Flecainide efficacy in outflow tract vs non-outflow tract premature ventricular contractions: A subanalysis of the UNIFLECA study

Background Premature ventricular contractions (PVCs) frequently originate from the ventricular outflow tracts (OT). Non-outflow tract (non-OT) PVCs, such as those arising from the papillary muscles or fascicular regions, often exhibit greater anatomic and electrophysiologic heterogeneity and may respond differently to medical or interventional treatment. Comparative data on the efficacy of flecainide in these two anatomic subtypes are limited. Purpose To compare the efficacy of flecainide in suppressing PVCs and improving symptoms in patients with OT versus non-OT morphology Methods This subanalysis of the multicenter, prospective UNIFLECA study included 82 patients without structural heart disease who received flecainide for idiopathic PVCs after declining catheter ablation. PVC morphology was classified as OT or non-OT based on anatomical estimation from ECG findings. A positive response was defined as a ≥80% reduction in 24-hour PVC burden or a significant improvement in symptoms. The proportion of non-responders was evaluated in each group. Results Of the 82 patients, 48 (58%) had OT PVCs and 34 (42%) had non-OT PVCs. In the OT group 43 patients (89.6%) achieved ≥80% burden reduction, while 5 (10.4%) were non-responders. In the non-OT group, 30 patients (88.2%) responded, and 4 (11.8%) were non-responders. The rate of complete symptom resolution was comparable between groups (p > 0.05). One patient discontinued treatment due to mild adverse effects. Conclusions Flecainide effectively reduced PVC burden regardless of anatomic origin, achieving comparable high response rates in both OT and non-OT morphologies. These findings support flecainide as a safe and efficient pharmacologic alternative to ablation in patients with idiopathic PVCs declining catheter ablation.