Platelet reactivity testing in association with perioperative microembolic signals during carotid endarterectomy.

After a first manifestation of cardiovascular disease there is an increased
risk for recurrence at the same or at another location in the vascular bed.
Platelet inhibitors reduce cardiovascular events, but increase bleeding risk.
Recent studies have showed significant platelet reactivity variability between
patients taking platelet inhibitors and high platelet reactivity is associated
with an increased risk of cardiovascular events. Monitoring platelet reactivity
may be beneficial to reduce over and undertreatment and finally reduce
thromboembolic and bleeding complications.
Currently, there is a wide range of tests which claim to measure platelet
reactivity in different ways. Before platelet function tests can be used to
determine the correct dose and type of platelet inhibitors in the vascular
patient, further research is to be done. In the present study we asses platelet
reactivity with thrombocyte P-selectine expression measurement, the VerifyNow
system, and the PFA-100 system.
Nowadays tromboembolic and bleeding complications have a relatively low
incidence and determining an association between the platelet function tests
and complications would require very large studies. Micro embolic signals (MES)
observed with transcranial Doppler (TCD) during carotid endarterectomy servers
as a powerful surrogate marker for direct clinical validation of the platelet
reactivity tests. This study will validate platelet reactivity tests with
direct clinical thromboembolism registration to improve antiplatelet therapy in
patients with atherosclerotic disease.

The primary aim of this study is to determine an association between the
selected thrombocyte function tests and microembolic signals/clinical outcome.
The test with the highest association will be the best strategy of assessing
platelet reactivity in patients undergoing carotid endarterectomy. Furthermore
we aim to identify the most important platelet activators in this setting. Our
results will help selecting the optimal antiplatelet treatment for individual
patients undergoing carotid endartectomy and will aid selecting antiplatelet
therapy in other patients with cardiovascular disease.

Observational cohort study

Patients will be burdened with blood collection (45 ml total in 4 withdrawals)
before and during surgery. Risks associated with blood collection are very
small in the setting of carotid surgery.