Flow Cytometry Based Platelet Reactivity Testing to Predict the Occurrence of Per-operative Solid Microemboli During Carotid Endarterectomy.

Objective: Peri-operative antiplatelet therapy (APT) aims to prevent thrombotic events such as stroke. High platelet reactivity ,despite the use use of APT, increases the risk of thrombotic events. Transcranial Doppler imaging (TCD) is used to detect peri-operative microembolic signals (MES) during carotid endarterectomy (CEA). Peri-operative MES are associated with an increased risk of procedural stroke and new silent lesions on diffusion weighted magnetic resonance imaging following surgery. The main components of TCD detected MES are platelet aggregates, and therefore patients displaying multiple MES during surgery could have benefited from more stringent APT. This study investigated whether the use of flow cytometry based platelet reactivity measurements were correlated with the incidence of pre-operative MES and thereby in the future suitable to predict patients at increased risk of peri-operative thrombotic events.

Methods: Bilateral TCD with MES detection was performed in 197 patients undergoing CEA. Platelet reactivity was assessed with a flow cytometry based platelet reactivity assay measuring platelet response in whole blood. High on treatment platelet reactivity status was assessed for all patients. The secondary outcome was major adverse cardiovascular events (MACE) within one year.

Results: In total, 197 patients were included, 49 had peri-operative MES. The platelet response to adenosine diphosphate (ADP) correlated with MES (p = .021), and high on treatment platelet reactivity after adenosine diphosphate stimulation was associated with MACE (OR 2.34, 95% confidence interval 1.126 - 4.890, p = .023).

Conclusion: Pre-operative platelet reactivity determined by flow cytometry after ADP stimulation correlated with the occurrence of intra-operative MES and post-operative MACE. Clopidogrel treatment showed the most substantial effect on reducing MES frequency and platelet reactivity measured by flow cytometry.