The V6R/V4R Index: A Novel ECG Parameter for Identifying Idiopathic Ventricular Arrhythmias Originating From the
Yoshihisa Naruse1, Kohki Nakamura2, Kanae Hasegawa3
1Division of Cardiology, Internal Medicine III, Hamamatsu University School of Medicine, Hamamatsu, Japan.
Insights
A new electrocardiogram (ECG) index, the V6R/V4R amplitude ratio, accurately distinguishes aortic cusp ventricular arrhythmias (VAs) from other left ventricular outflow tract (LVOT) VAs. This simple ECG tool aids in precise ablation targeting for improved patient outcomes.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Diagnostics
Background:
- Radiofrequency catheter ablation effectively treats left ventricular outflow tract (LVOT) ventricular arrhythmias (VAs).
- Successful ablation often requires targeting areas near the aortic cusp, including the aorto-mitral continuity and mitral annulus.
- Differentiating VA origin within or outside the aortic cusp is crucial for effective ablation.
Purpose of the Study:
- To identify electrocardiogram (ECG) indices that differentiate VAs originating from the aortic cusp from those originating outside the cusp within the LVOT.
- To evaluate the diagnostic accuracy of potential ECG markers for cusp-origin VAs.
Main Methods:
- Retrospective analysis of 159 idiopathic LVOT VAs undergoing successful radiofrequency ablation.
- Classification of VAs into cusp (n=125) and non-cusp (n=34) origin groups based on ablation site.
- Comparison of detailed premature ventricular contraction (PVC) morphologies between the cusp and non-cusp groups.
Main Results:
- The ratio of R-wave amplitude in lead V6 to lead V4 (V6R/V4R) was significantly higher in the cusp group (0.64) versus the non-cusp group (0.32) in the derivation cohort (p < 0.001).
- A V6R/V4R amplitude index > 0.55 demonstrated 80% sensitivity and 88% specificity for predicting cusp-origin VAs (AUC: 0.865).
- Validation cohort confirmed high accuracy: 84% sensitivity and 82% specificity for the V6R/V4R index > 0.55.
Conclusions:
- The V6R/V4R amplitude index is a simple, practical, and accurate ECG criterion for distinguishing aortic cusp VAs from other LVOT VAs.
- This ECG index can guide electrophysiologists in precise ablation targeting for LVOT VAs.
- High sensitivity and specificity support the clinical utility of the V6R/V4R index in routine practice.
Background:
Radiofrequency catheter ablation within the aortic cusp can eliminate left ventricular outflow tract (LVOT) ventricular arrhythmias (VAs). However, in a significant proportion of cases, successful ablation requires targeting the aorto-mitral continuity, the endocardium just below the left ventricular summit, and/or the mitral annulus. This study aimed to identify electrocardiographic (ECG) indices useful for differentiating VAs originating from the aortic cusp from those arising outside the cusp among LVOT-VAs.
Methods:
This retrospective study included 159 idiopathic VAs (79 in the derivation cohort and 80 in the validation cohort) successfully ablated from the LVOT. Based on the site of VA origin, VAs were classified into cusp (n = 125) and non-cusp (n = 34) groups. Detailed PVC morphologies were compared between the two groups.
Results:
In the derivation cohort (mean age 60 ± 16 years, 43 men), the ratio of R-wave amplitude in lead V6 to that in lead V4 was significantly higher in the cusp group than in the non-cusp group (0.64 [0.56-1.00] vs. 0.32 [0.24-0.40], p < 0.001). Receiver operating characteristic curve analysis showed that a V6R/V4R amplitude index > 0.55 predicted cusp-origin VAs with 0.80 sensitivity and 0.88 specificity (area under the curve, 0.865; 95% confidence interval [CI], 0.762-0.967). In the validation cohort, the sensitivity and specificity of a V6R/V4R amplitude index > 0.55 for predicting cusp origin were 84% and 82%, respectively.
Conclusion:
The V6R/V4R index is a simple and practical ECG criterion for distinguishing VAs originating from the aortic cusp from those arising outside the cusp among LVOT-VAs, with high accuracy.
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