THERAPY AND PREVENTION THROMBOLYSIS Sustained improvement in left ventricular function and mortality by intracoronary streptokinase administration during evolving myocardial infarction

One hundred eighty-eight patients with acute myocardial infarction were studied prospectively from August 1980 to September 1982. One hundred thirty-six of these patients were entered into a intracoronary streptokinase study after informed consent was obtained. The remaining 52 patients, who either met exclusion criteria for the study or refused to participate, served as a control group and were treated as those in the study group except that they did not undergo emergency cardiac catheterization. Left ventricular function was determined in both groups by gated radionuclide ejection fraction (EF) on admission to the hospital, at discharge, and 6 months after discharge. With successful reperfusion up to 18 hr after onset of chest pain, mean left ventricular function in the study group improved (EF 39 + 13% on admission and 46 + 12% at discharge; p < .001). Mean EF in control patients and those not achieving reperfusion did not change from admission to discharge. Mean EF at 6 month follow-up was not significantly different than at discharge in the study group or the control group. Total cardiac mortality in the control group was 19% compared with 10% in the study group (p = .06, NS). When patients admitted in pulmonary edema or shock (Killip class III or IV) were excluded from both groups, total cardiac mortality in the study group was significantly lower (4%) compared with in the control group (12.5%, p < .05). The administration of intracoronary streptokinase during evolving myocardial infarction up to 18 hr after onset of chest pain may result in decreased mortality and sustained improvement in left ventricular function. Circulation 68, No. 1, 131-138, 1983. STANDARD CURRENT THERAPY for acute myocardial infarction entails prevention or treatment of complications secondary to evolving myocardial necrosis. Mortality during the first 30 days after acute myocardial infarction has been reported to be between 16% and 30% in large series and no definite decrease in this rate was noted between 1960 and 1975.14 Although there is no universally accepted method for reducing myocardial damage, emergency aortocoronary bypass surgery has been reported to decrease mortalityl'6 in certain patients. Intracoronary streptokinase From the University of Texas Medical School at Houston. Presented in part at the AAP/AFCR/AFCI National Meeting, Washington, D.C., May 7-10, 1982. Address for correspondence: Richard W. Smalling, M.D., Ph.D., The University of Texas Medical School at Houston, 6431 Fannin/ MSMB 1246, P.O. Box 20708, Houston, TX 77030. Received Oct. 21, 1983; revision accepted March 24, 1983. Dr. Smalling is a recipient of the NHLBI Clinical Investigator Award 5-KO8-HL00840-03. Vol. 68, No. 1, July 1983 has been shown to be effective in lysing intracoronary thrombus and restoring blood supply to jeopardized myocardiumduring evolving myocardial infarction.7-'0 In reports of small series of patients, reperfusion with intracoronary streptokinase has induced improvement in left ventricular function by the time of hospital discharge.9-3 This report presents the first substantial data from a single center on the effects of intracoronary streptokinase therapy on mortality and left ventricular function at long-term follow-up.