European Journal of Vascular & Endovascular Surgery
Volume 36, Issue 4 , Pages 390-394, October 2008

Optimising the Timing of Carotid Surgery using a Carotid Risk Scoring System

  • O. Ehsan

      Affiliations

    • Corresponding Author InformationCorresponding author. O. Ehsan, Morriston Hospital, 4 Brandreth Gardens, Cardiff CF23 5NJ, United Kingdom. Tel.: +442920485246.
    • ,
  • S. Paravastu
    • ,
  • A. da Silva

Wrexham Maelor Hospital, Wrexham LL13 7TD, United Kingdom

Received 18 April 2008; accepted 27 June 2008. published online 26 August 2008.

Article Outline

Abstract 

Objectives

Transient ischaemic attacks (TIA's) have 4–20% risk of evolving into a major stroke within 90 days, with half of them occurring in the first 2 days. The Department of Health, UK, guidelines (2007) suggests all higher-risk patients with TIA and minor stroke need to be assessed by a specialist and treated within 24 hours. However, the reality in the health system is that the delay between the last cerebrovascular event (CVE) and surgery is often in excess of 90 days. Recently validated ABCD2 scoring stratifies the risk of stroke after CVE and can help in prioritizing patients for investigations and urgent carotid endarterectomy (CEA).

The aim of this pilot study was to stratify patients who underwent CEA, post cerebrovascular event, using the ABCD2 scoring method. This would help us assess our current CEA practice and, in future, prioritise surgery according to estimated stroke risk.

Design & methods

Retrospective analysis of ABCD2 scoring of patients who underwent CEA.

Results

The average delay between first presentation and carotid endarterectomy was 172.8 days (range 3 to 837 days). This average delay for the low, moderate and high risk groups was 200.8, 154.1 and 156.5 days, respectively.

Conclusion

The ABCD2 scoring is an easily applicable method to stratify patients post CVE at risk of further stroke. Our results suggest that to maximize the benefit of CEA within a limited resource health system, patients with a high ABCD2 score should be given the highest priority for investigations followed by CEA.

Keywords: Carotid Endarterectomy, ABCD2 scoring, Stroke risk scoring, Transient ischaemic attack scoring

 

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Introduction 

About 70,000 transient ischaemic attacks (TIAs) are diagnosed every year in the UK, with a majority of these caused by carotid stenosis, other minor causes being atrial fibrillation causing cardiac emboli, patent foramen ovale, carotid and vertebral artery dissection.1, 2, 3, 4 Although most patients with TIA will have a benign short-term course, there is a 4–20% risk of developing a stroke within 90 days. Half of these strokes may occur within the first 2 days.5, 6, 7, 8, 9, 10, 11 Therefore, Carotid Endarterectomy (CEA), as a stroke prevention tool, should be performed as close as possible to the last cerebrovascular event (CVE). However, the reality in the NHS is that the delay between the last CVE and surgery is often in excess of 90 days.12 Different scoring systems have been used in the past to assess the risk of stroke after TIA. These include ABCD scoring and California scoring.13, 14, 15 They were combined and an new scoring system (ABCD2) was developed.

ABCD2 scoring 

This scoring system allocates points based on age, blood pressure, clinical features, duration of TIA and diabetes. Overall score is used to stratify patients according to stroke risk. The scoring criteria are given in Table 1. The maximum score of 7 carries a stroke risk of 17.8% at 90 days compared to the risk of 3.1% with a score of 1.16

Table 1. ABCD2 Scoring

▪Age 60yr or older (1 point)

▪Blood pressure on first assessment after TIA
▪systolic >140 or diastolic >90 (1 point)


▪Clinical features of TIA
▪unilateral weakness (2 points) or

▪speech impairment without weakness (1 point)


▪Duration of TIA
▪>60min (2 points)

▪10–59min (1 point)


▪Diabetes (1 point)

Score 1–3 Low risk; Score 4–5 Moderate risk; Score 6–7 High risk.

The overall predicted stroke risk given by the ABCD2 scoring system is 3.9% at 2 days, 5.5% at 7 days and 9.2% at 90 days.

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Aims 

The aim of this pilot study was to stratify patients who underwent CEA, post TIA, using the ABCD2 scoring method. This would help us assess our current CEA practice in a district general hospital and, in future, prioritise surgery according to estimated stroke risk.

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Materials and Methods 

Case records of all consecutive patients undergoing CEA between 1996 and 2006 were retrospectively reviewed. Those undergoing CEA for asymptomatic carotid stenosis or for old cerebrovascular accident (CVA) were excluded as the scoring system is not applicable to this group of patients. The patients who had CEA for TIA's were scored according to the ABCD2 scoring system. Patient demographic data along with the timing of CEA, delay in referral to vascular surgeons and delay in obtaining diagnostic carotid imaging were recorded.

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Results 

A total of 100 carotid endarterectomies were performed during this time period and out of these, 49 symptomatic patients post TIA were classed according to the ABCD2 score. The male to female ratio was 1.7:1. Mean age was 68.5 years (range 46.4 to 85.6 years). The average age for the low, moderate and high risk groups was 69.5, 65.2 and 71.4 years, respectively.

The patient's first presentation was calculated from the time patient first consulted a doctor as specified in the validation paper of ABCD2 scoring.16 In the majority of NHS trusts across the UK, patients with a TIA present to either their GP, Ophthalmologist or to the A&E department. This is followed by a referral either to a stroke physician, as an inpatient, or to a stroke clinic. Diagnostic imaging of the carotid arteries is then obtained and patients who are candidates for surgical intervention are then referred on to a vascular surgeon. In our NHS hospital, the usual pathway of patients presenting with TIA, is shown in Fig 1.

Of the 49 patients in our study, 19 (38.8%) had a score of 3 or less (low risk group), 17 (34.7%) had a score of 4–5 (moderate risk group) and 13 (26.5%) had a score of 6 or 7 (high risk group) Fig. 2.

The average delay between first presentation and carotid endarterectomy was 172.8 days (range 3 to 837 days). This average delay for the low, moderate and high risk groups was 200.8, 154.1 and 156.5 days, respectively (Fig. 3).

The average delay between first symptoms and review by stroke physician was 22.3 days (range 0 to 361 days). This average delay for the low, moderate and high risk groups was 43.4, 9.3 and 2.3 days, respectively.

The average delay between first presentation and vascular referral was 93 days (range 0 to 382 days). This average delay for the low, moderate and high risk groups was 80.4, 102.5 and 99.1 days, respectively.

The average delay between vascular review and carotid endarterectomy was 81.1 days (range 1 to 569 days). This average delay for the low, moderate and high risk groups was 123.7, 51.6 and 57.4 days, respectively.

The average delay in obtaining an initial carotid duplex scan was 85.4 days (range 1 to 392 days). This average delay for the low, moderate and high risk groups was 83.9, 92.2 and 78.9 days, respectively.

Five patients had a post operative stroke within 10 days of surgery. Three of these, had the CEA performed within 90 days of TIA. Four out of these five were in moderate to high risk category (Fig. 4).

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Discussion 

The role of carotid endarterectomy in preventing prevent stroke after cerebrovascular events is well established.17, 18, 19, 20 However, its overall effectiveness is reduced by excessive delays from first symptom to surgery.21 The ABCD2 scoring clearly demonstrates that the stroke risk after TIA can be up to 17.8% at 90 days. Therefore the longer the patient waits for surgery, the less effective is the procedure, as a cohort of patients would be affected by stroke prior to CEA. One weakness of this study is the small number of patients involved, which relates to the practice of a single vascular surgeon. This can be explained due to the fact that this was a new vascular unit which initially lacked a dedicated vascular laboratory. This has now been addressed resulting in an increase in the number of referrals for carotid surgery.

The Carotid Endarterectomy Trialists Collaboration (CETC) have shown from combined data comprising >6000 patients, that surgery confers no significant benefit in symptomatic patients with a <70% stenosis (ECST). But, symptomatic patients with a 70-99% stenosis, excluding those with the string sign, gained significant benefit. A second CETC publication, stratified the delay from the time of the most recent event to surgery, using combined data for all symptomatic patients with significant stenoses.22 It was very clear, in this data analysis, that the longer the delay the less the overall benefit regarding stroke prevention. Delaying surgery in symptomatic patients with 70-99% stenosis for >12 weeks prevented only eight strokes per 1000 CEAs as compared to more than 180 strokes prevented, per 1000 CEAs, when CEA was performed within two weeks of the last CVE.22, 23, 24

National Stroke Guidelines in the United Kingdom recommend that all patients with suspected TIA should be investigated within seven days of the event. However, the median time from symptoms to surgery was shown to be 189 days in the UK national carotid audit (1997).25 The 2004 Royal College of Physicians Sentinel Stroke Audit also found that only 50% of patients had undergone a duplex scan within 12 weeks of their initial event.12 The most recent guidelines from the Department of Health recommend that diagnostic carotid imaging should be performed within hours of admission to an acute stroke unit, and appropriate surgery within 48 hours.26

If our unit's delays are reflected in other similar units in the UK, then the implementation of the most recent guidelines from the Department of Health26 is an uphill task. However, our data may be skewed as some patients waited in excess of one year for CEA.

Different studies from UK, over a period of time, have highlighted the delays in CEA for patients presenting with TIAs. A study from Newcastle recorded a median 120 day delay in 1995 whereas another audit from Oxford showed a median delay of 100 days.27, 28 Similar delay has been confirmed by GALA trial collaborators and also in a study from Sweden.29, 30

Our study suggests similar findings with delays occurring at all the different steps after the patients' first contact with the doctor about their symptoms. Our average delay from first presentation to CEA was 172.8 days. This average delay for a patient to be seen by stroke physician, to carotid duplex scan and to vascular review was 22.3, 85.4 and 94 days, respectively.

In our study, the patients in moderate to high risk group, on an average, were seen within 10 days of presentation by a stroke physician. However, there was a further delay in referral to a vascular surgeon. Similarly, the average interval between vascular review and CEA, for moderate to high risk group patients, was well within 90 days. This did not take into account the time delay prior to the vascular review.

Different studies have shown the perioperative risk of stroke with early CEA varying between 4.3% to 9.4%.31, 32, 33, 34 Our own results are on the high side and steps have been taken to address this issue. Increased stroke risk has been shown to be related to the presenting features at the time of TIA.16 The combined risk of neurologic and cardiac complications after urgent carotid surgery for crescendo TIA is higher than that expected after elective cases but is still acceptable considering the natural history of patients with unstable neurologic symptoms.15 The ABCD2 risk scoring may therefore be helpful in stratifying patients according to their risk and prioritizing them for investigations and swift surgical intervention.

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Conclusions 

The ABCD2 scoring is an easily applicable method to stratify patients post CVE at risk of further stroke. This study has been instrumental for us to learn our own shortcomings and to change our practice. For example, the delay from a stroke physician referral to a vascular surgeon appointment is now less than seven days. Our results suggest that to maximize the benefit of CEA within a limited resource NHS, patients with a high ABCD2 score (4 or higher) should be given the highest priority for investigations followed by urgent CEA. The national stroke audit has been influential in helping to develop specialised stroke units. This should help to redress the mismatch between current CEA practice and the latest stroke prevention recommendations.

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References 

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PII: S1078-5884(08)00370-5

doi:10.1016/j.ejvs.2008.06.031

European Journal of Vascular & Endovascular Surgery
Volume 36, Issue 4 , Pages 390-394, October 2008

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