Clinical Research Directory

Inclusion Criteria: 1. Patients who consecutively underwent an electrophysiological (EP) study between 2005 and 2023 at San Raffaele Scientific Institute are included if they met one of the following criteria: Patients referred for EP study due to: * EITHER clinical suspicion of paroxysmal supraventricular tachycardia without prior documentation of ventricular pre-excitation and/or supraventricular arrhythmia (SVA) on 12-lead surface electrocardiogram, OR with electrocardiographic evidence of SVA, AND electrophysiological confirmation of atrioventricular re-entrant tachycardia (AVRT) as the arrhythmic mechanism. * Ventricular pre-excitation documented on serial 12-lead surface ECGs, with or without clinical episodes suggestive of AVRT, who underwent catheter ablation of the accessory pathway based on: The presence of high-risk electrophysiological features (e.g., short antegrade effective refractory period of the AP, rapid conduction during atrial fibrillation), or Induction of sustained AVRT during the EP study. 2. Aged between 5 to 60 years old Exclusion Criteria: 1. Lack of pre-specified follow-up: only patients with at least 1 years follow-up ambulatory visit will be included in the study 2. REDO CA procedure