Imaging identifies asymptomatic people at risk for stroke

16 September 2014

Identifying the people that are most at risk of stroke can significantly help reduce the long-term health of patients, as well as reducing costs for recovery and care. Imaging has become a financially-viable way to highlight the persons in most danger of having these incidents, but a new study suggests that some could benefit from aggressive intervention.

The study, published in the journal Radiology, examined people with asymptomatic carotid artery stenosis. The condition, which sees the major blood vessels narrow, is the cause of up to 20 per cent of ischemic strokes - those that result from an obstruction within a blood vessel and represent 85 per cent of all incidents.

It is common for stroke victims to have revascularisation procedures, such as carotid endarterectomy or surgical removal of the plaque, to restore blood flow to their brain. However, using these preventive measures for asymptomatic patients is more controversial, according to Dr Ankur Pandya, assistant professor of healthcare policy and research and public health in radiology at Weill Cornell Medical College in New York City.

He said there are complications and costs associated with revascularisation procedures, and they are often carried out without knowing whether the risks and costs are worth the benefit to the patient.

Along with colleagues, Dr Pandya analysed the impact of cerebrovascular reserve (CVR) testing to measure blood flow to the brain on asymptomatic people with significant carotid artery stenosis. Although many different imaging modalities can be used in CVR testing, the team selected transcranial Doppler (TCD) sonography as it is an inexpensive and widely available option, which does not expose patients to ionising radiation.

By constructing a mathematical model, the researchers were able to make hypothetical comparisons from three different approaches: CVR testing, immediate revascularisation with carotid endarterectomy, and medical therapy-based management with subsequent revascularisation for patients whose stenosis got worse.

The CVR-based approach, which led to about half of the patients receiving revascularisation, appeared to be the most favourable option in terms of costs and benefits. The medical therapy-based strategy was associated with the lowest lifetime costs and the fewest revascularisations, but also had the lowest life expectancy and lifetime quality-adjusted years. 

The immediate revascularisation strategy had the highest costs, by a wide margin, and only incremental health benefits compared with the CVR-based approach.

The findings suggest that imaging can be a cost-effective tool to highlight which patients are at risk of stroke and help them choose between invasive, expensive interventions and less invasive options.

Dr Pandya said that CVR testing also has the potential to help characterise whether carotid artery plaque is causing abnormal brain blood flow patterns which may, therefore, identify the patients who are at greatest risk of stroke.

"CVR testing with ultrasound could be used to stratify patients by risk based on abnormal blood flow patterns to the brain, and then other imaging tests like MRI could be employed to look at the composition and stability of plaque, which may give greater insight into those plaques most likely to rupture and cause symptoms" Dr Pandya said.

Posted by Edward Bartel


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