An approximately 21,000-patient clinical trial designed to improve the standard of care for heart attack (acute myocardial infarction) patients was announced by Aventis.

ExTRACT-TIMI 25 (Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment-Thrombolysis In Myocardial Infarction - Study 25), an international multi-center study, will compare the low-molecular-weight heparin Clexaneâ/Lovenox (enoxaparin sodium) to unfractionated heparin (UFH) in patients with acute ST-segment elevation myocardial infarction (STEMI) receiving thrombolytic therapy.

"The standard of care for antithrombotic therapy in patients with acute ST-segment elevation myocardial infarction has been unfractionated heparin in most cases," said Elliott M. Antman, M.D., director of the Samuel A. Levine Cardiac Unit at Brigham and Women's Hospital, associate professor of medicine at Harvard Medical School and lead investigator of the ExTRACT-TIMI 25 clinical study. "However, all previous enoxaparin studies in patients with STEMI have revealed advantages over the standard of care and support the effort to further study the use of enoxaparin in these patients."

The ExTRACT study will evaluate the safety and efficacy of Clexane/Lovenox compared to UFH in patients with STEMI receiving thrombolytic therapy with streptokinase, alteplase, tenecteplase or reteplase.

ExTRACT is a randomized, double-blind registrational study that will be conducted in about 1,250 centers in the United States and 24 other countries. This is the largest cardiovascular trial ever conducted to investigate the use of Clexane/Lovenox in combination with a thrombolytic agent. All patients involved in the study will receive treatment with Clexane/Lovenox or UFH.

Investigators will evaluate clinical endpoints, including death and recurrent myocardial infarction, within 30 days after randomization. Other assessments that will be performed include chest pain leading to urgent revascularization and stroke.

The benefit of Clexane/Lovenox versus UFH in the management of STEMI was demonstrated in several earlier trials in heart attack patients.

ASSENT 3 (ASsessment of the Safety and Efficacy of New Thrombolytic regimens) found heart attack patients who received Clexane/Lovenox with full-dose tenecteplase experienced fewer ischemic complications of AMI than those treated with UFH and full-dose tenecteplase. These reductions were similar to those seen in the group receiving half-dose tenecteplase plus abciximab and UFH in that trial. Taking into account both efficacy and safety, as well as the ease of administration, the tenecteplase-enoxaparin arm emerged as the best treatment in that trial.

ENTIRE-TIMI 23 (ENoxaparin and TNK-tPA with or without GP IIb/IIIa Inhibitor as REperfusion strategy in ST elevation MI - Thrombolysis In Myocardial Infarction) found that Clexane/Lovenox could be an effective replacement for UFH in heart attack patients undergoing thrombolysis with tenecteplase with or without the addition of a glycoprotein IIb/IIIa receptor antagonist. Furthermore, researchers reported lower rates of death or recurrent heart attack at 30 days in patients treated with Clexane/Lovenox.

HART II (Heparins and Aspirin Reperfusion Therapy) demonstrated that patients who received Clexane/Lovenox in conjunction with rt-PA, or alteplase, achieved similar artery patency at 90 minutes as compared with those patients who received rt-PA and UFH.

AMI-SK (Acute Myocardial Infarction - StreptoKinase) found that combining Clexane/Lovenox and streptokinase significantly improved restoration of normal coronary blood flow and improved outcome in acute myocardial infarction patients.

Clexane/Lovenox is the most widely studied and used low-molecular-weight heparin in the world. Fourteen years of experience, including the treatment of 82 million patients in 96 countries, have proven Clexane/Lovenox to be safe and effective in the prevention and treatment of potentially life-threatening venous blood clots, and in the treatment of certain cardiac conditions such as unstable angina (UA) or non-Q wave myocardial infarction (NQMI). The product is known as Lovenox in the United States, Canada and France, and generally known as Clexane in the rest of the world. In 2001, sales of Clexane/Lovenox were €1.453 billion more than 37 percent higher than the previous year.