Abstract 12302: Intramural Foci of Ventricular Tachycardia in Patients With Nonischemic Cardiomyopathy
Introduction : In patients with nonischemic dilated cardiomyopathy (NIDCM), ventricular tachycardia (VT) arising from either epicardial or endocardial scar has been extensively documented. The potential for intramural foci (IMF) of VT, demonstrated in experimental models of NIDCM, has not been characterized clinically.
Methods : Fifty-six patients (88% male) with NIDCM underwent electroanatomical mapping and catheter ablation of VT. Left ventricular endocardial (LVEn) mapping was performed in all patients, epicardial (EPI) mapping in 42, and right ventricular endocardial (RVEn) mapping in 11. Mean patient agewas 57±11 yrs and mean left ventricular ejection fraction was 32±11%. The extent and distribution of low voltage areas and late potentials (LP) in all mapped chambers were characterized, as well as the pattern of activation and site of origin of induced VT. IMF were classified as either septal or free wall in origin. An IMF was considered present when 1) the earliest site of EPI (or RVEn) activation was located immediately adjacent to the earliest site of LVEn activation 2) a centrifugal pattern of activation from the focal source was present on both surfaces, and 3) elimination of VT required ablation at both the LVEn and the overlying EPI (or RVEn) site. VTs eliminated by either EPI or endocardial ablation alone were not considered IMF for this analysis. Ablation was performed with a 3.5 mm open tipped irrigation catheter in all pts.
Results : A total of 130 VTs were induced, and 102 VTs were targeted for ablation. An IMF was present in 29 VTs in 22 pts (38%). The IMF was septal in 15 VTs, and free wall in 14 VTs. For all IMF, the site of earliest LVEn and EPI (or RVEn) activation were within 20 ms. LP were not present at the site of VT origin in any IMF. Mean low voltage area in the RV was 24cm2±20, LV 27.7cm2±22.7 and epicardium 193cm2±146, and did not differ between patients with and without IMF.
Conclusions : IMF, requiring ablation on both surfaces of the ventricular wall, are frequently identified in patients with NIDCM.
- © 2010 by American Heart Association, Inc.