Coupling interval variability: A new diagnostic method for distinguishing left from right ventricular outflow tract origin in idiopathic outflow tract premature ventricular contractions patients with precordial R/S transition at lead V3.

•We presented a new simple method, a coupling interval variability (CIV) > 100 ms which could reliably distinguish LVOT from RVOT origin in idiopathic outflow tract premature ventricular contractions (IOT-PVCs) patients with precordial R/S transition at lead V3. This is the first study which applied CIV to distinguishing different origin sites in IOT-PVCs patients with precordial R/S transition at lead V3.•The new diagnostic method, a CIV > 100 ms was developed in a retrospective cohort of IOT-PVCs patients with precordial R/S transition at lead V3, then validated in a prospective cohort.•The new diagnostic method had several advantages. Firstly, a CIV of > 100 ms didn't only have a simpler computational and diagnostic algorithm but also had even higher accuracy. Secondly, the amplitudes of the PVCs or sinus beat even the integrated 12-lead ECG are unnecessary for CIV so that CIV could be obtained from and assessed on a 24-h ambulatory monitor or any monitor instrument as long as it is measurable for the duration of ECG. Thirdly, the possible respiratory variation, cardiac rotation, or variable lead positions of on the chest, which might vary depending on breast size, body habitus, and technician expertise when placing ECG leads would not exert an influence on the efficacy of the new diagnostic method.