The Detection of Microembolic Signals in Patients at Risk of Recurrent Cardioembolic Stroke: Possible Therapeutic Relevance

The clinical predictors and potential therapeutic implications of microembolic signals (MES) were investigated in 104 patients with ischemic stroke or transient ischemic attack associated with high-risk (n = 60) or low-risk (n = 44) cardiac emboligenic conditions. Patients with artificial valves and carotid stenosis were excluded. MES counts were based on 30-min bilateral middle cerebral artery transcranial Doppler (TCD) monitoring recordings. MES were detected in 15 subjects (14%). The mean number of MES per hour was 1.9. MES prevalence and counts were influenced neither by age, gender or type of cerebral event, nor by cardiac disease. MES were more frequently detected and greater in number in patients with multiple cerebral ischemic events and in subjects monitored within 1 month of the last event. By multiple logistic regression, TCD recording within 1 month of the last event [Odds ratio (OD) = 13.5; 95% confidence intervals (CI) = 3.3-54.3] and multiple cerebral events (OD = 4.7; 95% CI = 1.3-17.3) were the best MES predictors. MES were detected in 40% (4/10) of patients on heparin, 5% (2/4) of untreated subjects and 13% (5/39) of those on antiplatelet drugs. For patients on warfarin, MES counts and prevalence were similar in subjects with international normalized ratios (INR) below and within/above the therapeutic range. MES were detected in only 2 out of 16 subjects with INR <2 and in 1 with INR >2. MES detection can be potentially relevant to the selection of antithrombotic treatment in acute stroke associated with cardioembolic disease, but further studies are necessary to assess its effectiveness as an additional guide to monitor oral anticoagulant intensity.