FREQUENCY AND DETERMINANTS OF MICROEMBOLIC SIGNALS ON TRANSCRANIAL DOPPLER IN UNSELECTED PATIENTS WITH ACUTE CAROTID TERRITORY ISCHEMIA - APROSPECTIVE-STUDY

Background and Purpose: Few data exist regarding to the occurrence of microembolic high-intensity transient signals (HITS) on transcranial D oppler ultrasound (TCD) in unselected acute stroke patients. The aim o f this study was to investigate prospectively the frequency and determ inants of HITS in acute carotid territory ischemia. We hypothesized th at carotid artery disease, cardiac abnormalities, and nonlacunar infar cts were independent predictors of HITS in acute stroke. Methods: We i nvestigated 145 consecutive patients with acute internal carotid arter y territory ischemia. The median time interval between stroke and TCD examination was 2 days. TCD monitoring was performed for 30 min on eac h middle cerebral artery. The frequency of HITS was cross-classified w ith carotid artery status, potential cardiac sources of embolism, and nonlacunar infarct subtype. Multivariate logistic regression models de termined the independent relationship of these variables to HITS. Resu lts: Microembolic signals were detected in 35 patients (24.1%), Ipsila teral carotid artery disease was significantly and independently assoc iated with HITS (odds ratio 3.3, 95% confidence interval 1.4-7.8, p = 0.007), whereas potential cardiac sources (OR 1.07, 95% CI 0.48-2.4, p = 0.84) and infarct subtype (OR 0.84, 95% CI 0.29-2.4, p = 0.75) were not. Conclusions: High-intensity transient signals can be found in al most 25% of patients with acute anterior cerebral circulation ischemia and are significantly more prevalent among those with symptomatic car otid artery disease. Future clinical studies are required to determine whether HITS are a marker of increased stroke recurrence and can help to clarify stroke etiology in patients with competing stroke mechanis ms.