Efficacy of streptokinase (SK) administered beyond the period of coron
ary occlusion with regard to ultimate infarct size and the extent of h
emorrhagic infarction was assessed in primates. Eleven macaques underw
ent coronary occlusion for two hours and were then reperfused. Five of
them were given a 2,000 U IV bolus of SK followed by a 10,000 U IV in
fusion over ninety minutes. The remaining 6 served as controls. Macaqu
es were sacrificed seven days postocclusion. The left ventricle was se
ctioned parallel to the minor axis, and these were examined histologic
ally for infarct size and hemorrhage. Multiplying the planimetric valu
es by the thickness of the sections yielded the total volumes of left
ventricle, infarction, and hemorrhage. The mean percentage of left ven
tricle involved in infarction in the treated group was not significant
ly different from the controls (14.06 +/- 6.35 versus 16.50 +/- 4.67,
P > 0.10). SK-treated animals had a significantly greater volume of in
farct involved with hemorrhage as compared with controls (27.1 +/- 10.
8 versus 4.0 +/- 1.4, P < 0.05). SK infusions done concurrently with r
eperfusion following a two-hour occlusion did not result in a signific
ant reduction or increase in the size of infarct. However, SK infusion
s resulted in a significant increase in the amount of hemorrhagic infa
rction.