Influence of Residual Stenosis on Clinical Outcome and Restenosis After Middle Cerebral Artery Stenting

Background The purpose of this study was to assess whether the residual stenosis has effect on restenosis after stenting for atherosclerotic stenosis in the middle cerebral artery. Methods Sixty-seven patients underwent 69 single-stent procedures successfully for atherosclerotic stenosis >= 70% in the M1 segment of middle cerebral artery were reviewed retrospectively. All patients were classified into two groups: nonresidual (<= 30%) and residual (>30%) stenosis. The influence of residual stenosis immediately after stent placement on clinical outcomes and restenosis at follow-up was analyzed. Restenosis was defined as >= 20% stenosis on angiographic follow-up imaging after excluding postoperative residual stenosis. Results Between groups, it was no difference in the conventional risk factors of cerebrovascular diseases, characteristics of targeted vessels, and types of stent. The residual stenosis had no influence on any stroke or death, but the ipsilateral stroke had a trend in the residual stenosis group. The incidence of restenosis was higher in patients with residual stenosis >30% (17% vs. 45.5%, P = 0.04), and the increase of percent stenosis was 7.9 +/- 11.7 and 17.1 +/- 15.4, respectively (P = 0.03). The correlation coefficient was r = 0.37 (P < 0.01) between the residual stenosis and the increase of percent stenosis. Univariate and multivariate regression analysis showed that residual stenosis >30% was an independent risk factor for restenosis at follow-up (log-rank, Chi-square = 6.09, P = 0.01). Conclusions Residual stenosis immediately after stenting for atherosclerotic middle cerebral artery stenosis may be a predictor of clinical outcomes and restenosis at follow-up.