Sunday, August 21, 2011

Neurology: Ultrasound markers may predict high stroke risk

A pair of visual ultrasound markers may help physicians better determine which patients with asymptomatic carotid stenosis face a higher stroke risk, and better determine which patients might benefit from carotid endarterectomy (CEA), according to a study published online Aug. 17 in Neurology.

The absolute benefit of CEA is small, which has spurred concerns about the cost effectiveness and utility of the procedure. However, limiting the procedure to patients with asymptomatic carotid stenosis (CS) at higher risk for ipsilateral stroke could yield cost and clinical benefits.

Thus, Raffi Topakian, MD, of the department of neurology at Academic Teaching Hospital Wagner-Jauregg in Linz, Austria, and colleagues devised a study to determine whether a predictive score based ultrasonic plaque morphology assessment and the detection of asymptomatic emboli signals on transcranial Doppler ultrasound might improve prediction of stroke or transient ischemic attack (TIA).

The researchers leveraged data from 435 patients with  asymptomatic CS enrolled in the Asymptomatic Carotid Emboli Study (ACES). Participants were enrolled between July 1999 and August 2007 and had > 70 percent asymptomatic CS. Ultrasound was performed at study entry.

The primary endpoint was stroke or stroke/TIA risk predicted by plaque echolucency at study entry. Secondary endpoints were ipsilateral stroke alone, any stroke or cardiovascular death.

The research team analyzed plaque morphology and graded plaques as echolucent or echogenic, using a five-type classification scale.

Nearly 38 percent of plaques were graded as echolucent, and of the 428 patients with analyzable transcranial Doppler recordings, 17.1 percent had at least one emboli signal detected on either of the two baseline recordings.

During the nearly two-year follow-up, researchers recorded 10 ipsilateral strokes, 20 ipsilateral TIAs and 17 strokes in any territory, with 33 patients suffering any stroke or CV death.

Also, during follow-up, 33 patients underwent CEA and there were 29 deaths.

According to Topakian et al, plaque echolucency was associated with an increased risk of ipsilateral stroke and showed a trend toward association with ipsilateral stroke and TIA and any stroke. Subjects with both echolucency and embolic signal positivity at baseline faced a significant increase in risk for ipsilateral stroke and TIA, ipsilateral stroke and any stroke.

“[Patients] with both conditions present had at least a 10-fold increase in the risk of ipsilateral stroke with an annual risk of about 8.9 percent compared with a 0.8 percent risk in individuals without both risk markers,” wrote Topakian.

The researchers noted that the visual scale is relatively easy to use and could be incorporated into outpatient clinical management of patients with asymptomatic CS, while providing a strong prediction of future risk.

However, one limitation of the study is that physicians may have excluded high risk patients with asymptomatic CS from ACES.

Still, the researchers concluded that the combined markers enable differentiation between low-risk and high-risk patients and may help inform decision-making and selection of appropriate candidates for CEA.

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