A novel and effective ECG method to differentiate right from left ventricular outflow tract arrhythmias: Angle-corrected V2S

Figures

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  FIGURE 1. Example of calculating the V2S angle and several ECG algorithms. The TZ index was –0.5 according to the following formula: TZ score of OTVA minus TZ score of sinus beat (2–2.5 = –0.5). The V2S/V3R index was calculated with the following formula: V2S/V3R = 1.3 mV/1.4 mV = 0.93. The combined TZ index and V2S/V3R were calculated with the formula Y = –1.15 × (TZ)–0.494 × (V2S/V3R) = –1.15 × (–0.5)–0.494 × 0.93 = 0.116. These indexes indicate that this OTVA had a left ventricular outflow tract (LVOT) origin, though it was successfully ablated in the septal aspect of the right ventricular outflow tract (RVOT). The measurements of the V2S angle during the OTVAs are as follows: the S-wave amplitude in lead V2 is 1.3 mV. The angle (α) between the cardiac long-axis anatomically and the horizontal plane on chest radiography is 45.1°. The V2S angle was calculated with the following formula: (V2S × α) = 1.3 mv × 45.1° = 58.63 (mV°). The V2S angle was verified as accurate.

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  FIGURE 2. (A) Linear regression analysis for ECG characteristics and angle. The regression coefficient β and 95% CI of each independent variable are shown above. The final multiple linear regression model was statistically significant (F = 14.278, P < 0.001), and 38.9% of the variation in the dependent variable ECG algorithm could be explained by V1S, V2S, V3R, and angle (adjusted R2 = 0.389). (B) Receiver operating characteristic (ROC) curve analysis for anatomic prediction of RVOT origin was also performed. The area under the curve (AUC) of the V2S angle was 0.888, which was the highest among all indicators.

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  FIGURE 3. Predictive accuracy of the V2S angle and several ECG algorithms of previous studies. ROC curve analysis for anatomic prediction of RVOT origin. The AUC of the V2S angle was 0.888, which was the highest of all.

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  FIGURE 4. Scatterplot diagram of the V2S angle (A) and several ECG algorithms (B–H) between ventricular arrhythmias from RVOT and LVOT. The red dotted line indicates the optimal cut-off value of the V2S angle. The V2S angle of 58.28 mV° predicted the RVOT origin with 85.7% sensitivity and 95.2% specificity (PPV: 99.1%; NPV: 52.6%). Other diagnostic indexes for predicting RVOT origin (sensitivity, specificity, PPV, NPV) are shown in Table 3.

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  FIGURE 5. Receiver operating characteristic curve analysis of the V2S angle and the angle-corrected ECG algorithms. The predictive accuracy of several ECG algorithms was improved by correcting with the angle. The AUC of the V2S/V3R index angle (AUC = 0.916) was the highest of all, even greater than that of the V2S angle (AUC = 0.888).

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  FIGURE 6. Receiver operating characteristic curve analysis for the anatomic prediction of OTVA origin with V2S angle and previous indexes in the prospective cohort. The AUC of V2S angle was 0.851, similar to that of V2S/V3R (0.875) and the TZ index (0.892).

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  FIGURE 7. The procedure time when using different diagnostic indexes made up of ECG criteria for predicting RVOT origin. The procedure time with the V2S angle was shorter than with V2S/V3R or the TZ index before RFCA in the prospective cohort (n = 48) (P = 0.002) (A). The procedure time in the prospective cohort (n = 48) with the V2S angle was shorter than that in the retrospective cohort (n = 147) with V2S/V3R or the TZ index (B).