CAROTID ARTERY SURGERY FOR PEOPLE WITH EXISTING CORONARY ARTERY DISEASE

Transcription

1 *86 Coronary disease CAROTID ARTERY SURGERY FOR PEOPLE WITH EXISTING CORONARY ARTERY DISEASE Additional referenes appear on the Heart website DIAGNOSIS Correspondene to: Mr Ian Lane, Cardiff Vasular Unit, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, UK; ardiffandvale.wales.nhs.uk Ian Lane, John Byrne Carotid artery surgery for neurologial symptoms was first reported by Eastott and olleagues in 1954 following earlier reognition that extraranial atheroma was assoiated with ishaemi stroke. 1 Carotid endarteretomy rapidly established itself as one of the most frequently performed proedures in the USA, largely based on surgery for asymptomati atheroslerosis or a arotid bruit. Pratie in the UK was more autious, awaiting the results of European and US trials to larify management of symptomati disease with arotid stenosis of over 70%. OF CAROTID ARTERY DISEASE Atheroslerosis is a generalised disease, and while symptoms may be site speifi, inevitably disease elsewhere will influene the overall management of a patient. The risk of stroke is inreased during oronary artery surgery for angina in the presene of asymptomati arotid disease; onversely the risks of arotid endarteretomy are higher in patients with silent myoardial ishaemia. Early arotid artery wall disease is a preditor for oronary atheroslerosis and subsequent oronary vasular events. 2 The primary symptoms of arotid atheroslerosis are neurologial events and amaurosis fugax aused by embolisation from a plaque. Neurologial events inlude transient ishaemi attaks and stroke and must be related to the ontralateral side of the body from that of the stenosis. Events may be sensory, motor, or ombined and on oasion are onfined to intermittent dysarthria. Classially transient ishaemi attaks last less than 24 hours with full reovery. The 24 hour watershed is an epidemiologial tool and does not neessarily imply the absene of permanent brain damage. Imaging by omputed tomographi san has demonstrated multiple erebral infarts in patients showing full reovery after transient ishaemi attaks. The frequeny of attaks is variable and weeks or months may elapse between events. Multiple events within a timesale of hours (resendo transient ishaemi attaks) arry a high risk of stroke as they may preede arotid artery thrombosis. Loss of onsiousness, vertigo, diplopia and bilateral symptoms should not be attributed to arotid stenosis whih is more likely to be a oinidental finding. Within the population there is a high prevalene of asymptomati arotid stenosis, often oinidental to other auses of neurologial events. Disorders produing neurologial events, transient or permanent, inlude: intraerebral arteriovenous malformations demyelinating disease launar infarts intraranial tumours Heart 2002;87:86 90 arrhythmias systemi hypotension. Arterial embolisation annot be assumed to originate from atheroslerosis of the arotid bifuration. Alternative soures of emboli inlude: ardia mural thrombosis and valve disease atrial fibrillation left atrial myxoma aorti and great vessel atheroslerosis paradoxial embolus from the lower limb intraranial atheroslerosis, partiularly in the arotid siphon. Symptoms of amaurosis fugax onsist of intermittent loss of vision in one eye or part of an eye. They have the appearane of a mist or urtain obsuring vision. The presene of a arotid bruit is not an aurate determinant of either arotid stenosis or prognosis. It merely implies the presene of turbulene of flow together with the probability of atheroslerosis. Tight arterial stenoses may allow insuffiient flow to produe a bruit. Imaging of the arotid bifuration in patients with suspeted arotid artery disease is performed using olour duplex san whih is aurate and sensitive, providing information on the degree of stenosis and plaque morphology (fig 1). Ulerated plaque and intraplaque Heart: first published as /heart on 1 January Downloaded from on 6 September 2018 by guest. Proteted by opyright.

2 Figure 1 Colour duplex image showing internal arotid artery in red with a moderate stenosis haraterised as soft plaque. Charaterisation of plaque may be of prognosti value. haemorrhage arry a poorer prognosis than endothelialised stenosis. Duplex sanning measures stenosis aording to peak veloity of blood flow, but the tehnique an also measure arterial diameter from an image. Although it does not give the same detailed information on proximal or intraranial disease as angiography, in patients with appropriate symptoms further imaging is not required before surgery. Duplex sanning may not differentiate between a tight stenosis (95%) with trikle flow and an oluded arotid artery. In these ases magneti resonane angiography provides an aurate alternative to arteriography (fig 2). There is no indiation for surgery on an oluded arotid artery as the risk of embolisation has disappeared and re-establishment of flow may propel distal thrombus into the brain. There is little need in modern pratie for formal intra-arterial angiography. As well as loal ompliations at the site of arterial punture, there is a small but signifiant risk of stroke even without seletive arotid atheterisation. Intravenous digital angiography Figure 2 Magneti resonane angiogram with a ritial stenosis of the origin of the internal arotid artery on the right. Duplex san No ompliations Outpatient investigation No information on intraerebral irulation Requires operator expertise Provides information on plaque morphology May be inaurate with trikle flow Consider magneti resonane angiography for tight stenoses has proved disappointing in providing suffiient resolution of the arotid bifuration. Carotid imaging at the time of oronary angiography should be reserved for ases where proximal arterial or intraranial disease is suspeted as a ause for symptoms. MANAGEMENT OF THE DISEASE PROCESS Atheroslerosis should be treated by orretion of risk fators suh as hyperlipidaemia, smoking, hypertension, diabetes, and polyythaemia. In the presene of lassi symptoms and appropriate arotid stenosis a deision to intervene an be based on duplex san alone. Unless there is a ontraindiation, aspirin 300 mg/day will signifiantly redue the inidene of further neurologial events. The role of new antiplatelet agents suh as lopidogrel and tilopidine have not been subjeted to trial. Antioagulants are unproven and arry signifiant side effets, but may be useful when other treatment modalities have failed. CAROTID INTERVENTION Carotid endarteretomy under general anaestheti arries a low mortality in fit patients. Cardia disease was responsible for 49% of deaths in one large series of patients undergoing arotid endarteretomy with mortality due to myoardial infartion. 3 Those with severe ardia or respiratory dysfuntion an be treated under ervial blok or loal anaestheti, whih has the advantage that neurologial events are immediately identified and orreted by shunting. There is a requirement for the patient to remain immobile for the proedure whih may not be tolerated, although in one series 97% of 449 patients were suessfully treated under loal anaesthesia. 4 In one randomised ontrolled trial the rate of myoardial ishaemia in those treated under loal anaestheti was half that of general anaestheti, although the results did not reah signifiane. The dilemma should be resolved by the multientre general or loal anaesthesia for arotid endarteretomy (GALA) trial. Carotid angioplasty is tehnially possible and subjet to linial multientre trial. While the ranial nerve injuries assoiated with surgery are avoided, distal embolisation following arotid mobilisation an produe stroke, although this may be prevented by synhronous distal balloon olusion of the artery. In a multientre study of 504 patients randomised to surgery or angioplasty the ombined stroke and mortality rate at 30 days was 10% for both surgery and angioplasty. 5 There has been ritiism of the high stroke rate in the surgial arm of this trial. Modern interventional tehniques, inluding the use of stents together with erebral protetion devies, require further long term evaluation. SURGERY FOR SYMPTOMATIC CAROTID STENOSIS Symptomati arotid stenosis arries a stroke risk of approximately 15% in the year following a motor or sensory *87 Heart: first published as /heart on 1 January Downloaded from on 6 September 2018 by guest. Proteted by opyright.

3 Transient ishaemi attak *88 Figure 3 Digital subtration arotid angiogram revealing a deep ulerated plaque in the left arotid bulb and a severe irregular stenosis of the internal arotid artery on the right. Biplanar views are required to onfirm the degree of stenosis on the right. The vertebral artery is filled on the left. neurologial event, with the sequelae of amaurosis fugax having a more benign prognosis. While antiplatelet treatment will redue the risk of further events to 8% per year, before 1992 the evidene for effiay of arotid endarteretomy was not sientifially sound. Publiations were based on personal series with poor lassifiation of degree of stenosis, presene or absene of symptoms, use of antiplatelet mediation, and duration of follow up. Indiations for surgery Two multientre randomised ontrolled trials have demonstrated an advantage of arotid endarteretomy ombined with aspirin, ompared to aspirin alone, in the prevention of stroke following a neurologial event in patients with over 70% arotid stenosis. In a North Amerian trial, patients with stroke or transient ishaemi attak within three months of entry, ombined with symptomati arotid stenosis of over 70%, were randomised to arotid endarteretomy or aspirin 1300 mg/day. The umulative stroke risk for the surgial arm of the trial was 9% ompared to 22% for medial treatment. 6 A multientre European trial, in 80 entres, randomised patients with symptomati arotid stenosis of over 70% to surgery or best medial treatment. The qualifying neurologial event for entry into the trial had to have ourred within six months previously. The umulative risk of stroke was 12.3% for surgery ompared to 21.9% for medial treatment, although the 30 day ombined stroke and mortality rate for surgery was onsidered high at 7.5%. This may be due to some entres performing only low numbers of arotid endarteretomies. 7 Corret risk fators for atheroslerosis Duplex san Add antiplatelet treatment Consider surgery for arotid stenosis over 70% Angioplasty aeptable in high risk patients Intervention should be performed urgently Carotid restenosis is rarely symptomati Despite minor differenes between these two trials in terms of assessment of the arotid stenosis and time interval from qualifying event, the onlusions were that surgery has an advantage over medial treatment in symptomati arotid stenoses of 70% or over. Pre-olusive lesions are onsidered high risk for stroke although this has reently been hallenged. The role of surgery in patients with moderate stenosis of between 50 69% is unlear, but should be onsidered if symptoms are unontrolled by onventional treatment and maximum perioperative death and disabling stroke rate of 2% an be ahieved. 8 Oasionally embolisation an originate from a deep ulerated plaque in the absene of stenosis (fig 3). While endothelial remodelling may our, surgery should be onsidered if antiplatelet mediation fails to ontrol symptoms. Compliations of surgery The suess of arotid endarteretomy to prevent stroke depends on the perioperative stroke and death rate, whih should be less than 3%. Fators that inrease the risk of perioperative stroke inlude transient ishaemi attaks rather than amaurosis fugax, ontralateral arotid olusion, and irregular or ulerated plaque at the side of surgery. There is no signifiant effet of age above or below 65 years on stroke rate. 9 Patients must be provided with balaned information on the perioperative stroke rate and risk of damage to ranial nerves ompared to non-operative management, in order to enable informed partiipation in their own management. An analysis of the North Amerian symptomati arotid endarteretomy trial revealed an overall perioperative stroke and death rate of 6.5%, with permanently disabling stroke ombined with death of 2.0%. The risk of ranial nerve injuries was 8.6%, affeting the faial, hypoglossal, and vagus nerves, although the majority were desribed as mild in severity. 9 MANAGEMENT OF ASYMPTOMATIC CAROTID STENOSIS Asymptomati arotid stenosis arries a stroke risk of approximately 2% per year. This stroke risk appears related to the severity of stenosis and remains onstant with time, unlike the risk following a neurologial event in a symptomati arotid stenosis. 2 A trial omparing surgery to aspirin for asymptomati arotid stenosis showed no benefit from surgery although randomisation was inomplete. 10 In a multientre trial of 1662 patients (asymptomati arotid atheroslerosis study, ACAS) with over 60% asymptomati arotid stenoses randomised to surgery or medial treatment, at five years the ombined stroke and mortality rate for surgery was 5.1% ompared to 11% for medial treatment. 3 Although all entres were validated for low surgial morbidity, the stroke rate assoiated with arteriography was onsidered to be high at 1.2%. There should be aution when applying the results of this trial to a wide body of surgeons, espeially as the absolute Heart: first published as /heart on 1 January Downloaded from on 6 September 2018 by guest. Proteted by opyright.

4 risk redution for stroke was 1% per year. While surgery arries an advantage over antiplatelet mediation, 20 patients have to undergo arotid endarteretomy to prevent one stroke in every five years. 3 This ompares with four endarteretomies to prevent one stroke a year in symptomati patients. 6 Surgery for asymptomati disease may not be appropriate when many healthare systems are ritially examining ost and benefit. Appliation of the ACAS riteria would lead to a 10 fold inrease in rates of arotid endarteretomy; to put this in perspetive, it is estimated that in Sotland people would have an appropriate stenosis. The ACAS trial did not address asymptomati stenoses in patients over 79 years old, and although many series have shown that surgery an be performed safely in otogenarians, their low life expetany may prelude benefit from arotid endarteretomy. CAROTID ENDARTERECTOMY IN PATIENTS UNDERGOING CORONARY ARTERY SURGERY Coronary artery surgery arries an overall risk of stroke of 1.6% and this is inreased in reoperative surgery, presene of arotid stenosis, and in those over 75 years of age. In ertain subgroups the inidene is 9% and even higher in those undergoing valve surgery. Additionally, there is an exess of late neurologial events following ardiovasular surgery in the presene of unorreted arotid stenosis. 13 The oexistene of symptomati oronary artery disease and signifiant arotid artery stenosis ranges from % of the population. 14 Sreening for arotid artery disease in patients undergoing oronary artery surgery indiated a prevalene of 8.7% stenoses of over 75%, leading to a perioperative stroke rate of 14.3% in these patients. 15 Stenoses of less than 75% were assoiated with a postoperative neurologial defiit in 2%. Causes of stroke in the perioperative period inlude embolisation from the heart and great vessels, global brain ishaemia aused by hypoperfusion, air embolus, and intraranial bleeding preipitated by intraoperative antioagulation, in addition to emboli originating from the arotid bifuration. Inreased use of off-pump oronary artery bypass may redue the inidene of arotid related events. A prospetive study of 582 patients attempted to differentiate between global and foal ishaemi events. 16 Of the 12 postoperative strokes, arotid stenosis of over 50% or olusion was signifiantly assoiated with five of seven hemispheri events but none of the five global events. Unilateral stenosis of over 80%, bilateral stenosis of over 50% or unilateral olusion with ontralateral stenosis of over 50% was assoiated with a 5.3% risk of hemispheri stroke. No strokes ourred in patients with unilateral 50 79% stenosis. Although unilateral olusion is onsidered of poor prognosti signifiane, asymptomati patients derived no benefit from ipsilateral arotid endarteretomy ompared with medial treatment alone when analysed as part of the ACAS trial. The advantage of prophylati arotid endarteretomy in patients with over 80% arotid stenosis was shown to be signifiant in a retrospetive non-randomised series of 68 patients undergoing synhronous or staged oronary artery surgery. 17 Synhronous bilateral arotid endarteretomy was performed with 6.1% mortality, unrelated to primary ardia or erebrovasular events, in an unseleted series of urgent and eletive patients undergoing oronary artery surgery, but the number of ases was small and further studies are required. 13 In patients with a primary indiation for oronary revasularisation, arotid endarteretomy an be arried out safely at the time of oronary artery surgery. A retrospetive analysis of 206 ases revealed a stroke or neurologial defiit inidene of 3.5%. 18 In 1998 Darling and olleagues demonstrated a neurologial event rate of 2.9% and operative mortality of 2.4% in a prospetive series of 470 patients undergoing synhronous proedures. 19 A randomised trial of synhronous versus staged proedures revealed a higher stroke rate when arotid surgery followed oronary surgery. Conversely, the low morbidity and mortality of arotid endarteretomy alone in patients with oronary artery disease may not justify synhronous oronary revasularisation where this is not indiated primarily. Carotid endarteretomy under loal anaesthesia or regional blok may further redue the ardia risk in patients with oronary artery disease unsuitable for revasularisation, but needs onfirmation by a randomised trial. Patients requiring oronary revasularisation with symptomati arotid disease that fulfil the indiations for surgery should undergo arotid endarteretomy. In the absene of randomised trials, asymptomati patients should be managed reognising the high stroke risk assoiated with arotid stenosis of over 80% and arotid olusion. There is a need for randomised trials to larify the need for arotid endarteretomy at the time of oronary artery surgery. ACKNOWLEDGEMENTS We are grateful for the advie of Dr Liam Penny (onsultant ardiologist) and Professor Mark Wiles (professor of neurology) in the preparation of this artile. REFERENCES 1 Eastott HHG, Pikering GW, Rob CG. Reonstrution of the internal arotid artery in a patient with intermittent attaks of hemiplegia. Lanet 1954;ii: First published aount of arotid artery surgery, although the stenosis was reseted with end-to-end anastomosis of the arotid arteries. DeBakey had performed arotid endarteretomy one year previously although this was not reported for 19 years. 2 Rothwell PM. Carotid artery disease and the risk of ishaemi stroke and oronary vasular events. Cerebrovas Dis 2000;10: Pathophysiologial review of arotid stenosis and plaque morphology related to neurologial events in an attempt to identify prognosti markers. 3 Exeutive Committee for the Asymptomati Carotid Atheroslerosis Study. Endarteretomy for asymptomati arotid artery stenosis. JAMA 1995;273: Although surgery was benefiial, patients were seleted by partiipants whih may introdue bias. All surgeons were hosen after demonstrating low perioperative morbidity whih again may skew onlusions in favour of endarteretomy. 4 Darling RC, Paty PH, Shah DM, et al. Eversion endarteretomy of the internal arotid artery: tehnique and results in 449 proedures. Surgery 1996;120: CAVITAS. Endovasular versus surgial treatment in patients with arotid stenosis in the arotid and vertebral transluminal angioplasty study (CAVATAS): a randomised trial. Lanet 2001;357: Although similar outomes for the two proedures were present at 3 years, endovasular treatment avoided ranial nerve damage but appeared to be assoiated with more severe arotid stenosis beoming apparent. 6 North Amerian Symptomati Carotid Endarteretomy Trial Collaborators. Benefiial effet of arotid endarteretomy in symptomati patients with high-grade stenoses. N Engl J Med 1991;325: Landmark study demonstrating benefit of arotid endarteretomy over medial treatment for 70 99% arotid stenosis. 7 European Carotid Surgery Trialists Collaborative Group. Randomised trial of endarteretomy for reently symptomati arotid stenosis: final results of the MRC European arotid surgery trial (ECST). Lanet 1998;351: *89 Heart: first published as /heart on 1 January Downloaded from on 6 September 2018 by guest. Proteted by opyright.

5 *90 Similar outomes to NASCET in a multientre trial with interim results published in 199l. Critiised for a relatively high death and stroke rate at 30 days of 7.0% whih may be related to low numbers of patients entered by some entres, implying need for both audit of results and ritial numbers of patients. 8 European Carotid Surgery Trialists Collaborative Group. Endarteretomy for the moderate symptomati arotid stenosis: interim results from the MRC European arotid surgery trial. Lanet 1996;347: Ferguson GG, Eliasziw M, Barr HW, et al. The North Amerian arotid endarteretomy trial: surgial results in 1415 patients. Stroke 1999;30: Long term results at eight years for endarteretomy of both greater and less than 70% stenosis. Although other surgial ompliations are desribed as rarely linially important, 8.6% of patients sustained a ranial nerve injury. 10 CASANOVA Study Group. Carotid surgery versus medial therapy in asymptomati arotid stenosis. Stroke 1991;22: Although no benefit for surgery was demonstrated, all patients with stenoses greater than 90% underwent operation. 11 Hogue CW, Murphy SF, Shehtman KB, et al. Risk fators for delayed stroke after ardia surgery. Cirulation 1999;100: Riotta JJ, Faggioli GL, Castilone A, et al. Risk fators for stroke after ardia surgery: Buffalo Cardia-Cerebra study group. J Vas Surg 1995;21: Barnes RW, Nix ML, Sansonetti D, et al. Late outome of untreated asymptomati arotid disease following ardiovasular operations. J Vas Surg 1985;2: Dylewski M, Canver CC, Chandra J, et al. Coronary artery bypass ombined with bilateral arotid endarteretomy. Ann Thora Surg 2001;71: Fagioli GL, Curl GR, Riotta JJ. The role of arotid sreening before oronary artery bypass. JVasSurg1990;12: Perioperative stroke rates in 539 patients with only 19 patients submitted to prophylati arotid endarteretomy, thus not allowing an aurate assessment of intervention. 16 Shwartz LB, Bridgman AH, Kieffer RW, et al. Asymptomati arotid artery stenosis in patients undergoing ardiopulmonary bypass. J Vas Surg 1995;21: Hines GL, Sott WC, Shubah SL, et al. Prophylati arotid endarteretomy in patients with high-grade arotid stenosis undergoing oronary bypass: does it derease the inidene of perioperative stroke? Ann Vas Surg 1998;12: Chang BB, Darling RC, Shah DM, et al. Carotid endarteretomy an be safely performed with aeptable mortality and morbidity in patients requiring oronary artery bypass grafts. Am J Surg 1994;168: Darling RC, Dylewski M, Chang BB, et al. Combined arotid endarteretomy and oronary artery bypass grafting does not inrease the risk of perioperative stroke. Cardiovas Surg 1998;6: Heart: first published as /heart on 1 January Downloaded from on 6 September 2018 by guest. Proteted by opyright.