Abstract 15928: A Novel Transitional Zone Index Predicts the Accurate Origin of the Outflow Tract Ventricular Tachycardia
Background: Idiopathic outflow tract ventricular tachycardia or premature ventricular contractions (OT-VTs) with left bundle branch block (LBBB) morphology and inferior axis can originate from the right ventricular outflow tract (RVOT) and the aortic sinus cusp (ASC). Although several ECG algorithms have been proposed for differentiating the OT-VT origin, the accuracy of ECG algorithms is still limited, especially, when the precordial transition of the sinus beats rotates. The objective of this study was to assess whether a novel ‘cardiac rotation-adjusted’ transitional zone (TZ) index would be a useful maker to differentiate the RVOT from ASC origin.
Methods: We analyzed surface ECGs of OT-VTs with LBBB morphology and inferior axis in 110 patients who were successfully ablated in the RVOT (n=86) and ASC (n=24). According to the site of R-wave transition in the precordial leads, TZ score was graded with 0.5-point increments (e.g. V2=2-point, V2 to V3=2.5-point, V3=3-point, V3 to V4=3.5-point), and the TZ index was defined as follows: TZ score of OT-VT minus (2×TZ score of sinus beat).
Results: The TZ index was significantly lower in the ASC origin than in the RVOT origin (−4.8±1.7 vs. −2.9±1.3, p<0.0001). A cut-off value of the TZ index≤-4.0 predicted the ASC origin with 83% sensitivity and 85% specificity. The previously-reported R-wave duration index≥50% had a high specificity of 86% but a low sensitivity of 50%, and R/S amplitude index≥30% had 74% sensitivity and 78% specificity. The area under the curve by ROC analysis was 0.867 for the TZ index, which was higher than the R-wave duration index and R/S amplitude index (0.807 and 0.809) (Figure 1).
Conclusions: This novel TZ index can be a more useful maker to differentiate the OT-VT origin.
- Ventricular arrhythmia
- Ablation, radiofrequency
- Arrhythmia mapping
- Arrhythmias, treatment of
- Ventricular tachycardia
- © 2010 by American Heart Association, Inc.