Electroanatomic Left Ventricular Mapping in the Porcine Model of Healed Anterior Myocardial Infarction

BACKGROUND: Catheter ablation for ventricular tachycardia in healed infarction is limited to patients with inducible, tolerated arrhythmias. Strategies that would allow mapping during sinus rhythm might obviate this limitation. METHODS AND RESULTS: Two sets of experiments were performed in adult pigs to refine a new technique for left ventricular mapping. First, detailed endocardial maps were done in 5 normal pigs and 7 pigs 6 to 10 weeks after left anterior descending coronary artery infarction to characterize electrograms in normal and infarcted tissue by electroanatomic mapping (CARTO, Biosense). Electrogram recording sites were verified by intracardiac echo (ICE, 9 MHz) and grouped by location: infarct (area of akinesis by ICE), border (0.5-cm perimeter of akinetic area), and remote. Compared with remote sites, electrograms from infarct sites had smaller amplitudes (1.2+/-0.5 versus 5.1+/-2.1 mV, P<0.001), longer durations (74.2+/-26.3 versus 36.3+/-6.4 ms, P<0.001), and more frequent notched or late components. Border zone electrograms were intermediate in amplitude and duration. Second, infarct characterization by electroanatomic mapping was compared with pathological (exclusion of triphenyltetrazolium chloride staining) and ICE measurements. Infarct size by pathology correlated with the area defined by contiguous electrograms with amplitude </=1 mV (r=0.98, P=0.0001). Infarct size by ICE imaging correlated with the area defined by contiguous electrograms with amplitude </=2 mV (r=0.95, P=0.0016). CONCLUSIONS: Electroanatomic mapping during sinus rhythm allows accurate 3D characterization of infarct architecture and defines the relationship of electrophysiological and anatomic abnormalities. This technique may prove useful in devising anatomically based strategies for ablation of ventricular tachycardia.