INCLUSION:

• Males and females at least 18 years of age,
• Be able to provide written informed consent,
• Need anticoagulation for percutaneous coronary intervention (angioplasty, rotational atherectomy, directional coronary atherectomy, transluminal extraction catheter, or coronary stent),
• New diagnosis or history of clinically suspected or objectively documented HIT/HITTS, defined as:

(A) Positive heparin-induced platelet aggregation (HIPA) or other functional assay, defined as: (B) HIT: Thrombocytopenia associated with heparin therapy, where the platelet count: (i) has decreased to <100x10(9)/L (minimum of 30% drop from the platelet count before heparin treatment), OR (ii) has decreased to <150x10(9)/L (minimum of 40% drop from the platelet count before heparin treatment, OR, (C) HITTS: Thrombocytopenia (as defined above) PLUS arterial or venous thrombosis (deep-vein thrombosis, pulmonary embolism, mesenteric venous or arterial thrombosis, acute myocardial infarction, left ventricular thrombus, ischemic stroke, or occlusion or limb arteries), diagnosed by physical exam/lab evidence and/or appropriate imaging studies (duplex ultrasound, venography, ventilation-perfusion scan, venous or arterial angiography, MRI/MRA, catheterization).

EXCLUSION:

• Overt or known active significant bleeding,
• Definitive evidence of an alternative explanation for the thrombocytopenia (e.g.m DIC, sepsis, other consumptive coagulopathy, ITP, TTP, HUS, or bone-marrow failure),
• Coagulation disorder or bleeding diathesis unrelated to HIT/HITTS,
• Patients with renal impairment, defined as calculated creatinine clearance <30 mL/min, or any other medical conditions (including hepatic, pulmonary, gastrointestinal, endocrine, or psychiatric) that, in the investigator's opinion, would endanger the patient if she/he receives anticoagulant therapy,
• Nonhemorrhagic stroke within the past 6 months or any previous hemorrhagic stroke,
• Intracranial neoplasm, or cerebral/spinal arteriovenous malformation or aneurysm,
• Lumbar puncture, or spinal/epidural catheter placement within the past 7 days,
• Known prior hemorrhage (gastrointestinal, genitourinary, pericardia, pleural, retroperitoneal spaces), major surgery, or serious trauma within the past 6 weeks, unless attending physician believes the need for anticoagulation with PCI outweighs the potential bleeding risk,
• Puncture of a non-compressible vessel within 24 hours before the planned PCI,
• Confirmed uncontrolled hypertension (systolic blood pressure > or = 100 mmHg) at study entry,
• Ongoing anticoagulant therapy at study entry. However, patients may be entered if the therapy can be safely stopped periprocedurally, or, in the case of oral warfarin, if the prothrombin time INR can safely be brought to < or = 1.5 just before study drug infusion,
• Known or suspected pregnancy, or breast-feed. Women of childbearing potential must have a negative pregnancy test (urine or blood) and must be made explicitly aware that bivalirudin may cause excessive menstrual bleeding. Known or suspected pregnancy, or breast-feeding,
• Known hypersensitivity to bivalirudin or leech proteins,
• If the patient has participated in a drug trial within the past 48 hour, call the DCRI hotline.