The acute coronary syndrome (ACS) without ST elevation is a frequent pathology. The main evolutionary risk of these patients is the coronary thrombosis and its self complications. The platelets aggregation plays a major role in the physiopathology of the ACS. The therapeutic arsenal of the anti-thrombosis essentially resting on aspirin and heparin has been reinforced lately by the inhibitors of the glycoprotein anti GP IIb/IIIa. The profit of these products in the ACS with or without ST elevation, associated or not to coronarography, has clearly been demonstrated. This profit is more marked when patients are at high risk of complications. Thus, the use of an anti GP IIb/IIIa is recommended among patients at "high risk" for whom a coronarography is planned, in the last international recommendations of the European Cardiology Society (ESC), the American Heart Association and the American College of Chest Physician. Otherwise, some authors have proposed An early invasive strategy based on coronarography with discordant results.

The ideal delay of realization of this coronarography is unknown. It varies according to the studies between 2.5 hours to 48 hours. Once again, patients at high risk seem to benefit the more of such a strategy if it is set precociously.

Objective To compare an invasive strategy associating an early administration of tirofiban and a coronarography achieved in the 6 hours after the randomization to a conservative strategy in a population of high risk patients with ACS without ST elevation.

Design Multicentric, prospective, randomized study.