Introduction: In up to 25% of patients with an ischemic stroke, the standard investigations fail to identify a cause. Many of these cryptogenic strokes are thromboembolic, but without an established source, so called “embolic strokes of undetermined source” (ESUS). Non-stenotic carotid plaque is a potential source.
Hypothesis: We hypothesized that among patients with ESUS, there is an association between non-stenotic carotid atherosclerotic plaque diagnosed using CT angiography and ipsilateral ischemic stroke.
Methods: From a prospectively maintained stroke registry, we identified consecutive patients between January 2012 and March 2015 with a carotid territory ischemic stroke, who fulfilled the diagnostic criteria for ESUS. Two radiologists, blinded to clinical information, independently measured carotid plaque thickness ipsilateral and contralateral to the ischemic stroke using CT angiography.
Results: Eighty-five of 1038 ischemic stroke patients were included in the analysis. There was no difference in the degree of carotid artery stenosis ipsilateral versus contralateral to ischemic stroke (median 0% versus 0%, p=0.98). There was a weak correlation between degree of carotid artery stenosis and carotid plaque thickness (R2 = 0.26, p<0.001). Plaque thickness ≥ 5 mm (9/85 versus 1/85, p=0.008), ≥ 4 mm (16/85 versus 4/85, p=0.002), and ≥ 3 mm (30/85 versus 13/85, p=0.001) were each more common ipsilateral than contralateral to ischemic stroke. Plaque thickness ≥ 2 mm had the same frequency ipsilateral and contralateral to ischemic stroke.
Conclusions: Our data suggest that large, non-stenotic carotid plaque may be an important source of embolism in patients with ESUS. We evaluated non-stenotic plaque using routine CT angiography, a method that could be easily translated into clinical practice.