The aim is to determine the effect of extended ablation (pre-specified linear PF/RF lesion set) in addition to PVI in symptomatic persistent AF patients on AF/AT/AFL recurrence. The study is designed as multicenter, randomized trial. Eligible patients are patients with persistent AF (but not long-standing persistent AF) planned for a first-ever AF ablation procedure. Patients will be randomly assigned 1:1 either to: i) PVI-only, or ii) PVI-plus arms. Patients in both groups will undergo catheter ablation using an ablation system capable of performing PF and RF ablation (Sphere-9, Affera, Medtronic). Patients randomized to the PVI-only arm will undergo only PVI. Patients randomized to the PVI-plus arm will undergo PVI plus linear lesions (roof, bottom line, lateral or anterior MI line, and septal line in the LA; intercaval line and cavotricuspid line in the RA). The primary endpoint will be freedom from recurrent AF/AT/AFL, assessed as time-to-first recurrence in the period of 12 months after randomization (post 2-month blanking period). Secondary clinical endpoints will be 1) 12-month differences in AF/AT/AFL burden, 2) AF/AFL/AT-related outcomes (hospitalization or emergency visits), 3) Quality of life according to the AFEQT questionnaire score at 12 months, 4) MACE defined as cardiovascular death, stroke, myocardial infarction, or hospitalization for heart failure. Secondary endpoints will be evaluated throughout the entire (minimum 12-month) follow-up period.