Identification of the occluded artery in patients with myocardial ischemiainduced by prolonged percutaneous transluminal coronary angioplasty using traditional vs transformed ECG-based indexes

We have studied the spatial properties of ischemic changes as induced by pr olonged angioplasty and how the changes are related to different ECG indexe s. Indexes based on measurements at specific points in time (ST level at J + 60 ms point, maximal T wave amplitude and position, QT interval, and QRS duration) and global indexes (based on the Karhunen-Loeve transform and app lied to the QRS complex, ST-T complex, ST segment, and T wave), considering both repolarization and depolarization information, were analyzed. The cha nges during the occlusion period of the different indexes were used as vari ables in a multivariate discriminant analysis to determine which indexes sh owed the best discrimination of the three major occlusion sites (correspond ing to LAD, RCA, and LCX coronary arteries). Occlusions in LCX artery were the most difficult to classify. With three local indexes (ST60 level measur ed in lend V3, T wave amplitude in I, and ST60 in III) it was possible to c orrectly classify 76% of patients by the occlusion site, and with three KLT -derived indexes (first-order KLT index for ST-T complex in I and for QRS i n leads V3 and I) 83% of correct classification was obtained. Using six ind exes for local and KLT-derived indexes the correct classification was incre ased to 85 and 90% of patients, respectively. The use of different ECG inde xes (from different intervals) on quasiorthogonal leads permitted the ident ification of the occluded artery in patients undergoing PTCA and may be ext ended to more general use. (C) 1999 Academic Press.