Abstract
Objective: The aim of this study was to assess the different
risk factors and their impact on the final outcome of standard carotid
endarterectomy with dacron patch angioplasty.
Methods: From
January 1998 to December 2002, 805 (488 males, 317 females) patients underwent
standard carotid endarterectomy with dacron patch angioplasty at Texas Heart
Institute. The mean age was 69.5 years (range 34-93 years). The primary
outcomes were combined same-admission stroke/death and 30-day mortality rate.
While the secondary outcomes were same-admission perioperative transient
ischemic attack, cranial nerve injuries, myocardial infarction and take back to
secure hemostasis.
Results: There were 13
(1.6%) cases of same-admission stroke/death, and a total of 5 (0.6%) 30-day
deaths. Ten (1.2%) patients had postoperative transient ischemic attack.
Furthermore, 7(0.9%) patients had cranial nerve injury. Two patients
experienced acute myocardial infarction, and 14 (1.7%) patients were taken back
to the operating theater to secure hemostasis.
Conclusions:
Standard carotid endarterectomy with dacron patch angioplasty is associated
with low rates of morbidity and death, with reasonable outcomes in most
patients.
Key words:
Carotid endarterectomy, Carotid stenosis, Dacron Patch, Transient ischemic
attack, Stroke
JRMS
December 2010; 17(4): 5-10
Introduction
Extra cranial internal
carotid artery stenosis accounts for 15-20% of ischemic strokes, and carotid endarterectomy
(CEA) is the most frequently performed surgical intervention in stroke
prevention.(1) The era of
surgical prevention of stroke goes back half a century, when the first carotid
endarterectomy was performed in 1953.(2) After the initial
endorsement of carotid endarterectomy, confusion arose as to the appropriate
selection of patients and the allowable risk from the procedure.(3)
Since the publication of
positive findings from several large randomized controlled clinical trials,
including the North American Symptomatic Carotid Endarterectomy Trial (NASCET),
European Carotid Surgery Trial (ECST), Asymptomatic Carotid Atherosclerosis
Study (ACAS), and Asymptomatic Carotid Atherosclerosis Surgery Trial (ACST),
rates of CEA have increased dramatically as a method for preventing stroke in
patients with high grade carotid artery stenosis.(4-6) However, the development of perioperative
complications such as stroke or death is still a major concern because these
complications may negate the benefits of the procedure. Identification of risk
factors for adverse outcomes after carotid surgery is very important in surgical patient selection and patient counseling.
|
Table I. Base line characteristics of patients
|
Characteristic
|
No.
|
%
|
|
Sex
|
|
|
|
Male
|
488
|
61
|
|
Female
|
317
|
39
|
|
Age
|
|
|
|
< 80 yr
|
700
|
87
|
|
≥ 80 yr
|
105
|
13
|
|
Table II.
Coronary artery and cardiac risk status at base line
|
Risk
|
No.
|
%
|
|
Coronary artery disease
|
113
|
14
|
|
MI* during 6 months
|
16
|
2
|
|
Previous coronary revascularization
|
24
|
3
|
|
NYHA** functional class
|
|
|
|
I
|
469
|
58
|
|
II
|
301
|
37
|
|
III
|
35
|
5
|
|
Canadian Cardiovascular Society Class
|
|
|
|
0
|
467
|
58
|
|
1
|
209
|
26
|
|
2
|
89
|
11
|
|
3
|
32
|
4
|
|
4
|
8
|
1
|
*MI= Myocardial Infarction; **NYHA= New York Heart Association
|
|
Table III.
Cerebral and cerebrovascular risk status at base line
|
Risk
|
No.
|
%
|
|
Symptomatic
|
|
|
|
Stroke
only
|
89
|
11
|
|
Transient
ischemic attack only
|
208
|
26
|
|
Both
|
72
|
9
|
|
Asymptomatic
|
436
|
54
|
|
Previous carotid endarterectomy
|
|
|
|
Ipsilateral
|
30
|
4
|
|
Contralateral
|
137
|
17
|
|
Contralateral occlusion
|
49
|
6
|
|
History of neck irradiation
|
16
|
2
|
|
Table IV. Medical risk at base line
|
Risk
|
No.
|
%
|
|
History of pulmonary disease
|
196
|
24
|
|
History of renal impairement
|
32
|
3.9
|
|
Cigarette Smoking (past or present)
|
402
|
50
|
|
Hypertension
|
652
|
81
|
|
Diabetes Mellitus
|
|
|
|
Type 1
|
48
|
6
|
|
Type 2
|
145
|
18
|
|
Hyperlipidemia
|
402
|
50
|
|
Standard Carotid
endarterectomy with dacron patch angioplasty is an effective operation designed
to prevent stroke, several large multicenter studies have demonstrated that
endarterectomy is superior to the best medical management of high grade
symptomatic or asymptomatic carotid artery stenosis.(6-8)
Nonetheless, some physicians have argued that carotid angioplasty and stenting
may be preferable to CEA because it is less invasive, entails a shorter
recovery period, and may be less likely to produce adverse outcomes in high
risk patients.(9)
In this overview, we report the
operative outcomes in the management of patients with carotid artery stenosis
using standard carotid endarterectomy with dacron patch angioplasty, and we
examined the frequency of different outcomes and the possible contribution of
various risk factors to those outcomes.
Methods
The medical records of all
patients who underwent standard CEA with dacron patch angioplasty, at Texas
Heart Institute (THI), between January 1998 and December 2002 were retrospectively
reviewed.
Carotid endarterectomy was performed
if carotid artery stenosis was significant i.e.≥70% narrowing of its internal
diameter. The methods used to diagnose and quantify the degree of carotid artery
stenosis were: duplex Doppler ultrasound, magnetic resonance angiography, and carotid
arteriogram.
All the CEA procedures were
performed under general endotracheal anesthesia, with the head of the patient being
extended slightly and turned away from the operative site. The incision was typically
longitudinally placed along the anterior portion of the sternocleidomastoid
muscle and centered over the carotid bifurcation, as best judged from the
preoperative angiogram. Heparin was given before clamping of the carotid artery
in a dose-weight
standard of 1mg/kg. Shunts were used according to the
surgeon preference; the plaque was dissected free using a free elevator, or any
other convenient instrument. Closure of the arteriotomy proceeded next, using the
dacron patch, which was fashioned to the length of the vessel opening. Protamine
sulfate was given at the completion of angioplasty in a protamine-heparin ratio
of 1-2/1 ratio. Patients spent 3-4 hours in the recovery intensive care unit
before being sent to the surgical ward.
Exclusion criteria included
patients with concomitant CEA and coronary artery bypass, and patients in whom dacron
was used as an interposition graft rather than a patch.
We assessed the association
between the various patient characteristics, preoperative risk factors, and the
outcomes. These included (Tables I-IV): age, sex, previous CEA in the same
artery, previous neck irradiation, occlusion of the contralateral artery,
Canadian Cardiovascular Society (CCS) classification of functional limitation
related to angina, New York Heart Association (NYHA) classification of
functional limitation related to heart disease, previous Coronary Artery Bypass
Grafting(CABG) surgery, symptoms of carotid artery stenosis (stroke,Transient
Ischemic Attack(TIA) or both) within six
weeks before surgery, hypertension (blood pressure > 140/90 mmHg), Coronary
Artery Disease (CAD), cigarette smoking, Diabetes Mellitus(DM), hyperlipidemia, pulmonary disease (including
Chronic Obstructive Pulmonary Disease (COPD), asthma, emphysema, pulmonary
embolism) and renal impairment.
The rates of in hospital
same-admission stroke and death were relatively low, and so these were combined
into a single outcome (same-admission stroke/death) for the purpose of
analysis. TIA or other neurological events that had short periods i.e. < one
day were not classified as strokes. A stroke was defined as a permanent
neurological deficit confirmed by the surgeon and the neurologist, with a brain
computed tomography findings supporting the diagnosis.
The other outcomes were:
30-day mortality rate (the only outcome for which 30-day follow up data were
available for each patient), same-admission rate of post operative TIA,
cranial nerve injury, myocardial
infarction and take back for hemostasis.
We used χ² analysis and the Fisher
exact test with categorical variables. A 2-tailed P < 0.05 was considered
statistically significant for each outcome.
Results
Medical records of 805 (488 male, 317 female) patients,
who underwent standard CEA with dacron patch angioplasty in the period between
January 1998 and December 2002 were reviewed. Mean age of the patients was 69.5
years (range 34-93 yrs). Of the 805 procedures 370 (46%) were performed on
patients who had experienced symptoms of carotid stenosis within the six weeks
before surgery. Shunts were used in 713 (89%). The median time from surgery to
discharge was two days (range 1-112 days).
Twelve (1.5%) patients had stroke during the
CEA procedure or the in-hospital recovery period. Ten patients had strokes (one
fatal) in the cerebral hemisphere ipsilateral to the operated artery, one
patient had a stroke in the contralateral hemisphere, and one patient had
multiple infarcts in both brain hemispheres. There was one additional death
from acute myocardial infarction after an emergency aortocoronary bypass
surgery two days after CEA. There was a total same-admission mortality of two
(0.2%) patients, and a total of five (0.6%) 30-day deaths. The total incidence
of combined same-admission stroke/death was 13 (1.6%) (Table V).
Ten (1.2%) patients experienced TIA during the perioperative
period. Seven (0.9%) patients where found to have transient postoperative
cranial nerve injury, 14 (1.7%) were taken back to the operating theater for
bleeding issues after CEA was completed. Only two (0.2%) patients experienced
perioperative myocardial infarction, one of which was fatal. (Table VI)
Discussion
This study showed that 12 (1.5%)
patients had stroke during the CEA procedure or in the in-hospital recovery period,
one of them died, and an additional death was from an acute myocardial
infarction two days after CEA, so the total same admission mortality was two (0.2%),
and the total combined same-admission stroke/death was 13 (1.6%). Univariate
analysis showed that five factors were associated with increased risk of
same-admission stroke/death: NYHA functional class III (p=0.02), angina with
CCS classification of 2-4 (p=0.01), TIA within six weeks prior to surgery (p=0.02),
contralateral carotid artery occlusion (p=0.04), and past or present history of
cigarette smoking (p=0.01) (Table V).
Table V.
Univariate predictors of primary adverse outcomes in standard carotid
endarterectomy with dacron patch angioplasty (No. = 805):
|
Primary outcome
|
No. (%)
|
Factor
|
|
Rate (%)
|
P-value
|
|
Same-admission stroke/death
|
13 (1.6)
|
NYHA* classification
|
I
|
7/469 (1.5)
|
|
|
|
|
|
II
|
4/301 (1.3)
|
|
|
|
|
|
III
|
2/35 (5.7)
|
0.02
|
|
|
|
CCS** classification
|
0-1
|
7/676 (1.0)
|
|
|
2-4
|
|
|
|
6/129 (4.7)
|
0.01
|
|
|
|
Previous TIA‡ (past 6 wks)
|
No
|
4/525 (0.8)
|
|
|
|
|
|
Yes
|
9/280 (3.2)
|
0.02
|
|
|
|
Contralateral occlusion
|
No
|
10/756 (1.3)
|
|
|
|
|
|
Yes
|
3/49(6.1)
|
0.04
|
|
|
|
Cigarette smoking
|
No
|
2/403 (0.5)
|
|
|
|
|
(past or present)
|
Yes
|
11/402(2.7)
|
0.01
|
|
30-Day death
|
5 (0.6)
|
CAD† (any history)
|
No
|
2/692 (0.3)
|
|
|
|
|
|
Yes
|
3/113 (2.7)
|
0.02
|
|
|
|
Creatinine ≥ 2.0 mg/dl
|
No
|
4/773 (0.5)
|
|
|
|
|
|
Yes
|
1/32 (3.1)
|
0.01
|
|
|
|
Pulmonary disease (any)
|
No
|
1/609 (0.2)
|
|
|
|
|
|
Yes
|
4/196 (2.0)
|
0.01
|
*NYHA = New
York Heart Association; **CCS = Canadian
Cardiovascular Society; ‡TIA = Transient Ischemic Attack; †CAD = Coronary Artery
Disease.
Table VI.
Univariate predictors of secondary adverse outcomes in standard carotid
endarterectomy with dacron patch angioplasty (No. = 805):
|
Primary outcome
|
No. (%)
|
Factor
|
|
Rate (%)
|
P-value
|
|
Postoperative TIA*
|
10 (1.2)
|
Previous TIA* (past 6 wk)
|
No
|
3/525 (0.6)
|
|
|
|
|
|
Yes
|
7/280 (2.5)
|
0.04
|
|
|
|
Operated side
|
Right
|
1/383 (0.3)
|
|
|
|
|
|
Left
|
9/422 (2.1)
|
0.02
|
|
Cranial-nerve injury
|
7 (0.9)
|
Previous ipsilateral CEA**
|
No
|
5/775 (0.6)
|
|
|
|
|
|
Yes
|
2/30 (6.7)
|
0.03
|
|
Reoperation for hemostasis
|
14 (1.7)
|
Sex
|
Male
|
13/488 (2.7)
|
|
|
|
|
|
Female
|
1/317 (0.3)
|
0.01
|
Three patients died after
hospital discharge but within 30 days of surgery, so the total 30-day mortality
rate was five (0.7%). In univariate analysis, risk of death within 30 days of
CEA was associated with history of CAD (p=0.02), serum creatinine ≥ 2mg/dl (p=0.01),
and history of pulmonary disease (p=0.01) (table V).
There are obvious
difficulties in trying to compare a series of patients from different
institutions, with no reliable way of equating differences in indications for
operation, variations in population base, and surgical expertise. Nevertheless,
aware of these potential variables, our results were comparable to those of
large multi-institutional studies, such as: NASCET, ECST, ACAS, and ACST. The
30-day mortality rate shown in this study (0.6%), was not substantially
different from that observed in ACAS (0.1%)(10), ECST(1.0%),(11)
NASCET(1.1%),(12) and ACST (1.1%).(13)
The ACAS and ACST, which
included only asymptomatic (and, therefore, lower risk) patients, each found a
(1.4%) rate of stroke,(10,13) whereas NASCET and ECST which
included only symptomatic (higher-risk) patients found rates of (2.4%) and
(3.2%) respectively.(11,12) Our (1.5%) stroke rate seems to
fit in between these estimates, since about half (46%) of our patients were
symptomatic before going to surgery.
Contralateral internal
carotid artery occlusion is an important factor in consideration when
performing CEA. However, whether patients with internal carotid artery stenosis
and contralateral internal carotid artery occlusion have a higher risk of
perioperative stroke or stroke related death than patients with unilateral
internal carotid artery lesion with patent contralateral internal carotid artery
remains a controversial issue.(14,15) Moreover several
studies have found an increased stroke risk in patients with contralateral
internal carotid artery occlusion.(16,17) Not surprisingly,
this study showed that approximately (6.1%) of patients with contralateral
carotid artery occlusion had strokes or died in the post operative period, but
only (1.3%) of patients without contralateral occlusion had these adverse
outcomes (p=0.02).
External irradiation
to the neck area, poses aspecial challenge to the surgeon, because the lesion
may not be closely accessible and the plaque may be closely adherent, leading
to difficulty in achieving an adequate cleavage plane for endarterectomy,
making avoidance of cranial nerve injury more difficult, added to that the
carotid plaque in the irradiated neck contains more lipids and less fibrous tissue
than the typical plaques, this feature makes the plaque less stable and more
prone to move to the brain and causing stroke.(18) It was of
interest to note that there were no strokes or cranial nerve injuries among the
16 patients who had previous neck irradiation before CEA. However, because this
subgroup of patients was relatively small (16 out of 805), these findings did
not show definitively that previous neck irradiation is not a risk factor in
CEA.
Re-operation on a previously endarterectomized carotid
artery makes it difficult to identify the right plane of cleavage in the scar tissue.(18,19)
This study showed an increase in the incidence of cranial nerve injury in
patients with previous CEA (6.7%), compared to (0.6%) in patients with primary
CEA. Actually previous ipsilateral CEA was the sole predictor of cranial nerve
injury in univariate analysis (p=0.03) (Table VI). However it did not show any
significant effect of previous CEA on perioperative stroke/death or on 30 day
death rate.
One notable difference between our findings and those
of some multi-institutional studies is in the rate of postoperative cranial
nerve injury. Reported rates of postoperative cranial nerve injury were
considerably higher in both NASCET (8.6%)(18) and ECST (5.1%)(20)
Than it was in this study (0.9%). This
finding could be explained by the follow up protocols. In NASCET, all patients
underwent a neurological assessment on admission, and at regular periods after
CEA, regardless the patients are having symptoms of cranial nerve injury or not.(21)
The follow up protocol in ECST was also
similar, and included a detailed neurological examination.(22)
In our study, a neurologist assessed patients only if they had symptoms of
cranial nerve injury, thus the transient cranial nerve injury, which constitute
the majority of cranial nerve injuries, found in NASCET and ECST, were
undetected in our study.
Ten (1.2%)
patients experienced TIA in the postoperative recovery period, however
univariate analysis showed that post operative TIA was most likely to occur in
patients who had TIA in the preoperative period(p=0.04), or had CEA undertaken
on the left side. (p=0.02) (Table VI).
Fourteen (1.7%)
patients were taken back to the operating theater to secure bleeding issues
after the completion of CEA, this was predicted only by male sex (p=0.01) (Table
VI).
Limitations of the Study
Some potential limitations of the present study
must be acknowledged. There was no regular, detailed preoperative or
postoperative neurologic assessment, nor was there a systematic effort to
identify myocardial infarction, such as by routine measuring postoperative
troponin or creatine kinase levels.
Conclusion
Our experience with CEA with
dacron patch angioplasty showed that it is a procedure with low morbidity and
mortality. The number of patients studied and the variety of risk factors in
its population made data a good basis for comparison between different studies.
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