Análisis Espacial en la Evaluación de Cambios de la Despolarización Cardíaca durantes Isquemia Aguda de Miocardio

Abstract

In this study we evaluated the three main slopes of the QRS complex (upslope \(\mathcal{I}_{US}\) and downslope \(\mathcal{I}_{DS}\) of the R wave, and terminal slope \(\mathcal{I}_{TS}\) 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 \(\mathcal{I}_{US}\), \(\mathcal{I}_{DS}\) and \(\mathcal{I}_{TS}\) 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 \(\mathcal{I}_{US}\) and \(\mathcal{I}_{DS}\) computed over VCG and PCA leads present higher sensitivity to the ischemiainduced changes than the same indices evaluated over the standard 12-lead ECG. The mean relative factors of change RI were 10.5 and 12.4 for \(\mathcal{I}_{US}\) and \(\mathcal{I}_{DS}\) in PCA, and 7.87 and 13.7 in VCG, respectively, representing an increase in sensitivity of up to 103% for \(\mathcal{I}_{US}\) and 46% for \(\mathcal{I}_{DS}\) 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.