European Journal of Vascular & Endovascular Surgery
Volume 38, Issue 5 , Pages 556-559, November 2009

Patients Undergoing Cardiac Surgery with Asymptomatic Unilateral Carotid Stenoses have a Low Risk of Peri-operative Stroke

  • D. Baiou

      Affiliations

    • The Department of Vascular Surgery, Leicester Royal Infirmary, Clinical Sciences Building, Leicester LE2 7LX, UK
    • ,
  • A. Karageorge

      Affiliations

    • The Department of Vascular Surgery, Leicester Royal Infirmary, Clinical Sciences Building, Leicester LE2 7LX, UK
    • ,
  • T. Spyt

      Affiliations

    • The Department of Cardiac Surgery, Glenfield Hospital, Leicester, UK
    • ,
  • A.R. Naylor

      Affiliations

    • The Department of Vascular Surgery, Leicester Royal Infirmary, Clinical Sciences Building, Leicester LE2 7LX, UK
    • Corresponding Author InformationCorresponding author. Tel.: +44 116 2523252; fax: +44 116 2523179.

Received 3 August 2009; accepted 4 August 2009. published online 31 August 2009.

Article Outline

Abstract 

Background

There is considerable controversy regarding the optimal management of patients undergoing cardiac surgery who are found to have an asymptomatic, unilateral carotid artery stenosis. Prior to 2004, the policy of this Unit was to perform a synchronous cardiac and carotid revascularisation. After January 2004, the policy was changed and patients underwent their cardiac procedure without carotid revascularisation. The aim of this study was to audit the incidence of stroke in the peri-operative period following this change in practice.

Methods

Five-year audit of the 30-day risk of stroke after 61 consecutive open cardiac procedures in patients with unilateral, asymptomatic 70–99% (NASCET) stenoses who did not undergo prophylactic carotid endarterectomy.

Results

61 cardiac procedures; coronary artery bypass grafting (CABG)=44, valve replacement=6, CABG+valve replacement=9, CABG+repair of left ventricular aneurysm=2 were undertaken and the 30-day outcomes audited. There were three deaths (4.9%), all due to myocardial infarction. No strokes occurred in any patient in the 30-day post-operative period.

Conclusion

These results challenge the opinion that the presence of a unilateral, asymptomatic carotid stenosis in patients undergoing open cardiac surgery is associated with an increased risk of peri-operative stroke, sufficient to warrant routine prophylactic carotid revascularisation.

Keywords: Carotid stenosis, Stroke, Cardiac surgery

 

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Introduction 

There remains considerable controversy regarding the optimal management of patients undergoing open cardiac surgery who are found to have a unilateral, asymptomatic carotid stenosis.1 Current practices range from performing cardiac surgery without a prophylactic carotid intervention (isolated CABG), to synchronous/staged carotid and coronary revascularisations using either carotid endarterectomy (CEA) or carotid artery stenting (CAS).

Prior to 2004, the policy in Leicester was to offer prophylactic CEA (as a synchronous procedure) to patients undergoing cardiac surgery who presented with either symptomatic or asymptomatic 70–99% (NASCET) stenoses of the internal carotid artery, irrespective of whether the disease were unilateral or bilateral. However, following the publication of a series of systematic reviews in 2002 and 2003,2, 3, 4 this policy was revised and patients found to have a unilateral asymptomatic carotid stenosis underwent their cardiac procedure without prophylactic CEA.

Five years after the revised policy was introduced, an audit was undertaken to determine the incidence of stroke in the peri-operative period in these 61 patients.

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Materials and Methods 

Patients undergoing open heart surgery in the Cardiac Surgery Unit at the Leicester Glenfield Hospital undergo Duplex ultrasound screening for carotid artery disease if they present with; (i) significant left mainstem coronary artery disease, (ii) a carotid bruit or (iii) a history of transient ischaemic attack (TIA) or stroke. Prior to January 2004, all cardiac surgery patients found to have a unilateral or bilateral 70–99% stenosis (measured using the NASCET measurement method, ie equivalent to an 85–99% ECST stenosis) underwent a synchronous CEA and cardiac procedure. Following a policy change in January 2004, patients with an asymptomatic unilateral carotid stenosis did not undergo a prophylactic CEA.

All 61 patients underwent either coronary artery bypass grafting (CABG), valve replacement, or a combination of CABG and either valve replacement or left ventricular aneurysm repair. No cardiac surgery procedures were performed off-bypass and no cardiac surgery patient with a neurologically asymptomatic, unilateral carotid stenosis underwent prophylactic carotid revascularisation during this five-year period.

All survivors were reviewed by the referring cardiologists and/or cardiac surgeons four to six weeks post-operatively as part of an agreed audit of outcome. In January 2009 (five years after introduction of the policy change), a retrospective case-note review was undertaken to determine whether the performance of cardiac surgery without prophylactic CEA was associated with an increased risk of procedural stroke. The Leicestershire, Northamptonshire and Rutland Research Ethics Committee advised that this study did not fall under the remit of the NHS Research Ethics Committee as it was audit/service evaluation.

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Results 

Between 1st January 2004 and 31st December 2009, 61 consecutive patients undergoing cardiac surgery were found to have unilateral, asymptomatic 70–99% carotid stenoses; 34 (56%) also had a contralateral 50–69% asymptomatic carotid stenosis. The majority of patients underwent isolated CAGB (n=44), six underwent isolated valve replacement (aortic valve replacement (AVR)=4, mitral valve replacement (MVR)=1, AVR+MVR=1), nine underwent CABG plus valve replacement (AVR=4, MVR=5), while two underwent CABG plus repair of a left ventricular aneurysm.

Three patients (4.9%) died within 30-days of surgery, all as a consequence of myocardial infarction. Two had undergone isolated CABG, while one had undergone CABG plus valve replacement. None of the 61 patients in this series suffered a stroke in the peri-operative period.

For the purposes of comparison, the overall mortality rate was 1.6% following 2694 isolated CABG procedures (44/2694) performed during the same time period as this audit was undertaken, 4.7% following valve replacement surgery (74/1565), 7.8% following CABG+valve replacement surgery (9/116) and 9.2% following CABG+‘other’ procedures (12/131).

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Discussion 

Despite the fact that almost four decades have elapsed since Victor Bernhard first questioned whether patients with coexistent carotid and cardiac disease should undergo staged or synchronous carotid/coronary revascularisation,5 there is still considerable controversy and no overall consensus regarding what constitutes optimal management.1 The aetiology of post-CABG stroke is multifactorial and while carotid disease is certainly an important risk factor,2 the single most common cause is probably thromboembolism from the aortic arch.6 As a consequence of increasing awareness regarding the role of aortic pathology in post-CABG stroke, a number of vascular centres around the world have begun to question the value of prophylactic carotid endarterectomy (CEA) or carotid artery stenting (CAS) in the management of patients with combined carotid and cardiac disease.

Evidence suggests that cardiac surgery patients with a symptomatic carotid stenosis do face a significantly increased risk of procedural stroke.7 In this situation, staged or synchronous carotid and cardiac revascularisation can be justified. However, the management of cardiac surgery patients with unilateral or bilateral asymptomatic carotid disease remains enduringly controversial.1 For some, the available evidence is compelling enough to recommend staged CAS+CABG in all asymptomatic patients with unilateral carotid disease,8 while for others, the same evidence militates against any form of prophylactic carotid intervention.9

Prior to 2004, the policy in the Leicester Cardiac and Vascular Surgery Units was to screen all cardiac surgery patients for carotid disease if they presented with; (i) left mainstem disease, (ii) a history of TIA or stroke and (iii) a carotid bruit. Patients with a 70–99% stenosis (NASCET) then underwent synchronous carotid and coronary revascularisation, irrespective of neurological symptom status (asymptomatic/symptomatic) or extent of disease (unilateral/bilateral). However, following the publication of a series of themed systematic reviews,2, 3, 4 a review of practice was undertaken. This was because the available evidence suggested that; (i) the risk of stroke in cardiac surgery patients with unilateral asymptomatic carotid disease appeared to be low (3–5%),2 (ii) that 85% of stroke sufferers had no evidence of ipsilateral, significant carotid disease,2 while (iii) MRI studies suggested that up to 80% of post-CABG stroke patients had areas of infarction that were incompatible with having been caused primarily by carotid disease.10

After a review of practice, it was decided to continue offering prophylactic CEA to all cardiac patients with a previously symptomatic 70–99% carotid stenosis and also to patients with bilateral, asymptomatic 70–99% stenoses (contralateral occlusion). However, cardiac surgery patients with a unilateral 70–99% stenosis did not, thereafter, undergo prophylactic CEA.

In the five years since the policy was revised, 61 patients with a known asymptomatic 70–99% carotid stenosis underwent cardiac surgery without synchronous carotid revascularisation. The authors accept that an otherwise unknown number of unscreened patients will also have undergone cardiac surgery in the presence of significant carotid disease without prophylactic carotid revascularisation. Although three (4.9%) died (all following acute myocardial infarction), none of the 61 patients suffered a stroke in the first 30 days after cardiac surgery. This finding corroborates a 2005 audit from Manchester UK,9 where a similar policy of not offering prophylactic CEA to cardiac surgery patients with unilateral or bilateral asymptomatic carotid disease had been implemented. In Ghosh's study, 50 neurologically asymptomatic patients underwent CABG with no strokes being observed in the first 30 days.

There are few other directly comparable studies as it is; (i) often unclear from reading the constituent papers whether the unit selected some patients for prophylactic CEA but not in others and (ii) few studies provided separate outcome data for asymptomatic patients with unilateral and bilateral disease. However, several other studies are worthy of mention. Schwartz11 observed that in 67 CABG patients with a unilateral 50–99% asymptomatic carotid stenosis, the risk of stroke in patients undergoing CABG alone was only 1.5%. In 25 CABG patients with a unilateral 80–99% stenosis, the stroke risk was only 4%. Similarly, Nakamura reported a zero percent risk of stroke in 29 patients with significant, asymptomatic carotid disease (but no evidence of impaired cerebral vascular reserve) who then underwent isolated CABG.12 Finally, Manabe reported no peri-operative strokes in 41 cardiac surgery patients with unilateral, asymptomatic carotid stenoses (50–69% (n=34), 70–99% (n=7)) who underwent their cardiac procedures without concomitant carotid revascularisation.13

These studies (including our own) involve relatively small patient numbers, but they do challenge the hypothesis that performing a staged or synchronous cardiac and carotid revascularisation (by either CEA or CAS) will significantly reduce the risk of post-CABG stroke in patients with asymptomatic, unilateral carotid disease. Unfortunately, few constituent studies from the systematic reviews of staged/synchronous CEA+CABG have included data of sufficient quality to permit comparison with meta-analyses of 30-day stroke risks in asymptomatic patients with unilateral, carotid artery disease. Better quality data is, however, emerging from some of the CAS centres. In van der Heyden's series of 356 neurologically asymptomatic patients undergoing CAS prior to their cardiac surgery procedure,8 334 (94%) had unilateral carotid disease. Overall, the 30-day death/stroke rate following staged CAS+CABG was 6.7%. The authors thereafter concluded that the morbidity/mortality rate observed in their study was sufficiently low to justify staged CAS+CABG in patients with unilateral, asymptomatic carotid disease. Our study and those others cited above, would seem to question whether such a statement can be supported.

In conclusion, this single centre study is too small to provide conclusive evidence that the presence of a unilateral, asymptomatic carotid stenosis is not associated with an increased risk of stroke following cardiac surgery if prophylactic CEA is not performed. It does, however, challenge prevailing opinion that prophylactic CEA or CAS can be expected to significantly reduce the risk of stroke in this category of patient. In the absence of randomised trials, the authors urge colleagues who have adopted a similar policy of not offering prophylactic carotid revascularisation to cardiac surgery patients with asymptomatic, unilateral carotid stenoses to publish their experience and so further inform the debate.

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Conflict of Interest/Funding 

None.

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References 

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PII: S1078-5884(09)00410-9

doi:10.1016/j.ejvs.2009.08.001

European Journal of Vascular & Endovascular Surgery
Volume 38, Issue 5 , Pages 556-559, November 2009

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