The purpose of this study is to compare clopidogrel effectiveness between severe hemodynamically unstable versus stable patients with acute myocardial infarction.

Clopidogrel exists in oral form only. As a prodrug, it has to be metabolized to the active form by cytochrome system in the liver. Both facts could lead to lower efficacy of the drug in hemodynamically unstable patients, where splanchnic and liver hypoperfusion is present. We hypothesised that clopidogrel efficacy is insufficient in patients with acute myocardial infarction and severe hemodynamic instability. Therefore we would like to compare the effect of clopidogrel in unstable STEMI patients on mechanical ventilation with stable STEMI patients.

Inclusion Criteria for unstable group:

• acute STEMI
• mechanical ventilation
• the need for catecholamine support.

Inclusion Criteria for stable group:

• acute myocardial infarction

Exclusion Criteria for any:

• previous treatment with clopidogrel
• clopidogrel administration during transport by ambulance
• known intolerance to clopidogrel
• history of thrombocytopenia (<150,000 platelets/ml)
• pre-existing liver disease

Population of 40 consecutive patients is planned, all of them with acute myocardial infarction with ST-segment elevation.