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Updated: Feb 10, 2026

Assessment of Myofilament Ca2+ Sensitivity Underlying Cardiac Excitation-contraction Coupling
Published on: August 1, 2016
Predicting value of coupling interval variability in determining the origin of ventricular premature contractions
Umut Celikyurt1,2, Aysen Agir3, Irem Karauzum3
1Department of Cardiology, Kocaeli University Medical Faculty, Kocaeli, Turkey. ycelikyurt@gmail.com.
Purpose:
We aimed to investigate the predictive value of coupling interval variability (ΔCI) in determining the origin of idiopathic outflow tract ventricular tachycardia (OTVT) with V3 transition.
Methods:
We reviewed data from 126 patients who underwent catheter ablation of OTVT between 2015 and 2018 at our institution. We identified 32 patients of successful OTVT ablation with a precordial transition at V3 derivation. The ΔCI (maximum - minimum CI) was measured.
Results:
CI variability was significantly smaller for right ventricular (RV) OT than left ventricular (LV) OT premature ventricular contractions (PVCs) (p = 0.004). In multivariate analysis, including QRS duration, R-wave duration in lead V1, R-wave amplitude in V1, PVC burden, and ΔCI, ΔCI was the only independent predictor of PVC origin (OR 0.963, 95% CI, 0.939-0.988, p < 0.001). A CI variability ≥ 30 predicted a PVC from LVOT origin with a sensitivity of 83% and specificity of 89%. ΔCI was compared with other previously proposed ECG criteria used to differentiate LVOT from RVOT PVCs. ΔCI exhibited a greater area under the curve (AUC) (0.867) than the other ECG criteria. A ΔCI ≥ 30 ms exhibited a high sensitivity of 89% and a specificity of 83%.
Conclusions:
ΔCI is outperformed other ECG criteria to differentiate LVOT from RVOT PVCs, and this parameter may be useful for planning the ablation strategy.
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