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Introduction: Pulmonary vein isolation (PVI) using radiofrequency ablation (RFA) is an established treatment strategy for atrial fibrillation (AF). To improve PVI efficacy and safety, high‐power short‐duration (HPSD) ablation and pulsed‐field ablation (PFA) were recently introduced into clinical practice. This study aimed to determine the extent of myocardial injury and systemic inflammation following PFA, HPSD, and standard RFA using established biomarkers. Methods: We included 179 patients with paroxysmal AF receiving first‐time PVI with different ablation technologies: standard RFA (30–40 W/20–30 s, n = 52), power‐controlled HPSD (70 W/5–7 s, n = 60), temperature‐controlled HPSD (90 W/4 s, n = 32), and PFA (biphasic, bipolar waveform, n = 35). High‐sensitivity cardiac troponin T (hs‐cTnT), creatine kinase (CK), CK MB isoform (CK‐MB), and white blood cell (WBC) count were determined before and after ablation. Results: Baseline characteristics were well‐balanced between groups (age 63.1 ± 10.3 years, 61.5% male). Postablation hs‐cTnT release was significantly higher with PFA (1469.3 ± 495.0 ng/L), HPSD‐70W (1322.3 ± 510.6 ng/L), and HPSD‐90W (1441.2 ± 409.9 ng/L) than with standard RFA (1045.9 ± 369.7 ng/L; p <.001). CK and CK‐MB release was increased with PFA by 3.4‐fold and 5.8‐fold, respectively, as compared to standard RFA (p <.001). PFA was associated with the lowest elevation in WBC (Δ1.5 ± 1.5 × 109/L), as compared to standard RFA (Δ3.8 ± 2.5 × 109/L, p <.001), HPSD‐70W (Δ2.7 ± 1.7 × 109/L, p =.037), and HPSD‐90W (Δ3.6 ± 2.5 × 109/L, p <.001). Conclusion: Among the four investigated ablation technologies, PFA was associated with the highest myocardial injury and the lowest inflammatory reaction. [ABSTRACT FROM AUTHOR]

Background: Steam pops are a rare complication associated with radiofrequency (RF) ablation and are hard to predict. The aim of this study was to assess the influence of coverage between the RF ablation electrode and cardiac tissue on steam pop incidence and lesion size. Methods and results: An ex vivo model using porcine cardiac preparations and contact force sensing catheters was designed to perform RF ablations at different coverage levels between the RF electrode and cardiac tissue. During coverage level I, only the distal part of the ablation electrode was in contact with tissue. During coverage level II half of the ablation electrode, and during coverage level III the entire ablation electrode was embedded in tissue. RF applications (n = 60) at different coverage levels I–III were systematically performed using the same standardized ablation protocol. Ablations during coverage level III resulted in a significantly higher rate of steam pops (100%) when compared to ablations during coverage level II (10%) and coverage level I (0%), log rank p <.001. Coverage level I ablations resulted in significantly smaller lesion depths, diameters, and impedance drops when compared to higher coverage level ablations, p <.001. In the controlled ex vivo model, there was no difference in applied contact force or energy between different coverage levels. Conclusions: The level of coverage between RF electrode, cardiac tissue, and the surrounding fluid significantly influenced the incidence of steam pops in an ex vivo setup. Larger coverage between RF electrode and tissue resulted in significantly larger lesion dimensions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]