The WIDER PVI study is a multicentre randomized clinical trial to compare the efficacy of antral versus extended antral PVI in patients with paroxysmal or persistent AF undergoing this procedure using a cryoablation balloon capable of 28 mm diameter (antral isolation) or 31 mm diameter (extended antral isolation) applications. The aim is to evaluate an objective of superiority of the extended antral isolation strategy versus antral isolation in the recurrence of atrial tachyarrhythmias at 1-year follow-up, both in episodes of >30 seconds duration and in overall arrhythmic load.

Ablation has become a first-line therapy in the rhythm control strategy for atrial fibrillation (AF).

Pulmonary vein electrical isolation (PVI) is the cornerstone of ablation therapy, based on its efficacy profile, safety and lack of alternatives.

Single shot techniques have been increasingly used as the initial approach for PVI, employing cryoablation, i.e. release of cryoenergy into the endocardium via an inflatable catheter, to achieve isolation.

The most commonly used diameter in cryoablation is 28 mm. These generate antral isolation whose profile depends on the distance between veins. When the application is made with larger devices, as has been observed with the cryoballoon with an expandable diameter of 31 mm or ablation devices using pulsed electric fields, the isolation is also antral at the level of the carina, making the result of PVI more similar to that obtained when ablation is performed with a Wide Antral Circumferential Ablation (WACA) strategy using point-to-point radiofrequency (the gold standard for PVI).

The WIDER-PVI study aims to answer the question of whether single-shot ablation with a 31 mm diameter device is superior to conventional ablation with a 28 mm diameter device. The answer to this question is relevant in the context of the development of new, larger devices and concerns about the impact of larger ablation on atrial function.

Inclusion Criteria:

• Age over 18 years old.
• Previous diagnosis of paroxysmal or persistent atrial fibrillation less than 2 years after diagnosis.
• Clinical indication to undergo a pulmonary vein isolation procedure using balloon cryoablation.

Exclusion Criteria:

• Severe left atrial dilatation (indexed volume >48 ml/m2 or area >40 cm2 or indexed diameter >3.0 cm/m2).
• Previous endocardial or surgical ablation of atrial fibrillation.
• Severe frailty (Clinical Frailty Scale score 7 or higher) or life expectancy less than 1 year.
• Inability to understand or give informed consent.
• Performance of other left atrial ablations in addition to pulmonary veins.
• Need to use another catheter in addition to the cryoablation catheter to complete pulmonary vein isolation.
• Contraindication to anticoagulation or intolerance to heparin.
• Presence of intra-atrial thrombus.
• Reversible cause of atrial fibrillation.
• Severe mitral or aortic valve disease.
• Congenital heart disease.
• Pregnancy or the prospect of pregnancy in the next 12 months.

The operators will not be blinded and will be aware of patient randomisation, which is necessary for the performance of the ablation procedure. The patient participant and the recurrence evaluation committee will be blinded.