A New ECG Criterion for Distinguishing Left from Right Ventricular Outflow Tachycardia Origin

概要

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Several ECG criteria have been proposed for differentiating left from right outflow tract (OT) ventricular tachycardia (VT); however, VTs with left bundle blanch block (LBBB) that transition in lead V2–V4 remain a challenge. Individual patient (pt) differences in cardiac rotation, lead position, and cheat wall size may limit the accuracy of ECG algorithm. We hypothesized that correcting for the sinus rhythm precordial transition would aid in OTVT localization. We analyzed the surface ECG pattern from pts with OTVT with a precordial transition (R>S) in lead V2–V4 who underwent catheter ablation. The sinus rhythm and VT morphology were measured on the same 12-lead ECG. V2 transition ratios were calculated by computing the % R wave during VT (R/R+S)VT divided by the % R wave in sinus rhythm (R/R+S)SR. <B>Results:</B> Nineteen Pts (age 49.5±18.2, 12 males) with OTVT originating from right ventricular (RV) OT (n=15) or left ventricular (LV) OT (n=4) were studied. The V2 ratio was significantly greater for LVOT than RVOT origin (0.51±0.23 vs. 0.17±0.085; P=0.001). A V2 transition <0.5 predicted an RVOT origin with a sensitivity of 75% and specificity of 100%. <B>Conclusions:</B> A novel electrocardiographic measure, the V2 transition ratio, reliably distinguishes right from left ventricular outflow tract origin in patients with LBBB and V2–V4 transition. This measure may be useful for planning an ablation strategy.