Table 1: Proposed Electrocardiogram Criteria and Cut-offs for Epicardial Ventricular Tachycardia Origin.

ECG criteria Interval criteria	Abbreviation	Explanation	Cut-off
Interval criteria
QRS duration	QRSd	Interval measured from the earliest ventricular activation to the offset of the QRS in the precordial leads.	No cut-off proposed
Pseudo-delta wave	PdW	Interval measured from the earliest ventricular activation to the onset of the earliest fast deflection in any precordial lead	≥34 ms
Intrinsicoid deflection time	IDT	Interval measured from the earliest ventricular activation to the peak of the R wave in lead V2	≥85 ms
Shortest RS complex	SRS	Interval measured from the earliest ventricular activation to the nadir of the first S wave in any precordial lead	≥121 ms
Maximum deflection index	MDI	Interval measured from the earliest ventricular activation to the peak of the largest amplitude deflection in each precordial lead (taking the lead with shortest time) divided by the QRSd	≥55
Morphology criteria (site-specific)
Q wave in lead 1	QWL1	Q wave in lead 1 during VT
Q wave in inferior leads	QWIL	Q wave in inferior leads during VT
No Q wave in inferior leads	NQWIL	No Q wave in inferior leads during VT
QS in lead V2	QSV2	QS complex in lead V2 during VT