In vivo fibrinogenolysis during thrombolytic therapy. Plasmas from 14 patients undergoing thrombolytic therapy with either rt-PA (left) or SK (right) were assayed for fibrinogen-associated F-104 immunoreactivity by ELISA. Eight time points, including pretreatment and 24-hour posttreatment samples, were examined (plasmas for one 24-hour point, one 90-minute point, and three 15-minute time points were not available). Patients who exhibited radiographic evidence of reperfusion are identified by solid lines and symbols, while those who did not are identified by dashed lines and open symbols. Results are expressed as the percent of pretreatment F-104 immunoreactivity.