This is a prospective, multi-center, research study designed to evaluate the safety and efficacy of pulmonary vein (PV) isolation with high power short duration radiofrequency energy in patients with paroxysmal/persistent atrial fibrillation (AF).

Subjects with paroxysmal/persistent AF will undergo catheter ablation using commercially approved devices (mapping system and catheters).

Patients will be followed up for 12 months to measure the recurrence of AF and its predictors. The primary endpoint will be to investigate the association between clinical and procedural characteristics and the efficacy and the safety of PVI performed with HPSD.

At least 850 consecutive will be enrolled to have an adequate statistical power for the analysis of the primary endpoint. We assume that the freedom form AF recurrence at 12 months will be 80%. Expected R^2 (Cox-Snell) 0.1. Candidate variables to be included in the model:10. Shrinkage level: 0.9. Based on these assumption the minimum number of patients is 850 with 170 events and EPP 17.

Patients will be screened in ambulatory and scheduled for AF ablation according to current guidelines. Ablation will be usually performed under effective oral anticoagulation. Anticoagulation could be withdrawn before admission, so as antiarrhythmic drugs will be removed before scheduled procedure. Patients in AF or with a CHA2DS2-VASc score ≥ 1 will undergo transesophageal echocardiography within 48 hours prior to the ablation. For all other patients transesophageal echocardiography is optional. Cardiac MRI or Cardiac CT scan could be executed as a reference for volume estimations obtained with the mapping system.

Ablation will be carried out under mild or deep sedation, or general anesthesia according to center preference. At least 2 femoral vein access will be obtained and in some patients 1 subclavian vein. One diagnostic catheter will be positioned in the coronary sinus. One or two transseptal accesses to the left atrium will be achieved using a standard approach. Then, the mapping catheter (LASSO, Penta-ray, Octa-ray catheter) and the ablation catheter (QDot Micro catheter) will be placed in the left atrium. Heparin will be administered before the transseptal punctures to maintain an activated clotting time ≥ 300 seconds for the duration of the procedure. Left atrium mapping will be performed in sinus rhythm. Patients with atrial fibrillation at the beginning of the index procedure will undergo electrical cardioversion. After left atrium reconstruction the effective PV-left atrium electrical connection will be checked with the mapping catheter. In all patients a wide antrum circumferential ablation aimed at PV isolation will be performed using the QDot Micro catheter in QMode+ mode (90 w for 4 sec) for the whole ablation or in an hybrid mode (QMode + for posterior wall and QMode guided by AI in the anterior wall), according to the operator preference. The maximum interlesion distance will be <6 mm (16,17). According to operator preference it will be performed an ablation line encircling each PV or two ablation lines encircling the right and the left PVs. At the end of the ablation effective PV isolation (entry and exit block), will be checked with mapping catheter. After PV isolation will be achieved, the reconnection of the same vein will be evaluated after a 20 minute period from the initial isolation or after adenosine infusion or isoproterenol. If the vein reconnects to the atrium, the ablation will be directed to the gaps identified by the mapping catheter.

All patients will undergo a post-procedural ECG and, optional, an echocardiogram to exclude pericardial effusion or other acute complications.

After ablation, patients will undertake regular follow-up assessments (scheduled at 3 months) including a detailed history, physical examination, 12-lead standard electrocardiography, and 24-h Holter monitoring. Patients who will not report any symptoms related to the previous arrhythmia during a supplementary detailed follow up (6-12 months subsequent to catheter ablation) will be considered free of arrhythmia recurrence

Inclusion Criteria:

• Patients with paroxysmal/persistent AF who signed the informed consent
• Patients on active oral anticoagulation

Exclusion Criteria:

• Previous ablation for AF
• Patients with LVEF<35%
• Women potentially pregnant
• Contraindications to X-ray exposure
• Congenital heart disease or cardiac surgery within 1 month

Patients with paroxysmal/persistent AF with indication to catheter ablation according to current guidelines

all collected IPD

starting 6 months after publication on primary end point

The data will be shared on reasonable request to the corresponding author