Value of early two dimensional echocardiography in patients with acute myocardial infarction

Abstract

Seventy-five consecutive patients with acute myocardial infarction underwent two dimensional echocardiography 7.9 ±3.1 hours after admission (1) to determine if this procedure can detect regional left ventricular asynergy in an unselected series of patients; (2) to evaluate the relation of asynergy outside the electrocardiographic infarct zone to clinical events and coronary anatomic findings; and (3) to determine whether the procedure can identify patients at high risk for cardiogenic shock, before the onset of hemodynamic deterioration. For purposes of analysis, the left ventricle was divided into 11 segments; individual segments were evaluated for systolic wall motion and thickening, and a wall motion index was calculated as a measure of global left ventricular performance. Technically satisfactory two dimensional echographic studies were obtained in all 75 patients. Of 825 possible segments in the 75 patients, 795 (96 percent) or 10.6 segments per patient were deemed adequate for analysis. Akinesia or dyskinesia was detected in at least one segment in all patients, including 15 (20 percent) who underwent imaging within 4 hours of the onset of symptoms and 19 (25 percent) with nontransmural infarction. Severe wall motion abnormalities outside the infarct zone were observed in 47 percent of patients and correlated with a greater prevalence of death (p = 0.03), cardiogenic shock (p < 0.01), progression to a worse Killip class (p = 0.001), reinfarction (p = 0.01) and angina (p = 0.09). Echocardiographic findings were related to coronary anatomic findings in 26 patients; in 13 (93 percent) of 14 cases, remote asynergy occurred in the distribution of a second critically stenosed (90 percent or greater) coronary artery. Lastly, in 66 patients initially assigned to Killip class I to II, the wall motion index was highly predictive of later hemodynamic deterioration. If the numerical admission Killip class and wall motion index are introduced into a discriminant equation (1.44 [Killip class] + 2.11 [wall motion index]), and the discriminant result is 6.04 or greater, 78 percent of patients who had cardiogenic shock were identified. If the discriminant result is less than 6.04, 93 percent of patients without shock were correctly identified. Thus, two dimensional echocardiography performed soon after admission to the coronary care unit is technically feasible, provides useful information concerning regional and global left ventricular function and offers important predictive information about patients early in acute myocardial infarction.