Abstract 6186: Relationship Between Hypotension and Distribution of Microemboli on DW-MRI Following Carotid Angioplasty and Stenting
Objective: We have previously demonstrated a significant incidence of microemboli on diffusion weighted-MRI following CAS. The purpose of this study is to characterize the number, location, and 3-dimensional distribution of infarcts.
Methods: Fifty-three patients underwent CAS and were studied with pre- and post-procedure DW-MRI. Based upon the location and distribution of the ischemic lesions, patients were separated into groups by plotting images on a standard MR brain atlas. Clinical and imaging characteristics were compared between groups to determine associations between type of infarcts and patient demographics, anatomic features, and procedural characteristics.
Results: Twenty-nine patients (55%) were noted on post-procedure DW-MRI to have areas of restricted diffusion consistent with microemboli, although only three (5.7%) had transient neurologic changes resolving by 36 hours, and the 30-day stroke/death rate was 0%. Twelve patients (23%) developed hypotension during the procedure noted by a systolic BP drop >30 mmHg requiring intravenous pressor support. DW-MRI lesions localized into distinct patterns defined by the following groups: embolic only (n=14), watershed (n=12), and insular (n=3). Univariate analysis found peri-procedural hypotension to be associated with the watershed over the embolic group (40% vs. 7.1%, p=.04). Bilateral infarcts were significantly more common in the watershed group (75% vs. 21%, p=.02) as were ischemic lesions in proximity to preexisting infarcts (50% vs. 0%, p<.002). Total microemboli load (8.9 vs. 2.9, p=.02) and mean number of contralateral lesions (2.5 vs. 0.21, p=.02) were also greater in the watershed group.
Conclusion: Despite successful clinical outcomes, CAS procedures frequently generate cerebral microembolic events. Peri-procedural hypotension is correlated with a distinct pattern of microemboli within watershed territories after CAS. These infarcts tend to have higher embolic load, occur bilaterally, contralateral to the treatment site, and have more areas of diffusion brightness surrounding pre-existing infarcts. Although the long-term significance of microemboli remains uncertain, avoidance of peri-procedural hypotension may significantly reduce these events.