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ACST. Asymptomatic Carotid Surgery Trial (ACST) 5-year Results. CTSU, Oxford Clinical Trial Service Unit. ACST. ECST. The European Carotid Surgery Trial (ECST) randomised 3024 “symptomatic” patients to carotid endarterectomy (CEA) or control (CEA to be avoided for as long

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Presentation Transcript
slide2

ACST

ECST

  • The European Carotid Surgery Trial
  • (ECST) randomised 3024 “symptomatic”
  • patients to carotid endarterectomy (CEA)
  • or control (CEA to be avoided for as long
  • as possible) between 1981 and 1994.
  • ECST results showed that CEA
  • effectively prevented disabling and fatal
  • stroke in patients with 70-99%
  • “symptomatic” stenosis.
acst eligibility

ACST

ACST: Eligibility
  • “Tight” carotid artery stenosis in the
  • index artery
  • “Asymptomatic”: i.e., no ipsilateral
  • carotidterritory symptoms of stroke or
  • transient cerebral ischaemia in past
  • 6/12
  • Doctor & patient both substantially
  • uncertain about immediate CEA
acst follow up

ACST

ACST: Follow-up
  • Yearly follow-up
  • Major events (death or stroke) to be
  • reported to ACST
  • Duplex ultrasound measurements
  • requested at each follow-up to 5 years
  • Data on current drug therapy and blood
  • pressure
slide5

ACST

ACST: the world’s

largest vascular surgery trial

Entry1993 – 2003

3120 patients randomised

Immediate CEA

Deferral CEA

vs

(CEA: carotid

endarterectomy)

(i.e. deferral until CEA

seems more clearly needed)

slide6

ACST: 3120 patients

126 centres in 30 countries

Finland 18

Russia 10

Norway 47

New Zealand: 10

Brazil: 2

Canada: 30

USA: 16

Tunisia: 11

Sweden 532

Netherlands 132

UK 1069

Ireland 7

Czech Republic 18

Poland 88

Belgium 1

Hungary 59

Germany 98

France 2

Yugoslavia 77

Switzerland 6

Bulgaria 6

Austria 30

Italy 328

Israel 245

Cyprus 13

Slovenia 44

Portugal 13

Spain 196

Croatia 2

Greece 10

acst baseline data 1

ACST

ACST: Baseline data (1)
  • 1560 allocated immediate CEA
  • 1560 allocated deferral CEA
  • Mean follow-up 3.4 years
  • Baseline characteristics similar to
  • ACAS (1662 patients, mean follow-up
  • 2.7 years)
acst baseline data 2

ACST

ACST: Baseline data (2)

* ACAS: “Has your doctor ever told you you had high blood pressure or were hypertensive?”

slide9

ACST

Drug therapy at entry (%), by year of randomisation: 1993-1996, 1997-1999 (centre bar), 2000-2003

slide10

ACST

Medical treatment at 2002/3 follow-up

slide12

ACST

ACST: Numbers undergoing CEA after randomisation

slide13

ACST: Surgical mortality and morbidity

ACST

* Difference between groups in risk per CEA not significant

slide14

ACST

Perioperative hazards:

NO significant differences in CEA risk between male & female;

age <65, 65-74, 75+;

or any other factor (26 subgroups)

But, with data on only 51 perioperative strokes or deaths, such subgroup analyses are unreliable

slide18

ACST

Carotid territory ischaemic strokes: Laterality and severity

(fatal + disabling + not)

Excludes periop., & 12 vs 15 haemorrhagic or vertebrobasilar

slide22

ACST

Which types of patient gain worthwhile benefit from successful CEA?

5-year risks of carotid territory ischaemic stroke

slide25

ACST

WOMEN: Carotid territory ischaemic strokes within 5 years of randomisation

in ACST

* Excludes vertebrobasilar or haemorrhagic strokes (2 vs 2)

slide33

p<0.0001

Note: cholesterol lowering drug use was low initially but rose substantially

slide34

ACST

26 SUBGROUP ANALYSES

  • No definite heterogeneity of perioperative hazards,
  • or of proportional reductions by CEA in 5-year risk of
  • carotid ischaemic stroke
  • Maybe more benefit for those with cholesterol
  • >6.5 mmol/l (250 mg/dl), but still significant benefit
  • for those with lower cholesterol
  • Maybe less benefit for those aged over 75 (whose
  • mean age was ~80 and hence had short life
  • expectancy anyway)
slide35

ACST

CONCLUSION: NET BENEFIT

(AT LEAST UP TO AGE 75)

  • Overall in ACST, net 5-year risk of stroke
  • (including perioperative stroke/death):
  • ~ 6% with Immediate CEA
  • ~ 12% with Deferred CEA
  • Difference highly significant (2P = 0.00001)
  • Benefits significant for men & for women;
  • for age <65 & for age 65-74;
  • for ~70% stenosis on ultrasound & for ~80% or ~90%
  • More needed on which types of patient gain worthwhile
  • benefit, & on generalisability of findings
slide36

ACST

CONCLUSION (2):

Applicability of findings

  • The reduction of ~ 4/5 in carotid ischaemic stroke can be generalised to patients with severe carotid artery stenosis in a whole range of future circumstances
  • Although wider use of statins will somewhat reduce overall risk of carotid stroke, whatever risk remains from the carotid lesion should be avoidable by successful surgery
  • However, unsuccessful surgery can do much harm. In non-trial settings, unskilled surgeons, inadequate audits or poor selection of patients could result in widespread misuse of CEA
slide37

ACST

CONCLUSION (3):

Applicability of findings

  • Balance of risk and benefit depends on
  • - surgical morbidity rates
  • - risk of carotid stroke in absence of surgery
  • - what happens after fifth year of follow-up. Continued
  • divergence between treatment groups suggests
  • longer observation (to 10 years) could reveal further gain
  • Until 10-year stroke rates have been monitored, direct estimates of numbers needed to avoid one stroke, expected years of life gained or health economic evaluations are premature, and might undervalue immediate surgery
slide40

ACST

ACST: Trial Organisation

P.I.s: Alison Halliday, Averil Mansfield, Richard Peto, Dafydd Thomas

ACST Office: Alison Halliday (PI), Elizabeth Hayter, Dora Kamugasha, Joanna Marro (Trial co-ordinator), Carl Peto (Computing)

Steering Committee: John Potter (Chair), Martin Brown, Barbara Farrell, Delyth Morgan (MRC), Angela Rau, Charles Wolfe

(+ PIs & ACST office)

Audit: Michael Harrison (Chair), Rodney Foale, C Jamieson, Vaughan Ruckley

DMC: Charles Warlow (Chair), Rory Collins, Richard Gray, Jean-Marc Orgogozo

Clinical Trial Service Unit, Oxford (CTSU): A Baxter, J Burrett

R Collins, J Godwin, S Knight, R Peto, A Radley, S Richards