Arial fibrillation (AF) ablation outcome is still operator dependent. Ablation Index (AI) is a new lesion quality marker that has demonstrated to allow acute durable pulmonary vein (PV) isolation followed by a high single-procedure arrhythmia-free survival.

This prospective, multi-centre study was designed to evaluate the reproducibility of PV isolation guided by the AI.

A total of 490 consecutive patients with paroxysmal (80.4%) and persistent AF underwent first time PV encircling and were divided in four study groups according to operator preference in choosing the ablation catheter [a contact force (ST) or contact force surround flow (STSF) catheter] and the AI setting (330 at posterior and 450 at anterior wall or 380–500). Radiofrequency energy was delivered targeting interlesion distance ≤6mm.

At 12 months’ follow-up a high rate of freedom from AF recurrences was observed in patients with both paroxysmal and persistent AF (91% vs. 83.3%, P=0.039). There was no difference in the rate of atrial arrhythmias recurrence among the four study groups (4.5% in Group ST330–450, 12.2% in Group ST 380–500, 14.9% in Group STSF330–450, 9.4% in Group STSF380–500, P=0.083). At 12 months’ follow-up, the rate of atrial arrhythmias recurrence was also similar between patients treated with a ST catheter (8%) and STSF catheter (12.1%, P=0.2), between patients treated with an AI settings of 330–450 (10.9%) and an AI of 380–500 (10.3%, P=0.64), and among the several operators (P=0.84 and P=0.75 respectively in patients with paroxysmal and persistent AF) (Fig. 1).

An ablation protocol respecting strict criteria for contiguity and quality lesion resulted in high rate of one-year freedom from AF recurrence, both in patients with paroxysmal and persistent AF, irrespective of the ablation catheters, AI settings, and operator.