Are surveillance endomyocardial biopsies necessary during OKT3 induction therapy?

Background. To determine the utility of surveillance endomyocardial biopsies (EMBs) during a 14-day OKT3 induction course after cardiac transplantation, histologic results of the first two EMBs were retrospectively reviewed. Methods. Seventy-three consecutive cardiac transplant recipients who received an OKT3-based quadruple sequential immunosuppressive protocol were analyzed. Patients were predominantly white (85%) and male (72%), with ischemic cardiomyopathy (54%) and a pretransplant panel-reactive antibody level of <10% (93%). Results. The first EMB in 73 patients demonstrated no rejection in 70 patients (96%) and grade 1A rejection in 3 patients (4%). The second EMB showed no rejection in 64 patients (88%), grade 1A or 1B rejection in 8 patients (11%), and grade 3A rejection without hemodynamic compromise in only 1 patient (1%). Absolute CD3⁺ cells remained below 25 lymphocytes/mm³, and mean trough OKT3 serum levels exceeded 500 ng/ml throughout the 14 days of therapy, demonstrating the immunosuppressive efficacy of OKT3. Posttransplant echocardiograms showed normal left ventricular systolic function. Conclusions. Since 145 of 146 EMBs (99%) demonstrated no or minimal allograft rejection, a large cost savings could be realized if EMBs were performed only when clinically indicated during the 14-day OKT3 induction course in cardiac transplant recipients. Appropriate immunologic monitoring and echocardiographic testing may obviate the need for performing costly EMBs during OKT3 induction without an adverse clinical outcome.