Taylor HA, Chaitman BR, Rogers WJ, Kern MJ, Terrin ML, Aguirre FV, Sopko G, McMahon R, Ross RN, Bovill EC. The TIMI Investigators.
Race and prognosis after myocardial infarction. Results of the thrombolysis in myocardial infarction (TIMI) Phase II Trial.
Circulation 1993;88(4 Pt 1):1484-94.

The objective of this analysis is to gain further insight into the mortality patterns among black patients with myocardial infarction (MI), as well as the morbidity and mortality patterns among Hispanic American patients.

The data were collected as part of the TIMI II trial, which was performed in 24 clinical centers across the United States. Eligibility criteria included being of age less than 76 years and meeting specific clinical characteristics. For the current study, data from only 21 of the 24 centers were used due to the insufficient number of minority (black or Hispanic) at the remaining 3 centers. Data included a standardized medical history and physical examination, clinical assessment of status, and laboratory test results. Patients were also rated according to their risk of unfavorable outcome based on specific protocol.

All patients in the trial were treated with re-PA as per a detailed treatment protocol. Patients were randomly assigned to either the invasive or non-invasive strategy. Those assigned to invasive strategy were to have coronary and left ventricle angiography 18 to 48 hours after initiation of re-PA infusion. Coronary artery angioplasty (PTCA) was performed if clinically feasible; coronary artery bypass grafting (CABG) was performed if indicated. A sub-sample of patients were eligible for enrollment in the beta blocker therapy sub-study and were randomly assigned to either immediate or delayed administration of metoprolol.

Control variables included in these analyses were age, sex, various risk factors for coronary disease, and site of enrollment. There were racial patterns in the number of initial risk factors and in the risk of unfavorable outcome: blacks and Hispanics were at higher risk for both. Also, among patients receiving the invasive strategy, the angiographic data showed that black and Hispanic patients were more likely to have ejection fractions <35%. However, PTCA performance was similar among the racial groups (for those receiving this procedure), as was the (risk adjusted) mortality at one-year and the (adjusted) risk for reinfarction.

There were notable differences, however. First, with regard to outcome, for white and Hispanic patients, over one-half of the deaths occurred in the first three weeks after MI and more than 60% occurred by week six. However, for black patients, more than one-half of the one-year mortality occurred between six weeks and one-year from study entry. Also, there was a trend toward better outcomes for the Hispanic patients. With regard to response to therapy, this study noted racial difference in the baseline hemostatic factors and in response to rt_PA infusion (larger drop in fibrinoigen levels) which suggested a greater sensitivity to rt_PA among blacks. However, this study did not find the racial differences in patency rates, and hemorrhagic complications were not more prevalent in blacks.

Despite the limited number of minority patients enrolled and short (1-year) follow-up period, the authors conclude that Hispanic and black American may have prognoses similar to white patients after AMI treated with thrombolytic therapy. Unlike other reports, there was no evidence of racial patterns in 1-year mortality rates among patients in this trial after adjustment for baseline characteristics. The authors suggest three possible explanations for this pattern: the selection of patients with good prognosis, equal efficacy between blacks and whites of the trombolytic agent rt_PA, and ready access to effective intensive care for all patients. With regard to the selection of patients, the maximum blood pressure criteria might have had a larger selection effect on blacks in the study because blacks have a higher incidence of severe or uncontrolled hypertension. With regard to access, the current trial protocol required treatment within four hours of symptom onset, thus selecting for patients who presented promptly and were effectively provided access and state-of-the-art care. "Despite the more pronounced fibrinogenolysis, the risk versus benefit ratio appears to be no different for black patients than for others. Hispanics have outcomes after thrombolysis for MI at least as good as the rest."