Intracranial hemorrhage associated with thrombolytic therapy for elderly patients with acute myocardial infarction - Results from the cooperative cardiovascular project

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 estimati on of risk in individual patients may allow for withholding or using altern ate therapies among those at highest risk. Methods-To quantify the risk and identify predictors of intracranial hemorr hage associated with thrombolytic therapy, we performed a retrospective coh ort study using data from medical charts. The study involved nearly all acu te-care hospitals in the United States. All Medicare patients discharged wi th a principal diagnosis of acute myocardial infarction during a 9-month pe riod in 1994 to 1995 were included. The main outcome measure was intracrani al 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 greater than or equal to 75 years, female, black race, prior stroke, blood pressure greater than or equal to 160 mm Hg, tissue pl asminogen activator (versus other thrombolytic agent), excessive anticoagul ation (international normalized ratio greater than or equal to 4 or prothro mbin time greater than or equal to 24), and below median weight (less than or equal to 65 kg for women; less than or equal to 80 kg for men) were inde pendent 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 intra cranial hemorrhage was 0.69%; with 2 factors (n=10 509), 1.02%; with 3 fact ors (n=9074), 1.63%; with 4 factors (n=4298), 3.49%; and with greater than or equal to 5 factors (n=1071), 4.11% (Mantel-Haenszel; P<0.001). Conclusions-The rate of intracranial hemorrhage in older patients after tre atment 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.