[In-111 antimyosin-Fab uptake in contractile myocardium of old myocardial infarction].

As In-111 monoclonal antimyosin antibody (AM) has been thought to bind with human myosin exposed in myocytes irreversibly damaged by an ischemic event. The AM uptake in contractile myocardium after acute myocardial infarction was studied. AM planar images were obtained 48 hours later after injection of 74 MBq of AM in 6 patients 2-10 months later after acute myocardial infarction. Mean ejection fraction was 66% (75-58). Myocardial AM uptake was definite in comparison with mediastinum uptake in all 6 patients and mean heart lung ratio was 2.3 +/- 0.5. AM SPECT images and T1-201 SPECT images were obtained with dual mode. Mean T1-201 uptake at the region of maximal AM uptake was 77% (90-63). Echocardiography showed contractility of the region. Mean maximal AM uptake in the anterior wall region was 83% (100-75) and mean T1-201 uptake at the region was 81% (90-75) and shortening rate of the region was 34% (52-25). The region with AM uptake has been shown to correlate with the region salvaged from necrosis by reperfusion. It has been shown that AM was uptaken in contractile myocardium in chronic phase of acute myocardial infarction. It was suspected that myocardium under severe ischemic event may be salvaged by reperfusion therapy and retain contractility in chronic phase, however irreversible damage, which permit AM uptake, may remain in myocardium.