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Influence of Coronary Artery and Contralateral Carotid Artery Status on Long-Term Results of Carotid Artery Surgery
Influence of Coronary Artery and Contralateral Carotid Artery Status on Long-Term Results of Carotid Artery Surgery E. Chemla, MD, P. Julia, MD, PhD, G. Chatellier, MD, M. Landi, MD, F. Diemont, MD, D. Belhomme, MD, and J.N. Fabiani, MD, Paris, France
The main cause of death and long-term disability of patients undergoing carotid artery surgery is coronary artery disease. To identify the prognostic value of the status of the contralateral artery, we studied the course of 224 consecutive patients in whom one or both carotid arteries were operated on at our institution between 1985 and 1995. The 224 patients were divided into three groups: group I (n = 56) had an occluded contralateral carotid artery, in group II (n = 56) both carotids were operated on, and group III (n = 112) had a normal contralateral carotid artery. The clinical status of all patients except one was ascertained by one of us. We found that the status of the contralateral artery does not influence the long-term prognosis of patients undergoing carotid artery surgery. A periodic cardiological and vascular follow-up of these patients seems warranted to improve their survival. (Ann Vasc Surg 2000;14:334-339.) DOI: 10.1007/s100169910061
INTRODUCTION The indications of carotid artery surgery are well known, and results in terms of cerebral protection have been considerably improved over the past 10 years. The main cause of mortality in patients with unilateral or bilateral carotid stenosis, treated surgically or not, is coronary heart disease and its complications.1,2 Most authors have presented the perioperative risk of carotid surgery and the long-term neurological outcome in terms of status of the contralateral carotid artery; they have not reported on the subsequent coronary status of these patients.3 Studies dealing with long-term coronary or cardiac events after carotid surgery do not mention the condition of the contralateral carotid artery. There-
From the Department of Cardiovascular Surgery (E.C., P.J., M.L., F.D., D.B., J.N.F.) and the Department of Statistics and Epidemiology (G.C.), Hoˆpital Broussais, Paris, France. Correspondence to: J.N. Fabiani, MD, Department of Cardiovascular Surgery, Hoˆpital Broussais, 96, rue Didot, 75014 Paris, France. 334
fore, no author has yet resolved the following question: is bilateral carotid artery disease (bilateral stenosis or contralateral occlusion) a risk factor of atherosclerotic, and therefore coronary, disease?4,5 The frequency of fatal or nonfatal cardiac events becomes significant mainly after 3 years, and while all authors agree that strict cardiac follow-up is necessary for all patients who have undergone unilateral or bilateral carotid surgery, most fail to agree on a comprehensive prevention program. For this reason, we wanted to study the long-term neurological and cardiac outcome for a series of patients underling carotid surgery and presenting contralateral carotid stenosis or occlusion. The aim of our study was to collate all cardiac, neurological, and other events following carotid surgery carried out at our institution from 1985 to 1995.
PATIENTS AND METHODS Patients From January 1985 to December 1995, 694 patients underwent carotid surgery (endarterectomy or by-
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pass) at our institution. These patients were then divided into the three groups, based on the condition of their contralateral carotid arteries–either a contralateral stenosis or occlusion or a normal contralateral carotid artery. Group I (n = 56) had contralateral occlusion, group II (n = 56) had tight contralateral stenosis requiring bilateral two-stage surgery, and group III (n = 582) had a patent contralateral carotid artery, with no stenosis. The study was performed as follows. All patients in groups I and II were contacted. For technical reasons, it was not possible to get information on the entire cohort in group III. We selected a sample of 112 patients from the 582 patients in group III and stratified them by year of inclusion, using a series of random numbers generated by the ALEA function of the Excel software, and thus obtained a population equal to twice that of groups I and II (group III patients studied, n = 112). Methods To collate information concerning the long-term outcome for these patients, we drew up a questionnaire that was sent to the physicians treating the patients in groups I, II, and III. This document comprised four sections: neurological events, cardiac events, further cardiovascular surgery and death. In the neurological events section, data on incidence of transient ischemic attack (TIA) and stroke, the hemisphere involved, and the date of occurrence were recorded. The cardiac events section included data on myocardial infarction, heart failure, and date of occurrence. The section on further cardiovascular surgery indicated whether it was coronary bypass or angioplasty, whether peripheral revascularization occurred, and when this surgery took place. In the section on death the date and cause were recorded. All general practitioners who did not answer the questionnaire were systematically contacted by phone, and the questionnaire was filled in by phone. To limit variability in data collection, a single investigator (E.C.) was in charge of gathering the data for all patients. On the basis of the information received, we were able to assess the frequency of nonfatal neurological, cardiac, or vascular events, and the overall and cardiac mortality rates of all but one of our patients. Statistical Methods Results are presented as the average (one standard deviation) or median (extremes) when the distri-
Prognostic value of contralateral carotid artery 335
bution was non-Gaussian. Means have been compared using the t-test. Proportions were compared using the chi-squared test. Results were considered significant when p was <0.05. Survival curves were assessed by the KaplanMeier method and compared using a log-rank test with Staview and SAS software (Abacus Concepts, Berkeley, CA). To evaluate a specific event, patients were excluded at the moment of their death, when the latter was not due to the event considered.
RESULTS Comparison of Survival Rates among the 3 Pre-defined Groups The three groups were comparable in terms of age, gender, and prevalence of diabetes. Smoking and hypertension were more frequent in the first two groups than in the control group, and coronary heart disease was twice as frequent in the group with bilateral involvement as in the other two groups (Table I). Concerning preoperative symptoms (Table II), completed stroke was less frequent in the group with bilateral involvement than in the other two groups (4% vs. 17% and 14%, p < 0.05). In all groups, approximately half the patients had a preoperative TIA. There were significantly fewer asymptomatic patients in the group with contralateral occlusion than in the control group (26% vs. 40%). The 30-day postoperative cumulative morbidity–mortality rates were 1.8%, 7.1%, and 1.5%, respectively, for groups I, II, and III (p < 0.05). No deaths were noted during the postoperative period. Median follow-up periods for groups I, II, and III were 62 months (extremes 1, 149), 78 months (1, 157), and 65 months (1, 150), respectively. During the long-term follow-up we observed 11 fatal strokes ipsilateral to the surgically treated artery (2 in group I, none in group II, and 9 in group III). The various causes of death are given in Table II. In all groups the main cause of death was coronary heart disease. Others causes were cancer and neurological problems. There was no significant difference between the three groups concerning the mortality rates (p = 0.17). Eight cases of restenosis of the treated artery (3.5%) were observed, leading to repeat surgery in 6 cases. The overall survival rates were comparable in the three groups: 67%, 73%, and 72.5% at 5 years, and 39%, 51.5%, and 42% at 10 years for groups I, II, and III, respectively (Fig. 1). Stroke-free rates were also comparable in the three groups: 96%, 100%, and 91% at 5 years, and 96%, 100%, and 78.5% at 10 years for groups I, II, and III, respectively (Fig. 2).
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Table I. Baseline characteristics, preoperative symptoms, and revascularization rate (coronary artery bypass graft and peripheral revascularization) of patients in the three groups
Median age (years) Sex (M/F) Smokers, n (%) Hypertension, n (%) Diabetes mellitus, n (%) Coronary artery disease, n (%) History of stroke, n (%) History of TIA, n (%) Nonhemispheric symptoms, n (%) No symptoms, n (%) Coronary artery bypass graft, n (%) Peripheral revascularization, n (%)
Group I (n = 56)
Group II (n = 56)
Group III (n = 112)
pa
63.7 47/9 46 (82.1) 35 (62.5) 7 (12.5) 18 (32.1) 10 (17.8) 27 (48.2) 5 (8.9) 14 (25.0) 2 (3.5) 4 (7.1)
66.5 41/15 43 (76.8) 44 (78.6) 10 (17.8) 34 (60.7) 2 (3.5) 29 (51.7) 2 (3.5) 23 (41.0) 7 (12.5) 13 (23.2)
69.9 75/37 66 (59.0) 57 (51.0) 16 (14.0) 29 (25.9) 16 (14.2) 49 (43.7) 3 (2.7) 44 (39.3) 7 (6.2) 8 (7.1)
NS NS <0.01 <0.01 NS <0.01 <0.05 NS <0.05 <0.05 NS <0.05
NS, not significant. Group I, contralateral occlusion; group II, bilateral stenosis; group III, unilateral stenosis. a p-value obtained using a chi-squared test.
Table II. Comparison of death rates (30 days postoperative) in three groups of patients
Cause of death
Group I (n = 56) n (%)
Group II (n = 56) n (%)
Group III (n = 112) n (%)
Cardiac causes Neurological causes Cancers and other causes Alive Total
18 (32.1) 2 (3.5) 7 (12.5) 29 (51.8) 56 (100)
21 (37.5) 0 (0.0) 5 (8.9) 30 (53.6) 56 (100)
27 (24.1) 9 (8.0) 9 (8.0) 67 (59.8) 112 (100)
Group I, contralateral occlusion; group II, bilateral stenosis; group III, unilateral stenosis. Not significant: p = 0.17.
Actuarial freedom from risk of fatal or nonfatal cardiac events was comparable in all groups: 61%, 77%, and 79% at 5 years, and 48%, 52%, and 46% at 10 years for groups I, II, and III, respectively (Fig. 3). The actuarial rates of 10-year cardiac mortality were also comparable among all groups: 26%, 23%, and 19% at 5 years, and 49%, 42%, and 37% at 10 years for groups I, II, and III, respectively.
DISCUSSION Our results show that stroke-free rates are comparable for all groups. All strokes occurring during follow-up were ipsilateral to the surgically treated side, thus demonstrating for the group with contralateral occlusion that the hemisphere of the occluded side is well protected by preventive surgery of the contralateral carotid stenosis. These results contradict those of the North American Symptom-
atic Carotid Endarterectomy Trial (NASCET): the long-term stroke rate for patients with a contralateral occlusion was 22.1% at 2 years. This rate, which is very high compared with all other series in the literature and with ours, was nevertheless better than that for the same population receiving medical treatment; the stroke rate at 2 years was 69.4%.6 Results are identical in series, including ours, in which patients suffer from stenosis of both carotid arteries. Long-term freedom from stroke is good and is identical to that of a control population with a unilateral stenosis.5 These results lead us to ask whether involvement of the contralateral carotid artery is an index of severity of atherosclerosis. Authors who have studied this question in retrospective studies have concluded that the condition of the contralateral carotid artery has no influence on the long-term results of carotid surgery7,8 and that
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Fig. 1. Global survival rate among the three groups of patients. Survival curves were drawn according to the Kaplan-Meier method. The log-rank test showed no statistical difference between groups (p = 0.55).
Fig. 2. Actuarial stroke-free rate among the three groups of patients. Stroke-free rate curves were drawn according to the Kaplan-Meier method. The log-rank test showed no statistical difference between groups (p = 0.6).
Fig. 3. Actuarial cardiac event-free rate (fatal or nonfatal) among the three groups of patients. Cardiac event-free rate curves were drawn according to the Kaplan-Meier method. The log-rank test showed no statistical difference between groups (p = 0.3).
Prognostic value of contralateral carotid artery 337
the main cause of long-term mortality following carotid surgery, whatever the condition of the contralateral artery, is cardiac in origin.4-9 In a comparison of 598 patients with 63 patients who had contralateral occlusion, Mackey et al. reported that long-term mortality was identical in the two groups and that death was due mainly to cardiac, and more particularly, coronary, events.7 They concluded that carotid involvement was a purely local phenomenon and that the aim of carotid endarterectomy was to protect the two cerebral hemispheres, even in the presence of a contralateral occlusion. The only studies that do demonstrate a difference in long-term survival rates are those in which patients are divided into two groups on the basis of the seriousness of their coronary artery disease and coronary risk factors. Indeed, in most series in the literature, groups of patients with established coronary artery disease and those with numerous coronary risk factors have shorter long-term survival than other patients. The authors therefore recommend aggressive cardiac follow-up but fail to give clear indications of the approach to be adopted. Mackey and colleagues suggest selecting patients on the basis of their preoperative coronary status and recommend coronary arteriography 3 years after surgery for those with clinical signs of coronary artery disease or those with coronary risk factors but no clinical coronaropathy.10 Attempts have also been made to select patients preoperatively, not according to clinical criteria, but on the basis of other examinations, such as a stress test with or without myocardial scintigraphy. All of these authors report higher rates of late mortality in coronary patients or those who have coronary risk factors.7,9,10 None of the series, however, reports long-term survival rates for patients who have undergone peripheral or coronary revascularization.2 In our study, although patients in group II had significantly more preoperative coronary artery disease than those of the other groups, their survival rate was similar to that of the other groups. We were unable to demonstrate significant differences between the three groups concerning the overall actuarial long-term survival rates, actuarial freedom from fatal or nonfatal cardiac events, or the actuarial rate of cardiac mortality. We have had exactly the same results as those shown in the literature. In all groups the main cause of death was of cardiac, and more specifically, coronary, origin. This leads us to believe that carotid artery disease develops independently as a local phenomenon and that involvement of the contralateral carotid artery, in the form of stenosis or occlusion, is of no signifi-
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cant as a marker of the severity of possible coronary artery disease. Lacroix et al. reported an increase in life expectancy in patients with unilateral carotid artery disease compared to a group of patients with contralateral occlusion (at 10 years 67% vs. 43%). They concluded, however, that these data are not reliable because there were more women and less patients with overt coronary artery disease in the control group.11 The follow-up strategies of coronary artery disease are not well defined. Some authors practice preoperative selection on the basis of clinical or paraclinical criteria (stress ECG, myocardial scintigraphy, stress echocardiography, etc.);2 others prefer selection after 3 years, the point at which most survival curves turn downward on account of the increased frequency of coronary events.10-12 However, as far as we know, there is no series in which the outcome for a subgroup of patients undergoing coronary revascularization as a consequence of close cardiological follow-up has been reported. In a study similar to ours, Mattos et al. followed 354 patients who had undergone carotid surgery, 22.6% of whom had tandem stenoses (stenosis of the carotid siphon ipsilateral to the stenosis being surgically treated). The number of patients suffering preoperatively from coronary artery disease was similar in the two groups, and the results were similar with regard to stroke-free rate at 5 years (88.5% vs. 95% for the groups with and without tandem stenoses, respectively) and cardiac mortality (11.3% and 6% for the groups with and without tandem stenoses, respectively). The authors concluded that stenosis of the carotid siphon was not necessarily a marker of the seriousness of atherosclerotic disease and that it had no unfavorable impact on the long-term risk of stroke.13 In another study of 547 patients who were to undergo vascular surgery (aortic surgery, distal bypass grafts, carotid endarterectomy), cardiac morbidity and mortality were compared in the short and long term. Patients were divided into two groups: those with coronary heart disease risk factors and those without. Overall survival rates for patients in the group without risk factors were identical, regardless of the type of surgery involved. In the group of patients with coronary risk factors, survival rates were markedly lower among patients undergoing infrainguinal or carotid surgery than for those undergoing aortic surgery. Heart disease was the main cause of death, which occurred in most cases after 36 months.14 These results suggest that the follow-up of patients undergoing carotid surgery should be assessed not on the basis of the
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condition of the contralateral carotid artery but on the basis of the patient’s coronary status. What type of coronary surveillance can then be proposed? Authors differ in their answers to this question. Some suggest preoperative patient selection while others prefer to wait 3 years before including certain patients in a program of close cardiac surveillance with, in some cases, almost systematic use of coronarography.2,8-12 The preoperative strategy is based on examinations such as stress ECG and/or myocardial scintigraphy. The stress test cannot be completed by all patients, either because their average age is too high or they have simultaneous presence of occlusive arteriopathy of the lower limbs. Urbinati et al. suggest that patients unable to complete the exercise test be considered an intermediate-risk group who should benefit from close cardiac follow-up.15 Myocardial scintigraphy is of limited usefulness, as Baron’s group has already shown,16 and it does not seem reasonable to propose preoperative coronarography for all patients. This would only be possible if the combined risk of preoperative coronarography and possible subsequent coronary revascularisation was lower than the risk involved in carotid surgery alone for a vulnerable patient. Furthermore, the use of clinical coronary signs alone for patient selection seems inappropriate in view of the large number of cases of silent coronary artery disease. In our view, it is preferable that all patients undergoing carotid surgery, whatever the condition of their contralateral carotid artery, receive specialized cardiac follow-up, particularly 3 years after surgery, since this appears to be the moment at which, on average, fatal and nonfatal cardiac events increase in frequency. The type of examination that could then be offered remains to be decided. To our knowledge, there are no series comparing the effectiveness of coronarography and other methods of screening for coronary artery disease in patients who have undergone carotid surgery and who have been followed up over a long period.
REFERENCES 1. Matzsch T, Bergqvist D, Lindh M, Maly P, Takolander R. Natural history of patients with unoperated atherosclerotic carotid artery disease–results from a retrospective study. Eur J Vasc Surg 1993;7:166-70. 2. Ricco JB, Gauthier JB, Richer JP. The evolution of carotid and coronary artery disease after operation for carotid stenosis. Ann Vasc Surg 1992;6:408-412. 3. Koskas F, Kieffer E, Bahnini A, Ruotolo C, Rancurel G. Carotid eversion endarterectomy: short- and long-term results. Ann Vasc Surg 1995;9:9-15.
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4. Coyle KA, Smith R, Salam AA, Dodson TF, Chaikof EL, Lumsden AB. Carotid endarterectomy in patients with contralateral carotid occlusion: review of a 10-year experience. Cardiovasc Surg 1996;4:71-75. 5. Mattos F, Hodgson KJ, Londrey GL. Carotid endarterectomy: operative risks, recurrent stenosis, and long-term stroke rates in a modern series. J Cardiovasc Surg 1992;33:387400. 6. Gasecki AP, Eliasziw M, Ferguson GG, Hachinski V, Barnett HJ. Long-term prognosis and effect of endarterectomy in patients with symptomatic severe carotid stenosis and contralateral carotid stenosis or occlusion: results from North American Symptomatic Carotid Endarterectomy Trial (NASCET) Group. J Neurosurg 1995;83:778-782. 7. Mackey WC, O’Donnell TF, Callow AD. Carotid endarterectomy contralateral to an occluded carotid artery: perioperative risk and late results. J Vasc Surg 1990;11:778-785. 8. Roques XF, Baudet EM, Clerc F. Results of carotid endarterectomy in patients 75 years of age and older. J Cardiovasc Surg 1991;32:726-731. 9. Ricotta JJ, O’Brien MS, Weese JAD. Carotid endarterectomy for non-hemispheric ischaemia: long-term follow-up. Cardiovasc Surg 1994;2:561-566. 10. Mackey WC, O’Donnell TFJ, Callow AD. Cardiac risk in patients undergoing carotid endarterectomy: impact on peri-
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11.
12.
13.
14.
15.
16.
operative and long-term mortality. J Vasc Surg 1990;11:226234. Lacroix H, Hemelrijck JV, Carton H, Nevelsteen A, Suy R. Carotid artery surgery in the presence of an occlusion of the contralateral carotid artery: perioperative risk analysis and follow-up. Cardiovasc Surg 1994;2:26-31. Charanjit RS, Gersh BJ, Whisnant JP. Influence of coronary heart disease on morbidity and mortality after carotid endarterectomy: a population based study in Olmsted County, Minnesota (1970-1988). J Am Coll Cardiol 1992;19:12541260. Mattos MA, Bemmelen PSV, Hodgson KJ, Barkmeier LD, Ramsey DE, Sumner DS. The influence of carotid siphon stenosis on short- and long-term outcome after carotid endarterectomy. J Vasc Surg 1993;17:902-911. L’italien GJ, Cambria RP, Cutler BS. Comparative early and late cardiac morbidity among patients requiring different vascular surgery procedures. J Vasc Surg 1995;21:935-944. Urbinati S, Pasquale GD, Andreoli A. Preoperative noninvasive coronary risk stratification in candidates for carotid endarterectomy. Stroke 1994;25:2022-2027. Baron JF, Mundler O, Bertrand M. Dipyridamole-thallium scintigraphy and gated radionuclide angiography to assess cardiac risk before abdominal aortic surgery. N Engl J Med 1994;330:663-669.
The main cause of death and long-term disability of patients undergoing carotid artery surgery is coronary artery disease. To identify the prognostic value of the status of the contralateral artery, we studied the course of 224 consecutive patients in whom one or both carotid arteries were operated on at our institution between 1985 and 1995. The 224 patients were divided into three groups: group I (n = 56) had an occluded contralateral carotid artery, in group II (n = 56) both carotids were operated on, and group III (n = 112) had a normal contralateral carotid artery. The clinical status of all patients except one was ascertained by one of us. We found that the status of the contralateral artery does not influence the long-term prognosis of patients undergoing carotid artery surgery. A periodic cardiological and vascular follow-up of these patients seems warranted to improve their survival. (Ann Vasc Surg 2000;14:334-339.) DOI: 10.1007/s100169910061
INTRODUCTION The indications of carotid artery surgery are well known, and results in terms of cerebral protection have been considerably improved over the past 10 years. The main cause of mortality in patients with unilateral or bilateral carotid stenosis, treated surgically or not, is coronary heart disease and its complications.1,2 Most authors have presented the perioperative risk of carotid surgery and the long-term neurological outcome in terms of status of the contralateral carotid artery; they have not reported on the subsequent coronary status of these patients.3 Studies dealing with long-term coronary or cardiac events after carotid surgery do not mention the condition of the contralateral carotid artery. There-
From the Department of Cardiovascular Surgery (E.C., P.J., M.L., F.D., D.B., J.N.F.) and the Department of Statistics and Epidemiology (G.C.), Hoˆpital Broussais, Paris, France. Correspondence to: J.N. Fabiani, MD, Department of Cardiovascular Surgery, Hoˆpital Broussais, 96, rue Didot, 75014 Paris, France. 334
fore, no author has yet resolved the following question: is bilateral carotid artery disease (bilateral stenosis or contralateral occlusion) a risk factor of atherosclerotic, and therefore coronary, disease?4,5 The frequency of fatal or nonfatal cardiac events becomes significant mainly after 3 years, and while all authors agree that strict cardiac follow-up is necessary for all patients who have undergone unilateral or bilateral carotid surgery, most fail to agree on a comprehensive prevention program. For this reason, we wanted to study the long-term neurological and cardiac outcome for a series of patients underling carotid surgery and presenting contralateral carotid stenosis or occlusion. The aim of our study was to collate all cardiac, neurological, and other events following carotid surgery carried out at our institution from 1985 to 1995.
PATIENTS AND METHODS Patients From January 1985 to December 1995, 694 patients underwent carotid surgery (endarterectomy or by-
Vol. 14, No. 4, 2000
pass) at our institution. These patients were then divided into the three groups, based on the condition of their contralateral carotid arteries–either a contralateral stenosis or occlusion or a normal contralateral carotid artery. Group I (n = 56) had contralateral occlusion, group II (n = 56) had tight contralateral stenosis requiring bilateral two-stage surgery, and group III (n = 582) had a patent contralateral carotid artery, with no stenosis. The study was performed as follows. All patients in groups I and II were contacted. For technical reasons, it was not possible to get information on the entire cohort in group III. We selected a sample of 112 patients from the 582 patients in group III and stratified them by year of inclusion, using a series of random numbers generated by the ALEA function of the Excel software, and thus obtained a population equal to twice that of groups I and II (group III patients studied, n = 112). Methods To collate information concerning the long-term outcome for these patients, we drew up a questionnaire that was sent to the physicians treating the patients in groups I, II, and III. This document comprised four sections: neurological events, cardiac events, further cardiovascular surgery and death. In the neurological events section, data on incidence of transient ischemic attack (TIA) and stroke, the hemisphere involved, and the date of occurrence were recorded. The cardiac events section included data on myocardial infarction, heart failure, and date of occurrence. The section on further cardiovascular surgery indicated whether it was coronary bypass or angioplasty, whether peripheral revascularization occurred, and when this surgery took place. In the section on death the date and cause were recorded. All general practitioners who did not answer the questionnaire were systematically contacted by phone, and the questionnaire was filled in by phone. To limit variability in data collection, a single investigator (E.C.) was in charge of gathering the data for all patients. On the basis of the information received, we were able to assess the frequency of nonfatal neurological, cardiac, or vascular events, and the overall and cardiac mortality rates of all but one of our patients. Statistical Methods Results are presented as the average (one standard deviation) or median (extremes) when the distri-
Prognostic value of contralateral carotid artery 335
bution was non-Gaussian. Means have been compared using the t-test. Proportions were compared using the chi-squared test. Results were considered significant when p was <0.05. Survival curves were assessed by the KaplanMeier method and compared using a log-rank test with Staview and SAS software (Abacus Concepts, Berkeley, CA). To evaluate a specific event, patients were excluded at the moment of their death, when the latter was not due to the event considered.
RESULTS Comparison of Survival Rates among the 3 Pre-defined Groups The three groups were comparable in terms of age, gender, and prevalence of diabetes. Smoking and hypertension were more frequent in the first two groups than in the control group, and coronary heart disease was twice as frequent in the group with bilateral involvement as in the other two groups (Table I). Concerning preoperative symptoms (Table II), completed stroke was less frequent in the group with bilateral involvement than in the other two groups (4% vs. 17% and 14%, p < 0.05). In all groups, approximately half the patients had a preoperative TIA. There were significantly fewer asymptomatic patients in the group with contralateral occlusion than in the control group (26% vs. 40%). The 30-day postoperative cumulative morbidity–mortality rates were 1.8%, 7.1%, and 1.5%, respectively, for groups I, II, and III (p < 0.05). No deaths were noted during the postoperative period. Median follow-up periods for groups I, II, and III were 62 months (extremes 1, 149), 78 months (1, 157), and 65 months (1, 150), respectively. During the long-term follow-up we observed 11 fatal strokes ipsilateral to the surgically treated artery (2 in group I, none in group II, and 9 in group III). The various causes of death are given in Table II. In all groups the main cause of death was coronary heart disease. Others causes were cancer and neurological problems. There was no significant difference between the three groups concerning the mortality rates (p = 0.17). Eight cases of restenosis of the treated artery (3.5%) were observed, leading to repeat surgery in 6 cases. The overall survival rates were comparable in the three groups: 67%, 73%, and 72.5% at 5 years, and 39%, 51.5%, and 42% at 10 years for groups I, II, and III, respectively (Fig. 1). Stroke-free rates were also comparable in the three groups: 96%, 100%, and 91% at 5 years, and 96%, 100%, and 78.5% at 10 years for groups I, II, and III, respectively (Fig. 2).
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Table I. Baseline characteristics, preoperative symptoms, and revascularization rate (coronary artery bypass graft and peripheral revascularization) of patients in the three groups
Median age (years) Sex (M/F) Smokers, n (%) Hypertension, n (%) Diabetes mellitus, n (%) Coronary artery disease, n (%) History of stroke, n (%) History of TIA, n (%) Nonhemispheric symptoms, n (%) No symptoms, n (%) Coronary artery bypass graft, n (%) Peripheral revascularization, n (%)
Group I (n = 56)
Group II (n = 56)
Group III (n = 112)
pa
63.7 47/9 46 (82.1) 35 (62.5) 7 (12.5) 18 (32.1) 10 (17.8) 27 (48.2) 5 (8.9) 14 (25.0) 2 (3.5) 4 (7.1)
66.5 41/15 43 (76.8) 44 (78.6) 10 (17.8) 34 (60.7) 2 (3.5) 29 (51.7) 2 (3.5) 23 (41.0) 7 (12.5) 13 (23.2)
69.9 75/37 66 (59.0) 57 (51.0) 16 (14.0) 29 (25.9) 16 (14.2) 49 (43.7) 3 (2.7) 44 (39.3) 7 (6.2) 8 (7.1)
NS NS <0.01 <0.01 NS <0.01 <0.05 NS <0.05 <0.05 NS <0.05
NS, not significant. Group I, contralateral occlusion; group II, bilateral stenosis; group III, unilateral stenosis. a p-value obtained using a chi-squared test.
Table II. Comparison of death rates (30 days postoperative) in three groups of patients
Cause of death
Group I (n = 56) n (%)
Group II (n = 56) n (%)
Group III (n = 112) n (%)
Cardiac causes Neurological causes Cancers and other causes Alive Total
18 (32.1) 2 (3.5) 7 (12.5) 29 (51.8) 56 (100)
21 (37.5) 0 (0.0) 5 (8.9) 30 (53.6) 56 (100)
27 (24.1) 9 (8.0) 9 (8.0) 67 (59.8) 112 (100)
Group I, contralateral occlusion; group II, bilateral stenosis; group III, unilateral stenosis. Not significant: p = 0.17.
Actuarial freedom from risk of fatal or nonfatal cardiac events was comparable in all groups: 61%, 77%, and 79% at 5 years, and 48%, 52%, and 46% at 10 years for groups I, II, and III, respectively (Fig. 3). The actuarial rates of 10-year cardiac mortality were also comparable among all groups: 26%, 23%, and 19% at 5 years, and 49%, 42%, and 37% at 10 years for groups I, II, and III, respectively.
DISCUSSION Our results show that stroke-free rates are comparable for all groups. All strokes occurring during follow-up were ipsilateral to the surgically treated side, thus demonstrating for the group with contralateral occlusion that the hemisphere of the occluded side is well protected by preventive surgery of the contralateral carotid stenosis. These results contradict those of the North American Symptom-
atic Carotid Endarterectomy Trial (NASCET): the long-term stroke rate for patients with a contralateral occlusion was 22.1% at 2 years. This rate, which is very high compared with all other series in the literature and with ours, was nevertheless better than that for the same population receiving medical treatment; the stroke rate at 2 years was 69.4%.6 Results are identical in series, including ours, in which patients suffer from stenosis of both carotid arteries. Long-term freedom from stroke is good and is identical to that of a control population with a unilateral stenosis.5 These results lead us to ask whether involvement of the contralateral carotid artery is an index of severity of atherosclerosis. Authors who have studied this question in retrospective studies have concluded that the condition of the contralateral carotid artery has no influence on the long-term results of carotid surgery7,8 and that
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Fig. 1. Global survival rate among the three groups of patients. Survival curves were drawn according to the Kaplan-Meier method. The log-rank test showed no statistical difference between groups (p = 0.55).
Fig. 2. Actuarial stroke-free rate among the three groups of patients. Stroke-free rate curves were drawn according to the Kaplan-Meier method. The log-rank test showed no statistical difference between groups (p = 0.6).
Fig. 3. Actuarial cardiac event-free rate (fatal or nonfatal) among the three groups of patients. Cardiac event-free rate curves were drawn according to the Kaplan-Meier method. The log-rank test showed no statistical difference between groups (p = 0.3).
Prognostic value of contralateral carotid artery 337
the main cause of long-term mortality following carotid surgery, whatever the condition of the contralateral artery, is cardiac in origin.4-9 In a comparison of 598 patients with 63 patients who had contralateral occlusion, Mackey et al. reported that long-term mortality was identical in the two groups and that death was due mainly to cardiac, and more particularly, coronary, events.7 They concluded that carotid involvement was a purely local phenomenon and that the aim of carotid endarterectomy was to protect the two cerebral hemispheres, even in the presence of a contralateral occlusion. The only studies that do demonstrate a difference in long-term survival rates are those in which patients are divided into two groups on the basis of the seriousness of their coronary artery disease and coronary risk factors. Indeed, in most series in the literature, groups of patients with established coronary artery disease and those with numerous coronary risk factors have shorter long-term survival than other patients. The authors therefore recommend aggressive cardiac follow-up but fail to give clear indications of the approach to be adopted. Mackey and colleagues suggest selecting patients on the basis of their preoperative coronary status and recommend coronary arteriography 3 years after surgery for those with clinical signs of coronary artery disease or those with coronary risk factors but no clinical coronaropathy.10 Attempts have also been made to select patients preoperatively, not according to clinical criteria, but on the basis of other examinations, such as a stress test with or without myocardial scintigraphy. All of these authors report higher rates of late mortality in coronary patients or those who have coronary risk factors.7,9,10 None of the series, however, reports long-term survival rates for patients who have undergone peripheral or coronary revascularization.2 In our study, although patients in group II had significantly more preoperative coronary artery disease than those of the other groups, their survival rate was similar to that of the other groups. We were unable to demonstrate significant differences between the three groups concerning the overall actuarial long-term survival rates, actuarial freedom from fatal or nonfatal cardiac events, or the actuarial rate of cardiac mortality. We have had exactly the same results as those shown in the literature. In all groups the main cause of death was of cardiac, and more specifically, coronary, origin. This leads us to believe that carotid artery disease develops independently as a local phenomenon and that involvement of the contralateral carotid artery, in the form of stenosis or occlusion, is of no signifi-
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cant as a marker of the severity of possible coronary artery disease. Lacroix et al. reported an increase in life expectancy in patients with unilateral carotid artery disease compared to a group of patients with contralateral occlusion (at 10 years 67% vs. 43%). They concluded, however, that these data are not reliable because there were more women and less patients with overt coronary artery disease in the control group.11 The follow-up strategies of coronary artery disease are not well defined. Some authors practice preoperative selection on the basis of clinical or paraclinical criteria (stress ECG, myocardial scintigraphy, stress echocardiography, etc.);2 others prefer selection after 3 years, the point at which most survival curves turn downward on account of the increased frequency of coronary events.10-12 However, as far as we know, there is no series in which the outcome for a subgroup of patients undergoing coronary revascularization as a consequence of close cardiological follow-up has been reported. In a study similar to ours, Mattos et al. followed 354 patients who had undergone carotid surgery, 22.6% of whom had tandem stenoses (stenosis of the carotid siphon ipsilateral to the stenosis being surgically treated). The number of patients suffering preoperatively from coronary artery disease was similar in the two groups, and the results were similar with regard to stroke-free rate at 5 years (88.5% vs. 95% for the groups with and without tandem stenoses, respectively) and cardiac mortality (11.3% and 6% for the groups with and without tandem stenoses, respectively). The authors concluded that stenosis of the carotid siphon was not necessarily a marker of the seriousness of atherosclerotic disease and that it had no unfavorable impact on the long-term risk of stroke.13 In another study of 547 patients who were to undergo vascular surgery (aortic surgery, distal bypass grafts, carotid endarterectomy), cardiac morbidity and mortality were compared in the short and long term. Patients were divided into two groups: those with coronary heart disease risk factors and those without. Overall survival rates for patients in the group without risk factors were identical, regardless of the type of surgery involved. In the group of patients with coronary risk factors, survival rates were markedly lower among patients undergoing infrainguinal or carotid surgery than for those undergoing aortic surgery. Heart disease was the main cause of death, which occurred in most cases after 36 months.14 These results suggest that the follow-up of patients undergoing carotid surgery should be assessed not on the basis of the
Annals of Vascular Surgery
condition of the contralateral carotid artery but on the basis of the patient’s coronary status. What type of coronary surveillance can then be proposed? Authors differ in their answers to this question. Some suggest preoperative patient selection while others prefer to wait 3 years before including certain patients in a program of close cardiac surveillance with, in some cases, almost systematic use of coronarography.2,8-12 The preoperative strategy is based on examinations such as stress ECG and/or myocardial scintigraphy. The stress test cannot be completed by all patients, either because their average age is too high or they have simultaneous presence of occlusive arteriopathy of the lower limbs. Urbinati et al. suggest that patients unable to complete the exercise test be considered an intermediate-risk group who should benefit from close cardiac follow-up.15 Myocardial scintigraphy is of limited usefulness, as Baron’s group has already shown,16 and it does not seem reasonable to propose preoperative coronarography for all patients. This would only be possible if the combined risk of preoperative coronarography and possible subsequent coronary revascularisation was lower than the risk involved in carotid surgery alone for a vulnerable patient. Furthermore, the use of clinical coronary signs alone for patient selection seems inappropriate in view of the large number of cases of silent coronary artery disease. In our view, it is preferable that all patients undergoing carotid surgery, whatever the condition of their contralateral carotid artery, receive specialized cardiac follow-up, particularly 3 years after surgery, since this appears to be the moment at which, on average, fatal and nonfatal cardiac events increase in frequency. The type of examination that could then be offered remains to be decided. To our knowledge, there are no series comparing the effectiveness of coronarography and other methods of screening for coronary artery disease in patients who have undergone carotid surgery and who have been followed up over a long period.
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4. Coyle KA, Smith R, Salam AA, Dodson TF, Chaikof EL, Lumsden AB. Carotid endarterectomy in patients with contralateral carotid occlusion: review of a 10-year experience. Cardiovasc Surg 1996;4:71-75. 5. Mattos F, Hodgson KJ, Londrey GL. Carotid endarterectomy: operative risks, recurrent stenosis, and long-term stroke rates in a modern series. J Cardiovasc Surg 1992;33:387400. 6. Gasecki AP, Eliasziw M, Ferguson GG, Hachinski V, Barnett HJ. Long-term prognosis and effect of endarterectomy in patients with symptomatic severe carotid stenosis and contralateral carotid stenosis or occlusion: results from North American Symptomatic Carotid Endarterectomy Trial (NASCET) Group. J Neurosurg 1995;83:778-782. 7. Mackey WC, O’Donnell TF, Callow AD. Carotid endarterectomy contralateral to an occluded carotid artery: perioperative risk and late results. J Vasc Surg 1990;11:778-785. 8. Roques XF, Baudet EM, Clerc F. Results of carotid endarterectomy in patients 75 years of age and older. J Cardiovasc Surg 1991;32:726-731. 9. Ricotta JJ, O’Brien MS, Weese JAD. Carotid endarterectomy for non-hemispheric ischaemia: long-term follow-up. Cardiovasc Surg 1994;2:561-566. 10. Mackey WC, O’Donnell TFJ, Callow AD. Cardiac risk in patients undergoing carotid endarterectomy: impact on peri-
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operative and long-term mortality. J Vasc Surg 1990;11:226234. Lacroix H, Hemelrijck JV, Carton H, Nevelsteen A, Suy R. Carotid artery surgery in the presence of an occlusion of the contralateral carotid artery: perioperative risk analysis and follow-up. Cardiovasc Surg 1994;2:26-31. Charanjit RS, Gersh BJ, Whisnant JP. Influence of coronary heart disease on morbidity and mortality after carotid endarterectomy: a population based study in Olmsted County, Minnesota (1970-1988). J Am Coll Cardiol 1992;19:12541260. Mattos MA, Bemmelen PSV, Hodgson KJ, Barkmeier LD, Ramsey DE, Sumner DS. The influence of carotid siphon stenosis on short- and long-term outcome after carotid endarterectomy. J Vasc Surg 1993;17:902-911. L’italien GJ, Cambria RP, Cutler BS. Comparative early and late cardiac morbidity among patients requiring different vascular surgery procedures. J Vasc Surg 1995;21:935-944. Urbinati S, Pasquale GD, Andreoli A. Preoperative noninvasive coronary risk stratification in candidates for carotid endarterectomy. Stroke 1994;25:2022-2027. Baron JF, Mundler O, Bertrand M. Dipyridamole-thallium scintigraphy and gated radionuclide angiography to assess cardiac risk before abdominal aortic surgery. N Engl J Med 1994;330:663-669.