At the recent Charing Cross Symposium in London, UK, Interventional News was invited to a planning meeting for the TACIT (Transatlantic Asymptomatic Carotid Intervention Trial), organised by the Society of Interventional Radiology (SIR) Foundation and Cardiovascular and Interventional Radiological Society of Europe (CIRSE). The TACIT trial will be a three-pronged trial comparing the best medical therapy arm against surgery (carotid endarterectomy - CE) and best medical therapy, against carotid artery stenting (CAS) and best medical therapy. The aim is to recruit 50% of the patients to best medical therapy, with 25% undergoing CE and 25% undergoing CAS. The study aims to enrol 2,400 patients.
The Co-Principal Investigators are Barry Katzen, Miami, and Johannes Lammer, Vienna, Austria, and the Executive Committee will include John Rundback, Columbia Presbyterian, and Peter Gaines, Sheffield, UK. J P Mohr from Columbia is involved from a neurological standpoint, with Klaus Mathias on the CAS committee. The trial is currently establishing the protocols needed to take into account the various EU/FDA regulatory positions and agree on best surgical techniques. The planning meeting emphasised the need for greater sub-group analysis on the medical therapy side.
The planning meeting explored collaboration with other trials such as the Asymptomatic Carotid Surgery Trial (ACST) which is also looking at starting an asymptomatic carotid stenting trial. TACIT investigators felt that if the ACST joined forces with TACIT it would reduce competition for funding, clinicians and patients, with two trials suffering from lower recruitment. However, Allison Halliday, Principal Investigator of the ACST, said that the trials were mutually supportive and that the message would be stronger with collaboration rather than merging the proposed ACST carotid stenting study into the TACIT trial.
Martin Brown, Principal Investigator of the International Carotid Stenting Study, said that it is important that the field understands the fundamental questions so that the public health ramifications are proven. He emphasised that the trial needs to be neurologically, not surgically, run. Halliday and Brown said they saw no conflict of interest.
The superiority of CE over medical therapy in the management of symptomatic and asymptomatic CAS has been established in four randomised trials; the North American Symptomatic Carotid Endarterectomy Trial, the European Carotid Surgery Trial, the Asymptomatic Carotid Atherosclerosis Study (ACAS) and the European ACST. ACST confirmed the benefit of CE in patients with asymptomatic severe stenoses, showing for the first time that CE cut the risk of fatal stroke in half over five years.
In both the ACAS and ACST, an extremely low peri-operative stroke rate was achieved, without which there would be no benefit from surgical management of asymptomatic CAS. Whereas the CE trials clearly demonstrated the benefits of this modality over medical management in the treatment of CAS, the stringent eligibility requirements used in these studies excluded many patients at considerable risk for stroke from receiving surgical therapy for their disease. Increased rates of peri-operative stroke and death have been noted in observational studies reporting outcomes after CE in certain patient populations.
Barry Katzen emphasised the importance for such a transatlantic initiative, the largest trial in vascular therapy, and said he hoped it would be the 'pivotal' trial for the carotid area.
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