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Objectives. This study sought to determine the accuracy of the initial 12-lead electrocardiogram (ECG) in predicting final infarct size after direct coronary angioplasty for myocardial infarction and to examine which physiologic variables known to be determinants of outcome the ST segment changes most closely reflect. Background. Myocardium at risk, collateral flow and time to reperfusion have been shown to be independent physiologic predictors of infarct size in animal and clinical models. However, such measurements may be difficult to perform on a routine basis in patients with myocardial infarction. The standard 12-lead ECG is inexpensive and readily available. Methods. Sixty-seven patients with acute myocardial infarction, ST segment elevation and duration of chest pain

Prior studies that have demonstrated the prognostic utility of exercise thallium-201 (TI) imaging have been performed in tertiary care centers and potentially may have been influenced by patient-referral bias. To evaluate the prognostic value of TI imaging in a community-based population, 250 residents (age 58 ± 12 yrs, M164, F86) of Olmsted County, MN who underwent exercise TI tomographic imaging were followed for a median duration of 5.3 years. There were 32 initial cardiac events—5 deaths, 15 nonfatal myocardial infarctions (MI), and 12 “late” revascularization procedures performed g 3 mos after the TI study. Five-year event-free survival was 87%. The following table shows the univariate association with time to an event by Cox proportional hazards analysis: Variable X2 p Age 25.0 l 0.001 Gender 3.0 NS Prior MI 22.8 l 0.001 Chest pain class 0.4 NS Exercise duration 8.7 0.003 Magnitude ST depression 0.9 NS Exercise angina score 4.2 0.04 Any TI redistribution 6.8 0.009 #segments with TI redistribution 13.0 l 0.001 #abnormal TI segments post exercise 27.9 l 0.001 Increased lung uptake of TI 0.7 NS By multivariate analysis the only variables independently associated with outcome were age (x2 = 13.3, p = l 0.001) and the # abnormal TI segments post exercise (x2 = 8.0, p = 0.005). Conclusion As demonstrated previously for referral populations from tertiary care centers, exercise TI imaging is also useful for prognostic purposes in a community-based population.

This study examines the recently reported gender differences in cardiac responses to exercise. The study group consisted of 192 men and 67 women with a low probability of coronary artery disease who underwent supine exercise radionuclide angiography.Men had a lower rest ejection fraction than that of women (0.63 versus 0.66, p = 0.02) and greater increases in ejection fraction with exercise (0.08 versus 0.02, p = 0.0001). The slope relating ejection fraction to metabolic equivalents of exercise (METs) was greater (p = 0.004) for men, even after adjustment for differences in rest ejection fraction and end-diastolic volume index. Compared with men, women had a smaller rest end-diastolic volume index (87 versus 97 ml/m2, p = 0.003) and a greater increase in end-diastolic volume index with exercise (6 versus −2 ml/m2, p = 0.002).The slope relating end-diastolic volume to METs was greater for women, even after adjustment for differences in rest end-diastolic volume index and peak work load. There are clear gender differences in the supine exercise response of ejection fraction and end-diastolic volume that are not explained by differences in exercise capacity.

The exercise response of the ratio of systolic blood pressure to end-systolic volume was studied in 243 patients with chest pain and coronary artery disease who underwent supine rest and exercise equilibrium radionuclide angiography. There was a wide variation in both rest and exercise variables in this group. The exercise response of the systolic pressure/volume ratio also varied greatly, ranging from a decrease of 59% to an increase of 136%. Twenty-one clinical, catheterization and radionuclide angiographic variables were examined to determine their relation to the exercise response of the systolic pressure/volume ratio; nine variables were individually correlated with this ratio. Multiple regression analysis identified the change in end-diastolic volume index with exercise, rest systolic blood pressure, coronary artery Gensini score and peak work load as significant independent predictors of the exercise response of the systolic pressure/volume ratio; the latter correlated significantly with the change in ejection fraction with exercise (r = 0.73, p less than 0.0001). Its sensitivity for the detection of coronary artery disease in the study group (84%) and its "normalcy rate" in a group of 120 patients with a low likelihood of coronary artery disease (81%) were similar to those of the peak exercise ejection fraction (75 and 82%, respectively). These results demonstrate that the exercise response of the systolic pressure/end-systolic volume ratio is a complex response that is influenced by several pathophysiologic variables in the presence of coronary artery disease. It does not offer any advantage over ejection fraction measurements for the detection of exercise-induced ischemia.

The ability of exercise radionuclide angiography to predict the risk of having significant left main or three vessel coronary artery disease was examined in 681 patients who underwent both radionuclide and coronary angiography. There were significant differences in multiple variables between patients with or without such disease. Logistic regression analysis identified seven variables as independently predictive of the presence of left main or three vessel disease. Using these variables, low, intermediate and high probability groups could be identified. The four most important variables—the magnitude of exercise ST segment depression, peak exercise ejection fraction, peak exercise rate-pressure product and sex of the patient—can provide practical estimates of the risk of having ten main or three vessel disease. Exercise radionuclide angiography can provide a clinically useful uoninvasive estimate of the risk of having significant left main or three vessel disease.