Absence of Microemboli on Transcranial Doppler Identifies Low-Risk Patients With Asymptomatic Carotid Stenosis

Stroke Prevention & Atherosclerosis Research Centre, Robarts Research Institute, University of Western Ontario, London, Canada.
Stroke (Impact Factor: 5.72). 12/2005; 36(11):2373-8. DOI: 10.1161/01.STR.0000185922.49809.46
Source: PubMed


Carotid endarterectomy clearly benefits patients with symptomatic severe stenosis (SCS), but the risk of stroke is so low for asymptomatic patients (ACS) that the number needed to treat is very high. We studied transcranial Doppler (TCD) embolus detection as a method for identifying patients at higher risk who would have a lower number needed to treat.
Patients with carotid stenosis of > or =60% by Doppler ultrasound who had never been symptomatic (81%) or had been asymptomatic for at least 18 months (19%) were studied with TCD embolus detection for up to 1 hour on 2 occasions a week apart; patients were followed for 2 years.
319 patients were studied, age (standard deviation) 69.68 (9.12) years; 32 (10%) had microemboli at baseline (TCD+). Events were more likely to occur in the first year. Patients with microemboli were much more likely to have microemboli 1 year later (34.4 versus 1.4%; P<0.0001) and were more likely to have a stroke during the first year of follow-up (15.6%, 95% CI, 4.1 to 79; versus 1%, 95% CI, 1.01 to 1.36; P<0.0001).
Our findings indicate that TCD- ACS will not benefit from endarterectomy or stenting unless it can be done with a risk <1%; TCD+ may benefit as much as SCS if their surgical risk is not higher. These findings suggest that ACS should be managed medically with delay of surgery or stenting until the occurrence of symptoms or emboli.

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Available from: J. David Spence
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    • "Alexandrov et al are researching TCD ultrasound enhanced tPA induced thrombosis for patients suffering from ischemic strokes [18] [19] [20] [21] [22] [23] [24] [25]. Evans et al are investigating TCD monitoring of emboli that could cause ischemic stroke [26] [27] [28] [29] [30] [31]. "
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    ABSTRACT: Transcranial Ultrasound (TCD) is a neurosonological procedure to examine intracranial brain supplying arteries, by visualizing cerebral blood flow patterns. In patients suffering from severe blood flow disruption to the brain neurological pathology conditions such as stenosis, occlusions and vasospasm can be identified with TCD. Ischemic and hemorrhagic strokes require regular TCD monitoring. However, the TCD procedure is largely dependent on the operator's skills and experiences. Finding a suitable site on the temporal plane (an acoustic window) for transcranial insonoification can be challenging in patients with poor or no acoustic windows. In such cases, diagnosis and prognosis may be problematic. Approximately, 10-20% of patients have poor or no acoustic windows. Therefore, early detection of acoustic windows for transcranial sonograph is desirable. This paper examines ultrasound signals in-vitro bovine's biological transcranial media to early detect acoustic windows. The results suggest that transcranial acoustic windows can be detected with an ultrasound signal. Ultrasound attenuation-velocity and B-Mode Ultrasound detection contrast the temporal bone and the surrounding soft-tissue, suggesting that acoustic windows can be detected.
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    ABSTRACT: We showed in 2002 that patients in the top quartile of carotid plaque area had 3.4-fold higher risk of stroke, death or myocardial infarction, compared to those in the lowest quartile, after adjusting for age, sex, cholesterol, blood pressure, diabetes, homocysteine or treatment of lipids or blood pressure. During the first year of follow-up, those with plaque progression (50% of the patients) had twice the risk of these events, after adjustment for the same risk factors(11). We therefore changed the paradigm for treatment in our clinics, from treating risk factors to treating arteries: patients with plaque progression are treated more intensively regardless of the levels of their risk factors such as LDL(12;13). The proportion of patients with microemboli has been reduced by more intensive medical therapy from 12.6% before 2003 to 3.7% since 2003; this means that less than 5% of ACS patients could possibly benefit from revascularization. Figure 1. Decline of microemboli since introduction of more intensive medical therapy Microemboli have declined from 12.6% of patients with asymptomatic carotid stenosis to 3.7% (p
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