Differentiation between acute and healed myocardial infarction by signal averaging and color encoding two-dimensional...

To evaluate the ability of a system developed in our laboratory to differentiate between acute and healed myocardial infarction (MI), gated 2-dimensional echocardiography was performed in 10 patients with recent MI (within 48 hours) and 10 patients with healed MI (later than 4 weeks). The 2-dimensional echocardiographic images were digitized using a Datacube VG-120 videoframe digitizer and each digitized videoframe (320 X 240 matrix) was transmitted using a high-speed serial data link to a second computer and stored on floppy disc. Five gated video frames of each patient were time-averaged to give a smoothed digitized image. This image was displayed on high-resolution color monitor connected to a color graphic subsystem. Sixty-four colors indicated pixel intensity. The exact pixel value at any given location was determined using a high-resolution light pen. Color or pixel values were not significantly different between the area of acute MI (pixel intensity 23 +/- 3, mean +/- standard deviation) identified by a regional wall motion abnormality, and the adjacent normal muscle (23 +/- 4). In each patient with healed MI, an increase in color intensity and pixel value (43 +/- 6) was seen in the area of MI (i.e., area of regional wall motion abnormality) compared with adjacent normal muscle (23 +/- 2) (p less than 0.001). These preliminary data in selected patients indicate that this technique enables differentiation between acute and healed MI. It could be of value in management of patients with suspected MI.