Aims: To determine the relationship between a strategy of enoxaparin (ENOX), early ST-segment resolution (STRes), and clinical outcomes on patients with ST-segment elevation myocardial infarction (STEMI) after fibrinolysis.
Methods and results: Baseline and 180 min ECGs were analysed in 3208 of the 20 479 patients in the ExTRACT-TIMI 25 trial, which randomifzed patients with STEMI to ENOX vs. unfractionated heparin (UFH) as adjunctive therapy. STRes was defined as complete (70%), partial (30-70%), or none (<30%). There was no evidence for a difference in STRes between the groups assigned to the ENOX or UFH (median 69.4 vs. 67.2%; P = 0.13). Among patients with complete STRes (n = 1100), ENOX significantly reduced death or non-fatal recurrent MI at 30 days when compared with UFH (4.4 vs. 9.9%; OR(adj) 0.39; P < 0.001), whereas there was no difference in patients with only partial or no STRes [14.2 vs. 12.5%; OR(adj) 1.0; P = 0.98 (n = 368) and 16.2 vs. 15.9%; OR(adj) 1.0; P = 0.97 (n = 830), P for interaction = 0.008].
Conclusion: When compared with UFH, a strategy of ENOX significantly reduces death or non-fatal recurrent MI in patients who achieved complete STRes, but not in patients with less STRes. These data suggest that a strategy of ENOX improves outcomes by preventing re-occlusion in patients achieving initial successful reperfusion after fibrinolytic therapy rather than by facilitating initial reperfusion.