Multisize electrodes for substrate identification in ischemic cardiomyopathy: validation by integration of whole heart histology

ObjectivesThis study sought to evaluate the value of combined electrogram (EGM) information provided by simultaneous mapping using micro- and conventional electrodes in the identification of post–myocardial infarction ventricular tachycardia substrate.BackgroundVentricular tachycardias after myocardial infarction are related to scars with complex geometry. Scar delineation and ventricular tachycardia substrate identification relies on bipolar voltages (BV) and EGM characteristics. Early reperfusion therapy results in small, nontransmural scars, the details of which may not be delineated using 3.5 mm tip catheters.MethodsNine swine with early reperfusion myocardial infarction were mapped using Biosense Webster’s QDOT Micro catheter, incorporating 3 microelectrodes at the tip of the standard 3.5 mm electrode. Analysis of EGM during sinus rhythm , right ventricular pacing, and short-coupled right ventricular extrastimuli was performed. The swine were sacrificed and mapping data were projected onto the heart. Transmural biopsies (n = 196) corresponding to mapping points were obtained, allowing a head-to-head comparison of EGM recorded by micro- and conventional electrodes with histology.ResultsTo identify scar areas using standard electrodes, unique cutoff values of unipolar voltage