Download Outcome of Surgical Treatment of 110 Patients With Transient

CAROTID ENDARTERECTOMY/S/av/s/i, Nicholas and Gee
References
1. Eastcott HHG, Pickering GW, Rob C: Reconstruction of internal
carotid artery in a patient with intermittent attacks of hemiplegia.
Lancet 2: 994, 1954
2. Thompson JE, Austin DJ, Patman RD: Carotid endaftercctomy for
cerebrovascular insufficiency: Long-term results in 592 patients
followed up to thirteen years. Ann Surg 172: 663-678, 1970
3. DeWeese JA, Rob CG, Satran R, Norris FH, Lipchik EO, Zehl
DN, Long JM: Surgical treatment for occlusive disease of the
carotid artery. Ann Surg 168: 85-94, 1968
4. Carmichael JD: Carotid surgery in the community hospital. 467
consecutive operations. Arch Surg 115: 937-939, 1980
5. Easton JD, Sherman DG: Stroke and mortality rate in carotid endarterectomy: 228 consecutive operations. Stroke 8: 565-568, 1977
6. Modi JR, Finch WT, Sumner DS: Update of carotid endarterectomy in two community hospitals. Springfield revisited. Stroke 14:
128, 1983
959
7. West H, Burton R, Roon AJ, Malone JM, Goldstone J, Moore WS:
Comparative risk of operation and expectant management for carotid artery disease. Stroke 10: 117-121, 1979
8. Gee W: Carotid physiology with ocular pneumoplethysmography.
Stroke 13: 666-«73, 1982
9. Gee W, Rhodes M, Denstman FJ, Jaeger RM, Tilly DA, Stephens
HW, Morrow RA, Lin FZ: Ocular pneumoplethysmography in
head-injured patients. J Neurosurg 59: 46-50, 1983
10. Sandok BA, Furian AJ, Whisnant JP, Sundt TM: Guidelines for the
management of transient ischemic attacks. Mayo Clin Proc 53:
665-674, 1978
11. Ortega G, Gee W, Kaupp HA, McDonald KM: Postendarterectomy carotid occlusion. Surg 90: 1093-1098, 1981
12. Robertson JT, Auer NJ: Extracranial occlusive disease of the carotid artery. In: JR Yonmans, Neurological Surgery, WB Saunders,
West Washington Square, Philadelphia, Pa., 19105
Downloaded from http://stroke.ahajournals.org/ by guest on June 12, 2017
Outcome of Surgical Treatment of 110 Patients With
Transient Ischemic Attack
ANTTI M U U R O N E N ,
M.D.
SUMMARY Between 1980 and 1982, 227 consecutive patients with transient ischemic attack (TIA) or
ischemic brain infarction (IBI) were evaluated as possible candidates for carotid surgery in the Department
of Neurology, University of Helsinki. One hundred and ten patients (mean age 58, range 41-72 years) were
selected for surgery; 82 of them had had TIA and 28 IBI as the presenting symptom. After a total of 128
operations (84 unilateral and 18 bilateral endarterectomies, and 8 arterial reconstructions), 16 patients
(14.5%) developed neurological deficits. In 7 patients (6.4%), the deficit was severe and 4 of them (3.6%)
died within the first four days after surgery. Ten patients had occlusion of the contralateral internal carotid
artery and/or severe hypertension. Five of them suffered ischemic brain infarction after the operation and
two died. Operation on an occluded internal carotid artery in 7 patients was complicated by hernlparesls in
two patients, one of whom died. Patients with surgical complications more often had severe hypertension
(p < .001), total occlusion of the contralateral internal carotid artery, (n.s.) and severe angiographic
changes (n.s.) compared with patients without complications. During the follow-up the annual rate for IBI
was 3.3% and for acute myocardial infarction (AMI) 4.4%. Vascular death occurred with a frequency of
1.7% per year. The results emphasize that patients with TIA or IBI should be carefully evaluated before
recommending surgical treatment for prevention of threatened stroke. Patients with severe risk factors may
fare better on medical treatment than with surgical intervention.
Stroke Vol, 15, No 6, 1984
CAROTID ENDARTERECTOMY has been widely
used for 30 years in prevention of ischemic stroke in
selected patients. However, the indications for, and
the risks and value of the operation are controversial.
Indications for this procedure, have been generally
agreed to be TIA or minor stroke.1 The surgical technique, morbidity and mortality rate vary considerably
from one institution to another. The perioperative
"stroke-plus-death" rate ranges from 1 to 21%.'-* In
many surgical reports, strict diagnostic criteria have
not been used in selecting patients, so some series have
included many patients with nonfocal symptoms such
as dizziness and patients with asymptomatic bruits.
The value of carotid endarterectomy in the prevention
of stroke is still questioned: there is no definitive study
available which would allow the conclusion that paFrom the Department of Neurology, University of Helsinki, SF00290 Helsinki 29, Finland.
Address correspondence to: Antti Muuronen, M.D., Senior Neurologist, Department of Neurology, University of Helsinki, SF-00290 Helsinki 29, Finland.
Received July 3, 1984; Revision # 1 accepted September 7, 1984.
tients with TIA are benefited from carotid endarterectomy.9 The effectiveness and risks of carotid endarterectomy for patients with symptoms other than TIA are
even less clear. In this prospective study we have analyzed the risks of carotid ehdarterectomy in our hospital to obtain information about the factors determining
outcome in patients with TIA or minor stroke in connection with carotid endarterectomy.
Patients and Methods
This prospective study for evaluating possible candidates for carotid endarterectomy, included all the
patients with TIA (transient ischemic attack) or IBI
(ischemic brain infarction) seen in the Department of
Neurology, University of Helsinki from January 1980
to December 1982. During this period 227 patients
with TIA or IBI were studied, (fig. 1). There was no
control group.
All the patients were evaluated within a month of the
onset of symptoms. The clinical diagnosis of TIA or
IBI was based upon the case history and general phys-
STROKE
960
TIA-meeting 227 patients
Operation 110
patients
No operation 117
patients
128 operations
Neurologic deficit 16 patients
Follow-up 106 survivors
Downloaded from http://stroke.ahajournals.org/ by guest on June 12, 2017
102 patients alive at the end of the
FIGURE 1.
Flow chart of the study.
ical and neurological examination. Criteria for diagnosis were those suggested by the ad hoc Committee
established by the Advisory Council for the National
Institute of Neurological and Communicative Disorders and Stroke.10 Other organic etiological factors
except TIA and IBI were excluded by appropriate
methods such as case history, computed tomography,
brain scan, EEG and CSF examination.
All patients were studied by conventional aorticarch angiography and 4 patients also had selective carotid angiography. The author reviewed the angiographic pictures but, the angiographic data reported in
this paper was taken from the written reports of the
radiologist. In case of disagreement, the x-ray pictures
were reviewed. The angiographic criteria for grading
atherosclerotic lesions in the carotid bifurcation are
shown in table 1.
The decision regarding operative treatment was
made in joint biweekly meetings with the 3rd Department of Surgery and the Department of Radiology.
The patients presented in the TIA meetings by the
neurologist were classified according to the preoperative risk groups developed by Sundt et al." The definition of criteria for different preoperative risk factors
were as follows:
Medical risk factors: The presence of angina pectoris,
TABLE 1 Angiographical Criteria for Grading Atherosclerotic
Changes at the Carotid Bifurcation
Angiographical finding
Grade
No changes
0
Slight irregularities
1
Ulcerative plaques or stenosis less than 25%
2
25-60% stenosis
3
Stenosis more than 60%
4
VOL 15, No 6, NOVEMBER-DECEMBER
1984
or of myocardial infarction of less than 6 months'
duration, congestive heart failure, severe arterial hypertension ( > 160/110 mm Hg), chronic obstructive
pulmonary disease, chronologic age over 70 years, or
severe obesity.
Neurologic risk factors: A progressing neurologic deficit, a deficit of less than 24 hours' duration, frequent
daily TIA, or neurologic deficits secondary to multiple
cerebral infarctions.
Angiographicalfy defined risk factors: Occlusion of the
contralateral ICA (internal carotid artery); stenosis of
the ICA in the region of the siphon; extensive involvement of the vessel to be operated on with extension of
the plaque greater than 3 cm distally in the ICA or 5 cm
proximally in the common carotid artery; bifurcation
of the carotid artery at the level of C-2 in conjunction
with a short, thick neck; and evidence of a soft thrombus extending from an ulcerative lesion.
Patients at great neurologic risk were not considered
suitable for surgery (Sundt's risk groups 4 and 5) and
accordingly were not operated upon.
The patients were examined clinically by the author
1-2 days before surgery to detect new deficits, 5-7
days after the operation, and again one month after
surgery to reveal possible new deficits. When there
was a surgical complication, the examination was performed immediately postoperatively. All patients were
in good condition medically and all were independent
in the activities of daily life (ADL). Only two patients
had a major deficit prior to operation. In three quarters
of the patients, the indication for operation was TIA
(including amaurosis fugax) and, in a quarter, IBI with
a minor deficit together with an appropriate angiographical lesion at the carotid bifurcation.
All the patients were operated on within 2 months
after the initial onset of TIA or IBI but none were
operated on within the first 6 months after AMI (acute
myocardial infarction). Local anesthesia was used during the endarterectomy. All the patients had ASA and/
or dipyridamol postoperatively. At the beginning of
1983 (3-35 months postoperatively), the patients received a questionnaire concerning further TIAs,
strokes, myocardial infarctions, working capacity and
independence in the activities of daily life. In case of
suspected stroke or incomplete information, the patient was contacted by telephone. Complete information was not available in four living patients, but they
were known not to have had major complications during the follow-up. The Chi-square test with Yates correction was used in statistical analyses.
Results
Patients and Preoperative Evaluation
The mean age of the 110 patients selected for
surgery at the time of their initial TIA or IBI, was 57.9
years (range 41 to 72). Four-fifths of the patients were
aged from 50 to 69 years. Patients under 50 and over
70 years represent less than one fifth of the study
population. All the patients had had focal neurological
symptoms. The majority, 69/82 (84%) of the TIA patients had symptoms related to the internal carotid ar-
CAROTID ENDARTERECTOMY IN TIA/Muuronen
TABLE 2 Occurrence of Risk Factors in the HO Patients Operated on
Risk factors
Arterial hypertension
Myocardial infarction
Diabetes mellitus
Severe arterial hypertension (> 160/110)
Smoking
Absence of any of above by history
Patients
62 (56.4%)
22 (20.0%)
15 (13.6%)
7 (6.4%)
56 (50.9%)
15 (13.6%)
Downloaded from http://stroke.ahajournals.org/ by guest on June 12, 2017
tery but 13/82 (16%) had vertebrobasilar symptoms.
The majority of the patients also had other risk factors for cardiovascular accidents, only 15 patients of
110 had no other risk factors than TIA or IBI (table 2).
By angiography 141 (64%) out of the 220 carotid bifurcations of the 110 patients revealed a stenosis of
25% or more (grade 3 and 4) of the vessel diameter,
including 11 total occlusions of the internal carotid
artery. The grade of the pathological changes between
left and right carotid bifurcation did not differ significantly. Other major angiographical findings were subclavian steal in 9 cases and an aneurysm of the common carotid artery in one patient. Three quarters (106/
141) of the patients with grades 3 and 4 changes at the
carotid bifurcation were operated on but only one third
of the patients (14/38) with changes of grades 1 and 2.
Preoperative angiographic assessment caused transient
neurologic deficit in two patients.
The patients were classified into five preoperative
risk groups and only the patients in groups 1 to 3 were
selected for surgery, i.e. none of the patients had
symptomatic occlusion of the internal carotid artery or
preoperative neurologic risk factors such as a progressing neurologic deficit or frequent daily TIA or neurologic deficit secondary to multiple cerebral infarctions.
Three fifths (67/110) of the patients belonged to risk
group 3, one quarter (29/110) to risk group 2 and one
eighth (14/110) to risk group 1 respectively.
Operative Procedures and Postoperative Complications
Unilateral carotid endarterectomy was performed in
56 TIA and 28 IBI patients. Eighteen patients with TIA
were submitted to bilateral carotid endarterectomy.
Reconstruction of the subclavian artery was performed
in 7 patients with TIA. One patient had reconstruction
TABLE 3
Category
of the common carotid artery because of an aneurysm.
Bilateral carotid endarterectomy was carried out in 18
patients, 9 of whom had bilateral TIA, 6 of whom had
persistent TIA after the first operation and 3 because of
asymptomatic contralateral disease detected by angiography. There was no difference in frequency of surgery between the left and right carotid bifurcations for
patients with changes of grade 3 and 4. The majority
(95/120, 79%) of the operated carotid arteries were
symptomatic. Attempts to recanalize a totally occluded carotid artery were made in 7 of 11 occlusions
(67%).
All 13 patients with vertebrobasilar symptoms initially had carotid endarterectomy but none of them
suffered complications in connection with the surgery.
None of the eight patients with arterial reconstruction
(7 subclavian arteries and one common carotid artery)
suffered new deficits.
In total 128 operative procedures were performed in
110 patients. Complications in connection with the
surgery in different preoperative categories are shown
in table 3. Sixteen out of the 110 patients developed a
new neurological deficit in connection with the surgery. The deficit was slight in 9 patients (8%). In 7
patients (6%) the deficit was severe and 4 of them
(3.6%) died within the first four days after surgery. All
four patients who died suffered leftsided IBI in connection with the surgery, and the ipsilateral carotid artery
had been operated on. The cause of death was acute
myocardial infarction in one patient and IBI in three
patients. All the patients who died had had TIA as a
presenting initial symptom. In two of the four patients
who died, the disaster occurred in connection with the
second operation. Both of the two patients had continued to have TIAs after the first operation. Three of the
4 patients who died had severe arterial hypertension
and one of them also had occlusion of the opposite
internal carotid artery. Seven TIA patients had occlusion of the contralateral carotid artery and/or severe
arterial hypertension and this subgroup suffered three
severe strokes and two deaths in connection with the
surgery. All the severe complications following surgery in this study occurred in patients with TIA in risk
group 3.
There were no deaths or severe new deficits in patients with previous IBI. Only two of the 28 patients
with previous IBI initially had new postoperative defi-
Perioperative Complications in theDifferent Risk Groups in the 110 Patients Operated on
Complications
Risk
group
No. of
patients
New deficit
Slight
Severe
%
IBI
Mortality
AMI
%
17
TIA
1
12
2
82 pat
2
25
2
8
3
45
3
22
IBI
1
2
—
28 pat
2
4
3
22
2
110
9
Total
961
9
14.5
3.6
962
STROKE
Downloaded from http://stroke.ahajournals.org/ by guest on June 12, 2017
cits. Only two patients had multiple TIA as the initial
symptom combined with grade 4 angiographic
changes in the ipsilateral carotid bifurcation. Both of
them suffered severe stroke postoperatively. One patient with severe hypertension and occlusion of the
contralateral carotid artery suffered severe hemiplegia
postoperatively.
The attempt to recanalize an occluded internal carotid artery in 7 TIA patients without neurological deficit
was unsuccessful and in one case was complicated by
ipsilateral IBI and in an other with IBI and death. Ten
patients preoperatively had severe arterial hypertension and/or total occlusion of the contralateral internal
carotid artery. In this subgroup five patients (50%)
suffered a new neurological deficit and two of them
(20%) died. Three of the 10 patients had had IBI as the
initial presenting symptom and 7 had had TIA. All the
complications mentioned above occurred in TIA
patients.
Comparing the histories of the patients with complications to those of the patients who did not suffer
perioperative complications there were more patients
with severe arterial hypertension (p < .001) and occlusion of the contralateral carotid artery (n.s.) in the
former group.
The preoperative angiographical studies of the patients with complications more often showed severe
changes and total occlusions (n.s.) than did those of
patients without complications.
All complications occurred in connection with the
surgery. None of the patients had late (up to one
month) postoperative complications. None of the patients went through repeat angiography after surgery
but four of patients with major postoperative complications had computed tomography of the brain to exclude
a brain hemorrhage.
Follow up Morbidity and Mortality
In a follow-up period of mean 1.7 years fifteen patients experienced further TIA (table 4). Ten patients
with TIA as initial symptom continued to have TIA
postoperatively and 5 patients with previous IBI had
TIA postoperatively. Almost all of these patients (12
of 15) belonged to risk group 3. Six patients suffered
IBI (5.7% of the patients at risk) and eight patients
AMI (7.7% of the patients at risk), of which three were
fatal. One patient died of bronchial carcinoma. All the
severe events except two IBI occurred in the group of
VOL 15, No
6, NOVEMBER-DECEMBER
patients with previous TIA. Patients with previous IBI
did well both postoperatively and during the followup; they had no severe surgical complications and suffered only two IBI during the follow-up period. The
annual rates for IBI and AMI were 3.3% and 4.4%,
respectively, during the follow-up period. Deaths from
vascular disease occurred with a frequency of 1.7% per
year.
Out of the 102 patients alive at the end of the followup period 50 patients had a normal working capacity.
The reasons for retirement were age in 15 (29%); vascular diseases in 25 (48%); and other diseases in 12
(23%) patients. Of the survivors 92 (90%) were fully
independent in ADL, 7 (7%) required assistance, and 3
(3%) were completely disabled.
Discussion
The combined surgical morbidity-mortality of
18.1% in the present study is high, compared with
most other series. The best published results include a
stroke morbidity of about 3% and a mortality of 1%
from surgery.12-l8 Sundt gives a complication rate of
7% for his risk group 3 " (i.e. for the group with medical risk factors and accordingly a considerable complication rate), which is, however still clearly better than
the over-all complication rate in the present study. Our
results are comparable with those of Easton and Sherman's study with a combined morbidity-mortality rate
of 21% in two community hospitals. 6
Ignoring the slight complications in our patients the
combined morbidity-mortality rate decreases to 10%
with 6.4% morbidity and 3.6% mortality. The slight
neurological deficits after surgery were only noticed
upon detailed neurological examination. It can be assumed that most of them would have been passed over
in routine clinical examination.
The majority of the complications (14 out of 16)
occurred in patients with TIA as the initial symptom.
Only two patients with previous IBI had slight new
deficits. All the severe deficits (7) occurred in the
patients with previous TIA and all these patients belonged to risk group 3. Furthermore, all 4 patients with
fatal postoperative complications had also had TIA and
belonged to risk group 3. Though others have found a
significant difference in postoperative complication
rates between the TIA and IBI subgroups, surprisingly, in their studies the IBI patients suffered more complications than the TIA patients."- l3
TABLE 4 New Events during Follow-up in 106 Survivors
Category
TIA
78 pat
IBI
28 pat
Total
Risk
group
1
2
3
1
2
3
No. of .
patients
12
25
41
2
4
22
106
TIA
1
2
7
—
—
5
15
Morbidity
IBI
AMI
1
1
1
4
3
2
—
—
—
—
—
2
8
6
1984
%
25
28
31
—
—
32
27.4
IBI
—
—
—
—
—
—
—
Mortality
AMI
Other
—
—
1
—
2
1
—
—
—
—
—
—
3
1
%
—
4
7
—
—
—
3.8
963
CAROTID ENDARTERECTOMY IN JIMMuuronen
Downloaded from http://stroke.ahajournals.org/ by guest on June 12, 2017
The poor results of the present series cannot be
explained by neurological risk factors because we
excluded patients in the high-risk groups such as
neurologically unstable patients or patients with frequent daily TIA or neurological deficit secondary to
multiple cerebral infarctions. Only two patients had
severe hemiparesis preoperatively and all the patients
with previous IBI (28) were operated on after good
recovery.
A special high-risk group seems to be the TIA patients with occlusion of the contralateral carotid artery
and/or severe hypertension. This group of 7 patients is
responsible for 42% (3 of 7) of the new permanent
severe postoperative deficits and 50% (2 of 4) of the
deaths. Hypertension is a known risk factor for any
operation. Occlusion of the contralateral carotid artery
has been reported not to increase the risk of complications in endarterectomy14 but in that series 19 out of 23
patients with occlusion of the contraJateral carotid artery had a history of complete stroke. Our patients in
this special high risk group had all experienced TIA
initially. Only two slight deficits occurred in patients
with previous IBI.
Attempts to recanalize 7 occluded internal carotid
arteries were unsuccessful and complicated by hemiparesis in two patients, one of whom died. There is no
evidence of benefit for patients with this procedure"
and it should be undertaken only in rare circumstances,
if ever.
The follow-up morbidity in our patients after surgery was also relatively high. In the Joint Study1 there
was a stroke morbidity of 4% in a follow-up period of
42 months. Half of the strokes were fatal. In the present study stroke morbidity was 5.7% over 1.7 years
and morbidity for myocardial infarction 7.5%. During
the follow-up none of our patients died because of IBI
but three patients died because of AMI. These findings
are consistent with our earlier observations, where TIA
patients on conservative therapy died three times more
often from AMI than from IBI.16 In that series we had
an annual ischemic stroke rate of only 0.6% and a
vascular death rate of 1.3% against 3.3% and 1.7% in
the present series.
In a non-randomized study of TIA patients Toole
and co-workers18 reported a high surgical morbidity
(22%) and mortality (6%). However, the overall mortality (23% at 4 years) was similar in the medically and
surgically treated groups in the patients surviving the
initial postoperative period. Whisnant et al19 reported
good surgical results with a 3% stroke morbidity and
under 1% mortality postoperatively, in a series of
clearly defined patients who had experienced TIA in
one carotid territory and who were submitted to carotid
endarterectomy on the side corresponding to the ischemic symptoms. During the follow-up, ischemic stroke
occurred at a rate of 2% per year and death rate was 3%
per year. Seventy percent of the deaths were due to a
cardiac disorder. Fifteen percent of the patients continued to have TIA. In a multi-variable analysis with 17
variables they did not reveal any single factor or combination of factors which could be related to mortality.
The reason for this can be extremely careful selection
of patients for surgery, great surgical skill in the operation and variables not sensitive enough when investigating such a highly selected group of patients. The
good results during follow-up may be due to the fact
that patients selected for surgery tend to have better
prognosis than those patients selected for medical
therapy.
The great differences in the results of carotid endarterectomy obviously depend on patient selection and
surgical skill. The combination of careful patient selection and a well-trained operative team will probably
result in a low postoperative complication rate and in a
low long-term stroke morbidity. As of today there are
no controlled studies to prove this. New modes of
therapy, such as anti-aggregates have been introduced
and better resources for taking care of patients with
risk factors for stroke are available. If the complication
rate following surgery remains high, then less radical
measures may be of more importance.
Acknowledgment
I would like to thank The Paavo Ilmari Ahvenainen Foundation, The
Orion Scientific Research Fund and Paulo Foundation for grants.
References
1. Fields WS, Maslenikov V, Mever JS, Hass WK, Remington RD,
Macdonald M: Joint study of extracranial arterial occlusion. V.
Progress report of prognosis following surgery or nonsurgical treatment for transient cerebral ischemic attacks and cervical carotid
artery lesion. JAMA 211: 1993-2003, 1970
2. Wiley EJ, Ehrenfeld WK: Extracranial occlusive cerebral vascular
disease — diagnosis in management. WB Saunders Co. Phila,
220-221, 1970
3. DeWeese JA, Rob CG, Satran R, Marsch DO, Joynt RJ, Summers
D, Nichols C: Results of carotid endarterectomies for transient
ischemic attacks — five years later. Ann Surg 178: 258-263, 1973
4. Nunn DB: Carotid endarterectomy: Analysis of 234 operative
cases. Ann Surg 182: 733-738, 1975
5. Ojemann RG, Crowell RM, Robertson GH, Fisher CM: Surgical
treatment of extracranial carotid occlusive disease. Clin Neurosurg
22: 214-263, 1975
6. Easton JD, Sherman DG: Stroke and mortality rate in carotid endarterectomy: 228 consecutive operations. Stroke 8: 565-568, 1977
7. Sanford JR, Lubow M, Vasko JS: Prevention of stroke by carotid
endarterectomy. Surgery 83: 259-263, 1978
8. Toole JF, Yuson CP, Janeway R, Johnston F, Davis C, Cordell
AR, Howard G: Transient ischemic attacks: a prospective study of
225 patients. Neurology (NY) 28: 746-753, 1978
9. Whisnant JP: Indications for medical and surgical therapy for
ischemic stroke. In Thompson RA, Green JR (eds) Advances in
Neurology, Vol 16. Stroke. New York: Raven Press, 133-144,
1977
10. Committee on cerebrovascular disease: A Classification and Outline of Cerebrovascular Disease II. Stroke 6: 563-616, 1975
11. Sundt TM, Jr, Sandok BA, Whisnant JP: Carotid endarterectomy
complications and preoperative assessment of risk. Mayo Clin Proc
50: 301-306, 1975
12. Acheson RM: Mortality from cerebrovascular disease in the United
States. In Cerebrovascular Disease Epidemiology: A Workshop.
Public Health Monograph no. 76: Public Health Service Publication no. 1441. Washington, DC: Government Printing Office, 2 3 40, 1966
13. DeWeese JA, Rob CG, Satran R: Surgical treatment for occlusive
disease of the carotid artery. Ann Surg 168: 85-94, 1968
964
STROKE
14. Patterson RH: Risk of carotid surgery with occlusion of the contralateral carotid artery. Arc Neurol 30: 188-189, 1974
15. Landolt AM, Millikan CH: Pathogenesis of cerebral infarction
secondary to mechanical carotid artery occlusion. Stroke 1: 52-62,
1970
16. Muuronen A, Kaste M: Outcome of 314 patients with transient
ischemic attacks. Stroke 1: 24-31, 1982
17. Hass JS: An approach to the maximal acceptable stroke complica-
VOL
15, N o 6, NOVEMBER-DECEMBER
1984
tion rate after surgery for transient cerebral ischemia. Stroke 1:
104, 1979
18. Toole JF, Janeway R, Choi K, Cordell R, Davis C, Johnston F,
Miller HS: Transient ischemic attacks due to atherosclerosis: a
prospective study of 160 patients. Arch Neurol 32: 5-12, 1975
19. Whisnant VP, Sandok BA, Sundt TM: Carotid endarterectomy for
unilateral carotid system transient cerebral ischemia. Mayo Clin
Proc 58: 171-175, 1983
The Case Against Surgery for Asymptomatic Carotid Stenosis
BRIAN R. CHAMBERS, M B B S , FRACP, AND JOHN W. NORRIS, M D , FRCP, FRCP (C)
Downloaded from http://stroke.ahajournals.org/ by guest on June 12, 2017
SUMMARY Asymptomatic cervical bruits with their implication of underlying carotid artery disease,
carry an established but low risk of stroke. In spite of the rising numbers of patients subjected to carotid
endarterectomy for this condition, there is little evidence that the benefits outweigh the risks.
Outcome data from community studies and the current prospective Toronto study of patients with
asymptomatic neck bruits indicate that the annual stroke rate is 1-2%, and the annual cardiac death rate is
2-4%. Published data of the results of carotid surgery suggest that surgical risks outweigh any possible
benefits, unless a subgroup with spontaneous stroke risk of at least 5% can be identified.
Stroke Vol 15, No 6, 1984
ALTHOUGH
ASYMPTOMATIC
CAROTID
BRUITS are an established risk factor for ischemic
stroke,12 the management of asymptomatic patients
with carotid bruits and carotid stenosis remains controversial.3-4 Carotid endarterectomy is performed in increasing numbers of patients3 although its efficacy has
not been demonstrated convincingly for either asymptomatic or symptomatic disease. Since a requirement
of any treatment is that benefits should outweigh risks,
the stroke risk reduction after carotid endarterectomy
must outweigh the combined hazards of angiography
and surgery.
Jonas and Hass5 compared the outcome of patients in
operated and unoperated groups of the Extracranial
Arterial Occlusion Joint Study,6 and calculated that a
stroke complication rate greater than 2.9% is unacceptable for extracranial arterial surgery in symptomatic
patients. Since the spontaneous stroke rate in asymptomatic patients with carotid stenosis is less, an even
lower surgical complication rate would seem mandatory for successful surgical treatment.
The relatively benign outcome of patients followed
in the prospective Toronto Asymptomatic Cervical
Bruit (ACB) Study has prompted this evaluation of the
factors critical to the efficacy of carotid endarterectomy for asymptomatic carotid stenosis.
is obtained from community studies in Evans County1
and Framingham,2 where the overall stroke rates were
2.3% and 1.7% per annum. In addition to increased
stroke risk, these patients have an increased cardiac
risk, and an overall mortality, from causes other than
stroke, of approximately 4% per annum.
The best estimates of the protection afforded by
carotid endarterectomy are from studies in patients
with transient ischemic attacks (TIAs), figures which
may not apply to asymptomatic patients. Both the Extracranial Arterial Occlusion Joint Study* and the
Mayo Clinic7 reported a two-thirds reduction in stroke
rates following uncomplicated carotid endarterectomy. The reduced long-term risk is offset by the more
immediate complications of surgery. For carotid endarterectomy, surgeons with a high level of expertise
achieve peri-operative stroke and/or death rates less
than 5% (table I),*"13 operative stroke and death occurring with about equal frequency. Angiographic complications should also be considered, but are omitted
from further discussion because recent technological
refinements have reduced permanent neurological sequelae to well below 1%.I4~16
These data are the basis for evaluating the merits of
carotid endarterectomy in patients with asymptomatic
carotid stenosis.
Current State of Knowledge
The reported outcome of asymptomatic patients
with neck bruits varies widely but the best perspective
Selection of Endpoints
If stroke risk alone is considered, the net stroke
reduction at three years in the surgical group is 42%,
and the 'break-even point' is 13 months (fig. 1). The
'break-even point' is the moment when the number
of strokes in each group is equal. A randomized surgical trial would require 1214 patients in each group
to achieve a statistically significant result (table 2,
trial 1).
If both stroke and death risks are considered (fig. 2),
the net (stroke and/or death) risk reduction at three
From the MacLachland Stroke Unit and Department of Neurosciences, Sunnybrook Medical Centre, University of Toronto, Toronto,
Ontario, Canada.
Brian R. Chambers is a Stroke Research Fellow for the Ontario Heart
Foundation.
Address correspondence to: John W. Norris, M.D., Sunnybrook
Medical Centre, 2075 Bayview Avenue, Toronto, Ontario, Canada.
M4E 3M5.
Received April 18, 1984; revision # 1 accepted August 23, 1984.
Outcome of surgical treatment of 110 patients with transient ischemic attack.
A Muuronen
Stroke. 1984;15:959-964
doi: 10.1161/01.STR.15.6.959
Downloaded from http://stroke.ahajournals.org/ by guest on June 12, 2017
Stroke is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 1984 American Heart Association, Inc. All rights reserved.
Print ISSN: 0039-2499. Online ISSN: 1524-4628
The online version of this article, along with updated information and services, is located on the
World Wide Web at:
http://stroke.ahajournals.org/content/15/6/959
Permissions: Requests for permissions to reproduce figures, tables, or portions of articles originally published in
Stroke can be obtained via RightsLink, a service of the Copyright Clearance Center, not the Editorial Office.
Once the online version of the published article for which permission is being requested is located, click Request
Permissions in the middle column of the Web page under Services. Further information about this process is
available in the Permissions and Rights Question and Answer document.
Reprints: Information about reprints can be found online at:
http://www.lww.com/reprints
Subscriptions: Information about subscribing to Stroke is online at:
http://stroke.ahajournals.org//subscriptions/