RESET-PFA is a prospective, multicenter, non-randomized post-market study. All patients will be treated according to the standard care followed by each center. The protocol requires enrollment of consecutive patients from each center, according to eligibility criteria. During the 12 months follow-up period, clinical atrial fibrillation recurrence, occurrence of all kinds of atrial arrhythmias and of all Adverse Events in the study population will be collected.

The purpose of this study is to prospectively evaluate during time a large population of patients with an indication for ablation of AF, collecting data on procedural success in the acute and medium- to long-term follow-up. The primary objective of the study is the determination of up to 10 clinical and procedural parameters predicting a repeat ablation procedure after the blanking period in patients that had undergone an AF ablation with pulsed field ablation through a standard of care pathway.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice in the Western world, significantly impacting patient morbidity and mortality. Catheter ablation, specifically pulmonary vein isolation, has become the treatment of choice for rhythm control in patients with drug-refractory AF. Historically, thermal therapies such as radiofrequency (RF) and cryoablation have been used for pulmonary vein isolation. However, numerous studies have shown that a portion of AF recurrences pulmonary vein ablation can be attributed to pulmonary vein reconnections, suggesting suboptimal lesion durability. Pulsed field ablation (PFA), a novel non-thermal ablation technique using high-voltage, short-duration electrical pulses, has emerged as a promising alternative. PFA induces myocardial cell death via irreversible electroporation, achieving pulmonary vein isolation. Initial clinical trials demonstrated PFA's efficacy, efficiency, and safety, with favorable rates of durable pulmonary vein isolation at 3 months post-ablation.

Following commercialization and widespread adoption, multicenter registries have further confirmed PFA's efficacy and safety. Comparative studies have suggested superior long-term pulmonary vein isolation rates with PFA compared to conventional thermal therapies. Consequently, PFA has the potential to improve lesion durability and clinical outcomes for AF patients. While several studies have investigated pulmonary vein isolation durability in redo procedures in patients with clinical recurrences after PFA, results have been variable (isolation durability range: 63% - 71%), and more data is needed to fully understand the patterns of reconnection.

To our knowledge, all previous studies primarily focused on PFA during the technology's early stages and operator learning curves, potentially biasing results towards suboptimal isolation rates due to inexperience. Additionally, most studies were retrospective and single-center, with only one multicenter registry involving seven hospitals. Furthermore, none of these studies have analyzed the workflow of the index pulmonary vein isolation procedure to explain variations in lesion durability.

Therefore, the investigators present a multicenter, national, retrospective/prospective study of experienced operators to evaluate pulmonary vein isolation durability in patients with AF recurrences after PFA, focusing on the association between index procedure workflow and lesion durability.

The previous considerations seem to suggest the need to conduct a large multicentric registry of experienced operators aimed at observing current clinical practice. The registry should allow the analysis of clinical practice in relation to the current procedural recommendations, the observation of the type of methods and ablation workflow adopted and the reasons for the choices. The long-term follow-up of the patients would allow the estimation of the incidence of arrhythmic occurrences and the evaluation of the outcome, according to the clinical characteristics, the ablative strategy of the index procedure and the validation criteria at the end of the procedure. Furthermore, the prospective observation of a large number of patients treated in clinical practice approached with different ablation approaches would allow to evaluate lesion durability and residual pulmonary vein gaps that have a decisive weight in evaluating the real effectiveness of the therapy and the consequent ablation strategy during repeated ablation. These data could be extremely useful and could guide EPs in choosing the best treatment options.

The primary objective of the study is the determination of up to 10 independent predictors of repeated ablation procedure after the blanking-period in patients undergoing pulsed-field ablation of atrial fibrillation ablation through a standard of care pathway.

Secondary objectives of the study are: 12 months clinical success rate defined as freedom from any clinical atrial arrhythmia and the use of any Type I or Type III antiarrhythmic medication for the treatment of AF, AFL, or AT after the blanking period, rate and characteristics of repeated ablation procedures, association between additional applications (at the operator's discretion) at the index procedure on the durability of pulmonary vein isolation, association between occurrence of atrial arrhythmias and peri-procedural variables and ablation workflow at the index procedure, association between occurrence of atrial arrhythmias and ablation workflow at the repeated ablation procedure, analysis of repeat ablation procedures after an index PFA ablation with focus on lesion durability and type of arrhythmia recurrence.

Inclusion Criteria:

• Patients with an indication to a pulsed-field ablation procedure of Atrial Fibrillation according to current international and local guidelines (and future revisions), existing IFU or per physician discretion
• Patients who are willing and capable of providing informed consent, participating in all testing at an approved clinical investigational center or such consent will be provided by a legal representative, if required by local law or regulation.

Exclusion Criteria:

• Patients who are currently enrolled in another investigational study or registry that would directly interfere with the current study, except when the subject is participating in a mandatory governmental registry, or a purely observational registry with no associated treatments
• Patients who are unwilling or unable to sign an authorization to use and disclose health information or an Informed Consent.
• Patients unavailable or not willing to complete follow up visits and examination for the duration of the study at the center.
• Life expectancy ≤ 12 months per physician judgment.

All consecutive patients, clinically indicated for AF ablation, will be enrolled after signing an informed consent form and an authorization to use and disclose health information