Carotid
Stenosis
(and dissection)
Contents
Carotid
Stenosis (and dissection)
Clinical
manifestations
- Bruit
- Absent in
~30% of patients with known high grade stenosis
- 32% of
patients with bruit have normal carotids
- 35% of
patients have a clinically significant stenosis
(i.e. 70-99%)
- However
there is a correlation with carotid stenosis
Symptoms referrable to carotid disease
- Occular ischaemia
- Amaurosis fugax
- Cerebral ischaemia
- Anterior
circulation
- Syncope
- Rare, would
usually require severe bilateral disease
Diagnosis
- Carotid
duplex USS
- Not good at
differentiating >90% from occlusion
- Looses
sensitivity and specificity at 70-99% stenosis
- Can be
affected by calcification
- MRA
- Tends to
overestimate stenosis
- CTA
- Contrast
problems renal failure, allergy
- Radiation
·
Angiogram
o
Invasive risk of stroke (probably <1%)
·
Approach
o
One study showed that reliance on USS alone
resulted in inappropriate surgery 28% of the time
o
Combining two methods (USS and MRA) reduced this to
10%
o
If there is disagreement between non-invasive
methods then angiogram should be considered.
- Measurement
method
- There is
difference in what reference to use for defining stenosis
- NASCET
method % = ICA stenosis point width/distal
ICA width
- ECST method
- % = ICA stenosis point width/estimated
carotid bulb width
- Carotid stenosis index % = ICA stenosis
point width/ (1.2 x CCA width)
- NASCET
method has become the standard
Comparison
|
NASCET % |
ECST% |
|
30 |
65 |
|
40 |
70 |
|
50 |
75 |
|
60 |
80 |
|
70 |
85 |
|
80 |
91 |
|
90 |
97 |
Treatment
Medical management
·
Risk factor control advised but no specific
evidence for patients with stenosis
·
Aspirin not of specific proven benefit in patients
without prior stroke and carotid stenosis.
Symptomatic patients
- NASCET trial
(1991)
- Patients
with 70-99% stenosis with non-disabling stroke
within 3 months.
- Immediate
risk of stroke at 30 days (post-surgery was worse with CEA (5.8% vs 3.3%)
- Longer term benefit
of CEA lower risk of any ipsilateral stroke
(9% vs 26%) (RRR 0.65, ARR 17%)
- Lower risk
of major or fatal ipsilateral stroke (2.5% vs 13.1%)
- Moderate/marginal
benefit in 50-69% stenosis
- Older
patients get greater benefit
- ECST (1991)
- Studies a
number of groups
- Mild (0-29%)
stenosis harm with surgery
- For severe stenosis, immediate risk of surgery, however long
term benefits
- Ipsilateral CVA at 3 years 2.8 vs
16.8%
- Combined
results:
|
Stenosis |
|
RRR |
ARR |
NNT |
|
<30% |
Harmful |
|
|
|
|
30-49% |
No-benefit |
|
|
|
|
50-69% |
Benefit (<3/52) |
|
4.6% |
22 |
|
>70% |
Benefit (<3/12) |
|
16% |
6.3 |
|
>90% |
Benefit |
33%* |
|
3 |
|
Occluded |
No benefit |
|
|
|
|
|
|
|
|
|
*Different data set
- Timing
- For 70-99% stenosis benefit was seen out to 12 weeks but fell
significantly with time (ARR 30% down to 8%)
- For 50-69% stenosis benefit only seen if done within 2 weeks
- In
symptomatic patient with severe stenosis risk
of stroke prior to surgery is 0.5%/day
Asymptomatic Patients
- Small benefit
in stenosis 60-99%
- NNT to
prevent one stroke at 3 years in 33
- Benefit is
only seen after at least 2 years.
- ACAS and ACST
trials
- ACST-1
(10-year follow-up) Lancet Sept 2010 showed prolonged benefit
- At 10 years
stroke/death rate 13.4% vs 17.9% (ARR 4.6%, NNT
22)
Stenting vs CEA
·
Currently it is unclear if stenting
is equivalent or better than CEA
·
It is often used in high-risk patients,
however this practice also lacks evidence.
·
Recent re-analysis showed possible equivalence in
patients younger than 70 with increased risk from stenting
in older patients (Lancet Sept 2010)
CAVATAS
- Long term
data (Lancet Neurology October 2009)
- Trend towards
more strokes in endovascular groups however underpowered study
CREST (NEJM May 2010)
·
RCT, 2500 pts, 2.5 yr F/U
·
No difference between groups in primary end points
(Death, CVA etc.)
·
Periprocedural CVA was higher in
stent group (significant) and there was a trend to more AMI in CEA group.
Carotid Dissection
Treatment
- Trial in
Neurology (Neurology 2009 May 26; 72:1810)
- Small trial
comparing aspirin and heparin/warfarin
- Low rate of
recurrent ischaemic events in either group with
increased haemorrhage in anti-coagulation group, thus aspirin recommended.