Rethinking Stroke Prevention Strategies in Patients with Mild Atherosclerotic Carotid Stenosis

Stroke remains a major cause of death and long-term disability globally, with atherosclerosis-induced narrowing of the carotid artery accounting for approximately 30% of ischemic strokes. Traditionally, clinicians have evaluated stroke risk based on the extent of carotid artery narrowing (stenosis), guiding treatment decisions accordingly. However, recent research suggests that focusing solely on the degree of stenosis may overlook other critical factors influencing stroke risk, particularly in patients with mild but symptomatic carotid disease.

Remarkably, many patients classified as having 'low-risk' carotid stenosis—less than 50% narrowing—still experience recurrent ischemic events despite optimal medical therapy. This observation indicates that additional markers beyond stenosis severity are essential for comprehensive risk assessment.

In response to this gap, researchers from Toyama University, led by Lecturer Daina Kashiwazaki and Dr. Satoshi Kuroda, conducted the "Mild but Unstable Stenosis of Internal Carotid Artery (MUSIC)" study. This multicenter, prospective cohort investigation aimed to identify clinical and radiological features that could better predict stroke risk among this patient group. The study, published in the Journal of Neurosurgery in February 2025, involved 124 patients who had experienced cerebrovascular or retinal ischemic events on the same side as their mild carotid stenosis.

All participants received optimal medical therapy; however, 63 underwent additional surgical intervention, such as carotid endarterectomy or stenting. Patients were monitored over two years, with the primary focus on the occurrence of ipsilateral ischemic stroke.

Findings revealed that about 81% of patients had radiologically unstable plaque, with nearly 60% exhibiting intraplaque hemorrhage (IPH). This plaque feature was strongly linked to increased risks of ischemic events and plaque progression. Notably, patients who underwent surgical intervention experienced a significantly lower rate of stroke (1.7%) compared to those receiving only medical therapy (15.1%).

The presence of IPH and plaque instability emerged as key risk factors, emphasizing that plaque composition may be more important than the traditional measure of stenosis degree. Despite prior use of antithrombotic therapy, many patients still suffered cerebrovascular or ocular events, highlighting potential resistance to conservative management.

This study challenges existing guidelines, which typically do not recommend carotid endarterectomy for patients with symptomatic mild stenosis. The evidence suggests that evaluating plaque characteristics, especially IPH, could become essential in tailoring treatment strategies, possibly favoring surgical options in high-risk cases.

In essence, shifting focus from simply measuring stenosis severity to analyzing plaque composition could significantly enhance stroke prevention efforts. Personalized treatment plans that incorporate plaque features may better identify individuals at high risk for recurrent events and improve clinical outcomes.

This research advocates for a paradigm change in how stroke risk is assessed and managed in patients with mild carotid artery disease, emphasizing the importance of advanced imaging and targeted interventions for high-risk plaques.