Non-Stenotic Carotid Plaques and Rate of DWI-positive MRI in Patients with Lower-Risk Transient or Persistent Minor Neurologic Events: DOUBT Sub Study.

BACKGROUND & PURPOSE: Non-stenotic (< 50%) carotid plaques are increasingly recognized as a potential mechanism for ischemic stroke. We assessed the prevalence of such plaques in patients with low-risk neurologic events and evidence of DWI (Diffusion Weighted Imaging)-positive ischemia.

METHODS

This is a post-hoc exploratory analysis from the DOUBT study, a prospective, observational, multicenter study of patients with low-risk transient or persistent minor focal neurological symptoms. Patients who had baseline CT angiography (CTA) and an MRI within 8 days of their event were included in the study. We aimed to assess the prevalence of non-stenotic carotid disease in patients with versus without DWI-positive events, and in patients with ipsilateral DWI-positive events. A carotid-level analysis with univariable logistic regression analysis was performed to assess whether any of the assessed plaque features were associated with ipsilateral stroke.

RESULTS

Of the 334 patients (mean age 62.7 years, 50.4% females) with available vascular neuroimaging, 153 (45.9%) had non-stenotic carotid plaques (≤50% stenosis), 174 (52.1%) had no stenosis and 7 (2.1%) patients had >50% stenosis. Of those with non-stenotic carotid plaques, 31/153 (20.3%) had evidence of DWI-positive ischemia, approximately half (15/31; 48.4%) of which was in the territory of the carotid plaque. Amongst patients with DWI-positive ischemia, non-stenotic plaques were significantly more common on the side of DWI-positive lesions [31/49 (63.3%) versus 18/49(36.7%)]. Presence of non-stenotic plaque was a risk marker for DWI-positive events (RR 1.4, 95% CI 1.1-1.8, p 0.012). On matched analysis, non-stenotic plaques were more likely on the side of DWI+ ischemia (odds ratio 1.14, 95% CI 0.36-3.70, McNemar's p value 0.80). Plaque features, including hypodensity, irregularity and greater plaque thickness were significantly associated with a higher likelihood of ipsilateral DWI+ ischemia.

CONCLUSION

In patients with low-risk transient or persistent neurologic events, non-stenotic carotid plaques are more common in patients with DWI-positive ischemia. Plaque features like hypodense and irregular plaque were more common with DWI-positive changes in the territory of the affected carotid.