A 57-year-old man undergoing mitral valvoplasty underwent catheter ablation of symptomatic premature ventricular contractions (PVCs) with a right bundle branch block and right inferior axis QRS morphology. Left ventriculography revealed a normal left ventricular function and visualized the anatomical relationships between the left ventricular outflow tract and the mitral annuloplasty ring. Electroanatomic mapping during the PVCs revealed a centrifugal activation pattern arising from the mitral annulus, and the PVCs were likely to be idiopathic. Successful radiofrequency ablation was achieved at the site close to the antero-paraseptal end of the mitral annuloplasty ring, which was located adjacent to the fibrous trigone. (PACE 2009; 32:825-827) © 2009 Wiley Periodicals, Inc.
