1. Anti-thrombotic therapy in Carotid intervention (ACST-2) Anne Huibers 1,2, GJ de Borst 2, R. Bulbulia 3, A. Halliday 1 on behalf of all ACST-2 collaborators 1.Nuffield Department of Surgical Sciences, University of Oxford 2.Department of Vascular Surgery, University Medical Center Utrecht 3.Clinical Trial Service Unit, University of Oxford

2. ACST-2 Survey ACST-2 is a large randomized trial comparing CEA and CAS in patients with severe asymptomatic carotid artery stenosis. Currently, 1837 /3600 patients have been recruited We surveyed 77 ACST-2 active centres Anti-thrombotic regime for CEA and CAS (1) Do they test for antiplatelet resistance ? (2) What is their pre-procedural therapy ? (3) What is the intra-procedural therapy ? (4) Chosen post-procedural therapy and duration ?

3. Pre – procedural CAS (n=66) CEA (n=61) - Do you have a pre-procedural protocol ? Yes (98%) No (2%) Yes (90%) No (10%) -Aspirin -Clopidogrel -Dual AP therapy -Triple AP therapy 5% 8% 82% 5% 65% 3% 30% 1% Intra-procedural -Heparin + continued AP -Dextran additionally 98% 2% 98% 2% Post – procedural -Dual AP therapy -Aspirin -Clopidogrel -Aspirin or clopidogrel (no preference) -Triple AP therapy 86% 6% 2% 4% 24% 59% 6% 11% 0% - APT life-long -Dual AP life-long -Dual AP therapy for (median; range) then aspirin life-long then clopidogrel life-long 100% 9% 77% (3; 1-12) 68% 9% 100% 10% 14% (2,4; 1-5) 14% 0% Resistance - Do you test for antiplatelet resistance ?11 centres (14%) Response rate - 66 CAS centres (88%) - 61 CEA centres (79 %) in 20 countries CAS Pre: - 5% aspirin alone - 87% ≥ 2 APT Duration of DAPT - 3 m (1-12); 9% life-long CEA Pre: -65% Aspirin alone -30% DAPT Post: duration of DAPT - 2.4 m (1-5); 10% life-long Results

4. What is the evidence ? Randomized controlled trials of peri-procedural anti-thrombotic therapy in carotid intervention AuthorsnYearJournalCEA/CASRandomizationResults Boysen et al.3011988StrokeCEA 50-100 mg/day aspirin vs placebono significant effect of aspirin Lindblad et al.2321993StrokeCEA 75 mg/day aspirin starting pre-op and continued for 6 months vs placebo effect of aspirin at 30 days. No significant effect at 6 months Taylor et al.28491999LancetCEA 81-325 mg/day aspirin vs 650-1300 mg/day aspirin effect of low dose aspirin at 30 days and 3 months McKevitt et al472005EJVESCAS aspirin and 24h heparin vs aspirin and clopidogrel benefit of combined AP regime (premature termination of the study) Guidelines: Lack a statement on peri-operative anti-thrombotic agents and duration of antiplatelet therapy. * ESVS guidelines 2009; Society of Vascular surgery 2011; ASA/ACCF/AHA 2011

5. Conclusion In ACST-2, almost all centres prescribe dual antiplatelet therapy in CAS patients for around 3 months. Only one quarter of centres prescribe dual antiplatelet therapy following CEA for around 2.5 month. Evidence to help guide the duration of peri-procedural anti-thrombotic therapy in randomized trials is limited. Studies are needed to define optimal duration of DAPT and the relevance of antiplatelet resistance.