Certainly, the epidemiologic data from two recent studies of large patient populations have shown that the degree of exercise ST deviation, as measured from 12- and 15-lead electrocardiograms is a very strong and independent predictor of future coronary death and other clinical cardiac endpoints. A corollary of this reasoning is that CAD patients who fatigue on exercise in the absence of angina and who have, on average, the same degree of peak ST integral decrease as angina-limited single vessel CAD patients and normal subjects exercised to the same peak heart rate, may be viewed as having effective medical therapy and a relatively positive prognosis, as opposed to having nondiagnostic stress tests.
Another implication is that exercise stress is required to optimize the quantitative discriminating ability of ST integral BSPM. Resting negative ST integrals (Table 1) and the sum ST integral decrease between rest and 5 min recovery (Table 2) did not discriminate among patients with single- and multiple-vessel CAD. Stress also was important in the relationship between the sum ST integral decrease and the angiographic scores; correlations only were high with peak ST ischemia and not at 5 min recovery (Table 3). buy prednisone
One other implication of this study concerns the residual ST integral decrease at 5 min postcessation of exercise. Residual ST decrease was also a finding in our previous study of patients with isolated left anterior descending CAD. The findings of this larger study sample provide additional support for the concept that clinical myocardial ischemia is not a sudden, discontinuous on/off phenomenon, but rather a modification of myocardial metabolism that has an important and continuous temporal spectrum. A related implication is that all CAD patients may have “silent” ischemia; if not during ST segment depression- or fatigue-limited exercise, then during the late postexercise recovery period when angina has disappeared but ischemic ST changes persist.
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