Indium-111-monoclonal antimyosin antibody studies after the first year of heart transplantation. Identification of risk groups for developing rejection during long-term follow-up and clinical implications.

The long-term clinical course and results of biopsies in 21 patients studied with monoclonal antimyosin antibodies more than 12 months after heart transplantation according to the presence and degree of antimyosin-antibody uptake is described. Eighteen men and three women aged 20-52 years (39 +/- 9 years) were studied with antimyosin antibodies 12-40 months (mean, 22 +/- 9 months) after heart transplantation, and followed for a mean of 18 months (10-28 months). The number of biopsies performed during follow-up was 102. Results showed normal antimyosin-antibody studies in nine patients and abnormal studies in 12 patients. Myocyte damage was identified in 18 of the 102 biopsies (17.6%), one in the normal antimyosin-antibody group of patients and 17 in those patients with myocardial antimyosin-antibody uptake. Patients who developed rejection comprised 11% and 67% of each respective group; the mean number of rejection episodes per patient was 0.11 +/- 0.33 and 1.41 +/- 1.41, respectively (p less than 0.01). A trend was noted by which higher heart-to-lung ratios were associated with greater probability of rejection. Conclusively, 1) antimyosin-antibody studies performed after more than 1 year after heart transplantation indicate the presence and level of rejection activity, 2) groups of patients at risk for developing rejection at biopsy during long-term follow-up may be detected by antimyosin-antibody study, and 3) surveillance for rejection and the degree of immunosuppression should be tailored to meet individual patient needs.