Exercise Body Surface Potential Mapping in Single and Multiple Coronary Artery Disease: Results (Part 4)
As a discriminating variable, sum ST decrease — 4,000mV*s, cessation minus rest, appeared to provide the best criterion for prediction of single-vs multiple-vessel CAD in patients who achieved angina (Table 2). Retrospective application of this criterion to CAD groups 1 to 3 yielded a sensitivity of 85 percent, a specificity of 70 percent, a positive predictive value of 65 percent and a negative predictive value of 90 percent for the diagnosis of multiple-vessel CAD. Among CAD patients who achieved fatigue as their exercise endpoint, only four of 15 had sum ST decrease — 4,000 mV*s (Table 2). Among the normal control tests, three of ten had sum ST integral decrease < — 4,000 mV*s (Table 3). It is relevant to note the three normal tests with sum ST decrease <—4,000 mV*s were those with the three highest heart rates (tests la, 4 and 5; Table 3), substantially higher than the average of the normal group (Table 3) and the CAD patient groups (Table 2). These findings underline the importance of control groups to be matched for peak exercise heart rate.
Of the 51 CAD patients, 35 had qualitatively positive thallium scans, defined as reversible perfusion defects at peak exercise (Table 2). The quantitative thallium scores, although exhibiting a trend toward higher values with multivessel CAD, were not statistically different among the CAD groups, averaging five in group 1, four in group 2, seven in group 3 and two in group 4 (Table 2). flovent inhaler