Exercise Body Surface Potential Mapping in Single and Multiple Coronary Artery Disease: Discussion (Part 4)
The ability of BSPM to spatially discriminate the primary artery involved in the ischemic process is not yet established. Eigenfunction analysis has been reported to effectively discriminate left anterior descending from right CAD. In contrast, the data of this study and one other study using isointegral analysis suggest that there is marked overlap of the patterns of exercise ST decrease on the body surface among the vessel subpopulations of patients with CAD.
One difference between the results of this study and those of our previous exercise BSPM study of 14 patients with isolated left anterior descending CAD was the generally higher correlation coefficients of peak ischemic ST changes and quantitative angiographic measures of myocardium at ischemic risk. In the previous study, the highest r value was —0.52 for the relationship between peak ST ischemia and modified Gensini score; the correlations of the other angiographic scores were not, however, high (Greenlane, — 0.44; Pujadas, 0.03). The larger sample size of this study was probably responsible for the improved intertechnique correlations. birth control pills
A potential weakness of the present study is the smaller numbers of normal subjects and patients with multiple-vessel CAD, relative to those with singlevessel CAD. Nonetheless, the mapping data were normally distributed in each study group and the changes with exercise and recovery were consistent in all groups. Based on the differences in the sum of ST integral decreases from rest to immediate cessation of exercise between CAD groups 2 and 3, that is, between patients with double- and triple-vessel CAD, it is likely that if more patients had been recruited in each group there would have been a statistically significant greater ST decrease in patients with three-vessel CAD, compared with patients with two-vessel CAD (Table 2).