Detection, sizing and differential diagnosis of acute myocardial infarction with indium-111-labelled monoclonal antimyosin antibodies

74-80 MBq Indium-111-Antimyosin Fab-DTPA (Centocor, Leiden) were administered i.v. to 20 patients within 48 h of severe chest pain due to angina pectoris. The aim of this study was to evaluate 1) the sensitivity of antimyosin-scintigraphy for the detection of acute myocardial infarction 2) the specificity of the method in patients with severe angina pectoris but without infarct 3) the quantification of the infarct volume using SPECT. Immunoscintigraphy was performed 24 and 48 h p.i. (planar scintigraphy as well as ECT) and the results were compared with the enzyme release (CK, CK-MB), the clinical course, ECG, echocardiography, Thallium-201-myocardial scintigraphy and radionuclide ventriculography. An acute myocardial infarction was confirmed in 7/20 patients. Antimyosin scintigraphy showed clearly positive focal uptake in all of the infarct patients. The infarct volume as determined by SPECT showed a very good correlation to the infarct size estimated from enzyme release rates (r=0.99; p<0.002). None of the patients suffering from angina pectoris but not from infarction showed antimyosin uptake. These first results of immunoscintigraphy with Indium-111-labelled antimyosin antibodies demonstrate a high accuracy of the method in the detection of acute myocardial infarction and the possibility of quantification of infarct size by SPECT immunoscintimetry. The clinical value of this new procedure, however, needs further confirmation due to the long time interval between myocardial infarction and scintigraphic detection of antimyosin accumulation (orig.)