Evaluation of endomyocardial biopsy in the diagnosis of cardiac rejection. A study using bioptome samples of formalin-fixed tissue.

The reliability of endomyocardial bioptome samples in detecting cardiac rejection was assessed in 26 formalin-fixed previously transplanted hearts. Thirteen human donor hearts (mean postoperative survival 128 days) and 13 baboon donor hearts (mean survival 16.5 days) were studied. Twenty samples were taken under direct vision from the endomyocardium of each heart with an Olympus bioptome catheter. A total of 397 tissue samples was examined "blindly" histologically (177 human and 220 baboon). The bioptome samples were assigned a histological rejection score and then compared with the score accorded multiple tissue sections from the same heart. Sample scores agreed with tissue section scores as follows: humans 86% (samples showed more severe alterations in 5% and less severe in 9%) and baboons 57% (samples more severe in 40% and less severe in 3%). Only 2 false-negative samples were encountered among 285 tissue samples from hearts showing rejection. Changes of rejection were equally distributed between the left and right ventricles. Endomyocardial sampling proved an accurate means of detecting the presence of rejection. In the baboon hearts the endomyocardium tended to show more severe changes than the rest of the myocardium.