Parameters of complete blood count do not predict on-treatment platelet reactivity in acute coronary syndrome patients

LetterOver the past ten years, a large body of evidence clearly demonstrated that acute coronary syndrome (ACS) patients with persistent high on-treatment platelet reactivity (HTPR) despite a well conducted treatment with P2Y12 receptor antagonists are at higher risk for adverse cardiovascular events (ACVE) [1].Bothgeneticpolymor-phisms [2] and clinical variables [3] have been associated with HTPR, but all together these factors predict only a slight part of the observed variability in response to clopidogrel and other P2Y12-ADP receptor antagonists. Platelet function testing therefore remains the more accurate way to identify high risk patients with HTPR who may benefit from intensified antiplatelet regimen, even though ran-domized trials investigating the effect of antiplatelet regimen adjusted to the results of platelet function testing failed to demonstrate a clinical benefit yet. Nevertheless, platelet reactivity (PR) testing presents to date some limitations: it lacks of standardization, it requires specialized equipment and substantial blood sample volumes, and it is often costly and technically challenging. Recently, parameters of complete blood count (CBC) which are widely available for routine clinical use, reproducible, inexpensive and non-invasive, have gained an increasing interest in the cardiovascular setting. The mean platelet volume (MPV) was indeed proposed as a marker of platelet activity, since larger platelets are haemostatically more active and thought to display a greater prothrombotic potential than smaller platelets [4]. Scarce studies investigating whether MPV might increase on-treatment PR found conflicting results [5,6,7,8], but meanwhile MPV was shown to predict outcomes in ACS patients in several studies [9].Otherwise, inflammation has been demonstrated to be significantly associated with high PR [10].New inflammatory markers derived from CBC as the platelet-lymphocyte ratio (PLR) and the neutrophil-lymphocyte ratio (NLR) could also potently be associated with PR since they were recently demonstrated to correlate with adverse cardiovascular outcomes in myocardial infarction patients [11], and unstable angina patients [12]. The aim of the present study was to investigate, in a large sample size cohort of ACS patients treated with P2Y12-ADP receptor antagonists, whether any of these CBC parameters could independently predict on-treatment PR assessed with the well established vasodilator stimulated phosphoprotei