{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T12:20:28Z","timestamp":1773922828134,"version":"3.50.1"},"reference-count":25,"publisher":"American Physiological Society","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Heart and Circulatory Physiology"],"published-print":{"date-parts":[[2019,1,1]]},"abstract":"<jats:p>There is no known strategy to differentiate which multicomponent electrograms in sinus rhythm maintain reentrant ventricular tachycardia (VT). Low entropy in the voltage breakdown of a multicomponent electrogram can localize conditions suitable for reentry but has not been validated against the classic VT activation mapping. We examined whether low entropy in a late and diversely activated ventricular scar region characterizes and differentiates the diastolic path of VT and represents protected tissue channels devoid of side branches. Intraoperative bipolar electrogram (Bi<jats:sub>EGM<\/jats:sub>) activation and entropy maps were obtained during sinus rhythm in 17 patients with ischemic cardiomyopathy and compared with diastolic activation paths of VT (total of 39 VTs). Mathematical modeling of a zigzag main channel with side branches was also used to further validate structural representation of low entropy in the ventricular scar. A median of one region per patient (range: 1\u20132 regions) was identified in sinus rhythm, in which Bi<jats:sub>EGM<\/jats:sub>with the latest mean activation time and adjacent minimum entropy were assembled together in a high-activation dispersion region. These regions accurately recognized diastolic paths of 34 VTs, often to multiple inducible VTs within a single individual arrhythmogenic region. In mathematical modeling, side branching from the main channel had a strong influence on the Bi<jats:sub>EGM<\/jats:sub>composition along the main channel. The Bi<jats:sub>EGM<\/jats:sub>obtained from a long unbranched channel had the lowest entropy compared with those with multiple side branches. In conclusion, among a population of multicomponent sinus electrograms, those that demonstrate low entropy and are delayed colocalize to critical long-protected channels of VT. This information is pertinent for planning VT ablation in sinus rhythm.<\/jats:p><jats:p>NEW &amp; NOTEWORTHY Entropy is a measure to quantify breakdown in information. Electrograms from a protected tissue channel can only possess a few states in their voltage and thus less information. In contrast, current-load interactions from side branches in unprotected channels introduce a number of dissimilar voltage deflections and thus high information. We compare here a mapping approach based on entropy against a rigorous reference standard of activation mapping during VT and entropy was assessed in sinus rhythm.<\/jats:p>","DOI":"10.1152\/ajpheart.00581.2018","type":"journal-article","created":{"date-parts":[[2018,10,19]],"date-time":"2018-10-19T19:29:51Z","timestamp":1539977391000},"page":"H134-H144","source":"Crossref","is-referenced-by-count":4,"title":["Information theory to tachycardia therapy: electrogram entropy predicts diastolic microstructure of reentrant ventricular tachycardia"],"prefix":"10.1152","volume":"316","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7972-5375","authenticated-orcid":false,"given":"Sachin","family":"Nayyar","sequence":"first","affiliation":[{"name":"The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, 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