Characterization of Left Atrial Substrate in Patients With Ventricular Arrhythmias

The goal of this observational study is to analyze the characteristics of left atrial electroanatomical maps in patients without a history of atrial fibrillation but with a high clinical risk of developing it, as indicated by the presence of structural heart disease or a CHA2DS2-VASc score ≥ 2 points. The study cohort will be compared to a historical cohort of patients with diagnosed atrial fibrillation in a propensity-matched fashion. The main questions it aims to answer are: * Are the left atrial electroanatomical changes a consequence or a precursor to the development of atrial fibrillation? * Are the left atrial electroanatomical findings different between patients with atrial fibrillation and those at high risk of developing it? * What is the prognostic impact of left atrial pathologic changes in patients without diagnosed atrial fibrillation in terms of cardiovascular outcomes?