Relationship ofthelytic state tosuccessful reperfusion withstandard- andlow-dose intracoronary streptokinase

Theinfluence ofa systemic lytic state on reperfusion obtained after intracoronary streptokinase (SK)therapy hasbeenevaluated in15patients withacutemyocardial infarction and complete coronaryocclusion. Coronary angiographic studies andmeasurements ofbloodfibrinolytic parameters wererepeated at15minintervals during theinfusion ofa standard doseofSKandwere compared withtheresults withapproximately one-tenth thestandard dose. Successful reperfusion was obtained inonly20%(2/10) ofpatients receiving thelowdose, compared with a75%to80%success rateinpatients receiving thestandard dose asinitial treatment (4/5) orasfollow-up treatment ofpatients inwhomlow-dose therapy failed (6/8). Therewas a striking association between reperfusion and development ofthelytic state inthat all12treatments resulting inreperfusion alsocaused alytic state andall seventreatments that failed toproduce alytic state also failed toinduce reperfusion (p< .001). Amongthesuccessfully treated patients, thedoseofSK thatinduced a lytic state was relatively constant. However, coronaryarterial thrombi differed insusceptibility totreatment. Sensitive thrombi (5/12) dissolved before thelytic state occurred andatalower SKdosethanthat needed tocausealytic state; more resistant thrombi (7/12) required a longer timeanda significantly larger SK doseto dissolve. These results indicate that intrinsic properties ofthethrombus influence therateandoutcome oftreatment andthat aminimal doseofSK(about 200,000 U)isrequired toensurelasting reperfusion insusceptible patients. Furthermore, asystemic lytic state isaconstant accompaniment ofsuccessful therapy andmay evenbeanecessaryrequirement forattaining reperfusion withintracoronary adminis- tration ofSK. Circulation 71,No.3,562-570, 1985.