Quantification of area at risk in acute myocardial infarction by tomographic imaging

The purpose of this study was twofold: to validate, in a phantom heart model, a simple threshold technique for the quantification of defect size using 123I-15-(p-iodophenyl)-3-(R,S)-methyl pentadecanoic acid (BMIPP) imaging and to compare, in patients with acute myocardial infarction, defect size as shown by BMIPP imaging, with the extent of severe hypokinesis shown by left ventriculography.

In a phantom study, defect size was calculated using a standard geometric formula. In a clinical study, BMIPP imaging was performed in 20 patients 10 +/- 5 days after the onset of their infarction. Using the centerline method, the area at risk was defined by contrast ventriculography as the percentage of chords with wall motion >2 s.d. below normal.

In the phantom study, a threshold value of 60% yielded the best agreement between true and measured defect size. In the clinical study, the defect size shown by BMIPP imaging was greater in anterior than in inferior infarcts (p < 0.001) and correlated well with the risk area revealed by contrast ventriculography (r = 0.80, p < 0.0001)

The above preliminary data, admittedly from a small group of patients, suggest that tomographic BMIPP imaging provides an accurate quantification of defect size by means of a simple threshold technique and, in the subacute phase, permits determination of the amount of myocardium at risk after acute myocardial infarction.