Myocardial fibrinolytic activity in allogenic cardiac rejection.

The relationship between alterations in myocardial fibrinolytic activity and the degree of graft tolerance or rejection was studied in 22 nonimmunosuppressed heterotopic cardiac transplants in chacma baboons. Fibrinolysis was evaluated on tissue sections and tissue extracts. Fibrinolytic activity was compared with electrocardiographic voltage alterations and multiple myocardial biopsies and terminal heart specimens were examined by light and electron microscopy. Histopathology and reduction in fibrinolytic activity proved superior to electrocardiographic voltage reductions in assessing early cardiac rejection. The two former modalities correlated well with one another. Myocardial histology showed rejection change earlier than fibrinolytic activity reduction.