Significance of diabetes mellitus in patients with acute myocardial infarction receiving thrombolytic therapy. Investigators of the International Tissue Plasminogen Activator/Streptokinase Mortality Trial.

OBJECTIVES

The purpose of this study was to evaluate the risks and benefits associated with thrombolytic therapy in patients with diabetes presenting with acute myocardial infarction.

BACKGROUND

Diabetes mellitus is associated with adverse risk factors and a hypercoagulable state that may adversely affect the outcome of thrombolytic therapy.

METHODS

Data were analyzed from 8,055 of the 8,239 patients with acute myocardial infarction who received thrombolytic therapy in the International Tissue Plasminogen Activator/Streptokinase Mortality trial (diabetes history was missing for 184 patients).

RESULTS

There were 883 patients with and 8,272 patients without diabetes. Among the diabetic patients, 160 were receiving insulin therapy. Baseline risk factors were significantly worse in diabetic patients, who were older and had a higher rate of previous infarction and antecedent angina and a higher Killip grade at admission. Bleeding and hemorrhagic and ischemic stroke rates were similar among diabetic and nondiabetic patients. Hospital and 6-month mortality rates were highest among diabetic patients receiving insulin therapy (16.9% and 23.1%, respectively), followed by diabetic patients not receiving insulin therapy (11.8% and 17.8%), and lowest in nondiabetic patients (7.5% and 10.7%, p < 0.0001). Whereas diabetes of 5 years' duration was associated with a mortality rate similar to that of nondiabetic patients, a > 5-year duration was associated with a relative mortality risk of 1.38 (95% confidence interval [CI] 0.88 to 2.15) and a > 10-year duration with a relative mortality risk of 1.99 (95% CI 1.40 to 2.81). The independent relative risk for incremental mortality from discharge to 6 months was 1.74 (95% CI 1.21 to 2.50). Mortality rate among diabetic patients was lowest in patients who received both streptokinase and heparin (9.8% vs. 16.1% in patients who received streptokinase but no heparin, p < 0.05).

CONCLUSIONS

The relative mortality of diabetic versus nondiabetic patients was similar to that observed in previous studies of patients with myocardial infarction not receiving thrombolytic therapy, indicating that mortality in diabetic patients receiving thrombolytic therapy is reduced to the same extent as in nondiabetic patients. In addition, risk of bleeding and stroke was not increased, indicating that diabetic patients can safely receive thrombolytic therapy for the same indications as nondiabetic patients.