Annals of Vascular Surgery
Volume 21, Issue 1 , Pages 16-22, January 2007

Carotid Endarterectomy in Patients with Contralateral Carotid Artery Occlusion

1st Unit of Vascular Surgery, Policlinico San Donato, University of Milan, Milan, Italy

Milan, Italy

Article Outline

The aim of this study was to evaluate the 30-day outcome of carotid endarterectomy in patients with contralateral carotid artery occlusion and compare it to that in patients with patent contralateral carotid artery. We compared 2,959 carotid endarterectomies performed in patients with patent contralateral internal carotid artery to 373 carotid endarterectomies performed in patients with occlusion of the contralateral carotid artery in the same institute between 1988 and 2004. Patient demographics, surgical and anesthesiological strategy, perioperative neurological and cardiac events, and deaths were compared. The patients were grouped and analyzed according to the presence or absence of symptoms and to their gender. No significant difference was shown in perioperative cardiological and neurological events and deaths in patients with contralateral carotid occlusion versus patients without contralateral carotid occlusion. Females had significant more neurological events than males, in both the asymptomatic (P < 0.001) and symptomatic (P = 0.02) groups. Concomitant occlusion of the contralateral carotid artery was not associated with increased risk of perioperative cardiological or neurological adverse events. However, female gender was associated with higher risk for adverse neurological events.

 

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Introduction 

The North American Symptomatic Carotid Endarterectomy Trial (NASCET)1, 2, 3 and the Asymptomatic Carotid Atherosclerosis Study (ACAS)4, 5 suggest that total occlusion of the contralateral carotid artery (CO) is a predictor of poor outcome following ispilateral carotid endarterectomy (CEA). Recent studies of carotid stenting suggest that this technique may be preferable in patients with CO because of the perceived inferior results of surgical treatment.6, 7, 8 In contrast, multiple surgical series in the literature have reported excellent outcomes of CEA in patients with CO.9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25

The definition of high risk has not been established, and it varies considerably between advocates of surgical versus endovascular treatment of carotid stenosis. Many authors have challenged the concept of high-risk CEA, demonstrating that surgery can be safe, effective, and durable even in patients assumed to be at high risk.16, 17, 18, 19, 20, 26

The aim of this study was to evaluate the 30-day outcome of CEA in patients with CO and compare it with the outcome of CEA in patients with patent contralateral carotid artery. A comparison in the subgroups of symptomatic/asymptomatic patients and male/female gender was also performed.

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Patient Population and Methods 

Between January 1988 and December 2004, 2,891 patients underwent 3,332 CEAs, and their records were retrospectively analyzed. Patients who underwent CEA combined with cardiac surgery were excluded. All patients presented a symptomatic or asymptomatic high-grade internal carotid stenosis (≥70%). The diagnosis of carotid stenosis was made on the basis of preoperative angiography during the earlier part of the experience, but this was used with decreased frequency over the years; duplex ultrasound scanning and angio-magnetic resonance were used during the later part of the experience. The diagnosis of CO was made by angiography when performed and by color-duplex scanning or angio-magnetic resonance. In dubious cases of the duplex- and angio-magnetic resonance–assessed patients and when the string sign was present, digital subtraction angiography of the arch and carotid arteries was performed.

Clinical presentation was classified by a consultant neurologist as transient ischemic attack (TIA) for temporary hemispheric symptoms lasting no more than 24 hr and amaurosis fugax or stroke for neurological deficit persistent for more than 24 hr. Preoperative cerebral computed tomographic scanning was performed on all symptomatic patients.

CEA procedures involved traditional endarterectomy with direct closure of the vessel, traditional endarterectomy with Dacron® (DuPont, Wilmington, DE) or polytetrafluoroethylene patch, or eversion endarterectomy type I (section to the internal carotid artery, eversion endarterectomy and reimplantation to the common carotid artery) or type II (section to the carotid bifurcation, eversion endarterectomy, and circular anastomosis of the bifurcation to the common carotid artery). Most procedures were performed under local-regional anesthesia using a Javid shunt or a Pruit-Inahara shunt in patients with symptoms of cerebral ischemia. In the cases performed under general anesthesia, the shunt was used when advised by the neurologist who was performing a continuous electroencephalogram.

Statistical analysis was performed using the SPSS 13.0 statistical software package for windows (SPSS, Chicago, IL). Significance was assumed at P < 0.05 using the chi-squared test or the Fisher exact test in small numbers. Logistic regression multivariate analysis was conducted in order to determine independent predictors of adverse neurological or cardiological events and deaths. Myocardial infarction, neurological events, and deaths were compared in symptomatic and asymptomatic patients with and without CO, in males versus females, as well as in patients with and without CO.

Vertebral artery occlusion or aplasia, of at least one vertebral artery, was assessed in 1,195 patients who had an angiogram or angio-magnetic resonance. Patients who underwent only duplex scanning were excluded from the vertebral circulation assessment.

Separate analysis of symptomatic versus asymptomatic patients, with or without CO, males or females, in terms of 30–postoperative day myocardial infarction, neurological deficit, and deaths was also performed.

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Results 

Comparison of the patients' demographics between those with CO and those with patent contralateral internal carotid artery is shown in Table I. A significant difference was found with smoking history, diabetes mellitus, and concomitant coronary disease. No statistically significant difference was shown referring to age, (71.2 years for CO patients and 69.7 for patients with patent contralateral internal carotid artery), gender, or hypertension.

Table I. Patient characteristics
CharacteristicsContralateral occlusion (n = 373)Contralateral patent (n = 2,959)P
Malen = 257, 69%n = 2,139, 72.3%0.2
Femalen = 116, 31%n = 820, 27.7%
Smoking historyn = 196, 52.7%n = 1,237, 41.8%<0.001
Hypertensionn = 240, 64.1%n = 1,752, 59.2%0.1
CADn = 200, 53.8%n = 1,249, 42.2%<0.001
Diabetesn = 137, 36.6%n = 515, 17.4%<0.001
Hyperlipidemiaabn = 196, 52.5%n = 1,507, 50.9%0.2

CAD, coronary artery disease.

aLipid-lowering treatment for at least 6 weeks.

bLipid-lowering treatment was not available in the earlier period of this study.

Seven patients (5.22%) with CO had a concomitant occlusion of one vertebral artery, while 77 patients (7.26%) without CO had a concomitant occlusion of one vertebral artery. The difference was not statistically significant (P = 0.9, 95% confidence interval [CI] 0.9194-0.9467).

According to their neurological history, patients were classified as being asymptomatic, having a TIA, and having a stroke, separately for males and females. The difference between the patients with CO and without CO was significant regarding preoperative neurological status (Table II).

Table II. Neurological status prior to CEA
Preoperative statusContralateral occlusion (n = 373)Contralateral patent (n = 2,959)P
Asymptomaticn = 198, 53.2%n = 1,769, 59.8%0.025
Malen = 129, 65.2%n = 1,344, 76%<0.001
Femalen = 69, 34.8%n = 425, 24%<0.001
Symptomaticn = 175, 46.8%n = 1,190, 40.2%0.025
Malen = 128, 73.1%n = 795, 66.8%0.095
Femalen = 47, 26.9%n = 395, 33.2%0.095
TIAn = 79, 21.1%n = 805, 27.2%0.025
Malen = 59, 74.6%n = 592, 73.6%0.82
Femalen = 20, 25.4%n = 213, 26.4%0.82
Stroken = 96, 25.7%n = 385, 13%<0.001
Malen = 69, 71.8%n = 203, 52.7%<0.001
Femalen = 27, 28.3%n = 182, 47.3%<0.001

There was no significant difference in anesthesiological strategy in both groups. Patients with CO underwent CEA under cervical block in 91.2% of cases, and patients with patent contralateral internal carotid artery underwent CEA in 89.3% of cases.

Patients with CO were significantly less likely to tolerate clamping than patients without CO. There were 107 patients (28.7%) with CO who needed shunting, while only 210 patients (7.1%) without CO needed a shunt (P < 0.05). However, the majority of the patients with CO did, in fact, tolerate clamping during ipsilateral CEA (Fig. 1).

There was no significant difference between patients with patent or occluded contralateral internal carotid artery in terms of postoperative myocardial infarction, stroke, global neurological deficit, and deaths, also in both genders (Table III).

Table III. Perioperative major complications
30-Day complicationsContralateral occlusion (n = 373)Contralateral patent (n = 2,959)P
Myocardial infarctionn = 3, 0.8%n = 27, 0.9%0.702
Malen = 2n = 170.790
Femalen = 1n = 100.889
Neurological deficit (stroke + TIA)n = 12,a 3.2%n = 86,b 2.9%0.91
Malen = 8n = 520.51
Femalen = 4n = 340.7
Stroken = 8, 2.1%n = 52, 1.76%0.6
Malen = 5n = 300.56
Femalen = 3n = 220.75
Deathn = 3, 0.8%n = 21, 0.7%0.79
Malen = 2n = 120.889
Femalen = 1n = 90.889
Neurological complication + deathn = 15n = 1070.643
Malen = 10n = 640.787
Femalen = 5n = 430.623
Total adverse eventsn = 18n = 1340.811
Malen = 12n = 811
Femalen = 6n = 530.518

aEight patients had minor or major stroke, while four patients had a TIA.

bFifty-two patients had minor or major stroke, while 34 patients had a TIA.

Females were shown to have higher rates of neurological deficits in both the symptomatic and asymptomatic groups (symptomatic 5.16% vs. 2.71%, P = 0.026; asymptomatic 4.78% vs. 1.83%, P < 0.001) (Table IV). Males had higher rates of myocardial infarction in the symptomatic group (0.6% vs. 0.02%, P = 0.016). A significantly higher rate of neurological deficits was found in asymptomatic females with CO versus asymptomatic males with CO (8.16% vs. 1.34%, P = 0.034). A significantly higher rate of myocardial infarction was also found in symptomatic females without CO versus symptomatic males without CO (2.46% vs. 0.58%, P = 0.01).

Table IV. Separate analysis of patients with and without CO, symptomatic and asymptomatic, male and female
30-Day complicationsContralateral occlusion asymptomatic male (n = 149)Contralateral occlusion asymptomatic female (n = 49)P
Myocardial infarctionn = 1, 0.67%n = 1, 2.04%0.435
Neurological deficitn = 2, 1.34%n = 4, 8.16%0.034
Deathn = 0, 0%n = 1, 2.04%0.247
Contralateral patent asymptomatic male (n = 1,274)Contralateral patent asymptomatic female (n = 495)
Myocardial infarctionn = 8, 0.63%n = 6, 1.21%0.484
Neurological deficitn = 24, 1.88%n = 22, 4.44%0.31
Deathn = 5, 0.39%n = 5, 1.01%0.117
Contralateral occlusion symptomatic male (n = 132)Contralateral occlusion symptomatic female (n = 43)
Myocardial infarctionn = 1, 0.75%n = 0, 0%0.567
Neurological deficitn = 3, 2.27%n = 3, 6.98%0.159
Deathn = 1, 0.39%n = 1, 2.33%0.439
Contralateral patent symptomatic male (n = 865)Contralateral patent symptomatic female (n = 325)
Myocardial infarctionn = 5, 0.58%n = 8, 2.46%0.01
Neurological deficitn = 24, 2.77%n = 16, 4.92%0.066
Deathn = 6, 0.69%n = 5, 1.54%0.154
Asymptomatic male (n = 1,423)Asymptomatic female (n = 544)
Myocardial infarctionn = 9, 0.63%n = 7, 1.29%0.124
Neurological deficitn = 26, 1.83%n = 26, 4.78%<0.001
Deathn = 5, 0.35%n = 6, 1.1%0.054
Symptomatic male (n = 997)Symptomatic female (n = 368)
Myocardial infarctionn = 6, 0.6%n = 8, 0.02%0.016
Neurological deficitn = 27, 2.7%n = 19, 5.16%0.026
Deathn = 7, 0.7%n = 6, 1.63%0.0108

Finally, according to the regression analysis model, the prevalence of female gender in the asymptomatic group of patients was the only significant factor for adverse neurological events (P < 0.01, odds ratio = 1.8).

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Discussion 

This study showed significant differences on the demographics of patients with and without CO. Other studies have reported similar findings. Julia et al.27 found that smoking was significantly more common in patients with CO. Lacroix et al.28 noted that CO patients were significantly more likely to be male and to have a history of coronary disease. In contrast, other authors have reported no detectable significant differences in standard demographic factors between CO and non-CO.29 The ACAS trial30 noted no significant differences between the two patient groups with regard to traditional demographic factors. However, based on the majority of reports, it appears that patients with CO may have an increased prevalence of traditional atherosclerotic risk factors and presumably more severe or diffuse generalized atherosclerotic disease.

In the present study, there was a significant difference in the two groups of patients regarding previous stroke. Rockman31 found a significant difference of stroke before CEA in the two patient groups and Lacroix et al.28 noted that significantly more patients with CO had suffered a stroke prior to CEA. Julia et al.27 found that patients with CO were less likely to be asymptomatic prior to CEA and more likely to have a preoperative stroke. In contrast, other authors have noted no significant differences in the indications for ipsilateral CEA between CO and non-CO patients.

Authors agree about the importance of cerebral protection during CEA in patients with CO, but there is no agreement as to which methods of protection may be optimal in these cases.29 Some authors recommend shunts in all patients with CO,32, 33, 34, 35, 36, 37 some others recommend selective shunting based on a variety of criteria,28, 38, 39 while others recommend no shunting at all.40, 41 In our institution, regional anesthesia is preferred via cervical block and selective shunting in patients with clinical symptoms of cerebral ischemia. This study demonstrates a significant difference in the need for shunting in patients with CO. However, the majority of patents with CO tolerated carotid clamping without the need of shunt.

Major perioperative complications were compared in the two groups of patients with and without CO. No significant difference was found between the two groups regarding myocardial infarction, neurological events, and mortality. Because of the differences reported in ACAS3, 30 and NASCET42, 43, 44 with regard to CO cases, patients were also divided into asymptomatic and symptomatic groups. No significant difference was found in symptomatic patients with and without CO regarding myocardial infarction, neurological deficit, and deaths. However, ACAS3, 29 and NASCET42, 43, 44 have fewer than 100 patients with CO who underwent CEA. The ACAS trial agrees with the majority of the reports in the literature that the perioperative stroke rate following CEA in CO patients was equivalent to that in patients without CO. The NASCET trial demonstrated a high perioperative stroke rate only in a small cohort of symptomatic patients undergoing CEA.

A separate analysis of subgroups of symptomatic and asymptomatic patients, males and females, with and without CO, showed a higher rate of neurological deficit in females, both in the symptomatic and asymptomatic groups. The different benefit of CEA in males and females is supported by many authors.3, 45, 46 The reduction in carotid stroke was separately significant for men and women in the ACST trial,45 and the ECST trial46 showed that men derive rather more benefit from surgery than women because surgery itself seemed to be riskier in women. Therefore, it was deemed worth operating in about 90% of stenosis cases (80% for NASCET) in women and in about 80% (70% in NASCET) in men.46 Other authors3 have reported a difference only in the asymptomatic group. Our data showed a higher rate of adverse neurological events in asymptomatic females as well as in symptomatic patients. Female gender was also found to be a significant factor for adverse neurological events in the logistic regression analysis in the asymptomatic group of patients (P < 0.01) but not in the symptomatic group.

This study also shows that some subgroups of patients are at higher risk than others. Symptomatic males were more likely to have myocardial infarction than symptomatic females, independently from the condition of the contralateral carotid artery, occluded or not. In asymptomatic patients with CO, a postoperative neurological event was more likely if the patient was a female rather than a male; and in symptomatic patients with patent contralateral carotid artery, a postoperative myocardial infarction was more likely in females rather than in males.

In this study, the patients with CO were different from those without CO, regarding the fragility of the cerebral circulation and consequently the need of more shunting; but their outcome in terms of postoperative neurological events, myocardial infarction, and deaths did not differ significantly. Although the results of this study cannot be generalized only with respect to statistics, it seems clear enough that these patients, if treated with attention to intraoperative management (more frequent shunting), will likely have a good postoperative outcome.

The suggestion that patients with CO could be good candidates for carotid artery stenting14, 15 is consequently striking26 as to date there have been no studies specifically reporting the results of carotid stenting in patients with CO. The rationale for preferring carotid stenting over CEA in patients with CO appears to be based on two aspects that remain to be demonstrated: first, that CEA is a high-risk procedure and, second, that carotid stenting is safer that CEA. While awaiting the completion of prospective randomized trials evaluating the role of carotid stenting, CEA should remain the standard treatment even in such patients.26 Like many other studies,16, 17, 18, 19, 20, 26 the present one provides further proof that the loose definitions of patients at high risk used in the literature to justify extending carotid stenting to large numbers of patients outside of clinical trials are flawed. Prospective multicenter randomized trials are needed to determine the risk of CEA even in patients with CO and compare CEA and stenting in patients with CO.

In conclusion, patients who have to undergo CEA with concomitant contralateral CO do not appear to be at increased risk for perioperative incidence of myocardial infarction, neurological events, and death. Female gender was associated with higher risk for adverse neurological events, both in sypmptomatic and asymptomatic patients and in the subgroup of asymptomatic patients with CO.

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PII: S0890-5096(06)00024-0

doi:10.1016/j.avsg.2006.06.003

Annals of Vascular Surgery
Volume 21, Issue 1 , Pages 16-22, January 2007

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