Role of 201Tl in the management of cardiac transplantation

Serial percutaneous endomyocardial biopsy is the standard for diagnosis of cardiac rejection; it is generally done on a weekly basis for the first month and then as indicated by ECG voltage; but, this method is invasive, can be done only in specialized centers, not available for the many patients who return home, requires 18-24 h before a result is obtained, delaying institution of therapy, and it is aggressive for the endomyocardium of the graft. A reliable, rapid, and noninvasive test for detection of cardiac rejection is still not available. The aim of this work was to determine whether 201Tl uptake was significantly correlated with the histological findings presenting in cardiac rejection. Auxiliary heart transplantation was carried out on 60 male rats. Graft viability was evaluated by direct palpation, ECG voltage, and 201Tl uptake during the study (from 4-6 h after transplantation to 1 month). Syngenic rats (without rejection) were used as a control group. Histological studies were done at the end of the isotope study in all animals. The statistical significance of all results was determined by means of Student's t-test. A very significant correlation between the severity of the histological findings of rejection and 201Tl uptake was found (P less than 0.001). Our results have demonstrated that 201Tl uptake detected rejection earlier than ECG voltage; moreover, 201Tl uptake was more sensitive in detecting a mild degree of rejection while ECG only detected a moderate degree. We believe that 201Tl uptake should be the screening method for the follow-up of cardiac transplantation; it offers to surgeons the opportunity to select patients for endomyocardial biopsy, with a higher accuracy than the other noninvasive methods.