Noncentrifugal activation patterns in focal RVOT PVC/VT: New insights from high density multielectrode mapping

BACKGROUND: Activation from an automatic focus is thought to show centrifugal spread. In patients with premature ventricular complex/ventricular tachycardia (PVC/VT) from the right ventricular outflow tract (RVOT), the presence of preferential conduction and epicardial connections could however also lead to noncentrifugal wavefront propagation. OBJECTIVE: To study endocardial activation in RVOT PVC/VT using high-resolution 3D activation mapping. METHODS: Consecutive patients with frequent idiopathic PVC/VT were studied. High-resolution 3D activation maps were acquired using a multielectrode mapping catheter (Orion, Rhythmia, Boston Scientific). Noncentrifugal activation was defined as a pattern of wavefront propagation which does not show uniform propagation in all directions from one focus. Patients without sustained ablation success and patients with a left-sided PVC origin or with insufficient map density were excluded from the analysis. RESULTS: Sixteen patients (44% female) with a median age of 54 years (interquartile range [IQR], 47-64) and a median PVC burden of 19% (IQR, 15-27) were studied. High-resolution activation maps consisting of a median number of 1863 mapping points (IQR, 1195-2463 points) demonstrated a centrifugal activation in 6/16 (38%) and a noncentrifugal activation in 10/16 (62%). When comparing patients with centrifugal and noncentrifugal activation, patients with centrifugal activation were older (p = .01), but no differences were found in age, gender, QRS duration of the PVC's and sites of origin in the RVOT. No procedural complications occurred. CONCLUSIONS: High-resolution multielectrode mapping demonstrates the presence of noncentrifugal activation patterns in some of the patients with idiopathic RVOT PVC/VT. This may indicate the presence of preferential conduction and or epicardial/intramural connections in the outflow tract.