V 3 R/V 7 Index

Abstract

Background: Several algorithms have been proposed to predict the origin of outflow tract (OT) ventricular arrhythmias (VAs) using standard 12-lead ECG. However, the additive value of right precordial and posterior leads is unknown. Methods: Standard 12-lead ECG, right precordial leads ECG (V 3 R, V 4 R, V 5 R) and posterior leads ECG (V 7 , V 8 , V 9 ) were recorded and analyzed in a development cohort of consecutive patients undergoing OT-VAs ablation at a single center. These findings informed the development of a novel algorithm incorporating right precordial and posterior leads to discriminate between left ventricular OT (LVOT) and right ventricular OT (RVOT) foci. The performance of this novel algorithm which includes the V 3 R/V 7 index was prospectively tested in a validation cohort of consecutive patients undergoing OT-VA ablation at 4 centers and compared with published algorithms. The location of the foci was determined by the successful ablation site. Results: One hundred ninety-one patients were recruited, of which 94 formed the validation cohort (mean age of 45.7±15.6, 39% male, 79% RVOT foci). During OT-VAs, a QS pattern in lead V 3 R and an S wave in lead V 7 were exclusively recorded in RVOT and LVOT foci, respectively. The V 3 R/V 7 index of LVOT origin was significantly greater than that of RVOT (1.05±0.83 versus 0.28±0.23, P <0.001). The V 3 R/V 7 index ≥0.85 predicted an LVOT origin with 87% sensitivity and 96% specificity. In the prospective evaluation, when the V 3 R/V 7 index ≥0.85, an RVOT origin could be excluded with 98.6% accuracy. The area under the curve of V 3 R/V 7 index (0.954) was larger than that of previously reported ECG criteria, including V 2 S/V 3 R (0.896), V 2 transition ratio (0.792), and transition zone index (0.666). This novel index was also accurate in both patients without obvious LVOT or RVOT origins and subgroups with cardiac rotation or lead V 3 R/S transition. Conclusions: The V 3 R/V 7 index is a novel and accurate ECG criterion that predicts OT-VAs origin.