"Based on the results of the ExTRACT-TIMI 25 trial, we believe that a strategy using enoxaparin is now the preferred anticoagulant regimen in heart attack patients who receive clot-busting drugs," said Eugene Braunwald, M.D., M.A.C.C., Distinguished Hersey Professor of Medicine, Harvard Medical School, Chairman, TIMI Study Group, Brigham and Women's Hospital.
Researchers found that enoxaparin reduced the combined risk of death and MI within 30 days by 17 percent. Similarly, enoxaparin reduced the 30-day risk of nonfatal repeat MI by 33 percent, and the 30-day combined risk of death, nonfatal MI, and urgent need to re-establish blood flow to the heart by 19 percent. All of the findings were highly statistically significant.
The trial enrolled 20,506 patients from 674 medical centers in 48 countries. All patients had ST-elevation MI (STEMI), a serious form of heart attack characterized by elevation of the "ST segment" on the electrocardiogram. They were treated with a fibrinolytic, or clot-busting, medication within six hours of first experiencing chest pain, and were then randomly assigned to receive therapy with enoxaparin or unfractionated heparin.
To make sure there was no unintended bias in interpreting the results, the trial used a double-blind, double-dummy design: study participants received both intravenous infusions and twice-daily injections without the physician or the patient knowing which contained the study medication and which was the placebo.
The rates of serious bleeding were lower overall than reported in prior trials. Patients who were treated with the enoxaparin strategy were more likely to experience major bleeding. However, when researchers calculated net clinical benefit, which takes into account both effectiveness and safety, the enoxaparin strategy was, on balance, associated with significantly better outcomes.