Left-sided carotid arteries have a higher prevalence of intraplaque hemorrhage than right-sided: An asymmetric conundrum

Purpose: To assess whether an asymmetry exists in the prevalence of carotid artery intraplaque hemorrhage (IPH) between right- and left-sided arteries. Materials and methods: The records of all patients with atherosclerotic carotid artery disease that underwent neck magnetic resonance angiography imaging with high-resolution plaque sequences between 2017 and 2020 at our institution were retrospectively reviewed. The prevalence of stenosis and IPH was determined for all patients and compared between the left and right carotid arteries of those with unilateral anterior circulation ischemic strokes. Multiple regression analysis was performed to determine potential independent associations of IPH laterality with ischemic strokes. Results: A total of 368 patients were included overall and 241 were male (65.4%). There were a total of 125 asymptomatic patients and 211 patients with unilateral anterior circulation ischemic strokes. Of patients with ischemic strokes, 55.5% had left-sided strokes compared with 44.5% who had right-sided strokes (p = 0.03). Patients with left-sided strokes had a higher prevalence of ipsilateral IPH than those with right-sided strokes (64.1% versus 36.2%, p < 0.0001), despite similar degrees of stenosis. Both age (odds ratio (OR): 1.0; 95% confidence interval (CI): 1.0–1.1; p = 0.007) and the presence of left-sided IPH (OR: 3.2; 95% CI: 1.5–6.8; p = 0.003) were independently associated with unilateral ischemic strokes. Conclusions: Left-sided plaques more frequently have IPH and may be more likely to result in ipsilateral ischemic strokes compared with right-sided plaques. The underlying mechanism of asymmetric distribution of IPH between right and left carotids remains unclear.