Idiopathic ventricular arrhythmias originating from the tricuspid annulus: Prevalence, electrocardiographic characteristics, and results of radiofrequency catheter ablation.

Background: Idiopathic ventricular tachycardias (VTs) and premature ventricular contractions (PVCs) arising from the tricuspid annulus have been reported.

Objective: The purpose of this study was to clarify the prevalence and characteristics of VT/PVCs originating from the tricuspid annulus.

Methods: The ECG characteristics and results of radiofrequency (RF) catheter ablation were analyzed in 454 patients with idiopathic VT/PVCs.

Results: Thirty-eight (8%) patients had VT/PVCs arising from the tricuspid annulus: 28 VT/PVCs (74%) originated from the septal portion of the tricuspid annulus and the remaining 10 (26%) from the free wall of the tricuspid annulus. QRS duration and Q-wave amplitude in each of leads V1-V3 were greater in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (all P < .01). "Notching" of the QRS complex was observed more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .01). A Q wave in lead V1 was observed more often in VT/PVCs arising from the septum of the tricuspid annulus than those from the free wall of the tricuspid annulus (P < .005). R-wave transition occurred beyond lead V3 more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .005). RF catheter ablation eliminated 90% of the VT/PVCs arising from the free wall of the tricuspid annulus but only 57% of the VT/PVCs arising from septum of the tricuspid annulus.

Conclusion: Idiopathic VT/PVCs arising from tricuspid annulus are not rare, and the detailed origin can be determined by ECG analysis. The preferential site of origin was the septum but also could be the free wall of the tricuspid annulus.