Identification of patients prone to infarct expansion by the degree of regional shape distortion on an early two–dimensional echocardiogram after myocardial infarction

Abstract

Early detection of potential expanders (patients who develop clinically significant infarct expansion with acute left ventricular (LV) dilatation and failure but no necrosis) after acute myocardial infarction (AMI) is necessary in order to apply preventive therapy. To determine whether the degree of regional shape distortion (RSD), or dilatation, on early two-dimensional echocardiogram (2-D echo) after AMI can identify potential expanders, serial clinical and echocardiographic data were studied prospectively in 244 consecutive patients with a first Q-wave AMI. Initial (mean 2 days) and final (mean 10 days) two-dimensional echocardiograms were compared for regional LV asynergy, RSD, and conventional indices of expansion measured on endocardial diastolic outlines of mid-LV short-axis sections. Analysis of clinical and 2-D echo data revealed 51 expanders and 193 nonexpanders. Expanders showed greater LV dysfunction and more inhospital deaths (27% vs. 8%, p less than 0.001) compared with nonexpanders; conventional indices of expansion showed more marked increase between initial and final two-dimensional echo in expanders, but initial indices were not predictive. In contrast, the new RSD index Pk, a measure of the outward bulge, was markedly greater in expanders than nonexpanders on both initial (16.5 vs. 2.4 mm, p less than 0.001) and final echo. Furthermore, expanders with greater than or equal to 30% increase in Pk (to 21 mm) developed rupture of the ventricular septum (n = 10) or free wall (n = 2). Also, 50 of 51 expanders compared with 3 of 193 nonexpanders had a Pk greater than or equal to 10 mm on the initial echo. A simpler index, the depth of RSD (rd), provided similar discrimination as Pk. Thus, the degree of diastolic RSD on an early 2-D echo after AMI can identify potential expanders.