapping system or by recording electrical activity + pacing maneuvers. No major complications occurred, while 2.4% minor complications were detected. During a median follow-up of 273 [191-379] days, 41 patients (16.5%) experienced an arrhythmic recurrence after the 90-day blanking period, with a mean time to recurrence of 223 ± 100 days and no differences among ablation strategies.

CONCLUSION

LAPWI with PFA demonstrates feasibility, rapidity, and safety in real-world practice, offering a viable alternative for PeAF patients. LAPWI is achievable even with a fluoroscopy-only method and does not significantly extend overall procedural times.

Local impedance and contact force guidance to predict successful cavotricuspid isthmus ablation with a zero-fluoroscopy approach

Introduction

A new technology capable of monitoring local impedance (LI) and contact force (CF) has recently been developed. At the same time, there is growing concern regarding catheter ablation performed under fluoroscopy guidance, due to its harmful effects for both patients and practitioners. The aim of this study was to assess the safety and effectiveness of zero-fluoroscopy cavotricuspid isthmus (CTI) ablation monitoring LI drop and CF as well as to elucidate if these parameters can predict successful radiofrequency (RF) applications in CTI ablation.

Methods

We conducted a prospective observational study recruiting 50 consecutive patients who underwent CTI ablation. A zero-fluoroscopy approach guided by the combination of LI drop and CF was performed. In each RF application, CF and LI drop were monitored. A 6-month follow-up visit was scheduled to assess recurrences.

Results

A total of 767 first-pass RF applications were evaluated in 50 patients. First-pass effective RF applications were associated with greater LI drops: absolute LI drops (30.05 ± 6.23 Ω vs. 25.01 ± 5.95 Ω), p = 0.004) and relative LI drops (-23.3 ± 4.9% vs. -18.3 ± 5.6%, p = 0.0005). RF applications with a CF between 5 and 15 grams achieved a higher LI drop compared to those with a CF below 5 grams (29.4 ± 8.76 Ω vs. 24.8 ± 8.18 Ω, p < 0.0003). However, there were no significant differences in LI drop between RF applications with a CF between 5 and 15 grams and those with a CF beyond 15 grams (29.4 ± 8.76 Ω vs. 31.2 ± 9.81 Ω, p = 0.19). CF by itself, without considering LI drop, did not predict effective RF applications (12.3 ± 7.54 g vs. 11.18 ± 5.18 g, p = 0.545). Successful CTI ablation guided by a zero-fluoroscopy approach was achieved in all patients. Only one patient experienced a recurrence during the 6-month follow-up.

Conclusions

LI drop (absolute and relative values) appears to be a good predictor of successful RF applications to achieve CTI conduction block. The optimal CF to achieve a good LI drop is between 5 and 15 g. A zero-fluoroscopy approach guided by LI and CF was feasible, effective, and safe.