INCIDENCE AND TIME-COURSE OF LEFT-VENTRICULAR DILATION IN THE EARLY CONVALESCENT STAGE OF REPERFUSED ANTERIOR WALL ACUTE MYOCARDIAL-INFARCTION

The incidence and early process of left ventricular (LV) dilation in 5 2 Patients with reperfused anterior wall acute myocardial infarction ( AMI) were assessed. All patients achieved coronary reflow within 24 ho urs of the onset and had a patent infarct-related artery in the conval escent stage. Left ventriculography was performed at pre reflow and 25 days (mean) later to determine LV end-diastolic volume (ml) with the area/length method. Short-axis echo images at the midpapillary muscle level were recorded at days 1, 7, 14, and 28 of the AMI. With use of t he papillary muscles as the internal landmarkers, the LV wall was divi ded into the anterior and posterior segments, and length and thickness of each segment were determined. Among 52 patients, 10 (19%) had a gr eater-than-or-equal-to 20% increase in end-diastolic volume in the con valescent stage. Echocardiographic studies demonstrated that there wer e no significant changes in lengths and thicknesses of the anterior an d posterior segments during follow-up study relative to his or her bas e-line value in 42 patients without LV dilation. In the patients with LV dilation, however, the anterior segment exhibited a mean increase o f 25% in its length with a mean decrease of 21% in its thickness at da y 7 relative to their baseline values, but no progressive expansion wa s observed after day 7. A mean increase of 7% in the posterior segment length without reduction in its thickness first became evident at day 28. It is concluded that (1) LV dilation is observed in a relatively small population of patients (19%) with reperfused anterior wall AMI, and (2) in patients with LV dilation, infarct expansion progresses unt il day 7, followed by the secondary eccentric hypertrophy of the nonin farcted segment being evident at day 28 of the AMI.