Platelet hyperreactivity and stent thrombosis in patients undergoing coronary stenting

Stent thrombosis (ST) is a rare but very serious event complicating percutaneous coronary intervention (PCI) procedures. Both procedure- and patient-related factors, including inadequate platelet inhibition are well known predictors of ST. According to the present guidelines, a dual antiplatelet treatment regimen consisting of aspirin and a P2Y12 receptor inhibitor such as clopidogrel, prasugrel or ticagrelor is routinely administered to ACS patients and to patients undergoing PCI in order to prevent thrombotic vessel occlusions. In recent years, evidence has grown that patients showing high on-treatment platelet reactivity (HPR) under clopidogrel intake exhibit a higher risk for the occurrence of ischemic events including ST. For assessing HPR, different platelet function assays are currently available and have already found their way into routine clinical practice in several centers. Along with this development, more potent P2Y12 receptor inhibitors like prasugrel and ticagrelor are substitutes for clopidogrel in specific circumstances such as in ACS patients or in patients who do not adequately respond to standard clopidogrel treatment. Utilizing platelet function monitoring, patients showing HPR can be identified and an optimized antiplatelet treatment regime can be tailored for these patients. This review paper aims to summarize the important facts in relation to ST and antiplatelet therapy with a particular focus on P2Y12 receptor inhibition and its ex vivo assessment in patients undergoing coronary stent placement.