Comparison of endocardial catheter mapping with intraoperative mapping of ventricular tachycardia.

To validate the accuracy of catheter endocardial mapping to localize the origin of ventricular tachycardia (VT), we compared cathether endocardial mapping with intraoperative epicardial and endocardial mapping of 24 morphologically distinct VTs in 18 patients undergoing surgery. Twelve had VT with left bundle branch block morphology and 12 had VT with right bundle branch block morphology. Catheter endocardial mapping localized 23 VT morphologies to the border of a left ventricular aneurysm or myocardial infarction and one VT to a right ventriculotomy scar. Intraoperative epicardial mapping showed epicardial breakthrough on the right ventricle in 10 VTs with left bundle branch block morphology and on the left ventricle in two. In 12 VTs with right bundle branch block morphology, intraoperative epicardial mapping revealed the earliest site of VT with left bundle branch block morphology (11 patients) and VT with right bundle branch block morphology (12 patients) at the border of a left ventricular aneurysm, and one VT with left bundle branch block morphology in the right ventricle. Catheter endocardial mapping predicted the origin of VT within 4--8 cm2 of that determined by intraoperative endocardial mapping, which always identified the earliest site. These data validate the accuracy of catheter endocardial mapping in localizing the origin of VT.