Quantitative electrocardiogram morphology—part 2: application to prediction of myocardial ischemia

Abstract

the representative beat was used as the global T wave for symmetry computation. Three types of wave symmetry were checked: (1) the maximum slope of tangent lines, (2) the area, and (3) the slope of the longest secant line. The symmetry score is the ratio of 2 sides (smaller/ larger), and the average of 3 scores is the final symmetry score. Symmetry score more than 85 was considered highly symmetric. Moreover, ECGs presenting left bundle-branch block, right bundle-branch block, LVH, RVH, ST-segment elevation myocardial infarction, and other ST-segment deviations greater than 0.05 mV were excluded. A total of 42 ECGs met the criteria from admission ECGs of patients with acute coronary syndrome in the emergency department of a local hospital. The control set included 3116 healthy subjects without known cardiac abnormality selected from an epidemiology study. Results: Among the 42 cases, cardiac catheterization reports confirmed proximal to middle LAD occlusion in 30, computed tomography confirmed computed tomography angiography (CVA) in 3, echocardiography confirmed cardiomyopathy in 5, and the remaining 4 had other conditions such as lupus, diabetes, and left wall abnormalities. Combining proximal to middle LAD occlusion with CVA and cardiomyopathy, the positive predictive value of the algorithm reached 92.9%. The negative predictive value was 99.9%, and the specificity was 100%. Conclusions: Our validation confirms the close association between the ECG pattern of deeply inverted T wave in V2 to V4 and proximal to middle LAD occlusion, CVA, and cardiomyopathy. The available data set in our study is too small to further separate proximal to middle LAD occlusion from CVA and cardiomyopathy.