Carotid Endarterectomy for Stroke Prevention

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1 uriginai ivrucie Carotid Endarterectomy for Stroke Prevention Rajiv Parakh, Sandeep Agarwal, Ashok Gupta, Tarun Grover Department of Peripheral Vascular & Endovascular Surgery, Sir Ganga Ram Hospital, New Delhi Abstract Introduction: Several randomized trials now have established guidelines regarding patient selection for zarotid endarterectomy (CEA) that have been widely accepted but have little relevance unless they are considered in the context ofperioperative risk. The Purpose of this study was to demonstrate the feasibility of zarly outcome assessment for stroke prevention. Material and methods: Since 1993 demographic information and in hospital results for all C.E.A performed by pur department have been entered into a prospective registry for the purpose of this report, we have analyzed the stroke and mortality rates for 369 consecutive CEAs (358 patients) including 355 that were oerformed as isolated operations and 14 that were combined with simultaneous coronary artery bypass grafting 'CABG). Minor complications like, transient nerve injuries which recovered completely, wound hematoma v.hat did not require evacuation or blood transfusion and wound infection which did not require any intervention uere not included in this study. Conclusions: Prospective outcome assessment is essential to reconcile the indications for CEA with its actual esults and it may lead incidentally to important observations concerning patient care. (J. Vase Surg 1997; 26: 1-10). To conclude, CEA is a safe procedure with a beneficial role in stroke prevention but strict selection -.riteria and precise and safe operative details must be adhered to, to prevent the procedure from going into iisrepute. It has a learning curve, which is evident from our experience. INTRODUCTION Carotid surgery as we know it today was developed in the 1950s. A number of different procedures were described for treating atheromatous stenosis of carotid arteries. These included resection of the stenosis and replacement with a homograft or saphenous vein jraft. These have been largely abandoned and ;arotid endarterectomy has become the operation jf choice. Since then, indications for carotid 3ndarterectomy, as well as technical aspects of the operation, have been subjected to constant 3valuation. Since 1991 the results of several prospective, randomized trials either have strongly implied or have conclusively Paper received: December 2001 Paper accepted: January 2002 \ddress for correspondence Dr. Rajiv Parakh 3-6/59-A. S.D. Area, Mew Delhi rparakhl@yahoo.co.in demonstrated the superiority of carotid endarterectomy (CEA) over non-operative management for stroke prevention in both asymptomatic and symptomatic patients who have severe carotid stenosis. 1 ' 5 Furthermore, a number of representative case series previously have suggested that the freedom from stroke conferred by CEA is exceedingly durable, often in the range of 85 % to 90 % as long as 10 years after surgical treatment. 610 The long-term benefit of CEA is substantially influenced by its perioperative stroke and mortality rates, however, and the randomized trials also might have been interpreted quite differently if they had been associated with an unacceptable incidence of early complications. The safety of CEA depends on many factors, including patient selection, surgical technique, and, according to some reports, the volume of experience with this procedure among individual hospitals and surgeons In an attempt to establish performance guidelines for CEA, its 30 day stroke morbidity and mortality :

2 Parakh et al rates be continuously audited for comparison with the following criteria: less than 3% in patients whose operations are performed for asymptomatic stenosis, less than 5% in those who have a history of transient ischaemic attacks (TIAs), less than 7% in those with prior strokes, and less than 10% in patients who require reoperations for recurrent carotid stenosis. 14 Centres at which such audits have been conducted generally report a favorable influence on surgical outcome. 15 ' 16 Our department has maintained a registry of all surgical procedures performed since January This registry contains basic demographic data, the indications for intervention, relevant technical details (e.g. graft and patch materials, inflow and outflow vessels), and specific descriptions of both fatal and nonfatal in-hospital complications. The present reportdescribes the cumulative experience with CEA of one surgeon from 1993 through Its purpose is to demonstrate the feasibility of prospective outcome assessment in collective series of CEAs. MATERIAL AND METHODS We performed 369 consecutive CEAs in 358 patients during the 8 years that comprise this review, including 355 isolated, or solo, procedures and 14 others that were combined with simultaneous coronary artery bypass grafting (CABG). Gender and age distributions were similar in the isolated and combined groups, but patients who were selected for combined CEAs were more likely to have asymptomatic carotid stenosis as their indication for intervention (Table 1) Table 1: Basic demographic data No. % Procedures % Men Women % 33% Age (yr) Range Mean 54 Symptomatic stenosis % TIA or Amaurosis % Prior Stroke 48 13% Asymptomatic 29 8% Surgical indications Preoperative intra-arterial digital subtraction angiograms were obtained for the vast majority of the patients in this series. Throughout the study period, we consistently used the following angiographic indications for elective surgical treatment. Symptomatic patients At least 70% stenosis of the internal carotid artery (ICA), unless a lesion of less severity was associated with persistent TIAs despite antiplatelet therapy. Asymptomatic patients At least 80% stenosis of the ICA, or 60% to 79% stenosis in the presence of an occlusion of the contralateral ICA. All these cut off points were established on the basis of a comparison between the residual lumen at the site of maximum stenosis and the estimated normal diameter of the ICA at the same level, usually corresponding to the carotid bulb. Thus our criteria are equivalent to those that were used in the European Carotid Surgery Trial (ECST). 2 Candidates for combined operations were selected angiographically after Doppler ultrasound (duplex) scans had revealed appropriate indications for CEA in patients who were discovered to have either asymptomatic carotid bruits or a history of previous neurologic symptoms before CABG. We have implemented mass non-invasive screening for carotid disease in the general coronary bypass population at our centre. Technical considerations With rare exceptions, nearly all CEAs were performed with the patient under locoregional anesthesia with routine intraluminal shunting. The CEA was completed before the median sternotomy was performed during combined CEA and coronary artery bypass procedures, but the cervical incision was not closed until heparin had been reversed with protamine sulfate at the conclusion of the entire operation. Three techniques have been described for CEA of which standard endarterectomy via a

3 (ACAS), 5 and other similar randomized investigations conducted by the Veterans Administration (VA) and in Europe suggest. 24 It is also likely that much of this renewed interest in CEA will be focused on the management of asymptomatic carotid stenosis. Therefore, because both the ACAS and the VA asymptomatic trial have clearly indicated that the margin of benefit for CEA in asymptomatic patients depends largely on the attainment of low operative stroke and mortality rates, it is now more imperative than ever for these risks to be documented at every hospital in which CEA is performed. Neurologic complications in conjunction with CEA nearly always involve the ipsilateral cerebral hemisphere, not infrequently are caused by early postoperative ICA thrombosis or platelet embolization and occasionally may be reversible if they are promptly recognized. There were no differences in early outcome between patients older or younger than 70 years of age. Others have made the same observation using the age of 75 as their criterion 1820 although Cronenwett et al. 21 recently have developed a Markov model that suggests that beyond this age CEA becomes considerable less cost-effective as means of long-term stroke prevention in patients with asymptomatic carotid stenosis. Although specific factors that may influence the outcome of CEA are discussed below, certain aspects of general technique are useful in reducing the risk of complications. Whilst not subjected to critical assessment the authors believe them to be important. They include: a) Careful positioning of the patient on the operating table-excessive rotation or extension of the neck may compromise cerebral blood flow during carotid clamping, b) Minimal manipulation of the carotid arteries ('no-touch' technique) during dissection to reduce the risk of embolism, c) Infusion of low molecular weight dextran-40 during the clamping and immediately after restoration of flow has also found to be useful in reducing the particulate embolisation during the procedure, d) The use of magnifying loupes for endarterectomy and removal of residual fragment and strands, and for vessel repair, e) The use of sharp bent-on-flat scissors for clean transaction of the proximal endartefectomy site and appropriate use of proximal and distal tacking sutures, and f) Careful flushing of debris or air with heparinised saline and continuous back-bleeding of the internal carotid artery (ICA) during final closure of the arteriotomy, followed by initial reperfusion of the external carotid artery (ECA). Perioperative stroke rate were 0.66 % for synthetic patching, compared with % for primary arteriotomy closure. Overall these differences were significant and were relatively consistent irrespective of gender or surgical indication. These results as further support to our earlier impression that patch angioplasty enhances the early outcome of CEA. 17 CONCLUSIONS The 30 day postoperative stroke and 266 US Vol. 64, No. 3,

4 Carotid endarterectomy longitudinal arteriotomy (scea) is most widely used. Whilst eversion endarterectomy (ecea) has gained in popularity, interposition grafting should be reserved for revisional carotid surgery, Data from both prospective randomised trials and retrospective studies have failed to show a difference in early ICA thrombosis and 30 day combined stroke and mortality rates, or in the frequency of cranial nerve injury and myocardial infarction, between scea and ecea. 22 In our series eversion endarterectomy was reserved for patients who had torturous ICA distal to stenosis. Twelve patients (3.25%) underwent eversion endarterectomy in our series Patch angioplasty following scea may reduce the rate of early ICA thrombosis (reduced thrombogenicity of the endarterectomy site, improved ICA diameter) and late restenosis (neointimal hyperplasia) and thus improve both early and long-term stroke rates. 23 In our experience, patch angioplasty has been associated with a lower incidence of perioperative stroke, early ICA thrombosis and late recurrent stenosis than primary arteriotomy closure during CEA. 17 Therefore, carotid patching was preferentially used in conjunction with 300 (81%) of the 369 operations in the present series, polytetrafluroethylene (PTFE) patches were used in all patients. RESULTS Postoperative Deaths Three patients (0.83%) died during the same duration to the hospital for CEA (Table 2.) The three postoperative deaths after CEA were caused by fatal hemorrhagic stroke in one patient, bilateral cortical stroke in one and one patient died of chronic renal failure. Table 2: Operative mortality rates No! %~ All procedures 3/ % Men 2/ % Women Age 1/ % < 70 yr 1/ % >70 yr 2/ % Asymptomatic stenosis TIA or amaurosis 0/29 2/292 0% 0.68% Prior stroke 1/ % Perioperative Strokes Any central neurologic deficit that either persisted longer than 24 hours or was associated with a new infarct on a computed tomographic (CT) scan of the brain was defined as a perioperative stroke. 11 patients sustained such events (Table 3). The perioperative stroke rate was 10.4 % in patients who had previous history of stroke. This subgroup did not constitute a large number of patients as compared to other subgroups therefore, there was no statistical significance. Moreover, most of these patients were cases subjected to CEA in the early part of our study. This outcome clearly advocates that this procedure has a definite learning curve. Table 3: Perioperative stroke rates No %~ All procedures 11/ % Men 7/ % Women 4/ % Age < 70 yr 4/ % 70yr 7/ % Asymptomatic stenosis 0/29 0% TIA or amaurosis 6/ % Prior stroke 5/ % Perioperative stroke rate are stratified with respect to method for arteriotomy closure in the total 369 cases of CEAs (Table 4). Above data suggest that complications following direct repair are greater when the diameter of the ICA is 5 mm or less, particularly in women, in^whom the mean diameter of the ICA ( mm) is 8-15% less than in men ( mm). In summary, available evidence favours patch angioplasty after scea. Nine patients (82%) of the eleven strokes in conjunction to the ipsilateral cerebral hemisphere, one (9 %) suffered in the contralateral hemisphere and one (9 %) had in the posterior cerebral circulation. DISCUSSION There predictably will be a larger number of CEAs performed in future as the results favoring surgical treatment that have been reported from the North American Symptomatic Carotid Endarterectomy Trial (NASCET), 1 the Asymptomatic Carotid Atherosclerosis Study

5 mortality rates for CEA were 5.8% in the 8 NASCET, > 7.5 % on the ECST, 2 4.3% in the VA asymptomatic trial, 4 and 1.5 % in the ACAS. 5 Our results have been calculated on the basis of in-hospital events, and therefore, are not strictly equivalent to the data reported from these randomized studies. Nevertheless, our mortality rates for CEAs in symptomatic subgroup of patients which were total 340 is 0.88 %, and asymptomatic patients which were 29 is 0 %. Stroke rates in symptomatic patients was 3.23 and 280 symptomatic patients in which patch angioplasty was done the perioperative stroke rate was 1.42 %. In our series no patient out of asymptomatic subgroup suffered from perioperative stroke. Our data shows sufficiently low perioperative stroke and mortality rate to justify our continued reliance on surgical treatment for stroke prevention. REFERENCES 1. North American Symptomatic Carotid Endarterectomy Trial Collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with highgrade carotid stenosis. N Engl J Med 1991; 325: European Carotid Surgery Trialist' Collaborative Group. MRC European Carotid Surgery Trial: interim results for symptomatic patients with severe (70-99%) or with mild (0-29%) carotid stenosis. Lancet 1991; 337: Mayberg MR, Wilson SE, Yatsu F, et al. Carotid endarterectomy and prevention of cerebral ischaemia in symptomatic carotid stenosis. JAMA 1991; 266: Hobson RW, Weiss DG, Fields WS, et al. Veterans Affairs Cooperative Study Group. Efficacy of carotid endarterectomy for asymptomatic carotid stenosis. N Engl J Med 1993; 328: Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid artery stenosis. JAMA 1995; 273: Moore WS, Boren C, Malone JM, et al. Asympt'>' carotid stenosis: immediate and long-term resu'' prophylactic endarterectomy. Am J Surg 1979; i Bernstein EF, Humber PB, Collins GM, et al. Life Expectancy and late stroke following carotid ' endarterectomy. Ann Surg 1983; 198: Hertzer NR, Arison R. Cumulative stroke and survival ten years after carotid endarterectomy. J Vase Surg 1985; 2: Carotid endarterectomy K Rosenthal D, Rudderman R, Borrero E, et al. Carotid endarterectomy to correct asymptomatic carotid stenosis: ten years later. J Vase Surg 1987; 6: Thompson JE. Carotid endarterectomy for asymptomatic carotid stenosis: an update. J Vase Surg 1991; 13: Hertzer NR. Presidential address: outcome assessment in vascular surgery results mean everything. J. Vase Surg 1995; 21: Hsia DC, Krushat WM, Moscoe LM. Epidemiology of carotid endarterectomies among Medicare beneficiaries. J Vase Surg 1992; 16: Segal HE, Rummel L, Wu B. The utility of PRO data on surgical volume: the example of carotid endarterectomy. Q Rev Biol 1993; May: Beebe HG, Clagett GP, DeWeese JA, et al. Assessing risk associated with carotid endarterectomy: a statement of health professionals by an ad hoc committee on carotid surgery standards of the stroke council, American Heart Association. Circulation 198S; 79: L5. Till JS, Toole JF, Howard VJ, et al. Declining morbidity and mortality of carotid endarterectomy: the Wake Forest University Medical Center experience. Stroke 1987; 18: Mattos MA, Modi JR, Mansour MS, et al. Evolution of carotid endarterectomy in two community hospitals: Springfield revisited- seventeen years and 2243 operations later. J Vase Surg 1995; 21: Hertzer NR, Beven EG, O'Hara PJ, et al. A prospective study of vein patch angioplasty during endarterectomy: three- year results for 801 patients and 917 operations. Ann Surg 1987; 206: L8. Plecha FR, Bertin VJ, Plecha EJ, et al. The early results of vascular surgery in patients 75 years of age and older: an analysis of 3259 cases. J Vase Surg 1985; 2: L9. Pinkerton JA, Gholkar VR. Should patient age be a consideration in carotid endarterectomy? J Vase Surg 1990; 11: Perler BA, Williams GM. Carotid endarterectomy in the very elderly: is it worthwhile? Surgery 1994; 116: Cronenwett JL, Birkmeyer JD, Nakman GB, et al. Cost - effectiveness of carotid endarterectomy in asymptomatic patients. J Vase Surg 1997; 25: Counsell C, Salinas R, Naylor AR, et al. Routine or selective carotid artery shunting during carotid endarterectomy and the different methods of monitoring in selective shunting (Cochrane Review). The Cochrane Library 1996; Issue 3: Cao P, Giordano G, Rango P, et al, Collaborators of the EVEREST Study group. A randomized study of eversion versus standard carotid endartectomy: Study design and preliminary results: The EVEREST Trial J Vase Surg 1998; 27: D