Disclosed are methods of preventing adverse clinical events in a patient undergoing a percutaneous coronary intervention procedure or a peripheral percutaneous interventional procedure comprising administering a therapeutically effective amount of a thrombin receptor antagonist, such as SCH 530348, to the patient. Administration of a loading dose of about 40 mg of SCH 530348 in as little as one hour prior to the procedure can result in therapeutically effective levels of platelet aggregation.