IMPACT:
Does the absolute magnitude of Platelet Inhibition inversely correlates with the number of TCD-detected microemboli during and after CAS in
asymptomatic patients undergoing carotid artery stenting prior to cardiac surgery who are being pre-treated with either a 300 mg or a 600 mg loading dose of clopidogrel?

As with coronary artery stenting, activation and embolisation of platelets
occurs with carotid artery stenting(CAS). Based on promising data on the use of
clopidogrel plus aspirin in coronary stenting this dual antiplatelet regimen
has been introduced as adjunctive treatment during CAS. There is as yet,
however, no randomized controlled trial which compared different loading doses
of clopidogrel during CAS. Taking into account that a wide interindividual
variability in the response to a loading of clopidogrel exists, this study is
intended to establish the optimal loading dose of clopidogrel. Therefore
platelet function testing and a 1-hour of postprocedural TCD (transcranial
doppler) monitoring will be performed.

Firstly, to investigate whether the absolute magnitude of Platelet Inhibition
inversely correlates with the number of TCD-detected microemboli during and
after CAS in patients who are being pre-treated with either a 300 mg or a 600
mg loading dose of clopidogrel. Secondly, if there is any impact on early
neurological outcome determined by the loading dose of clopidogrel.

This is prospective, double-blinded, randomized, single center study.

All patients will receive a loading dose of 600mg of study medication. The
first group will receive 300 mg of clopidogrel and 300 mg placebo, the second
group will receive 600mg of clopidogrel

For the group of patients receiving a loading dose of 600 mg clopidogrel, one
could assume that bleeding complications are higher than in the group receiving
standard 300 mg clopidogrel however this has not been described in previous
conducted trials examining safety of both loading doses during coronary
intervention. Therefore, it is very likely that the patient is not exposed to a
higher risk when participating in this trial. Venous blood samples, necessary
for measurement of platelet-inhibition will be taken together with standard
blood samples before and after procedure without imposing extra venous puncture