Wall motion abnormalities and electrocardiographic changes in acute transmural myocardial infarction: Implications of reciprocal ST segment depression

Abstract

Left ventricular ejection fraction and regional wall motion were assessed by multigated equilibrium radionuclide ventriculography within 24 hours of onset of first acute transmural myocardial infarction (MI) in 32 patients. Abnormal left ventricular wall motion was noted in all 16 patients with anterior infarction and in 14 of 16 (87.5%) patients with inferior infarction. Regional wall motion abnormalities frequently included areas adjacent to and remote from those predicted by the ECG location of ST elevation and pathologic Q waves. Such remote wall motion abnormalities were associated with reciprocal ST segment depression in 17 of 18 (94%) patients, and conversely reciprocal ST segment depressions were associated with remote wall motion abnormalities in 17 of 24 (71%) patients. The left ventricular ejection fraction was lower in patients with a reciprocal ST segment depression compared to those without (anterior MI 0.29 ± 0.07 vs 0.43 ± 0.08, p < 0.01; inferior MI 0.45 ± 0.11 vs 0.63 ± 0.06, p < 0.001). In addition, the peak MB-CK levels were higher in patients with compared to those without reciprocal ST segment depression (anterior MI 268 ± 183 vs 102 ± 60, p < 0.05; inferior MI 186 ± 120 vs 67 ± 20, p < 0.05). Thirteen of 18 (72%) patients with reciprocal ST segment depression compared to 4 of 13 (31%) patients without reciprocal ST segment depression had a complicated clinical course during their hospital stay. These observation suggest that global left ventricular dysfunction in first acute transmural MI is greater when reciprocal ST segment depression is present on the 12-lead ECG. Such reciprocal changes are frequently associated with enzymatic evidence of larger infarction, regional left ventricular dystunction extending to segments remote from the ECG predicted site of transmural infarction, and an unfavorable clinical course.