Which Therapy for Acute Heart Attacks? (The WEST Study)

Inclusion Criteria: * Male or non-pregnant female patients aged \>18 years * Patients with symptoms presumed secondary to STEMI lasting at least 20 minutes and accompanied by ECG evidence \>2 mm of ST elevation in 2 or more contiguous precordial leads or in 2 or more limb leads;or \> 1mm ST elevation in 2 or more limb leads coupled with \>1 mm ST depression in 2 or more contiguous precordial leads such that the total ST deviation is \>4 mm; or presumed new left bundle branch block * Earliest point of care and randomisation must be within 6 hours of onset of symptoms as defined in previous criteria * Females of child-bearing age, not using a generally accepted method of contraception must have a negative urine pregnancy test * Written informed consent prior to randomisation of study Exclusion Criteria: * PCI expected to commence within \< 60 minutes from identification of suitable candidate * Inability to have angiography/PCI within 3 hrs from randomisation * Active bleeding or known hemorrhagic diathesis * Any history of stroke, transient ischemic attack, dementia or structural CNS damage e.g. neoplasm, aneurysm, AV malformation * Major surgery or trauma within the past 3 months * Previous Coronary Artery Bypass Graft (CABG) * Use of abciximab (ReoPro) or other GP IIb/IIIa antagonists within the preceding 7 days * Any minor head trauma and/or any other trauma occurring after onset of the current myocardial infarction * Significant hypertension (i.e. SBP \> 180 mm HG and/or DBP \> 110mm HG) at any time from presentation (earliest point of care) to randomisation * Current treatment with vitamin K antagonist (warfarin) resulting with an INR \> 1.5 * Anticipated difficulty obtaining vascular access * Prolonged (\>10 min) cardiopulmonary resuscitation or cardiogenic shock * Patients who have participated in an investigational drug study within 7 days prior to randomisation * Known renal insufficiency (prior creatinine \>2.5 mg% for men and \>2.0 mg% for women) * Treatment with standard unfractionated heparin (heparin sodium) \>5000 IU or a therapeutic dose of any low molecular weight heparin, within 6 hours prior to randomisation * Known thrombocytopenia (prior platelet count below 100 000/ul) * Known sensitivity to TNKase, clopidogrel, heparin, low molecular weight heparin or abciximab * Pregnancy or lactation, parturition within the previous 30 days * Any serious concomitant systemic or life limiting disorder that would be incompatible with the trial * Inability to follow protocol and comply with follow-up requirements