Author + information
- Received March 12, 1992
- Revision received June 1, 1992
- Accepted June 4, 1992
- Published online December 1, 1992.
- Manuel D. Cerqueira, MD, FACC∗,
- Charles Maynard, PhD,
- James L. Ritchie, MD, FACC,
- Kathryn B. Davis, PhD and
- J.Ward Kennedy, MD, FACC
- ↵∗Address for correspondence: Manuel D. Cerqueira, MD, Seattle Veterans Affairs Medical Center (115), 1660 South Columbian Way Seattle, Washington 98108.
Objectives. The aim of this study was to determine whether streptokinase treatment improves long-term survival in patients with acute myocardial infarction.
Background. Thrombolytic treatment for acute myocardial infarction reduces early mortality and improves the 1-year survival rate, but the long-term (3 to 8 years) survival benefits of treatment and the relation between survival and baseline clinical characteristics, infarct size and ventricular function have not been established.
Methods. We assessed survival status at a minimum of 3 and a mean of 4.9 ± 2.3 years in 618 patients randomized between 1981 and 1986 to receive conventional treatment (n = 293) or thrombolysis with streptokinase In = 325) in the Western Washington Intracoronary (n = 250) and Intravenous (n = 368) Streptokinase in Myocardial Infarction trials. The relation between long-term survival and thrombolytic treatment, admission baseline clinical characteristics and late radionuclide tomographic thallium-201 infarct size and ejection fraction was assessed in a subset of patients.
Results. Survival at 6 weeks was 94% in patients who received streptokinase versus 88% in the control group (p = 0.01). However, survival at 3 years was 84% in the streptokinase group and 82% in the control group and for the total period of follow-up, there was no significant survival benefit (p = 0.16). Analysis by infarct location showed a higher survival rale at 3 years for patients treated with anterior infarction (76% vs. 67% for the control group), but no overall survival benefit (p = 0.14). Survival at 3 years for patients with an inferior infarction was 89% in the streptokinase group and 91% in the control group (p = 0.62).
By stepwise Cox regression analysis, admission clinical variables associated with decreased long-term survival were anterior infarction, advanced age, history of prior infarction and the presence of pulmonary edema or hypotension. Although streptokinase therapy was associated with improved survival, it was not an independent determinant of survival (p = 0.069). Ejection fraction and thallium-201 infarct size measured approximately 8 weeks after enrollment had a strong association with long-term survival. Univariate analysis in a subgroup of 289 patients with complete data selected infarct size, ejection fraction, age and history of prior infarction as predictors of survival. In the muluvariate model, only ejection fraction (p < 0.0001), age (p = 0.008) and prior myocardial infarction (p = 0.02) remained strong predictors.
Conclusions. In these early trials of thrombolytic therapy for acute myocardial infarction, streplokinase improved early survival, but there was little long-term survival benefit. This failure to show an improvement in the 3- to 8-year survival rate may also reflect the need to study a larger group of patients or to initiate treatment earlier after symptom onset.
☆ This study was presented in part al the 63rd Scientific Sessions of the American Heart Association, Dallas, Texas, November 1990. It was supported in part by the W.M. Keck Foundation, Los Angeles, California; Grant HL 33300 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda. Maryland and by the General Medical Research Services of the Department of Veterans Affairs, Washington, D.C. Thallium-201 was supplied by the Medical Products Department of the E.I. Du Pont dc Nemours and Company, Inc., North Billerica, Massachusetls.
- Received March 12, 1992.
- Revision received June 1, 1992.
- Accepted June 4, 1992.