RACIAL-DIFFERENCES IN RESPONSES TO THROMBOLYTIC THERAPY WITH RECOMBINANT TISSUE-TYPE PLASMINOGEN-ACTIVATOR - INCREASED FIBRIN(OGEN)OLYSIS IN BLACKS

To determine whether there are differences in responses to thrombolytic therapy in certain populations, the data for the Thrombolysis and Angioplasty in Myocardial Infarction (phase 1) study were analyzed for black and white patients. Baseline variables including risk factors and extent of coronary artery disease were similar in the 352 white and 24 black patients. The time from onset of chest pain to recombinant tissue-type plasminogen activator (rt-PA) therapy and rt-PA dosing regimens were the same in the two groups. The patency rate of the infarct-related artery at 90 minutes was 91% for blacks and was 72% for whites (p = 0.051). Blacks displayed significantly lower nadir fibrinogen levels (0.57 +/- versus 1.3 =/- 0.76 g/l, p < 0.0001), greater DELTA fibrinogen (baseline-nadir) (2.7 +/- 1.1 versus 1.7 +/- 1.1 g/l, p < 0.0001), and increased peak levels of fibrin(ogen) degradation products (837 +/- 865 versus 245 +/- 475-mu-g/ml, p < 0.0001). rt-OA antigen levels tended to be higher in blacks than in whites (2.8 +/- versus 2.2 +/- 3.2 mu-g/ml [p = 0.10] at the peak and 1.6 +/- 1.3 versus 0.99 +/- mu-g/ml [p = 0.06] at the end of the maintenance infusion). Major clinical outcomes including survival until time of hospital discharge (92% black versus 93% white, p = 0.68) were not significantly different. However, despite undergoing fewer angioplasty procedures (25% versus 46.3%, p = 0.047), blacks received more transfusions (58.8% versus 19.5% were administered greater-than-or-equal-to 2 units packed erythrocytes, p = 0.001). Inconclusion, black patients have an apparent enhanced sensitivity to rt-PA, which is manifested by increased thrombolytic efficacy, a more pronounced systemic fibrinogen breakdown, and increased transfusions.