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

Abstract

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 ≈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.

Keywords: collateral circulation; diagnostic imaging; diagnostic techniques, neurological; stroke, acute.

© 2014 American Heart Association, Inc.

Figures

Figure 1

Quantification of the CIS based on an AP cerebral angiogram. A. The site of ischemia was the middle cerebral artery (MCA). The arrow marks the anterior cerebral territory. CIS = 3 for this image. B. CIS = 0 for this image.

Figure 2

Theoretical relationship between good outcomes and time. The 50% barrier is caused by a decline in rCBF so steep that early treatment cannot reverse tissue damage. Group 1: rarely enrolled in studies due to early signs of irreversible ischemia. Group 2: patient population in most IAT-AIS trials. Group 3: patients excluded from most studies due to artificial time window.

Figure 3

Logarithmic time curve: the infarction threshold distinguishing between reversible and irreversible ischemia as a function of rCBF and time from ictus. The vertical lines are an approximation and have not yet been validated.