State of the Art: Mapping Strategies to Guide Ablation in Ischemic Heart Disease
William G. Stevenson, Travis D. Richardson, Arvindh N. Kanagasundram, Harikrishna Tandri
Abstract
Catheter ablation to prevent ventricular tachycardia (VT) that emerges late after a myocardial infarction aims to interrupt the re-entry substrate. Interruption of potential channels and regions of slow conduction that can be identified during stable sinus or paced rhythm is often effective and a number of substrate markers for guiding this approach have been described. While there is substantial agreement with different markers in some patients, the different markers select different regions for ablation in others. Mapping during VT to identify critical re-entry circuit isthmuses is likely more specific, and most useful when VT is incessant or frequent during the procedure or when sinus rhythm substrate ablation fails. Both approaches are often combined. These methods for identifying and characterizing post-infarct–related arrhythmia substrate and the re-entry circuits are reviewed. • Re-entry circuits causing ventricular tachycardia after myocardial infarction can have a complex 3-dimensional anatomy. • The bipolar voltage map is a good marker of the infract but fibrosis may extend intramurally beyond the endocardial low-voltage area. • Electrogram and pacing markers of potential re-entry substrate can be targeted for ablation based on mapping during sinus rhythm. • Mapping during ventricular tachycardia is particularly useful when substrate ablation fails or the arrhythmia is incessant.