Capillary Index Score in the Interventional Management of Stroke Trials I and II

Background and Purpose-The Capillary Index Score (CIS) is a simple angiography-based scale for assessing viable tissue in the ischemic territory. We retrospectively applied it to Interventional Management of Stroke (IMS) trials I and II to evaluate the predictive value for good outcomes. Methods-CIS was calculated from pretreatment diagnostic cerebral angiograms blinded to outcome. IMS I and II diagnostic cerebral angiogram images of sufficient quality were reviewed and CIS calculated for treated subjects with internal carotid artery or M1 occlusion. CIS scoring (0-3) was dichotomized into favorable (f CIS; 2 or 3) and poor (p CIS; 0 or 1). Modified thrombolysis in cerebral infarction score 2b or 3 was considered good revascularization. CIS and modified thrombolysis in cerebral infarction scores were compared with good outcome, defined as modified Rankin Scale score <= 2 at 90 days. Results-Twenty-eight of 161 subjects met the inclusion criteria. Thirteen (46%) had f CIS. Good clinical outcome was significantly different between the 2 CIS groups (62% for f CIS versus 7% for p CIS; P=0.004). Good reperfusion correlated to good outcome (P=0.04). No significant differences in time to intravenous or intra-arterial treatment were identified between f CIS and p CIS groups (P>0.25). Conclusions-A f CIS was found in approximate to 50% of subjects and was a virtual prerequisite for good outcome in this study subgroup of IMS I and II. We call this the 50% barrier.