VALUE OF BODY-SURFACE MAPPING IN LOCALIZING THE SITE OF ORIGIN OF VENTRICULAR-TACHYCARDIA IN PATIENTS WITH PREVIOUS MYOCARDIAL-INFARCTION

Objectives. This study examined the performance of the 62-lead body su rface electrocardiogram (ECG) in identifying the site of origin of ven tricular tachycardia in patients with a previous myocardial infarction . Background. Because the accuracy of ECG localization of ventricular tachycardia using standard 12-lead recordings is restricted to the ide ntification of rather large ventricular areas, application of multiple torso lead recordings may augment the resolving power of the surface ECG and result in more discrete localization of arrhythmogenic foci. M ethods. Thirty-two patients were selected for electrophysiologically g uided ablative therapy for drug-resistant postinfarction ventricular t achycardia. In these patients, QRS integral maps of distinct monomorph ic ventricular tachycardia configurations were correlated with a previ ously generated infarct specific reference data base of paced QRS inte gral maps. Each paced pattern in the data base corresponded with ectop ic endocardial impulse formation at 1 of 18 or 22 discrete segments of the left ventricle with a previous anterior or inferior myocardial in farction, respectively. Electrocardiographic localization was compared with the results obtained during intraoperative or catheter endocardi al activation sequence mapping. Results. Body surface mapping was perf ormed during 101 distinct ventricular tachycardia configurations. Comp ared with the activation mapping data that were acquired in 64 of 101 ventricular tachycardias, body surface mapping identified the correct segment of origin in 40 (62%) of 64 tachycardias, a segment adjacent t o the segment where the arrhythmia actually originated in 19 (30%) of 64 tachycardias and a segment disparate from the actual segment of ori gin in 5 (8%) of 64 tachycardias. With respect to infarct location, th e segment of origin was correctly identified in 28 (60%) of 47 ventric ular tachycardias in patients with anterior, 7 (70%) of 10 tachycardia s in patients with inferior and 5 (71%) of 7 tachycardias in patients with combined anterior and inferior myocardial infarction. Conclusions . This study shows that body surface mapping enables precise localizat ion of the origin of postinfarction ventricular tachycardia in 62% and regional approximation in 30% of tachycardias. The multiple-lead ECG may be used to guide and shorten catheter-based mapping procedures dur ing ventricular tachycardia and to provide relevant information on the origin of tachycardias that cannot be mapped with conventional single -site mapping techniques because of unfavorable characteristics.