Abstract 3326: Detection of the Diastolic Pathway, Circuit Morphology and Inducibility of Human Post-Infarction Ventricular Tachycardia from Mapping in Sinus Rhythm
Background: We examined the relationship between electrical discontinuities in the endocar-dial border zone and reentrant circuit features of clinical ventricular tachycardia to address the hypothesis that the diastolic pathway (isthmus) can be detected during sinus rhythm.
Method: In each patient, unipolar electrograms were acquired at 256 virtual endocardial sites using non-contact mapping. Electrograms were marked for activation time and mapped on a three-dimensional grid. Spatial differences in sinus rhythm activation time were correlated to isthmus location and size, and activation through the diastolic pathway during tachycardia, based on presence of contiguous lines of slow conduction and block.
Results: Nineteen tachycardia morphologies were analyzed in eleven patients. Fourteen sustained reentrant circuit morphologies occurred in 9 patients, with dual morphologies having a shared isthmus occurring in 5/9. Dual morphologies were caused by changes in entrance-exit point location about the stationary isthmus. One transient circuit morphology occurred in 3/9 patients also having sustained reentry. The estimated isthmus determined from sinus rhythm activation overlapped 87.0±10.5% of the actual diastolic pathway determined from tachycardia maps. Mean difference in sinus rhythm activation time across the isthmus border was larger in transient compared with sustained circuit morphologies (32.7±9.6ms versus 22.7±1.9ms), while isthmus size was smaller (4.8±1.1cm2 versus 10.1±1.1cm2), entrance-exit points were narrower (7.0±1.5mm versus 9.3±0.8mm), with greater activation time difference across them (16.2±3.5ms versus 10.1±1.0ms).
Conclusion: In postinfarction tachycardia patients, endocardial reentry characteristics correlate with sinus rhythm electrical discontinuities at the isthmus perimeter. Characterization of the diastolic pathway from sinus rhythm data may enable ablation targeting without tachycardia induction.