Reciprocal ST change in acute myocardial infarction: assessment by electrocardiography and echocardiography.

To evaluate the incidence, time course and significance of reciprocal change, 25 consecutive patients admitted with their first acute transmural myocardial infarction were studied with serial electrocardiography and two-dimensional echocardiography. Reciprocal change was noted in all patients with inferior infarction (mean maximal ST segment depression 3.53 +/- 1.97 mm) and 70% of patients with anterior infarction (mean maximal ST depression 1.45 +/- 0.8 mm, p = 0.001). When initially present, reciprocal change had resolved within 24 hours in 59% of patients. The sum of reciprocal ST depression correlated with the sum of ST elevation in anterior (r = 0.92, p less than 0.001) and inferior (r = 0.55, p = 0.035) infarction, and this relation persisted when maximal ST depression and elevation were considered. Echocardiographic evidence of contraction abnormalities in areas of the left ventricle remote from the infarction was seen in 45% of patients. However, its presence did not correlate with the presence of reciprocal change. Although reciprocal change progressively diminished on serial electrocardiograms (maximal ST depression 2.73 +/- 1.77 mm at 19 hours after onset of symptoms; 1.0 +/- 0.92 mm at 2 to 3 days; and 0.22 +/- 0.26 mm at 7 to 10 days; p less than 0.05), the corresponding serial echocardiograms showed no change in the function of the remote wall (remote wall motion index 1.87 +/- 0.65, 1.81 +/- 0.62, 1.86 +/- 0.47, respectively, p = NS). These data, therefore, do not support the hypothesis that reciprocal ST depressions during early acute transmural myocardial infarction reflect remote ischemia. Rather, these changes are influenced by factors determining the degree of acute ST elevation, previously shown to include infarct size, shape, location, transmurality and duration.