2.1 Study population
The retrospective study included 139 patients with VAs originating from the LVS who underwent electrophysiological study and three-dimensional mapping and ablation at two large centers (Taipei Veterans General Hospital and Cheng-Hsin Hospital, Taipei, Taiwan) between 2013 and 2019. The study complied with the Declaration of Helsinki, and each institutional review board approved the protocol. Data on the baseline demographic characteristics of the patient’s left ventricular ejection fraction (LVEF), PVC burden, medical therapy, electrocardiographic (ECG) characteristics, use of multisite ablation, procedural details, administration of anti-arrhythmic drugs (AADs) before and after ablation, mapping parameters, and ablation outcomes were collected. The patients were divided into two groups: the patient with LV dysfunction (Group 1, LVEF less than 50%) and the patient with preserved LVEF (Group 2, LVEF ≥ 50%) 16. The routinely performed coronary angiography excluded ischemic heart disease before ablation, and significant structural heart disease was ruled out by echocardiography.