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Baseline QRS axis distinguishes para-Hisian PVC from outflow tract PVCs
Masafumi Sugawara1, Jakub Sroubek1, Justin Lee1
1Cardiac Electrophysiology and Pacing Section, Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio.
Heart Rhythm
|May 1, 2026
Summary
Distinguishing para-Hisian premature ventricular contractions (PVCs) from other outflow tract PVCs (OT-PVCs) is crucial. Comparing the QRS axis during PVC and sinus rhythm (SR) effectively differentiates para-Hisian PVCs, aiding pre-procedural diagnosis.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Diagnostics
Background:
- Para-Hisian premature ventricular contractions (PVCs) present diagnostic challenges.
- Distinguishing them from other outflow tract PVCs (OT-PVCs) pre-procedurally is vital for effective treatment.
- Electrocardiogram (ECG) morphology is key for differentiation.
Purpose of the Study:
- To determine if para-Hisian PVCs can be differentiated from right and left ventricular outflow tract (RVOT and LVOT) PVCs.
- To achieve this by comparing the QRS axis during PVCs and normal sinus rhythm (SR).
Main Methods:
- Retrospective analysis of 160 idiopathic PVC cases.
- Site of origin confirmed by successful ablation.
- Calculation of SR and PVC QRS axes using leads I and III.
- Comparison of axis differences among para-Hisian, RVOT, and LVOT PVCs.
Main Results:
- Para-Hisian PVCs showed the smallest deviation between SR and PVC axes (-4.9°).
- RVOT and LVOT PVCs exhibited larger axis deviations (42.1° and 61.2°, respectively).
- An axis difference of ≤18° accurately identified para-Hisian PVCs (sensitivity 0.94, specificity 0.82).
Conclusions:
- Baseline SR axis deviation can influence idiopathic OT-PVC morphology.
- Comparing SR and PVC axes is essential for accurate diagnosis of para-Hisian PVCs.
- This method aids in distinguishing true para-Hisian PVCs from other OT-PVCs.
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