LGALS3 and cardiac arrhythmia: This cohort study showed that: (1) up to 40% of patients addressed for ablation of persistent AF may present with a reduced left ventricular systolic function; (2) up to 70% of these patients may partially or totally recover left ventricular systolic function after ablation, including some patients with a previous history of structural heart disease; these so-called 'responders to ablation' have a highly favorable 1-year prognosis; (3) higher baseline galectin-3 level identifies non-responders to ablation, i.e. patients at higher risk of arrhythmia recurrence and with a worse outcome.