Relationship between microemboli in the internal carotid artery and the occurrence of ischemic stroke after transient ischemic attack.

Microembolic signals (MES) have been reported to be an independent risk factor for stroke and transient ischemic attack (TIA). We examined the relationship between MES in the internal carotid artery and the occurrence of ischemic stroke in patients with TIA. A total of 67 patients who had a TIA were examined with transcranial Doppler ultrasonography to detect microemboli in the internal carotid artery 1, 3, and 7 days after admission, and 3 months after discharge. The relationship between the presence of MES and the subsequent occurrence of ischemic stroke was the primary outcome of interest. 35.8% (24/67) of patients were MES(+). During follow-up, ischemic stroke occurred significantly more frequently in patients who were MES(+) compared with patients who were MES(-) (6/24; 25.0% versus 2/43; 4.7%, p=0.021), as did TIA (11/24; 45.8% versus 4/43; 9.3%). MES(+) status was significantly associated with the occurrence of ischemic stroke after adjusting for age, sex, hypertension, diabetes mellitus, and drug therapy (odds ratio: 8.30; 95% confidence interval: 1.37-50.42; p=0.021). The positive and negative predictive values of MES status for predicting ischemic stroke were 25.0% and 95.4%, respectively. The presence of microemboli in the internal carotid artery appears to be an important risk factor for the occurrence of ischemic stroke after TIA. The MES(+) rate in patients with transient ischemic attack with severe internal carotid artery stenosis is markedly higher than in patients without internal carotid artery stenosis.