Key result
A difference of ≤18° between sinus rhythm and PVC QRS axes accurately distinguished para-Hisian PVCs from other outflow tract PVCs (AUC 0.94, sensitivity 0.94, specificity 0.82).
Why the study?
Para-Hisian PVC is challenging and needs to be pre-procedurally distinguished from other outflow tract PVCs based on ECG morphology.
Can the difference between sinus rhythm and PVC QRS axes distinguish para-Hisian PVCs from other outflow tract PVCs?
Observational (n=160)
Can the difference between sinus rhythm and PVC QRS axes distinguish para-Hisian PVCs from other outflow tract PVCs?
Comparing the QRS axis difference between sinus rhythm and PVCs provides a highly sensitive and specific method to distinguish para-Hisian PVCs from other outflow tract PVCs.
Hypothesis-generating for para-Hisian PVC identification; leaves open prospective validation before clinical adoption.
BACKGROUND: Para-Hisian premature ventricular contraction (PVC) is challenging and needs to be distinguished pre-procedurally from other outflow tract PVCs (OT-PVCs) based on ECG morphology. OBJECTIVE: To investigate whether para-Hisian PVCs can be distinguished from right and left ventricular outflow tract (RVOT and LVOT) by comparing QRS axis of PVC and sinus rhythm (SR). METHODS: We retrospectively analyzed 160 idiopathic PVC cases without conduction abnormalities. The site of origin was defined by the successful ablation site. Baseline SR and PVC axes were calculated using the net QRS amplitudes in leads I and III. Differences between SR and PVC axes were compared among para-Hisian, RVOT, and LVOT PVCs. RESULTS: Seventeen para-Hisian, 84 RVOT, and 59 LVOT PVCs were identified. The mean differences between SR and PVC axes were -4.9±26.1°, 42.1±21.0°, and 61.2±22.9°, with para-Hisian PVCs showing the smallest deviation from baseline SR axis. An axis difference of ≤18° strongly supports a para-Hisian PVC, rather than other OT-PVCs (area under curve=0.94; sensitivity=0.94; specificity=0.82). As SR axis deviated leftward, positive component in lead I became more prominent in RVOT or LVOT PVCs, resulting in some cases exhibiting QRS morphologies mimicking para-Hisian PVCs (n=14/84 and n=4/59, respectively). However, these PVCs exhibited substantial difference between SR and PVC axes. In contrast, para-Hisian PVCs consistently showed similarity between SR and PVC axes, regardless of baseline axis deviation. CONCLUSIONS: The axis of idiopathic OT-PVC can be influenced by baseline SR axis deviation. Comparison of SR and PVC axes is essential to distinguish true para-Hisian PVCs from other OT-PVCs.
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Sugawara et al. (2026) conducted an observational in Idiopathic premature ventricular contractions (PVCs) (n=160). Comparison of sinus rhythm (SR) and PVC QRS axes vs. Standard ECG morphology alone was evaluated on Distinguishing para-Hisian PVCs from other outflow tract PVCs using the difference between SR and PVC axes (AUC 0.94). A difference of ≤18° between sinus rhythm and PVC QRS axes accurately distinguished para-Hisian PVCs from other outflow tract PVCs (AUC 0.94, sensitivity 0.94, specificity 0.82).
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