This calculator estimates the 5-year ipsilateral stroke rate in a recently symptomatic patient with carotid stenosis of 50% or more treated with modern optimised medical therapy (OMT) - the Carotid Artery Risk score (CAR score). The algorithm used to calculate the CAR score is the Carotid Stenosis Risk Prediction Tool (Stroke Prevention Research Unit; University of Oxford),^{1, 2} with recalibration to take account of the effects of modern medical management of carotid stenosis.²

The calculator also assesses whether a patient is suitable for the ECST-2 trial based on their CAR score. ECST-2 (ISRCTN 97744839) is an international randomised trial investigating the optimal treatment of patients with symptomatic or asymptomatic moderate or severe carotid stenosis at low or intermediate risk of future stroke. The trial compares the risks and benefits of treatment by modern OMT alone versus the addition of immediate carotid surgery (or stenting) to OMT. N.B. Asymptomatic stenosis and stenosis that has not caused symptoms for at least 180 days are automatically eligible for ECST-2.

The CAR score calculated must be regarded as provisional until it has been validated by the results of ECST-2, therefore it is primarily intended as an aid to assessing suitability of patients for ECST-2. It is not intended to substitute for the judgement of experienced clinicians considering the wider context of all relevant information available about the individual patient.

Notes for answering the questions in the calculator

Stenosis: this is the stenosis of the symptomatic internal carotid artery as measured by NASCET criteria - values should be between 50 and 99%. Enter a whole number only. If reported by ultrasound as a range of values use the middle of the range, rounding up as necessary e.g. for a report saying stenosis 50-59%, enter the value 55. A red box around the number will mean you have entered an unacceptable value.

Near occlusion: this is present if there is severe stenosis associated with collapse of the carotid artery distal to the stenosis.

Time in days from last event to expected day of randomisation or treatment: If the patient is a possible candidate for ECST-2, estimate the number of days from most recent event to the likely day the patient would be randomised in ECST-2 if suitable. If the patient is not being considered for ECST-2, use the day the patient would receive carotid endarterectomy or stenting to calculate the time from event. If the patient has had more than one event, give the time in days from the most recent event even if it is not the most severe event.

Definition of Events: Major stroke = non-disabling stroke with residual signs present or expected to persist for more than 7 days. Minor stroke = stroke with signs and symptoms lasting or expected to last between 24 hours and 7 days. TIA = symptoms lasting less than 24 hours irrespective of imaging findings. Monocular = amaurosis fugax or retinal infarction.

Plaque ulceration: Only answer yes if there is clear evidence of ulcerated plaque on non-invasive imaging.

MI: history of myocardial infarction

PVD: history of peripheral vascular disease

1. Rothwell PM, Warlow CP on behalf of the European Carotid Surgery Trialists' Collaborative Group. Prediction of benefit from carotid endarterectomy in individual patients: a risk modeling study. Lancet 1999; 353: 2105-10.
2. Rothwell PM. Z Mehta, SC Howard, SA Gutnikov, CP Warlow. From subgroups to individuals: general principles and the example of carotid endartectomy. Lancet 2005; 365; 256-65.

For further information or to report errors, please contact office@ecst.com.

This app was created by Sealed Envelope.

Version 1.1.0