High on-treatment platelet reactivity – definition and measurement

Abstract

SummaryIn the last decade, several studies revealed inter-patient response variability to antiplatelet agents: patients who display negligible or no responses to these drugs are considered poor responders, or “resistant” to treatment. In order to identify poor responders to an antiplatelet drug, laboratory tests of platelet function that specifically explore the platelet activation pathway that is targeted by the drug should be utilised. In addition, they should be performed both at baseline and during treatment: however, most studies explored platelet function during antiplatelet treatment, in order to identify those patients with “high on-treatment platelet reactivity” (HPR), which exposes them to increased risk of major adverse cardiovascular events (MACE). Many tests of platelet function have been used, most of which are able to identify patients at risk of MACE. Unfortunately, universal cut-off values for HPR have not been clearly established yet. In addition, the concordance among different tests in the identification of patients at risk is very poor and the most effective and safe treatment for patients at risk is still unknown.

MMP-2, MMP-9, and TIMP-4 and Response to Aspirin in Diabetic and Nondiabetic Patients with Stable Coronary Artery Disease: A Pilot Study

“…Data showed that plasma concentrations of MMP-2, MMP-9, and TIMP-4 were similar both in HPR patients and their counterparts (Figure 1). Since concordance among different tests in the identification of patients with HPR is limited [35], we have compared the concentrations of matrix metalloproteinases and their inhibitor in HPR patients classified by different methods. Despite testing different criteria for aspirin-HPR (cut off point >15%, >20%, >30 AU, >3.1 ng/ml, and >5.8 ng/ml, as appropriate), we did not show a significant difference in MMP-2, MMP-9, and TIMP-4 concentrations in plasma of aspirin responding and aspirin-HPR patients (Table 2).…”

Genetic Determined Low Response to Thienopyridines is Associated with Higher Systemic Inflammation in Smokers

“…Multiple methods (e.g., VASP, impedance aggregometry, light transmission aggregometry, PFA-100 ® system, flow cytometry, etc.) are used to measure the level of platelet reactivity during antiplatelet treatment [17]. Accordingly, several criteria have been proposed by expert working groups to define high on-treatment platelet reactivity in the setting of PCI.…”

Aspirin Resistance in Neurovascular Diseases

“…Methods for the determination of antiplatelet therapy efficacy currently have low specificities and sensitivities (7,15). The issue of resistance to antiplatelet therapy has raised many questions in the area of neurovascular diseases (26)(27)(28).…”