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.

Comparing pulsed field electroporation and radiofrequency ablation for the treatment of paroxysmal atrial fibrillation: design and rationale of the BEAT PAROX-AF randomized clinical trial.

AIMS: Using thermal-based energy sources [radiofrequency (RF) energy/cryo energy] for catheter ablation is considered effective and safe when performing pulmonary vein isolation (PVI) in patients with paroxysmal atrial fibrillation (AF). However, treatment success remains limited and complications can occur due to the propagation of thermal energy into non-target tissues. We aim to compare pulsed field ablation (PFA) with RF ablation in terms of efficacy and safety for patients with drug-resistant paroxysmal AF. METHODS AND RESULTS: The BEAT PAROX-AF trial is a European multicentre, superiority, open-label randomized clinical trial in two parallel groups. A total of 292 participants were recruited in 9 high-volume European clinical centres in 5 countries. Patients with paroxysmal AF were randomized to PFA (FARAPULSE Endocardial Ablation System©, Boston Scientific) or RF using the CLOSE protocol with contact force sensing catheter (SmartTouch© catheter and CARTO© Biosense Webster). The primary endpoint will be the 1-year recurrence of atrial arrhythmia, and the major secondary safety endpoint will be the occurrence of acute (<7 days) procedure-related serious adverse events, or pulmonary vein stenosis, or atrio-oesophageal fistula up to 12 months. Additionally, five sub-studies investigate the effect of PFA on oesophageal safety, cerebral lesions, cardiac autonomic nervous system, durability of PVI as assessed during redo ablation procedures, and atrial and ventricular function. The study began on 27 December 2021 and concluded recruitment on 17 January 2024. Results will be available in mid-2025. CONCLUSION: The BEAT PAROX-AF trial aims to provide critical insights into the optimal treatment approach for patients with paroxysmal AF.

First clinical data on artificial intelligence-guided catheter ablation in long-standing persistent atrial fibrillation.

INTRODUCTION: Despite advanced ablation strategies and major technological improvements, treatment of persistent atrial fibrillation (AF) remains challenging and the underlying pathophysiology is not fully understood. This study analyzed the multiple procedure outcome and safety of catheter ablation of spatiotemporal dispersions (DISPERS) detected by artificial intelligence (AI)-guided software in patients with long-standing persistent AF. METHODS AND RESULTS: The Volta VX1 software was used for 50 consecutive patients undergoing catheter ablation for persistent AF. First, high-density mapping (78% biatrial) with a multipolar mapping catheter was performed. In addition to pulmonary vein isolation (PVI), ablation of DISPERS was performed aiming at homogenizing, dissecting, isolating, or connecting DISPERS areas to nonconducting anatomical structures. Follow-up contained regular visits at our outpatient clinic at 1, 3, 6, and 12 months including 7-day Holter electrocardiograms. Patients were mainly suffering from long-standing persistent AF (mean AF duration 50.30 ± 54.28 months). Following PVI, ablation of left atrial and right atrial DISPERS areas led to AF cycle length prolongation (mean of 162.0 ± 16.6 to 202.2 ± 21.6 ms after) and AF termination to atrial tachycardia (AT) or sinus rhythm (SR) in 12 patients (24%). No stroke or pericardial effusion occurred; major groin complications (pseudoaneurysm n = 1, atrioventricular fistula n = 1) were detected in two patients. After a blanking period of 6 weeks, recurrence of any atrial arrhythmia was documented in 26 patients (52%). The majority of patients presented with organized AT (n = 15) while AF was present in n = 9 patients and AT/AF was observed in n = 2 patients. Twenty-two patients underwent reablation. During a mean follow-up of 363.14 ± 187.42 days and after an average of 1.46 ± 0.68 procedures, 82% of patients remained in stable SR. CONCLUSION: DISPERS-guided ablation using machine learning software (the Volta VX1 software) in addition to PVI in long-standing persistent AF ablation resulted in high long-term success rates regarding AF and AT elimination. Most arrhythmia recurrences were reentrant AT. After a total of 1.46 ± 0.68 procedures, freedom from AF/AT was 82%. Despite prolonged procedure times complication rates were low. Randomized studies are necessary to evaluate long-term efficacy of dispersion-guided ablation using AI.

Renal function and periprocedural complications in patients undergoing left atrial catheter ablation: A comparison between uninterrupted direct oral anticoagulants and phenprocoumon administration.

BACKGROUND: Data regarding uninterrupted oral anticoagulation in patients with chronic kidney disease (CKD) during catheter ablation for left atrial arrhythmias is limited. This study aimed to evaluate the safety and efficacy of periprocedural uninterrupted direct oral anticoagulants (DOAC) compared with uninterrupted phenprocoumon in patients with CKD undergoing left atrial catheter ablation. METHODS AND RESULTS: We conducted a retrospective single-center study of patients who underwent left atrial catheter ablation between 2016 and 2019 with underlying chronic kidney disease (glomerular filtration rate (GFR) between 15 and 45 ml/min). The primary objective of this study was to investigate whether direct oral anticoagulant (DOAC) therapy or warfarin presents a superior safety profile in patients with chronic kidney disease (CKD) undergoing left atrial catheter ablation. We compared periprocedural complications (arteriovenous fistula, aneurysm, significant hematoma (> 5 cm)) and/or bleeding (drop in hemoglobin of >2 g/dl, pericardial effusion, retroperitoneal bleeding, other bleeding, stroke) between patients receiving either uninterrupted DOAC or warfarin therapy. Secondary analysis included patient baseline characteristics as well as procedural data. A total of 188 patients (female n = 108 (57%), mean age 75.3 ± 8.1 years, mean GFR 36.8 ± 6 ml/min) were included in this study. Underlying arrhythmias were atrial fibrillation (n = 104, 55.3%) and atypical atrial flutter (n = 84, 44.7%). Of these, n = 132 patients (70%) were under a DOAC medication, and n = 56 (30%) were under phenprocoumon. Major groin complications including pseudoaneurysm and/or AV fistula occurred in 8.9% of patients in the phenprocoumon group vs. 11.3% of patients in the DOAC group, which was not statistically significant (p = 0.62). Incidence of cardiac tamponade (2.3% vs. 0%; p = 0.55) and stroke (0% vs. 0%) were low in both DOAC and phenprocoumon groups with similar post-procedural drops in hemoglobin levels (1.1±1 g/dl vs 1.1±0.9 g/dl; p = 0.71). CONCLUSION: The type of anticoagulation had no significant influence on bleeding or thromboembolic events as well as groin complications in this retrospective study. Despite observing an increased rate of groin complications, the uninterrupted use of DOAC or phenprocoumon during left atrial catheter ablation in patients with CKD appears to be feasible and effective.

Long-Term Follow-Up of Empirical Slow Pathway Ablation in Pediatric and Adult Patients with Suspected AV Nodal Reentrant Tachycardia.

BACKGROUND: The aim of this study was to assess long-term efficacy and safety of empirical slow pathway (ESP) ablation in pediatric and adult patients with a special interest in patients without dual AV nodal physiology (DAVNP). METHODS: A retrospective single-center review of patients who underwent ESP ablation between December 2014 and September 2022 was performed. Follow-up included telephone communication, letter questionnaire and outpatient presentation. Recurrence was based on typical symptoms. RESULTS: 115 patients aged 6-81 years (median age 36.3 years, 59.1% female; 26 pts < 18 years) were included. A typical history was present in all patients (100%), an ECG documentation of narrow complex tachycardia in 97 patients (84%). Patients were divided into three groups: Group 1 without DAVNP (n = 23), Group 2 with AH jump (n = 30) and Group 3 with AH jump and at least one AV nodal echo beat (n = 62). No permanent AV block was observed. During a median follow-up of 23.6 ± 22.7 months, symptom recurrence occurred in 7/115 patients (6.1%) with no significant difference between the groups (p = 0.73, log-rank test). Symptom recurrence occurred significantly more often in patients without (5/18 patients; 27%) as compared to patients with ECG documentation (2/97 patients; 2.1%; p = 0.025). No correlation between age and success rate was found (p > 0.1). CONCLUSIONS: ESP ablation is effective and safe in patients with non-inducible AVNRT. Overall, recurrence of symptoms during long-term follow-up is low, even if no DAVNP is present. Tachycardia documentation before the EP study leads to a significantly lower recurrence rate following ESP ablation.

The influence of electrode-tissue-coverage on RF lesion formation and local impedance: Insights from an ex vivo model.

BACKGROUND: The influence of power, duration and contact force (CF) on radiofrequency (RF) lesion formation is well known, whereas data on local impedance (LI) and electrode-tissue-coverage (ETC) is scarce. The objective was to investigate their effect on lesion formation in an ex vivo model. METHODS AND RESULTS: An ex vivo model was developed utilizing cross-sections of porcine heart preparations and a force-sensing, LI-measuring catheter. N = 72 lesion were created systematically varying ETC (minor/full), CF (1-5 g, 10-15 g, 20-25 g) and power (20 W, 30 W, 40 W, 50 W). In minor ETC, the distal tip of the catheter was in electric contact with the tissue, in full ETC the whole catheter tip was embedded within the tissue. Lesion size and all parameters were measured once per second (n = 3320). LI correlated strongly with lesion depth (r = -0.742 for ΔLI; r = 0.781 for %LI-drop). Lesions in full ETC were significantly wider and deeper compared to minor ETC (p < .001) and steam pops were more likely. Baseline LI, ΔLI, and %LI-drop were significantly higher in full ETC (p < .001). In lesions resulting in steam pops, baseline LI, and ΔLI were significantly higher. The influence of CF on lesion size was higher in minor ETC than in full ETC. CONCLUSIONS: ETC is a main determinant of lesion size and occurrence of steam pops. Baseline LI and LI-drop are useful surrogate parameters for real-time assessment of ETC and ΔLI correlates strongly with lesion size.

Mechanisms of late arrhythmia recurrence after initially successful pulmonary vein isolation in patients with atrial fibrillation.

BACKGROUND: Catheter ablation is an effective treatment for atrial fibrillation (AF,) but arrhythmia recurrence occurs in a relevant number of patients. Mechanisms of late occurring arrhythmias after ablation procedures are not fully understood. We analyzed electrophysiological mechanisms of early and late arrhythmia recurrences in patients who underwent radiofrequency-based catheter ablation of AF. METHODS AND RESULTS: Consecutive patients who underwent repeat ablation procedures after initial pulmonary vein isolation (PVI) for symptomatic arrhythmia recurrence were analyzed. A total of 110 consecutive patients who underwent catheter ablation for paroxysmal (79%) or persistent AF (21%) were included. Forty-seven patients suffered from early arrhythmia recurrence (group #1: 3-24 months), 29 patients from mid-term arrhythmia recurrences (group #2: 2-5 years), and 34 patients from late arrhythmia recurrences (group #3: > 5 years). Electrical PV reconnection was found in 98% in group #1, 72% in group #2 and 56% in group #3 (p < .001). Mode of arrhythmia recurrence was organized tachycardia in 25%, 28%, and 65% of patients in groups #1, #2, and #3 (p = .001), respectively. Patients with late arrhythmia recurrence had more pronounced left atrial low voltage as compared to patients with early arrhythmia recurrence based on two published scoring system. CONCLUSION: Electrical PV reconnection was found in the majority of patients with early AF recurrence after PVI. In patients with late arrhythmia recurrences this mechanism may play an inferior role, with many patients presenting without PV reconnection, but with LA structural alterations. Thus, early and late occurring arrhythmia recurrence after catheter ablation may be the same symptom of different diseases.

Ultrasound-Guided Access Reduces Vascular Complications in Patients Undergoing Catheter Ablation for Cardiac Arrhythmias.

Background: Femoral vascular access using the standard anatomic landmark-guided method is often limited by peripheral artery disease and obesity. We investigated the effect of ultrasound-guided vascular puncture (UGVP) on the rate of vascular complications in patients undergoing catheter ablation for atrial or ventricular arrhythmias. Methods: The data of 479 patients (59% male, mean age 68 years ± 11 years) undergoing catheter ablation for left atrial (n = 426; 89%), right atrial (n = 28; 6%) or ventricular arrhythmias (n = 28; 6%) were analyzed. All patients were on uninterrupted oral anticoagulants and heparin was administered intravenously during the procedure. Femoral access complications were compared between patients undergoing UGVP (n = 320; 67%) and patients undergoing a conventional approach (n = 159; 33%). Complication rates were also compared between patients with a BMI of >30 kg/m2 (n = 136) and patients with a BMI < 30 kg/m2 (n = 343). Results: Total vascular access complications including mild hematomas were n = 37 (7.7%). In the conventional group n = 17 (10.7%) and in the ultrasound (US) group n = 20 (6.3%) total vascular access complications occurred (OR 0.557, 95% CI 0.283−1.096). UGVP significantly reduced the risk of hematoma > 5 cm (OR 0.382, 95% CI 0.148, 0.988) or pseudoaneurysm (OR 0.160, 95% CI 0.032, 0.804). There was no significant difference between the groups regarding retroperitoneal hematomas or AV fistulas (p > 0.05). In patients with BMI > 30 kg/m2, UGVP led to a highly relevant reduction in the risk of total vascular access complications (OR 0.138, 95% CI 0.027, 0.659), hematomas > 5 cm (OR 0.051, 95% CI 0.000, 0.466) and pseudoaneurysms (OR 0.051, 95% CI 0.000, 0.466). Conclusion: UGVP significantly reduces vascular access complications. Patients with a BMI > 30 kg/m2 seem to particularly profit from a UGVP approach.

Late arrhythmia recurrence after atrial fibrillation ablation: incidence, mechanisms and clinical implications.

BACKGROUND AND OBJECTIVES: Catheter ablation of atrial fibrillation (AF) has become a well-established and widely used therapy, with pulmonary vein isolation (PVI) being the key modality of ablation. However, arrhythmia recurrences after PVI are common, with a relevant number of patients undergoing repeat ablation. Arrhythmia recurrence after PVI may vary regarding time point and mode of recurrence. While early arrhythmia recurrences of AF after PVI are mostly found to be the product of electrical reconnection of the pulmonary veins, the exact mechanisms of very late arrhythmia recurrence, occurring later than 12 months after successful PVI, remain unclear. This review provides an overview on the current evidence on time point and mechanisms of arrhythmia recurrence after PVI focussing on late arrhythmia recurrence. RECENT FINDINGS: The incidence of late arrhythmia recurrence after PVI can lie at a rate of up to 30% according to long-term follow-up studies. Mechanisms of recurrence include electrical reconnection of previously isolated pulmonary veins and development of atrial fibrosis. The use of cryoballoon ablation is likely to be more effective in reducing late arrhythmia recurrences compared to radiofrequency ablation. Novel scores such as the MB-LATER score or the APPLE score may become useful tools in predicting arrhythmia recurrence after PVI. RESULTS AND CONCLUSION: Late arrhythmia recurrence after PVI is common and leads to a relevant impairment of long-term success. Relevant data are currently limited and exact mechanisms of arrhythmia recurrence remain unclear. Further studies are needed to elucidate pathogenetic mechanisms of late arrhythmia recurrence after PVI in order to improve treatment strategies.