Analisis Espacial en la Evaluacion de Cambios de la Despolarizacion Cardiaca durantes Isquemia Aguda de Miocardio

摘要

In this study we evaluated the three main slopes of the QRS complex (upslope I_(US) and downslope I_(DS) of the R wave, and terminal slope I_(TS) of the S wave) in both standard and derived ECG leads obtained from spatial QRS loops, either by the vectorcardiogram (VCG) or by principal component analysis (PCA), in 79 patients undergoing prolonged, elective percutaneous coronary intervention (PCI). For each patient, the slope indices I_(US), I_(DS) and I_(TS) were evaluated in the PCI recording as well as in a control recording acquired before the PCI procedure, and relative factors of change during PCI were calculated. We showed that I_(US) and I_(DS) computed over VCG and PCA leads present higher sensitivity to the ischemia-induced changes than the same indices evaluated over the standard 12-lead ECG. The mean relative factors of change R_I were 10.5 and 12.4 for I_(US) and I_(DS) in PCA, and 7.87 and 13.7 in VCG, respectively, representing an increase in sensitivity of up to 103% for I_(US) and 46% for I_(DS) compared to measurements obtained in lead V3. We conclude that evaluation of slope indices in leads derived from QRS loops significantly increases their potential value for detection of acute myocardial ischemia.