CT/CT Angiography and MRI Findings Predict Recurrent
Stroke After Transient Ischemic Attack and Minor Stroke
Results of the Prospective CATCH Study
Shelagh B. Coutts, MD; Jayesh Modi, MD; Shiel K. Patel, BSc; Andrew M. Demchuk, MD;
Mayank Goyal, MD; Michael D. Hill, MD; for the Calgary Stroke Program
Downloaded from http://stroke.ahajournals.org/ by guest on September 29, 2016
Background and Purpose—Transient ischemic attack and minor stroke portend a substantial risk of recurrent stroke. MRI
can identify patients at high risk for a recurrent stroke. However, MRI is not commonly available as an emergency. If
similarly clinically predictive, a CT/CT angiographic (CTA) imaging strategy would be more widely applicable.
Methods—Five hundred ten patients with consecutive transient ischemic attack and minor stroke underwent CT/CTA and
subsequent MRI. We assessed the risk of recurrent stroke within 90 days using standard clinical variables and predefined
abnormalities on the CT/CTA (acute ischemia on CT and/or intracranial or extracranial occlusion or stenosis ⱖ50%) and
MRI (diffusion-weighted imaging-positive).
Results—There were 36 recurrent strokes (7.1%; 95% CI, 5.0 –9.6). Median time to the event was 1 day (interquartile
range, 7.5). Median time from onset to CTA was 5.5 hours (interquartile range, 6.4 hours) and to MRI was 17.5 hours
(interquartile range, 12 hours). Symptoms ongoing at first assessment (hazard ratio, 2.2; 95% CI, 1.02– 4.9), CT/CTA
abnormalities (hazard ratio, 4.0; 95% CI, 2.0 – 8.5), and diffusion-weighted imaging positivity (hazard ratio, 2.2; 95%
CI, 1.05– 4.7) predicted recurrent stroke. In the multivariable analysis, only CT/CTA abnormalities predicted recurrent
stroke. In a secondary analysis, CT/CTA and MRI were not significantly different in their discriminative value in
predicting recurrent stroke (0.67; (95% CI, 0.59 – 0.76 versus 0.59; 95% CI, 0.52– 0.67; P⫽0.09).
Conclusions—Early assessment of the intracranial and extracranial vasculature using CT/CTA predicts recurrent stroke
and clinical outcome in patients with transient ischemic attack and minor stroke. In many institutions, CTA is more
readily available than MRI and physicians should access whichever technique is more quickly available at their
institution. (Stroke. 2012;43:1013-1017.)
Key Words: CT angiography 䡲 minor stroke 䡲 MRI 䡲 recurrent stroke 䡲 transient ischemic attack
T
here are approximately half a million patients who
present with transient or mild focal neurological symptoms every year in North America alone. Approximately 15%
to 30% of disabling strokes are heralded by nondisabling
transient ischemic attacks (TIAs) or minor strokes, commonly
within the 7 days preceding stroke.1 After a TIA or minor
stroke, there is an estimated 10% risk of recurrent stroke
within 90 days.2 With the majority of these recurrent strokes
occurring within 48 hours of their TIA,2,3 there is a need to
identify the highest risk patients urgently to implement
appropriate early treatments.4,5 Imaging is 1 potential way to
stratify the risk of recurrent stroke.
A substantial proportion of patients with TIA and minor
stroke have ischemic injury observed on diffusion-weighted
imaging (DWI). The presence of an acute DWI lesion or an
intracranial occlusion identifies patients with TIA and minor
stroke at increased risk of recurrent stroke.6 – 8 Furthermore,
almost 50% of patients with TIA with acute DWI lesions
have evidence of an extracranial or intracranial large artery
occlusion or stenosis suggesting that vascular imaging is a
critical factor.9 Finally, we infer that the clinical distinction
between TIA and minor ischemic stroke is largely irrelevant,
particularly when the assessment occurs before 24 hours have
elapsed preventing a clear application of the World Health
Organization clinical definition of TIA.10
Multislice helical CT scanners with CT angiography
(CTA) capability are widely available in many emergency
departments. CTA uses the administration of intravenous
contrast media to assess the intracranial and extracranial
vasculature with high spatial resolution. The addition of CTA
adds ⬍5 minutes to a standard CT of the brain and can be
safely completed in most patients.11 It has been demonstrated
Received August 26, 2011; final revision received November 21, 2011; accepted November 30, 2011.
From the Departments of Clinical Neurosciences (S.B.C., S.K.P., A.M.D., M.G., M.D.H.), Radiology (S.B.C., J.M., A.M.D., M.G., M.D.H.),
Community Health Sciences (M.D.H.), and Medicine (M.D.H.), and the Hotchkiss Brain Institute (S.B.C., A.M.D., M.G., M.D.H.), University of Calgary,
Calgary, Alberta, Canada.
Correspondence to Shelagh B. Coutts, MD, Foothills Hospital, C1261, 1403 29th Street NW, Calgary, Alberta, T2N 2T9, Canada. E-mail
scoutts@ucalgary.ca
© 2012 American Heart Association, Inc.
Stroke is available at http://stroke.ahajournals.org
DOI: 10.1161/STROKEAHA.111.637421
1013
1014
Stroke
April 2012
that an intracranial arterial occlusion identified by CTA is an
independent predictor of poor outcome in patients with acute
stroke and TIA.12,13 Furthermore, large artery disease is
readily identifiable on CTA and is the stroke mechanism with
the highest risk of early stroke recurrence.14,15
We hypothesized that with the fast assessment of the
intracranial and extracranial vasculature, CTA could predict
recurrent stroke in patients with TIA and minor stroke. We
secondarily sought to compare prediction of recurrent stroke
with CT/CTA compared with acute DWI.
Table 1. Baseline Characteristics Stratified by
CT/CTA-Positive Metric (Acute Ischemia on CT, Extracranial or
Intracranial CTA Occlusion, or Stenosis >50%)
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CT/CTAPositive,
% (no./No.)
CT/CTANegative,
% (no./No.)
P
Age ⱖ60 y
76 (133/174)
66 (221/336)
0.015
Female sex
39 (68/174)
42 (140/336)
0.63
Diabetes mellitus
15 (26/174)
15 (51/336)
1
Hypertension
58 (101/174)
55 (184/336)
0.51
Methods
Current smoker
17 (30/174)
15 (49/336)
0.44
Consecutive patients aged at least 18 years presenting with a
high-risk TIA focal weakness or speech disturbance lasting ⱖ5
minutes) or minor ischemic stroke (National Institute of Health
Stroke Scale score ⱕ3) who were referred to the stroke team at
Foothills Medical Centre were prospectively considered for enrollment. Patients were examined by a stroke neurologist and had a CT
brain and CTA of the circle of Willis and neck within 24 hours of
symptom onset. Most patients had a stroke MRI completed. Exclusion criteria included premorbid modified Rankin Scale ⱖ2, acute
treatment with a thrombolytic drug, or a serious comorbid illness that
would likely result in death within 3 months. The local institutional
ethics committee approved this protocol and patients provided
written informed consent. Detailed baseline clinical and outcome
information was prospectively collected for each patient.
Atrial fibrillation
6 (11/174)
7 (25/326)
0.72
Ongoing symptoms at first
assessment
70 (121/174)
57 (192/336)
0.007
Systolic blood pressure ⱖ140 or
diastolic ⱖ90 mm Hg
72 (126/174)
75 (250/336)
0.67
Glucose ⬎8 mmol/L
18 (31/172)
14 (46/332)
0.24
Aspirin treatment*
87 (151/173)
84 (283/335)
0.28
Clopidogrel treatment*
46 (80/173)
27 (91/335)
⬍0.0001
Combined aspirin and clopidogrel
treatment*
42 (72/173)
23 (78/334)
⬍0.0001
Statin treatment*†
73 (125/172)
53 (177/334)
⬍0.0001
Baseline Imaging and Interpretation
All CT imaging was performed on a Siemens 64-slice scanner.
Standard whole brain axial CT was performed with a sequential
(nonhelical) technique at 5-mm slice thickness. CT was immediately
followed by CTA from the aortic arch to skull vertex with a helical
scan technique at 0.6 mm thickness using 75 to 100 mL contrast
bolus injected into the antecubital vein at 3 to 5 mL/s. CTA source
images were reformatted into thin 3-mm sagittal, coronal, and axial
images and thick 24-mm axial maximum intensity projection slabs
for the intracranial circulation and 3-mm oblique sagittal section
through the carotid bifurcations. MRIs were completed on either a
GE 3-T scanner or a Siemens 1.5-T MR scanner. All imaging was
assessed by a neuroradiologist who remained blinded to the results of
the other imaging modality and was given information regarding the
clinical symptoms only. CT was assessed for the presence of any
acute ischemia.16 CTAs were assessed for the presence of any
symptomatic intracranial or extracranial occlusion or stenosis
ⱖ50%. The severity of extracranial stenosis was calculated using the
standard North American Symptomatic Carotid Endarterectomy
Trial (NASCET) method applied to reformatted axial CTA images.17
Intracranial stenosis was measured in a similar manner and vessels
were fully assessed as distal as was technically possible. A priori we
chose the following CT/CTA parameters to define a high risk
phenotype of CT/CTA (CT/CTA-positive metric): acute ischemic
change seen on CT or intracranial or extracranial vessel occlusion or
stenosis ⱖ50% ipsilateral to the clinically relevant ischemic brain
tissue.18 MRI was assessed for acute or hyperacute lesions on DWI
(DWI-positive) using axial DWI, apparent diffusion coefficient, and
fluid-activated inversion recovery sequences.7
Patient Outcomes
Patients received routine clinical care including antihypertensive and
lipid-lowering therapy at the discretion of the treating physician.
Patients whose symptoms resolved within 24 hours of onset were
classified as TIA; those with symptoms persisting ⬎24 hours, even
if minor, were classified as ischemic stroke.10 At the time of the
90-day follow-up, the treating physician rated the stroke mechanism19 and modified Rankin Scale. Recurrent stroke was defined as
a functional deterioration in neurological status of vascular origin
lasting ⱖ24 hours or a new sudden focal neurological deficit of
vascular origin lasting at least 24 hours (that was not felt to be
Variable
CTA indicates CT angiography.
*All drug treatments refer to whether the patient was either started on the
drug or continued on it (if previously on it) when assessed in the emergency
room for this event.
†Statin treatment refers to use of any statin agent at any dose.
secondary to other nonvascular factors: drugs, fever, infection).2,10,20
A panel of 3 physicians, which included 2 stroke neurologists
(S.B.C. and A.M.D.) and a neuroradiologist (M.G.), reviewed and
adjudicated the imaging and clinical information on any patient with
a recurrent stroke.
Statistical Analysis
Statistical analysis was completed with Stata (Version 11). The
primary outcome was the first recurrent stroke event within 90 days.
The risk of recurrent stroke was assessed using standard clinical
variables and predefined abnormalities on the CT/CTA at risk
metric. For the primary outcome, univariable analysis was conducted
using a simple Cox proportional hazards model. A multivariable Cox
proportional hazard model was developed using predefined variables
that were chosen either from statistically significant results from the
univariable analysis or that have been previously shown to predict
recurrent stroke as part of the ABCD2 score.20 Variables were
removed in a stepwise fashion if not predictive of recurrent stroke.
The proportional hazards assumption was tested and found to be
valid. To allow the direct comparison of CT/CTA and DWI MRI for
the secondary analysis, missing MRI results were imputed using a
multiple imputation based on a previously published meta-analysis
of predictors of DWI positivity. This included motor or speech
symptoms, atrial fibrillation, symptomatic carotid stenosis ⱖ50%,
and symptom duration ⬎60 minutes.21 A logistic regression model
predicting DWI positivity was created. Predicted values from this
equation were generated and the probability threshold corresponding
to the point of maximization of sensitivity and specificity of the
model was chosen to define a DWI-positive or -negative imputation
result. A secondary analysis to compare the accuracy of prediction of
recurrent stroke with CT/CTA and DWI MRI was then completed
using receiver operator characteristic curves.
Results
Over a period of 29 months, 510 patients were enrolled of
whom 491 (96.3%) were admitted to the hospital. Median
Coutts et al
Predicting Stroke After TIA and Minor Stroke
1015
Table 2. The Effect of Various Clinical and Imaging
Parameters on Recurrent Stroke
Variable
Recurrent
Stroke,
% (no./No.)
No Recurrent
Stroke,
% (no./No.)
Hazard Ratio
(95% CI)
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Age ⱖ60 y
81 (29/36)
69 (321/463)
1.8 (0.8 – 4.0)
Female sex
47 (17/36)
41 (189/463)
1.3 (0.7–2.5)
Diabetes mellitus
22 (8/36)
15 (68/463)
1.6 (0.7–3.5)
Hypertension
61 (22/36)
56 (259/463)
1.2 (0.6–2.4)
Current smoker
11 (4/36)
16 (72/463)
0.7 (0.3–2.0)
Atrial fibrillation
0 (0/36)
8 (36/463)
…
Transient ischemic attack or
stroke in the preceding 7 d
8 (3/36)
6 (30/463)
1.3 (0.4–4.0)
Systolic blood pressure
ⱖ140 or diastolic
ⱖ90 mm Hg
78 (28/36)
73 (340/463)
1.2 (0.6–2.7)
Glucose⬎8 mmol/L
17 (6/36)
15 (68/457)
1.1 (0.5–2.7)
Ongoing symptoms at first
assessment
78 (28/36)
60 (279/463)
2.2 (1.02–4.9)
Motor weakness
69 (25/36)
64 (295/463)
1.3 (0.6–2.6)
Speech disturbance without
weakness
22 (8/36)
31 (145/463)
0.64 (0.3–1.4)
Treatment
Aspirin treatment*
95 (34/36)
84 (391/463)
Clopidogrel treatment*
39 (14/36)
33 (152/463)
3.0 (0.7–12.7)
1.3 (0.7–2.5)
Combined aspirin and
clopidogrel treatment*
36 (13/36)
28 (133/463)
1.4 (0.7–2.7)
Statin treatment*†
66 (24/36)
59 (274/463)
1.3 (0.7–2.7)
Acute ischemia on CT
14 (5/36)
12 (56/463)
1.2 (0.5–3.0)
Intracranial occlusion or
stenosis ⱖ50%
56 (20/36)
18 (84/463)
5.1 (2.6–9.9)
Intracranial occlusion
27 (14/36)
6 (38/463)
6.1 (3.1–11.9)
Extracranial carotid occlusion
or stenosis ⱖ50%
19 (7/36)
9 (40/463)
2.4 (1.05–5.5)
CT/CT angiography-positive
metric
67 (24/36)
32 (147/463)
4.0 (2.0–8.0)
Diffusion-weighted
imaging-positive
75 (27/36)
57 (262/463)
2.2 (1.05–4.7)
Imaging findings
All described findings are of the presumed symptomatic vessel. CT/CTApositive metric is a composite of CT/CTA findings including: acute stroke on CT,
intracranial or extracranial vessel occlusion, or ⱖ50% stenosis.
CTA indicates CT angiography.
*All drug treatments refer to whether the patient was either started on the
drug or continued on it (if previously on it) when assessed in the emergency
room for this event.
†Statin treatment refers to use of any statin agent at any dose.
patient age was 69 years (range, 27–99 years). The median
time from symptom onset to CT was 292 minutes (interquartile range, 62 minutes) and the median delay from CT to CTA
was 4 minutes (interquartile range, 6 minutes). Median time
to MRI was 17.5 hours (interquartile range, 12 hours). The
CT/CTA-positive metric was present in 171 patients (34%).
No patient deteriorated before the CT/CTA was completed.
Four hundred twenty (82%) patients had an MRI for their
acute event (before any recurrent event) and 243 of these
were DWI-positive (58%; 95% CI, 53– 63). MRI results
Figure 1. Kaplan-Meier survival free from recurrent stroke stratified by CT/CTA metric. The upper curve represents with a positive CT/CTA metric and the bottom those without. The shaded
area represents 95% confidence limits around the line with red
surrounding the CT/CTA-positive group and blue surrounding
the CT/CTA-negative group. Log-rank test for equality of survivor functions for CT/CTA (P⬍0.0001). CTA indicates CT
angiography.
were imputed for 90 patients. After imputation of missing
MRI results, the rate of DWI positivity was unchanged
(n⫽295[58%]; 53– 62). Table 1 shows the baseline characteristics stratified by CT/CTA-positive metric. Age ⱖ60
years, ongoing symptoms on first assessment, treatment
with dual antiplatelet agents, and treatment with statins for
the presenting event were more frequently present in
patients with the CT/CTA-positive metric.
Eleven patients (2.2%) were lost to follow-up and 5
patients (1%) died during the 90-day follow-up period. In
88% of patients, the follow-up was completed in person; the
remainder was completed by telephone. In 92% of patients,
the final diagnosis was ischemic stroke (237 patients) or TIA
(232 patients). The principal alternate final diagnoses included migraine (n⫽14), somatoform disorder (n⫽7), seizure
(n⫽3), and other (n⫽17). Eighty-five percent of patients
were treated with aspirin for ⬎1 day (and 100% of patients
received at least 1 dose of an antiplatelet agent in the
emergency department), 34% with clopidogrel (including
29% on both aspirin and clopidogrel), and 60% with a statin.
Twenty-nine patients (6%) underwent carotid revascularization with a median time from onset to carotid artery stenting
of 6 days and to carotid endarterectomy of 8 days. There were
no recurrent events as a result of carotid revascularization.
There were 36 primary outcome events (36 of 510 [7.1%];
95% CI, 5.0 –9.6). Of these, 19 (53%) events were considered
progression of the presenting event and 17 distinct recurrent
strokes. Nineteen of 36 (53%) recurrent events resulted in
disability on the modified Rankin Scale (ⱖ2) at the time of
90-day follow-up. Median time to recurrent event was 1 day
(interquartile range, 7.5 days). Table 2 shows that the predictors of recurrent stroke were: ongoing symptoms on first
assessment, intracranial artery occlusion or stenosis ⱖ50%,
intracranial occlusion, extracranial carotid stenosis ⱖ50%,
DWI MRI, and the combined CT/CTA-positive metric. Treatment with aspirin, clopidogrel, aspirin and clopidogrel, or
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Figure 2. Kaplan-Meier survival free from recurrent stroke stratified by DWI-positive MRI. The upper curve represents those
who were DWI-positive and the bottom those who were DWInegative. The shaded area represents 95% confidence limits
around the line with red surrounding the DWI-positive group and
blue surrounding the DWI-negative group. Log-rank test for
equality of survivor functions for DWI MRI (P⫽0.03). DWI indicates diffusion-weighted imaging.
statin was not protective. In only 1 recurrent stroke was the
presence of an acute stroke on CT the only positive component in the CT/CTA-positive metric. In the multivariable
analysis, only the CT/CTA-positive metric remained predictive of recurrent stroke. Analysis including only patients with
a final diagnosis of TIA or ischemic stroke did not result in
substantive change to either of the results. Figures 1 and 2
illustrate the risk of recurrent stroke stratified by CT/CTApositive metric and by DWI MRI. The risk of a new event in
patients with CT/CTA-positive metric was not affected by
stratifying by DWI positivity. The reverse was also true.
There was heterogeneity in the risk of recurrent stroke based
on the final Trial of ORG 10172 in Acute Stroke Treatment
(TOAST) classification derived at 90-day follow-up: large
artery disease, 8 of 71 (11%); cardioembolic, 10 of 91 (11%);
small vessel disease, 9 of 45 (20%); cryptogenic, 8 of 232
(3%); and other, 1 of 19 (5%; P⬍0.001).
Diagnostic accuracy of the CT/CTA-positive metric and
DWI MRI is shown in Table 3. Using receiver operating
characteristic analysis, CT/CTA and MRI were not significantly different in their discriminative value in predicting
recurrent stroke (0.67; 95% CI, 0.59 – 0.76 versus 0.59; 95%
CI, 0.52– 0.67; P⫽0.09 ␹2).
Discussion
Early assessment of the intracranial and extracranial vasculature using CT/CTA predicts recurrent stroke and clinical
outcome in patients with TIA and minor stroke. We found
Table 3.
that the presence of a symptomatic intracranial or extracranial
severe arterial stenosis or occlusion was predictive of recurrent stroke.
Previous work has shown that much of the risk of recurrent
stroke in TIA and minor stroke is front-loaded with the
highest risk period being in the first 48 hours from symptom
onset.2,3 The median time to event in our study was 1 day with
immediate separation of the survival curves followed by a
gradual separation at later time points (Figure 1). Therefore,
assessment of these patients at later time points misses those
at the highest risk.
The ideal screening imaging modality would be quick and
available 24 hours a day, 7 days a week in most emergency
departments. The median time from symptom onset to CTA
was just ⬎5 hours in this study demonstrating that acute
CT/CTA imaging can be done very quickly. We were much
slower in getting access to MRI, which is both a potential
limitation of this work and a reality for many institutions.
This study is unique because of the rigorous early clinical
and imaging subject assessments. One reason for the usefulness of CTA is that intracranial stenoses or occlusions can
occur from both intrinsic atherosclerotic disease and cardioor atheroembolic disease. Because patients with cardioembolic stroke and many with large artery disease have proven
treatments that could be implemented immediately, this has
direct clinical relevance. An important caveat to using CTA
in the immediate care of these patients is that for small vessel
disease, some of these patients are at risk of symptom
progression, which cannot be identified using CTA. Extracranial carotid disease was not a major predictor of recurrent
stroke in this data set. We suspect that this was because of
early definitive treatment.22 The importance of abnormalities
in the intracranial vasculature as shown in this study illustrates the need for more comprehensive imaging of both the
intracranial and the extracranial vessels. Future work should
include assessment of nonstenotic ulcerated plaque or other
plaque characteristics and perfusion imaging as potential
markers of increased risk. At our institution, many CT/CTApositive patients were treated with early dual antiplatelet
therapy (Table 1). A pilot study suggested that this treatment
may be beneficial23 but this remains unproven. Randomized
controlled trials of more aggressive treatments must be
implemented if identification of high-risk patients is to make
any difference in patient outcomes.4,24 We have also started
using a normal CT/CTA to identify patients who can be
investigated as an outpatient rather than being admitted to the
hospital. This approach also needs further investigation.
We included patients very early into their presentation at a
time when distinctions of TIA or minor stroke cannot be
made. Assessment at this early time point makes comparisons
with published experience of cohorts examined later in their
Accuracy of CT/CTA and DWI MRI in Predicting Recurrent Stroke
Sensitivity
Specificity
PPV
NPV
CT/CTA-positive metric
67% (49 – 81, 24/36)
68% (64 –72, 316/463)
14% (9 –20, 24/171)
96% (94 –98, 316/328)
DWI-positive
75% (57–88, 27/36)
43% (39–48, 201/463)
9% (6–13, 27/289)
96% (92–98, 201/210)
Results are shown as percent (95% CI, no./No.).
PPV indicates positive predictive value; NPV, negative predictive value; CTA, CT angiography; DWI, diffusion-weighted imaging.
Coutts et al
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course uncertain.25 Early evaluation identifies an unstable
population in whom new treatments are needed. Waiting for
these patients to stabilize over the next 24 hours misses the
patients at highest risk. The use of motor or speech symptoms
as the enrollment criterion for TIA events reflects our
understanding of the benign nature of isolated transient
sensory events.26 However, these results cannot therefore be
extrapolated to transient sensory events. A number of patients
cannot or refuse to undergo MRI scanning and limiting this
study only to patients who could get an MRI would bias our
sample, hence our emphasis on CT/CTA. Our imputation of
the DWI MRI result for a number of patients is a limitation;
however, our use of imputation did not substantially change
the conclusion, only the precision of the point estimate.
Using CT/CTA to assess patients with TIA and minor
stroke is a practical solution to assessment of these patients
and has the potential to benefit many people worldwide.
Adoption of CT/CTA into clinical practice for the assessment
of patients with TIA and minor stroke identifies a high-risk
group suitable for aggressive acute stroke prevention treatment. Randomized controlled trials of treatment options in
these high-risk patients with minor stroke and TIA are
urgently needed.
Sources of Funding
Supported by the Canadian Institute of Health Research (CIHR) and
a Pfizer Cardiovascular research award.
Disclosures
Dr Coutts received salary support from the Alberta-Innovates-Health
solutions and the Heart and Stroke Foundation of Canada’s Distinguished Clinician Scientist award supported in partnership with the
Canadian Institute of Health Research (CIHR), Institute of Circulatory and Respiratory Health and AstraZeneca Canada Inc. Dr Hill
receives salary support from Alberta Innovates-Health Solutions and
by the Heart & Stroke Foundation of Alberta/NWT/NU. Dr Demchuk receives salary support from Alberta Innovates-Health
Solutions.
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CT/CT Angiography and MRI Findings Predict Recurrent Stroke After Transient
Ischemic Attack and Minor Stroke: Results of the Prospective CATCH Study
Shelagh B. Coutts, Jayesh Modi, Shiel K. Patel, Andrew M. Demchuk, Mayank Goyal and
Michael D. Hill
Downloaded from http://stroke.ahajournals.org/ by guest on September 29, 2016
Stroke. 2012;43:1013-1017; originally published online February 1, 2012;
doi: 10.1161/STROKEAHA.111.637421
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22
Stroke 日本語版 Vol. 7, No. 2
Abstract
CT/CT 血管造影および MRI の結果は一過性脳虚血発作お
よび軽症脳卒中後の脳卒中再発を予測する
— 前向き CATCH 試験の結果
CT/CT Angiography and MRI Findings Predict Recurrent Stroke After Transient Ischemic
Attack and Minor Stroke ― Results of the Prospective CATCH Study
Shelagh B. Coutts, MD1,2,5; Jayesh Modi, MD2; Shiel K. Patel, BSc1; Andrew M. Demchuk, MD1,2,5; Mayank
Goyal, MD1,2,5; Michael D. Hill, MD1,2,3,4,5; for the Calgary Stroke Program
1 Departments of Clinical Neurosciences, 2 Radiology, 3 Community Health Sciences, 4 Medicine, and 5 the Hotchkiss Brain Institute, Universitu of
Calgary, Calgary, Alberta, Canada
背景および目的：一過性脳虚血発作および軽症脳卒中は，
脳卒中を再発するリスクがかなり高いことを予測する。
MRI によって脳卒中再発の高リスク患者の特定が可能で
ある。しかし MRI は通常，緊急では利用できない。同様
に臨床的予測が可能であれば，CT/CT 血管撮影（ CTA ）
は
より広く適用可能である。
方法：一過性脳虚血発作および軽症脳卒中を発症した連続
510 例の患者に CT/CTA を，次いで MRI を実施した。標
準的な臨床変数および予め定義された CT/CTA 上（ CT 上
の急性虚血および / または頭蓋内もしくは頭蓋外の閉塞ま
たは≧ 50％の狭窄 ）および MRI 上（拡散強調画像陽性 ）の
異常を用いて，90 日以内に脳卒中を再発するリスクを評
価した。
結果：36 件の脳卒中が再発した（ 7.1％，95％ CI：5.0 ～
9.6 ）。イベントまでの期間の中央値は 1 日（ 四分位範囲：
7.5 ）であった。発症から CTA までの時間の中央値は 5.5
時間（ 四分位範囲：6.4 時間 ）
，MRI までの時間の中央値は
17.5 時間（ 四分位範囲：12 時間 ）であった。初回評価時に
進行中の症状（ ハザード比＝ 2.2，95％ CI：1.02 ～ 4.9 ），
CT/CTA 上の異常
（ ハザード比＝ 4.0，95％ CI：2.0 ～ 8.5）
および拡散強調画像陽性
（ ハザード比＝ 2.2，95％ CI：1.05
～ 4.7 ）は，脳卒中の再発を予測した。多変量解析では，
CT/CTA 異常のみが脳卒中再発を予測した。副次解析で
は，CT/CTA および MRI の脳卒中再発予測に対する識別
能に，有意差は認められなかった（ 0.67，95％ CI：0.59 ～
0.76 対 0.59，95％ CI：0.52 ～ 0.67，p ＝ 0.09）。
結論：一過性脳虚血発作および軽度脳卒中の患者におい
て，CT/CTA を用いた頭蓋内および頭蓋外血管系の早期
評価は，脳卒中の再発と臨床的転帰を予測する。多くの施
設で，CTA は MRI よりも利用しやすい。医師は各自の施
設で，速やかに利用可能ないずれかの検査技術を利用すべ
きである。
Stroke 2012; 43: 1013-1017
TIA/軽症脳卒中後の脳卒中再発までの期間
TIA/軽症脳卒中後の脳卒中再発までの期間
CT/CTAで層別化
.3
.2
0
.1
脳卒中再発の割合
.2
.1
0
脳卒中再発の割合
.3
DWI MRIで層別化
0
リスク症例数
CT/CTA 陰性 328
CT/CTA 陽性 171
30
314
152
60
発症後の期間（日）
305
146
90
155
66
CT/CTA 評価基準によって層別化した，脳卒中無再発期間
の Kaplan-Meier 生存曲線。上側の曲線は CT/CTA 評価
基準陽性を，下側の曲線は CT/CTA 評価基準陰性を示す。
図 1 網掛け部分は，曲線周囲の 95％信頼区間を示す。赤色の
囲みは CT/CTA 陽性群，青色の囲みは CT/CTA 陰性群で
ある。CT/CTA に関する生存関数の同等性のログランク検
定（p ＜ 0.0001）。CTA：CT 血管造影。
0
リスク症例数
DWI 陰性 210
DWI 陽性 289
30
199
267
60
90
192
259
96
125
発症後の期間（日）
DWI 陽性 MRI によって層別化した，脳卒中無再発期間の
Kaplan-Meier 生存曲線。上側の曲線は DWI 陽性を，下
側の曲線は DWI 陰性を示す。網掛け部分は，曲線周囲の
図2
95％信頼区間を示す。赤色の囲みは DWI 陽性群，青色の
囲みは DWI 陰性群を示す。DWI MRI に関する生存関数の
同等性のログランク検定（p ＝ 0.03 ）。DWI：拡散強調画像。