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

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.

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.

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.

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.