Shear-induced platelet aggregation in aspirin-treated patients: initial experience with the novel PlaCor PRT device

Abstract

Introduction: Whole blood platelet function testing is widely used to evaluate the effect of antiplatelet agents. Most platelet function tests employ agonists to evaluate drug-specific platelet-activating pathways. Shear-based tests may better reflect physiological conditions in vivo compared with agonist-based tests. The novel PlaCor PRT provides a global platelet reactivity test based on shear-induced platelet aggregation. We evaluated the PlaCor PRT and its agreement with two widely used platelet function tests.

Materials and methods: We evaluated platelet function in 85 patients with angiographically verified coronary artery disease on aspirin mono-therapy. Blood sampling was performed one hour after aspirin ingestion. The following platelet function tests were used: PlaCor PRT, multiple electrode aggregometry (Multiplate, agonists: arachidonic acid 1.0 mmol/L and collagen 1.0 μg/mL) and VerifyNow Aspirin.

Results: PlaCor PRT results correlated significantly with multiple electrode aggregometry induced by arachidonic acid (r=-0.38, p<0.001), but not with multiple electrode aggregometry induced by collagen (r=-0.05, p=0.64) or with turbidimetric aggregometry performed with VerifyNow Aspirin (r=-0.13, p=0.23). There was a strong correlation between PlaCor PRT results and platelet count (r=-0.60, p<0.0001), whereas no correlation with haematocrit or von Willebrand factor antigen was found. A relatively large number of instrument errors occurred with the PlaCor PRT device in this initial testing.

Conclusions: PlaCor PRT is a portable, rapid and user-friendly point-of-care test. It shows a modest agreement with comparable tests, and results depend considerably on platelet count. Further validation of the PlaCor PRT is warranted.