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Translating Evidence into Practice: Surveillance after Carotid Interventions

Open ArchivePublished:May 31, 2018DOI:https://doi.org/10.1016/j.ejvs.2018.04.019
      “Everyone is a prisoner of his own experiences. No one can eliminate prejudices; just recognise them”Ed Murrow, 1955
      As a trainee then Consultant in Edinburgh and Leicester, duplex ultrasound (DU) surveillance following carotid endarterectomy (CEA) was adopted during the performance of randomised controlled trials (RCTs) and/or audit projects, but then dropped following their completion. Since 2002, no Leicester CEA patient has undergone serial post-operative DU surveillance. The main reason is the absence of compelling evidence that such a strategy prevented stroke in the territory of the operated and/or non-operated carotid artery. By contrast, Leicester does offer serial DU surveillance following carotid artery stenting (CAS). This is because it was perceived that CAS was associated with higher restenosis rates (than CEA), which might translate into higher rates of late, ipsilateral stroke if left untreated. To any independent observer, this clearly represents polarised practice (based on “experience and prejudice”) with little quality evidence to justify either surveillance strategy.
      Few guidelines provide recommendations regarding the management of restenosis, although all advise that patients with symptomatic 50–99% restenoses should undergo redo-CEA or CAS,
      • Brott T.G.
      • Halperin J.L.
      • Abbara S.
      • Bacharach J.M.
      • Barr J.D.
      • Bush R.L.
      • et al.
      2011 ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS guidelines on the management of patients with extracranial carotid and vertebral artery disease.
      • Naylor A.R.
      • Ricco J.B.
      • de Borst G.J.
      • Debus S.
      • de Haro J.
      • Halliday A.
      • et al.
      Management of atherosclerotic carotid and vertebral artery disease: 2017 Clinical practice guidelines of the European Society for Vascular Surgery.
      with the choice reflecting local expertise/preference. The real controversy relates to the management of asymptomatic restenoses. The 2011 14-Society guidelines advise that most asymptomatic restenoses are benign and can be treated medically, while suggesting that there might be a role for reintervening in CEA patients with “asymptomatic stenoses of pre-occlusive severity”.
      • Brott T.G.
      • Halperin J.L.
      • Abbara S.
      • Bacharach J.M.
      • Barr J.D.
      • Bush R.L.
      • et al.
      2011 ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS guidelines on the management of patients with extracranial carotid and vertebral artery disease.
      However, meta-analyses suggest that two thirds of patients undergoing restenosis re-interventions are asymptomatic,
      • Fokkema M.
      • Vrijenhoek J.E.P.
      • den Ruijter H.M.
      • Groenwald R.H.H.
      • Schermerhorn M.L.
      • Bots M.L.
      Stenting versus endarterectomy for restenosis following prior ipsilateral carotid endarterectomy: an individual patient data meta-analysis.
      suggesting that surgeons/interventionists are reluctant not to reintervene.
      Preparation of the 2017 European Society for Vascular Surgery (ESVS) carotid guidelines
      • Naylor A.R.
      • Ricco J.B.
      • de Borst G.J.
      • Debus S.
      • de Haro J.
      • Halliday A.
      • et al.
      Management of atherosclerotic carotid and vertebral artery disease: 2017 Clinical practice guidelines of the European Society for Vascular Surgery.
      required me to address my own “personal prejudices” regarding DU surveillance. Rather than relying on the usual observational study data, the recommendations were largely based on a new meta-analysis on rates of stroke ipsilateral to asymptomatic 70–99% restenoses that had not been subject to redo CEA or CAS.
      • Kumar R.
      • Batchelder A.
      • Saratzis A.
      • AbuRahma A.
      • Ringleb P.
      • Lal B.
      • et al.
      Restenosis after carotid interventions and its relationship with recurrent ipsilateral stroke: a systematic review and meta-analysis.
      The unique features of this meta-analysis were (first) that it used RCTs rather than retrospective observational studies (offering better, independent scientific scrutiny), and (second) the eight RCT Principle Investigators (overseeing 4803 randomised patients) were asked to review their DU surveillance records in order to provide stenosis severity data for the surveillance scan which preceded stroke onset, rather than reporting stenosis severity data after stroke onset, which had otherwise become the norm. To date, these are the best available, prospective data to guide surveillance strategies.
      The meta-analysis observed that restenosis rates >70% were 10% 5 years after CAS, versus 6% at 4 years after CEA.
      • Kumar R.
      • Batchelder A.
      • Saratzis A.
      • AbuRahma A.
      • Ringleb P.
      • Lal B.
      • et al.
      Restenosis after carotid interventions and its relationship with recurrent ipsilateral stroke: a systematic review and meta-analysis.
      However, contrary to intuition, an asymptomatic, untreated 70–99% restenosis after CAS was hardly ever associated with late ipsilateral stroke (1/119 [0.8%] at 4 years), compared with a 2.0% risk (36/1813) of late ipsilateral stroke in CAS patients with 0–69% restenoses (OR 0.87; 95% CI 0.24–3.21). By contrast, an untreated asymptomatic 70–99% restenosis after CEA was associated with a small, but significantly higher risk of late ipsilateral stroke (7/135 [5.2%] at 3 years), compared to a 1.5% risk of late ipsilateral stroke (40/2704) in patients with 0–69% restenoses (OR 4.77; 95% CI 2.29–9.92): an approximate absolute risk difference of 3.7%.
      • Kumar R.
      • Batchelder A.
      • Saratzis A.
      • AbuRahma A.
      • Ringleb P.
      • Lal B.
      • et al.
      Restenosis after carotid interventions and its relationship with recurrent ipsilateral stroke: a systematic review and meta-analysis.
      The theme of this debate is “translating evidence into practice”. In the past, I was probably guilty of “translating prejudice into practice” and I have now decided to adopt most of the 2017 ESVS recommendations. First (and in a change to my historical practice), I now see no role for routine serial DU surveillance after CAS, with the caveat being that the very rare CAS patient who suffers a late ipsilateral TIA/stroke should seek urgent medical assistance. The meta-analysis suggests that if we retained our practice of surveying and reintervening on asymptomatic 70–99% stenoses after CAS, 97% of ipsilateral late strokes would still occur.
      • Kumar R.
      • Batchelder A.
      • Saratzis A.
      • AbuRahma A.
      • Ringleb P.
      • Lal B.
      • et al.
      Restenosis after carotid interventions and its relationship with recurrent ipsilateral stroke: a systematic review and meta-analysis.
      However, I am still not minded to advocate routine, serial DU surveillance after CEA, even though the 2017 ESVS guidelines advise that “re-intervention may be considered in CEA patients with an asymptomatic 70–99% restenosis, following multidisciplinary team review” (Class IIb, Level B).
      • Naylor A.R.
      • Ricco J.B.
      • de Borst G.J.
      • Debus S.
      • de Haro J.
      • Halliday A.
      • et al.
      Management of atherosclerotic carotid and vertebral artery disease: 2017 Clinical practice guidelines of the European Society for Vascular Surgery.
      My rationale for not offering routine DU surveillance after CEA is that with an absolute risk difference of about 3.7% (see above), once the peri-operative risks of redo-CEA or CAS are factored in (3% in Fokkema's meta-analysis
      • Fokkema M.
      • Vrijenhoek J.E.P.
      • den Ruijter H.M.
      • Groenwald R.H.H.
      • Schermerhorn M.L.
      • Bots M.L.
      Stenting versus endarterectomy for restenosis following prior ipsilateral carotid endarterectomy: an individual patient data meta-analysis.
      ), overall stroke prevention will be absolutely minimal and not a cost-effective use of resources.
      However, and in a change to my previous practice, I would now advocate serial DU surveillance in CEA/CAS patients who displayed evidence of a critical fall in intra-procedural cerebral blood flow that might otherwise render these patients more likely to suffer a stroke if any future asymptomatic restenosis progressed to occlusion. The ESVS guidelines advise that patients with the following criteria should be considered for DU surveillance and re-intervention: (1) onset of neurological deficit, coma, or seizures during carotid clamping with CEA under local anaesthesia; (2) onset of neurological deficit, coma, or seizures during balloon inflation (or proximal flow reversal) during CAS; and (3) significant electrophysiological abnormalities and/or mean middle cerebral artery velocities <15 cm/second during carotid clamping with CEA under general anaesthesia.
      • Naylor A.R.
      • Ricco J.B.
      • de Borst G.J.
      • Debus S.
      • de Haro J.
      • Halliday A.
      • et al.
      Management of atherosclerotic carotid and vertebral artery disease: 2017 Clinical practice guidelines of the European Society for Vascular Surgery.
      Intuitive reasoning and prejudice (and perhaps some financial reasons) have dominated decision making regarding surveillance after carotid interventions. The latest data, which underpin the ESVS recommendations, suggest that evidence rather than prejudice can now be used to develop pragmatic surveillance strategies.

      References

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        • Halperin J.L.
        • Abbara S.
        • Bacharach J.M.
        • Barr J.D.
        • Bush R.L.
        • et al.
        2011 ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS guidelines on the management of patients with extracranial carotid and vertebral artery disease.
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        Management of atherosclerotic carotid and vertebral artery disease: 2017 Clinical practice guidelines of the European Society for Vascular Surgery.
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        • Kumar R.
        • Batchelder A.
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        Restenosis after carotid interventions and its relationship with recurrent ipsilateral stroke: a systematic review and meta-analysis.
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