SummaryIt was the aim of this study to compare the efficacy of early platelet inhibition by 600 mg clopidogrel and acetylsalicylic acid (ASA) to a triple therapy including a glycoprotein IIb-IIIa receptor blocker. Immediate percutaneous coronary intervention (PCI) is recommended for high-risk acute coronary syndromes. In this setting the efficacy of platelet inhibition is unknown. One hundred patients were randomized to receive ASA and 600 mg clopidogrel, or additional open-label tirofiban (bolus of 10 µg/kg body weight followed by continued infusion of 0.15 µg/kg body weight per minute) as soon as non-ST - segment elevation myocardial infarction was diagnosed. The primary endpoint was the reduction of infarct size determined by post-interventional increases of cardiac troponin T (cTnT). Secondary endpoints included platelet function measured by optical and impedance aggregometry using ADP (5 and 20 µM) and collagen (1 µg/ml) as platelet agonists. Tirofiban maximized platelet inhibition (p<0.0001) immediately and was associated with significantly lower post-interventional cTnT concentrations (p=0.0352). In the dual platelet inhibition arm, clopidogrel was not effective in 69% of patients at the time of coronary intervention, and still in 47%, if pre-treatment time was >120 minutes. The frequency of cardiovascular (death, myocardial infarction, revascularization) and bleeding events was comparable. Platelet aggregation is not adequately inhibited in cTnT - positive patients in the setting of immediate PCI with very short pre-treatment times. Only tirofiban provided consistent and effective inhibition of platelet aggregation at the time of immediate or very early invasive therapy.
Clinical outcome following percutaneous coronary intervention in patients with acute coronary syndromes and optimal platelet inhibition: results from a prospective registry of 864 patients