Vascular Trials
Overview
Vascular surgery arguably has some of the strongest evidence base behind it of all the surgical disciplines, particularly in carotid endarterectomy (CEA) and AAA repair. This chapter summarises some of the most well-known trials in the ‘big three’ vascular operations that have changed practice along with their headline contributions, or, in some cases, consensus documents that have consolidated previous research. Of course, this is the tip of the iceberg!
Carotid
North American Symptomatic Carotid Endarterectomy Trial (NASCET)1
- Multicentre randomised controlled trial of CEA versus BMT in symptomatic patients (1991, NEJM).
- N = 1415.
- Demonstrated a highly beneficial effect of CEA in high-grade carotid stenosis (70–99%). Modest benefit for moderate-grade stenosis (50–69%)
European Carotid Surgery Trial (ECST)2
- Multicentre randomised controlled trial of CEA versus BMT in symptomatic patients (1991, Lancet).
- N = 3024.
- The same principal result: demonstrated a highly beneficial effect of CEA in high-grade carotid stenosis (70–99%); modest benefit for moderate-grade stenosis (50–69%).
Carotid Endarterectomy Trialists Collaboration3
The above 2 studies along with a similar study, the Veteran’s Affairs trials, were amalgamated into one very large dataset of over 6000 patients. This has provided the best evidence for CEA, and the group have published several papers. Essential points:
Numbers Needed to Treat to prevent a stroke at 5 years:
- Stenosis 70–99% = 6 patients.
- Stenosis 50–69% = 13 patients.
- Stenosis <50% or completely occluded = no benefit.
- Subgroup analysis shows maximum benefit in recently symptomatic patients (best within 2 weeks).
Interpretation of symptomatic CEA trials: patients with a 70–99% stenosis should undergo CEA within 2 weeks. Occluded carotids do not benefit from surgery. Stenoses 50–69% are contentious. Stenoses <50% have no benefit.
Asymptomatic Carotid Atherosclerosis Study (ACAS)4
- Multicentre randomised controlled trial of CEA versus BMT in asymptomatic patients (1995, JAMA).
- N = 1662.
- In patients with a 60–99% stenosis, very modest benefit of CEA.
- Numbers Needed to Treat to prevent a stroke at 5 years = 20 patients.
Asymptomatic Carotid Surgery Trial5
- Multicentre randomised controlled trial of CEA versus BMT in asymptomatic patients (2004, Lancet).
- N = 3120.
- Confirmed the findings of ACAS, similar figures.
Interpretation of asymptomatic CEA trials: surgeons differ in how they interpret these trials. Some never offer CEA for asymptomatic carotids, some always do, some offer selectively. Subgroup analysis of these trials has shown, for instance, that there is no benefit of CEA in asymptomatic women aged over 75.
Abdominal Aortic Aneurysms
UK Small Aneurysm Trial6
- Multicentre randomised controlled trial of elective AAA repair or U/S surveillance in AAAs 4.0–5.5 cm diameter (1998, Lancet).
- N = 1090.
- No difference in survival between the groups at 6 years; therefore supports 5.5 cm minimum threshold for elective surgical repair.
US Aneurysm Detection and Management (ADAM)7
- Multicentre randomised controlled trial of elective AAA repair or U/S surveillance in AAAs 4.0–5.4 cm diameter (2002, NEJM).
- N = 569.
- No difference in survival between the groups; therefore supports 5.5 cm minimum threshold for elective surgical repair.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
