Intracranial microembolic signals in 500 patients with potential cardiac or carotid embolic source and in normal controls

Background and Purpose We undertook this study to evaluate the prevalence and clinical correlations of Doppler microembolic signals (MES) in stroke-prone patients. Methods Patients with potential cardiac (n=300) or carotid (n=100) embolic source and control subjects (n=100) were monitored with transcranial Doppler sonography for MES. Transthoracic (n=192) and/or transesophageal (n=134) echocardiography and carotid studies (continuous-wave Doppler, n=181; color-coded duplex, n=47) were performed in all patients with potential native cardioembolic source. Carotid disease was evaluated by means of continuous-wave Doppler (n=87), color-coded duplex (n=70), or intra-arterial angiography (n=24) in patients with potential carotid embolic source. Results Overall MES prevalence was 23% in patients with potential native cardioembolic source (infective endocarditis [n=7] 43%, left ventricular aneurysm [n=38] 34%, intracardiac thrombus [n=23] 26%, dilative cardiomyopathy [n=39] 26%, nonvalvular atrial fibrillation [n=24] 21%, valvular disease [n=80] 15%), 55% in patients with prosthetic cardiac valves (mechanical [n=77] 58%, porcine [n=7] 43%, homografts [n=5] 20%), 28% in patients with carotid disease (symptomatic [n=46] 52%, asymptomatic [n=54] 7%; P<.01), and 5% in control subjects. No relationship between MES counts and patients' age, sex, or actual medication was noted. The sensitivity and specificity of MES detection in identifying patients with potential embolic sources were 31% and 95%, respectively. Conclusions Our study confirmed the reported clinical significance of MES in patients with carotid disease and the high specificity of this technique. The demonstrated low sensitivity of MES detection could be due to short monitoring duration or application of antihemostatic treatment. Prospective large-scale studies are needed to determine the definitive value of MES detection as a diagnostic method in patients with potential cardioembolic source.