Two hundred thirty-one patients with a first acute
myocardial infarction were randomly allocated within 5 h after the onset of symptoms either to treatment with
anisoylated plasminogen streptokinase activator complex (
APSAC), 30 U over 5 min, or to conventional
heparin therapy, 5,000 IU in a bolus injection.
Heparin was reintroduced in both groups 4 h after initial
therapy at a dosage of 500 IU/kg per day. One hundred twelve patients received
APSAC and 119 received
heparin within a mean period of 188 +/- 62 min after the onset of symptoms. Both groups were similar in age, location of the acute
myocardial infarction, Killip functional class and time of randomization. Elective coronary arteriography was performed on an average of 4 +/- 1.2 days after initial
therapy. Follow-up
radionuclide angiography and
thallium-201 single photon emission computed tomography were performed before hospital discharge.
Infarct size was estimated from single photon emission computed tomography and expressed as a percent of total myocardial volume. The patency rate of the
infarct-related artery was 77% in the
APSAC group and 36% in the
heparin group (p less than 0.001). Left ventricular ejection fraction determined from contrast angiography was significantly higher in the
APSAC group than in the
heparin group. This was true for the entire study group (0.53 +/- 0.13 versus 0.47 +/- 0.12; p = 0.002) as well as for the subgroups of patients with anterior and inferior wall
infarction (0.47 +/- 0.13 versus 0.40 +/- 0.11; p = 0.04 and 0.56 +/- 0.10 versus 0.51 +/- 0.11; p = 0.02, respectively). At 3 weeks, the difference remained significant for the anterior
myocardial infarction subgroup. A significant 31% reduction in
infarct size was found in the
APSAC group (33% for the anterior
infarction subgroup [p less than 0.05] and 16% for the inferior
infarction subgroup [p = NS]). A close inverse relation was found between the values of left ventricular ejection fraction and
infarct size (r = -0.73, p less than 0.01). By the end of a 3 week follow-up period, seven
APSAC-treated patients and six
heparin-treated patients had died. In conclusion, the early infusion of
APSAC in acute
myocardial infarction produced a high early patency rate, significant limitation of
infarct size and significant preservation of left ventricular systolic function, mainly in anterior wall
infarction.