On the prognostic potential of the sequential 123-I-HDA-tomoscintigram after the first MI

Seven-pinhole tomography (SPT) using 123-I-heptadecanoic acid (HDA) is highly sensitive in confirming, sizing and localizing myocardial infarcts (MIs). Its prognostic value, however, is unknown. Thirty-five consecutive patients coming for a routine SPT within 10 days after MI underwent a second examination approximately 20 weeks later. These examinations combined an early (5 min) and a late (30 min) SPT after administration of 4 mCi 123-I-HDA, as well as a first pass radiocardioangiography. Scars and infarcts without residual HDA catabolism were related to lesions which followed (from 5 min to 30 min) a cool-cool or cold-cold behaviour. Cool-warm lesions (due to low HDA uptake and prolonged washout) were considered ischaemic. This ischaemic behaviour could not be correlated to the later course of the illness: in those patients with higher initial ischaemic scores, the ejection fraction did not increase disproportionately nor was the size of the lesion significantly smaller in the later examination than in those patients with lower ischaemic scores. Only a slightly better reduction of the end-diastolic volume was found in the patients with initially predominantly ischaemic lesions. Thus, SPT with HDA seems to be of limited value for an early prognostic evaluation of patients with MI.