The objectives of the proposed project are:
(a) the identification of a subgroup of patients with asymptomatic carotid stenosis at risk of ipsilateral stroke greater than 4% p.a.;
(b) the identification of a subgroup of patients with a risk of ipsilateral stroke less than 1% p.a. and
(c) the identification and standardisation of non-invasive tests or combinations of such tests and appropriate criteria that can achieve (a) and (b).
For the first time there is evidence that carotid endarterectomy in patients with asymptomatic carotid stenosis will reduce the incidence of stroke. However, one may need to operate on at least 20 patients to prevent one stroke in 5 years or 100 patients to prevent one stroke in one year. This means that one is operating unnecessarily on a large number of patients. What is needed is to identify those who are at high risk (>4% stroke incidence p.a.) Even more important is to identify those who are at low risk (>1% p.a.) and spare them from an unnecessary operation which carries an inherent mortality and morbidity risk.
The objectives of the project will be achieved by reinforced concertation. It is proposed that patients with asymptomatic carotid stenosis greater than 50% will be entered into the study from different centres, and a number of non-invasive tests will be performed in order to determine the degree of stenosis, the presence of ulceration, plaque characterisation, presence of silent infarcts on CT-brain scans and cerebral reactivity to hypercapnia. Patients will be followed up for three years with the main endpoint being stroke. Training, quality control and software will be provided by the Co-ordinating Centre.
The contribution of such a study will be the establishment of standardised methodology that can be used eventually not only by the partners taking part, but by centres throughout the European Community. The motivation will be the ability to identify patients at risk of stroke.
The European added value will be that as a result of the identification of high risk and low risk subgroups, only patients at high risk may be considered for carotid endarterectomy while patients at low risk will be spared from such unnecessary and expensive surgery. As a result there will be a more appropriate utilisation of resources with a marked saving of Community funds.