Determinants of Micro-embolic Signals in Patients with Atherosclerotic Plaques of the Internal Carotid Artery

Background and purpose: This study aimed to investigate the embolic potential of carotid plaques, employing both the presence and the rate of micro-embolic signals (MESs), based on the presence and timing (current or past) of symptoms, degree of stenosis and ultrasonic characteristics of plaques. Methods: We used the transcranial Doppler (TCD) to monitor MES and the Doppler ultrasound to classify carotid plaques in newly symptomatic (acute stroke or transient ischaemic attack (TIA)), formerly symptomatic (relevant stroke or TIA per anamnesis) and asymptomatic patients with internal carotid artery (ICA) stenosis. Results: Stroke-related arteries evidenced a significantly greater presence of MES than the TIA-related and asymptomatic arteries (p = 0.04), with no significant difference found between the latter two groups (stroke: 42/90, 46.7%; TIA: 15/49, 30.6%; asymptomatic: 40/130, 30.8%). Adjustment for anti-platelet treatment did not change this finding. The degree of stenosis, ultrasonic characteristics of texture and the density of plaques were not found to be associated with the presence or quantity of MES. Conclusion: MESs are present significantly more often in stenosed, stroke-related carotid arteries as compared with TIA-related or asymptomatic arteries. Neither the ultrasonic characteristics nor the degree of stenosis were found to influence the presence or rate of MES.