Endomyocardial biopsy detection of acute rejection in cardiac allograft recipients.

Endomyocardial biopsy provides a safe, reliable, morphologic index of acute rejection and has an important role to play in the management of patients in whom acute rejection occurs. Repeated endomyocardial biopsies are well tolerated, permitting monitoring of acute rejection in cardiac recipients. Some patients have undergone over 30 serial biopsies. Adequate sampling requires at least four pieces of tissue. The biopsies are graded in the following manner: Mild acute rejection is characterized by a perivascular and mild interstitial infiltrate of pyroninophilic lymphoblasts without myocyte necrosis. Moderate acute rejection has an increased infiltrate extending into the interstitium and causing focal myocyte necrosis. This requires augmentation of immunosuppression. Severe acute rejection, which is more difficult to reverse, includes a more prolific infiltrate with the addition of neutrophils, hemorrhage, and increased myocyte necrosis. Ongoing acute rejection implies that the degree of acute rejection is the same, or worse, than the previous biopsy. Resolving or resolved acute rejection shows reparative changes with diminishing or absent inflammatory infiltrate following treatment. Recipients treated with Cyclosporin-A develop rejection and respond to treatment more slowly than with conventional treatment. This group also develops endocardial infiltrates and a dose-related fine perimyocytic cardiac fibrosis. The endomyocardial biopsy is also useful in identifying infectious agents, for example, toxoplasmosis in cardiac recipients.