ABSTRACT
Objective: To assess the frequency of
significant carotid artery disease among the study group patients who underwent
cardiac surgical procedures and highlight the importance of pre-operative Carotid
Duplex Ultrasonography Scanning.
Methods: This is a descriptive study which was conducted on
a consecutive series of 102 Jordanian patients who underwent cardiac surgical
procedures at Queen Alia Heart Institute between January and December 2009, and
were pre-operatively examined for carotid artery disease. Median age of the
study group patients was 63 (range 40-78) years, there were 84 males and 18
females, 76(74.5%) were hypertensive, 62(60.7%) diabetics, 67(65.6%) had
history of smoking, 45(44%) had a Body Mass Index >30, 13(12.7%) had
significant left main disease. Ten patients (9.8%) had a pre-operative history
of transient ischemic attack or cerebrovascular accident. Chi-square was used to
determine significance of the study variables, P value<0.05 was considered
significant.
Results: Seventeen
patients (16.6%) were found to have 50% or
greater stenosis of one or both carotid arteries whereas for an 80% or greater
stenosis; it was 6(5.8%). Frequency of a 50% or greater stenosis of one or both
carotid arteries was 3(6.5%) in patients between age 60 and 69 years,
increasing to 11(42.3%) for patients age of 70 years and older. Independant risk factors for the presence of
>50% stenosis in one or both carotid arteries in this group of patients were
a previous history of transient ischemic attack or cerebrovascular accident, left
main coronary disease, hypertension, history of smoking. Among 4 patients found
to have concomitant significant carotid lesions and were hemodynamically stable
with no critically stenotic coronary arteries, management was staged, carotid
stenting was performed as a first stage in 2 patients and carotid
endarterectomy was performed as a first stage in another 2 patients, cardiac
procedures were performed successfully as a second stage in these 4 patients.
Conclusion: Concomitant significant Carotid Artery
Disease among the study group patients above the age of 70 who underwent cardiac
procedures is relatively high, selective pre-operative Carotid Duplex Ultrasonography
should be mandatory.
Key
words: CAS: Carotid
Artery Stenosis, CAD: Coronary Artery Disease, CABG: Coronary Artery By-pass Grafting.
JRMS
March 2012; 19(1): 5-10
Introduction
Atherosclerosis
is a systemic disease involving the intima of large- and medium-sized arteries-
including the aorta, carotid, coronary, and peripheral arteries. It is
characterized by intimal thickening due to the accumulation of cells and
lipids, thus carotid artery involvement in patients with coronary artery
disease is expected, it frequently occurs at the carotid bifurcation and the
proximal internal carotid artery. In
general adult population, the prevalence of Carotid Artery Stenosis (CAS)
approaches 4% while in patients with Coronary Artery Disease (CAD) it can reach
(30-70%), whereas for those underwent
Coronary Artery By-pass Grafting (CABG), the incidence of significant CAS is
17-22%.(1,2,3) The
overall incidence of cerebrovascular accident after CABG is 2.1-5.2%(4,5,6,7,8)
with related mortality of (0-38%).(4,9) evidence
suggests that the risk of post CABG Cerebrovascular Accident (CVA) is 15%-18%(7,10,11)
in patients with prior history of CVA or Transient Ischemic Attacks (TIA’s) and
who had unilateral 70-90% stenosis.(10) Increasing to 26% with
bilateral 70-99% stenosis or contra lateral occlusion.(10)
Significant CAD is a well established risk factor for perioperative stroke in
patients undergoing CABG, and it accounts for 30% of strokes associated with
CABG.(11) Postoperative neurological complications, not only
increase mortality, but also prolong hospital stay, increase hospital costs and
affect postoperative quality of life. Screening of the carotids may reduce the
incidence of cerebrovascular events, some investigators have identified risk
factors for carotid disease that can be used for more selective screening,
these include: old age, prior neurological events, peripheral vascular disease,
hypertension and smoking.(1,9,6,12-14)
In
this study, we aim to assess the frequency of significant carotid artery
disease among the study group patients who underwent cardiac surgical
procedures and highlight the importance of pre-operative carotid duplex
ultrasonography scanning.
Methods
This
is a descriptive study which was conducted on a consecutive series of 102
Jordanian patients who underwent cardiac surgical procedures at Queen Alia
Heart Institute between January and December 2009, and were pre-operatively
examined for carotid artery disease. Median age of the study group patients was
63 (range 40-78) years, there were 84
males and 18 females, 76(74.5%) were hypertensive, 62 (60.7%) were diabetics,
67 (65.6%) had history of smoking, 10(9.8%) had history of CVA or TIA, 45(44%)
had a Body Mass Index > 30, 13 (12.7%) had significant LMA disease, as shown
in Table I. Chi square was used to determine significance of the study
variables, P value <0.05% was considered significant.
Results
Out
of 102 patients included in this study, 88 patients (86.3%) had CAS, 17 patients
(16.6%) had significant lesions; that is to say 50% or greater stenosis of one
or both carotids. Frequency of
significant CAS in the age group (60-69) years was 3/26 (6.5%) (P<0.01), increasing to 11/26 (42.3%) for
patients aged above 70 years (P<0.001), as demonstrated in Table II. Most of the patients were in the age group
(60-69) years 45% in contrast to 4.9% of patients less than 50 years, as
illustrated in Table III.
Out of the 17 patients with significant CAS,
6(5.8%) had severe stenosis >80%, 2(1.9%) of them had asymptomatic severe
disease, while the remaining 4(3.9%) had symptomatic severe CAS, in addition to
that 3 of the above 6 patients (2.9%) had bilateral stenosis >80%. Ten (9.8%) had unilateral lesions (>50%),
whereas 7(6.8%) had bilateral lesions (>50%). With increasing age,
especially >70 years, there is a tendency towards having severe bilateral
CAS, >80% as shown in Tables IV and V. Independent risk factors for the
presence of >50% stenosis in one or both carotid arteries among this sample
of patients were a previous history of transient ischemic attack or Cerebrovascular
Accident (CVA) (P<0.05), Left Main Coronary Disease (LMA) (P<0.05), hypertension
(P<0.05), history of smoking (P<0.05), as seen in Table VI. Hypertension was found to be incremental risk
factor, whereas diabetes was not found to be incremental risk factor for CAS in
this sample of patients undergoing CABG (P>0.05). Smoking as well as LMA
disease were found to be an incremental risk factor for CAS, on the other hand
neither being female nor male were found to be independent risk factor for CAS (P>0.05).
Of the 13 patients with significant LMA disease included in this study, 5 had
significant CAS (38%), while the incidence of LMA disease in patients
undergoing CABG was only 12.7%. CVA or history of TIA was found in 10 patients,
4 of which had significant CAS (40%). In
4 patients found to have concomitant
significant CAS lesions and were hemodynamically stable, with no critically stenotic coronary arteries, the procedures were staged; with carotid stenting or carotid endarterectomy as first stage followed by CABG. Carotid stenting was performed in 2 patients, and carotid endarterectomy in another 2 patients. On the other hand we had 2 cases, with asymptomatic stenosis >80%, CABG was performed with no intervention for their carotid disease, and they did not develop any Neurological complication.
Table
I: Clinical characteristics of the study group
patients
|
Variables
|
Number
|
%
|
|
Hypertension
|
76
|
74.5
|
|
Diabetes
mellitus
|
62
|
60.7
|
|
Smoking
history
|
67
|
65.6
|
|
Left
Main Coronary Artery Disease
|
13
|
12.7
|
|
History
of CVA or TIA’s
|
10
|
9.8
|
|
BMI*.>30
|
45
|
44
|
*BMI: Body Mass Index
Table II: Carotid artery
stenosis (CAS) among the study group patients
|
Age group
|
<50% stenosis
|
>50% stenosis
|
%
|
P value
|
|
Number
|
%
|
Number
|
%
|
|
40-49
years
|
5
|
|
|
|
|
|
|
50-59
years
|
22
|
88
|
3
|
12
|
25
|
Insignificant
|
|
60-69
years
|
43
|
93.5
|
3
|
6.5
|
6.5
|
<0.01
|
|
>70 years
|
15
|
57.69
|
11
|
42.3
|
42.3
|
<0.001
|
Table III: Patients age
distribution of the study group patients
|
Age group
|
Number
|
%
|
|
<50
years
|
5
|
4.9
|
|
50-59
years
|
25
|
24.5
|
|
60-69years
|
46
|
45
|
|
70-79years
|
26
|
25.5
|
Table IV: Carotid artery
stenosis
|
Age group
|
<80% stenosis
|
>80% stenosis
|
P value
|
|
Number
|
%
|
Number
|
%
|
|
50-59
years
|
3
|
2.9
|
|
|
*
|
|
60-69
years
|
3
|
2.9
|
|
|
*
|
|
>70years
|
5
|
4.9
|
6
|
5.8%
|
<0.02
|
*=irrelevant for comparison
Table V: Distribution of
Unilateral vs. Bilateral stenosis according to age
|
Age group
|
Unilateral stenosis >50%
|
Bilateral stenosis >50%
|
Bilateral stenosis >80%
|
|
Number
|
%
|
Number
|
%
|
Number
|
%
|
|
50-59year
|
2
|
1.96
|
1
|
0.098
|
|
|
|
60-69
year
|
2
|
1.96
|
1
|
0.098
|
|
|
|
>70 year
|
6
|
5.8
|
5
|
4.9
|
3
|
2.9
|
Table VI: Risk factors
|
Risk Factor
|
CAS seen on Duplex Scanning
|
No. CAS seen on Duplex Scanning
|
P value
|
|
Hypertension
|
16
|
60
|
<0.05
|
|
Diabetes
mellitus
|
8
|
54
|
Insignificant
|
|
Smoking
history
|
15
|
52
|
<0.05
|
|
Hx
of CVA or TIA
|
4
|
6
|
<0.05
|
|
Left
Main Coronary Artery Disease
|
5
|
69
|
<0.05
|
|
Female
sex
|
2
|
16
|
Insignificant
|
|
Male
sex
|
15
|
69
|
Insignificant
|
Discussion
Atherosclerosis
is a systemic disease involving large and medium sized muscular arteries,
carotid arteries are expected to be involved in this disease. In our study, we
found that 86.3% of patients had CAS which is similar to a large study by PC
Rath(8) with incidence
of CAS in 84.5% of patients, wherase a study conducted by Fracesca Cirilo(7)
found incidence of CAS in 61.6% of patients. 17% of the patients over the age
65 years scheduled for CABG had by ultrasonic duplex scanning a greater than
50%, stenosis of one internal carotid artery and 6% had greater than 80%
stenosis of one internal carotid artery.(2) which is close to
our results (16.6%), (5.8%) respectively, additional study conducted by D’Agostino
and his colleagues on a larger number of patients showed that CAS >50% was
seen in 20% and 8% of patients had CAS stenosis >80%,(13) also
Berens and associates found in a prospective study on 1,087 patients older than 65 years, 17%
prevalence of CAS>50% and 5.9%
prevalence of stenosis > 80%, furthermore another study conducted by Daniel
J and associates showed significant CAS >50% in 13.4% of patients.(9)
Moreover, a recent study by Anna Drohomirecka showed that CAS >50% was
detected in 18%.(14) on the other hand Abbas et al
found in a study conducted on 1604 patients that only 1.3% of patients had
significant CAS >50%.(4) We found unilateral lesions >50%
in 9.8% of patients and bilateral lesions >50% in 6.8% of patients in
addition to that 2.9% of patients had bilateral stenosis >80%. A study by Anna Drohomirecka found unilateral
lesions in 12.9%,and bilateral lesions in 5.1%, also D’Agostino and his
colleagues found bilateral lesions >80% in 1.8% of patients. The proposed criteria for pre-operative
carotid scanning are based on risk factors shown in the literature to be
independently and significantly associated with either carotid disease or
cerebrovascular event.(3) in our study these include older
age group, hypertention, history of smoking, history of CVA, LMA disease. Age
was clear incremental risk factor for the presence of high grade carotid artery
stenosis as seen in the tremendous increase in the percentage of patients who
have CAS >50% with increasing age, especially above the age of 70 years
(42.3%), furthermore, a study performed by Faggioli and colleages on a larger
sample of patients showed that the rate of significant CAS rose from 3.8% for
patients younger than 60years to 11.3% for patients above the age of 65 years.(15)
The incidence of associated carotid artery disease has been 50% among patients
with left main CAD, compared with 19% among the general patients undergoing
CABG. Conversely, the incidence of left main CAD has been 37% in patients with
combined carotid and coronary artery disease compared with 14.2% incidence in
all CABG patients.(2) which is also close to our results (29.4%),
(12.7%) respectively, moreover a study conducted by Abbas showed that significant
LMA disease was seen in 12.1%,(4)
also another syudy by PcRath showed prevalence of about 12.0%,(8)
regarding significance of LMA disease as predictor of CAS, a study by Thomas J
Kiernan found that LMCA was not associated with significant CAS,(3)
in contrast to that Berens and colleagues found that LMCA stenosis was
independent predictor of significant CAS, in addition to that studies conducted
by Robert G,(1) and Daniel J(9) showed that
LMCA was found to be significant independent predictor of CAS. Prior hx of CVA
or TIA have already been reported by many studies to be significant independent
predictor of CASO.(9,13,14) In our study, this was found to be strong
independent predictor of CAS. Smoking was seen to be significant predictor in
our study, in contrast to Abbas and his colleges who found that smoking had no
influence on the developing of CAS in their patients, on the other hand many
studies found smoking to be significant risk factor.(1,3,13) Diabetes was not found, in our study to be
significant predictor of CAS, also a study by Abbas and his colleagues found
that diabetes was also not significant predictor of CAS, on the other hand,
other studies(1,13,16) found that diabetes was significant
predictor of CAS. Hypertention was found to be significant risk factor for CAS
in our study, actually many studies
found the same result.(1,4,8,13) neither male or
female gender were found in our study to be significant predictor of CAS which
is also seen in a study by Robert G, however other studies(3,4,13)
found female gender to be significant predictor. Perioperative stroke is
a dreadful complication after CABG, the risk of perioperative stroke after CABG
ranges in normal patients between 0.2% and 5.3%, but it increases to 15% in
patients with carotid lesions >70%.(7) Potential causes of
neurological deficit include reduced cerebral perfusion across hemodynamically
significant stenosis or embolization from the Aorta, coronary or carotid
arteries.(16) It is important to discriminate between cardiac
surgery patients with past history of TIA or minor stroke, and those who are
neurologically asymptomatic. In D’Agostino’s series, the risk of post CABG
stroke was 18% in patients reporting a prior history of stroke or TIA and who
had unilateral 70-90% stenosis, increasing to 26% in patients with bilateral
70-99% stenosis or contra lateral occlusion. Literature review suggests that
the risk factor of post CABG stroke increases from 1.7% in patients with no
carotid disease, to 3% in patients with unilateral 50-99% stenosis and 5% in
patients with bilateral 50-99% stenosis, the highest stroke risk is, however,
observed in CABG patients with carotid occlusion.(10)
The
management of patients with combined carotid and coronary artery disease
remains controversial. According to the 2004 AHA guidelines:(17)
1.
Carotid endarterectomy is probably recommended
before CABG or concomitant to CABG in patients with symptomatic carotid artery
stenosis or in asymptomatic patients with unilateral or bilateral internal
carotid stenosis of 80% or more (level of evidence: c).
2.
Carotid screening probably indicated in the
following subsets: age greater than 65 years, left main CAD, PVD, and history
of smoking, history of TIA or stroke, or carotid bruit on examination
3. The use of
ultrasound carotid screening in patients requiring CABG is very important in
the selection of patients for combined CABG and carotid endarterectomy,
planning perfusion techniques, operative approach, and treatment of carotid
stenosis, can decrease the incidence of postoperative neurological
complications. Neurological complications represent the most frequent cause of
mortality in patients undergoing myocardial revascularization,(18)
therefore in light of our results, it seems that the presence of factors such as,
LMA disease, previous hx of CVA, or TIA, advanced age (>70 years),
hypertension, hx of smoking renders pre-operative carotid scanning necessary,
as pre-operative screening for carotid disease reduced the risk of neurological
complications in patients undergoing CABG.
4. It seems
that our results are consistent with other studies done on carotid ultrasound
scanning pre-operatively regarding frequency and possible predictors of
associated significant CAS in patients undergoing CABG, but further analytical
studies on a larger number of patients are needed.
Conclusion
Concomitant
significant Carotid Artery Disease among the study group patients above the age of 70 who underwent
cardiac procedures is relatively high, selective pre-operative Carotid Duplex Ultrasonography
should be mandatory.
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