Background and purpose: Intracranial hemorrhage is a serious complication of thrombolytic therapy for acute myocardial infarction, especially among the elderly, but little information exists on estimating risk. Better estimation of risk in individual patients may allow for withholding or using alternate therapies among those at highest risk.
Methods: To quantify the risk and identify predictors of intracranial hemorrhage associated with thrombolytic therapy, we performed a retrospective cohort study using data from medical charts. The study involved nearly all acute-care hospitals in the United States. All Medicare patients discharged with a principal diagnosis of acute myocardial infarction during a 9-month period in 1994 to 1995 were included. The main outcome measure was intracranial hemorrhage among those treated with thrombolytic therapy.
Results: The rate of intracranial hemorrhage was 1.43% (455 of 31 732). In a logistic model, age > or =75 years, female, black race, prior stroke, blood pressure > or =160 mm Hg, tissue plasminogen activator (versus other thrombolytic agent), excessive anticoagulation (international normalized ratio > or =4 or prothrombin time > or =24), and below median weight (< or =65 kg for women; < or =80 kg for men) were independent predictors. A risk stratification scale was developed on the basis of these factors: with none or 1 of the factors (n=6651), the rate of intracranial hemorrhage was 0.69%; with 2 factors (n=10 509), 1.02%; with 3 factors (n=9074), 1.63%; with 4 factors (n=4298), 2.49%; and with > or =5 factors (n=1071), 4. 11% (Mantel-Haenszel; P<0.001).
Conclusions: The rate of intracranial hemorrhage in older patients after treatment with thrombolytic therapy exceeds 1%. Readily available factors can identify elderly patients with acute myocardial infarction at high and low risk for intracranial hemorrhage associated with thrombolytic therapy.