Key result
An R-S difference index greater than 20.9 predicted a left ventricular outflow tract aortic sinus cusp origin of premature ventricular contractions with 73.7% sensitivity and 86.3% specificity.
Why the study?
Differentiating idiopathic PVCs originating from the right and left ventricular outflow tracts with an LBBB morphology is relevant to catheter ablation planning and lowering complications.
Does the R-S difference index accurately differentiate idiopathic PVCs originating from the LVOT-ASC versus the s-RVOT in patients with a LBBB pattern?
Observational (n=259)
No
Does the R-S difference index accurately differentiate idiopathic PVCs originating from the LVOT-ASC versus the s-RVOT in patients with a LBBB pattern?
Effect estimate: AUC 0.867
The R-S difference index is a novel and accurate ECG criterion for differentiating LVOT-ASC from s-RVOT origins in patients with idiopathic PVCs presenting with a LBBB pattern, which may aid in catheter ablation planning.
May aid pre-ablation localization of outflow tract PVCs; leaves open prospective validation before clinical adoption.
Introduction: Differentiating idiopathic premature ventricular contractions (PVCs) originating from the right and left ventricular outflow tracts with a left bundle branch block (LBBB) morphology is relevant to catheter ablation planning and important for lowering the risk of complications. This study established a novel electrocardiographic (ECG) criterion to discriminate PVCs originating from the septum of the right ventricular outflow tract (s-RVOT) and those originating from the aortic sinus cusp of the left ventricular outflow tract (LVOT-ASC). Methods: A total of 259 patients with idiopathic PVCs originating from ventricular outflow tract with a LBBB pattern who underwent successful catheter ablation were retrospectively included. Among them, the PVCs originated from the s-RVOT in 183 patients and from the LVOT-ASC in 76 patients. The surface ECGs of the PVCs and sinus beats were analyzed using an electronic caliper. The R-S difference index in the precordial leads was calculated as V2R + V3R + V4R − V1S. Results: PVCs originating from both the s-RVOT and LVOT-ASC displayed an inferior axis (dominant R waves in leads II, III, and aVF). Compared with the s-RVOT group, the R-wave amplitudes on leads II, III, and aVF were significantly larger in the LVOT-ASC group ( p < 0.001, p < 0.003, and p < 0.001, respectively). Compared to the LVOT-ASC group, the s-RVOT group showed smaller R-wave amplitudes on leads V1–V6 ( p = 0.021, p < 0.001, p < 0.001, p < 0.001, p < 0.001, and p < 0.001, respectively) and larger S-wave amplitudes on leads V1–V3 ( p < 0.001, p < 0.001, and p < 0.001, respectively). Lead V3 was the most common transitional lead in both groups. Analysis of the receiver operating characteristic curve showed that the R-wave amplitude on lead V3 had the largest area under the curve (AUC) of 0.856 followed by the R-wave amplitudes on leads V4 (0.834) and V2 (0.806). The AUC of the R-S difference index was 0.867. An R-S difference index greater than 20.9 predicted an LVOT-ASC origin with 73.7% sensitivity and 86.3% specificity. This index is superior to previous criteria in differentiating PVCs with LBBB morphology and inferior axis originating from s-RVOT vs. LVOT-ASC. Conclusions: The R-S difference index in precordial leads is a useful new ECG criterion for distinguishing LVOT-PVCs from RVOT-PVCs with LBBB morphology.
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Zhao et al. (2022) conducted an observational in Idiopathic premature ventricular contractions (n=259). R-S difference index vs. Other ECG criteria was evaluated on Diagnostic accuracy (AUC) for differentiating LVOT-ASC from s-RVOT origin (AUC 0.867). An R-S difference index greater than 20.9 predicted a left ventricular outflow tract aortic sinus cusp origin of premature ventricular contractions with 73.7% sensitivity and 86.3% specificity.
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