ABILITY OF ANTIMYOSIN SCINTIGRAPHY MONITORING TO EXCLUDE ACUTE REJECTION DURING THE 1ST YEAR AFTER HEART-TRANSPLANTATION

Background: Antimyosin Fab fragment has been shown to bind to myosin l eaked from necrotic cardiac cells but not to myosin in undamaged cells . The purpose of this investigation was to evaluate indium 111-antimyo sin Fab fragment scintigraphy as a noninvasive technique in the diagno sis of acute rejection after heart transplantation. Simultaneous endom yocardial biopsy served as the gold standard. Methods: Twenty-two pati ents had scintigraphic studies at weeks 3 to 4, 6, 10, 26, and 52, but the next 16 patients underwent scintigraphy more often, that is, at a ll scheduled biopsies performed from week 3 to week 26 after transplan tation. From analysis of the first 70 studies, an interstudy decrease in the patient's heart-to-lung ratio was classified as normal, that is , no rejection, whereas an unchanged or increased heart-to-lung ratio was considered pathologic. Results: By use of this definition of negat ive and positive scintigraphic results, prospective analysis of 88 con clusive, consecutive studies showed 6 true- and 31 false-positive stud ies (prevalence of rejection 8%), giving a low predictive value of a p athologic change in heart-to-lung ratio. Of the 51 studies with decrea sing heart-to-lung ratio only 1 was a false negative, giving a predict ive value of a negative study of 98% (95% confidence limits 90% to 100 %).Conclusions: In conclusion, antimyosin scintigraphy is a promising noninvasive technique in the routine surveillance of acute heart rejec tion. Because of many false-positive results in the studies, biopsy sh ould be used as a control for a pathologic heart-to-lung ratio.