The effects of early intracoronary
streptokinase (SK) on enzymatic
infarct size and rate of
enzyme release were studied in a randomized multicenter trial. A total of 533 patients with acute
myocardial infarction (AMI) were allocated to either the SK treatment group (n = 269) or the conventional (control) treatment group (n = 264). Enzymatic
infarct size was represented by the cumulative quantity of
alpha-hydroxybutyrate dehydrogenase (HBDH) released by the heart per liter of plasma in the first 72 hours. Rate of
enzyme release was represented by the ratio of HBDH quantities released in 24 hours and 72 hours. On an "intention to treat" basis, the SK group had a smaller (by 30%; p = 0.0001) median enzymatic
infarct size and a higher (by 35%; p = 0.0001) median rate of
enzyme release than the control group. Limitation of
infarct size was less apparent in patients treated with intracoronary SK only (25%) than in patients treated with intravenous plus intracoronary SK (34%). Compared to the control group, the
enzyme release rate in patients treated with intracoronary SK only was slightly less (34%) than that in patients treated with intravenous plus intracoronary SK (38%). Patients with a patent
infarct-related coronary artery at acute angiography had a median
infarct size which was 55% (p = 0.0001) smaller than the median
infarct size of the control group, and the median rate of
enzyme release was 38% (p = 0.001) higher than the median release rate of the control group. Patients with successful recanalization during intracoronary SK infusion had a median
infarct size which was 31% (p = 0.002) smaller than the median
infarct size of the control group and a median rate of
enzyme release which was 42% (p = 0.0001) higher than the median release rate of the control group. Patients with persistent
coronary occlusion in spite of
thrombolytic therapy had a median
infarct size which was 11% (NS) higher than the median
infarct size of the control group, although the median rate of
enzyme release was still 23% (p = 0.02) higher than the median release rate of the control group. It is concluded that thrombolysis in the early phase of AMI limits
infarct size and that intracoronary SK treatment itself accelerates the process of
enzyme release from infarcted myocardium, independent of the angiographic result.