PO-05-065 HIGH DENSITY PACE-MAPPING TO IDENTIFY FUNCTIONAL ARRHYTHMOGENIC SUBSTRATE IN SCAR-MEDIATED VENTRICULAR TACHYCARDIA

The location of conduction abnormality including activation slowing and wavefront discontinuity, which often corresponds to the critical zones reentrant circuit in scar-mediated ventricular tachycardia (VT), is affected by direction during substrate mapping. We hypothesized that an abrupt change paced-QRS morphologies may occur at region with abnormality. This study assessed velocity mapping least two rhythms where was obtained. In a retrospective review 57 patients who underwent functional for VT, 21 it multiple rhythms, intrinsic rhythm paced high-density pace-mapping area interest. 10 these patients, those sites, as determined direct termination ablation (4 VTs, 33%) or findings (8 67%) were identified total 12 VTs. Conduction velocities isthmus based on difference local time between sites along site scores changed abruptly. Pace-mapping scores, obtained adjacent presumed isthmus, showed 92% [interquartile range [IQR] 89-96%] exit side 48% [IQR 41-56%] entrance side. Ten (71±9 years, 9 (90%) male, 6 (60%) nonischemic) sinus (n=7) right pacing (n=5) left (n=7). pacemap 0.37m/sec 0.19-0.43 m/sec], no slower than 0.25 m/sec, defined previous studies. However, faster one significantly slowed down when changing other (0.41 m/sec 0.25-1.05 m/sec] vs. 0.09 [IQR0.07-0.22 P<0.01) (Fig.1). morphology novel strategy, shown independent mapping, can identify high-yield regions being reentry.