Electrophysiology Study
The electrophysiology study (EPS) was performed in 92 out of 138
patients (66.7%). Baseline measurements of conduction intervals and
programmed ventricular stimulation were recorded. The programmed
ventricular stimulation (PVS) was performed on two sites (right
ventricular apex and right ventricular outflow tract, unless the patient
had inducible ventricular tachycardia at the first location), with
energy of twice the diastolic threshold, using two drive cycles (S1: 600
and 430 ms) up to 3 extra stimuli (S2 to S4) with 200ms as the shortest
coupling time. The EPS result was considered positive if sustained VF or
VT was induced.14 Ventricular effective refractory
period (VERP) was defined as the longest S1-S2 interval that fails to
achieve ventricular capture. If there was conduction under 200ms, VERP
was defined as “less than 200ms”.10