Coexistence of external carotid artery embolus and internal carotid artery occlusion in acute ischemic stroke: An indicator of cardioembolic etiology?

•The etiology was mostly embolic in patients with ECA embolism.•ECA embolisms may serve as a guide in determining the etiology of stroke.•ECA embolisms in the initial vascular imaging may play an important role in determining the endovascular strategy. This study aims to evaluate whether the presence of an external carotid artery embolism accompanying internal carotid artery occlusion may contribute to identifying the etiology of internal carotid artery occlusion in the early period. The presence of external carotid artery embolism was evaluated in 117 patients who were adjudicated for internal carotid artery occlusion based on digital subtraction angiography images. Embolus in the external carotid artery was detected in 8 (6.8%) of the 117 patients with internal carotid artery occlusion (7 (87.5%) patients were found to have tandem and 1 (12.5%) patient had carotid T occlusion). In all of these patients, the thrombus was of embolic origin. Evaluation of the etiology revealed cardioembolic etiology in 4 patients and dissection in 1 patient, and the cause could not be determined in the remaining 3 patients. Patients with external carotid artery embolism accompanying an internal carotid artery occlusion had significantly higher The National Institutes of Health Stroke Scale scores at admission and significantly lower recanalization success compared to those without external carotid artery embolism (p = 0.009, p = 0.01). In the comparison of prognosis, poorer prognosis was observed in those with external carotid artery embolism, although without a statistically significant difference (p = 0.07). This study observed that the etiology was mostly embolic in patients with external carotid artery embolism accompanying an internal carotid artery occlusion, most of whom were found to have tandem embolic occlusion, and cardiac origin appeared to be the prominent etiology of stroke.