WHAT FACTORS DETERMINE IN-111 ANTIMYOSIN MONOCLONAL-ANTIBODY UPTAKE IN PATIENTS WITH MYOCARDIAL-INFARCTION

The intensity of indium-111 antimyosin monoclonal antibody uptake for visualization of myocardial infarction seems partially dependent on the state of the infarct related coronary artery. The aim of this study is to determine the factors which could account for the monoclonal antibody uptake variability. For this purpose, we investigated 27 patients (mean age 52.7 +/- 9.6 years) with a first proven myocardial infarction, by monoclonal antibody scintigraphy and coronary arteriography within the same period of time (7.12 +/- 6 days). The monoclonal antibody uptake was quantified by the heart/lung ratio on images recorded 24 h after injection. The infarct size was quantitatively estimated on wall motion analysis of twelve segments in 30-degrees right anterior-oblique view with a radial method. The infarct related coronary artery state was assessed by the Thrombosis in Myocardial Infarction grade and the functional characteristics of collateral vessels by Rentrop's classification. These three variables as well as location of myocardial infarction, left ventricular ejection fraction, administration of a thrombolytic therapy, delay between myocardial infarction and monoclonal antibody scintigraphy were studied using non parametric test, or by linear regression method in order to determine whether these factors would influence the heart/lung ratio. None of these parameters except infarct size was related to heart/lung ratio. Consequently, monoclonal antibody uptake is only dependent on the extent of infarcted myocardium and the intensity of uptake cannot predict the patency of an infarct related coronary artery.