If I could go back to the studies that were done, in the early 1990s carotid endarterectomy was a common procedure in Canada. When we got into the mid-1990s, the neurology group thought the carotid did not need to be fixed surgically and it could be controlled by giving drugs. They subsequently did a trial called the NASCE trial—the North American symptomatic carotid endarterectomy trial—and they looked at several thousand patients.They were looking at the outcome of patients treated with carotid endarterectomy versus the outcome of patients treated with drugs. The trial was abandoned after it had gone on for several months because the patients who had carotid endarterectomy did significantly better statistically than patients who were treated with drugs.
You're right, the trial looked at a 70% stenosis, but more studies have been done since then, specifically the ACAS trial—asymptomatic carotid atherosclerosis study—and it suggested that there is significant benefit, though not as significant as the other study, in doing carotid endarterectomy on patients who are asymptomatic. More studies have been done, and there is good data now that supports doing a carotid endarterectomy on patients with greater than a 50% stenosis. That's current data.
To answer your other question, as to where we should go at this point, I agree with Mark Haacke totally. The amount of time it's going to take to get the answers to the question with each individual centre doing 40 or 50 studies a year will take a very long time, and will be done at the significant cost of patient lives. If we collaborate and put all the data together, the question will be answered fairly quickly.
Part of the problem is the cost of doing the studies. Patients need to be treated now because patients are dying. You can gain a lot of information by treating people now, putting them in a registry, having them as part of an ongoing, open-ended study in collecting the data. If you do that, you achieve two goals. You achieve the scientific goal, which is actually generating the science on it, determining who should be treated, and so on, as you collect the data. At the same time, you can treat people with significant disease now. If they have significant CCSVIs demonstrated on an MRV and on a duplex scan, then they should be treated.
[Applause]