As can be seen from various parts of Vascular News there emerges a difference in attitude amongst vascular surgeons and interventional radiologists as far as carotid angioplasty is concerned. In simple terms the interventional radiologists sees the opportunity of advancing the sphere of influence. The vascular surgeons see the possibility of losing one more of his favourite operations! A turf war is undoubtedly with us. What position should the vascular surgeon take?
The vascular surgeon just recovered from the indictment of the physicians in the United States who said that carotid endarterectomy was an operation unproven. Dr Henry Barnett in Canada prepared North America for the ultimate trial, which compared carotid endarterectomy and best medical treatment against best medical treatment in a variety of symptomatic patients. The resulting North American Symptomatic Carotid Endarterectomy Trial (NASCET) proceeded alongside the European Carotid Surgical Trial (ECST) which had a very similar protocol. Both trials found in favour of carotid endarterectomy with increasing benefit for patients with greater stenoses. Thus it became finally clear that carotid endarterectomy was beneficial for all patients with symptomatic carotid stenoses >70% and up to 99% stenoses. The vascular surgeons took a deep breath at the beginning of the 1990s and felt that the war was over and at last it was clear that the operation was beneficial. There was a little embroidering of the facts.
The surgical arms of the study included surgeons of a variety of ability and nevertheless easily beat the opposite group. But the surgical stroke rate was in the region of 7% compared with 24% in the non-surgical group. This was a finding declared at 18 months. Many surgeons who performed the operation repeatedly, knew that they could get better results than 7% and since the NASCET and ECST there have been many series reported with stroke rates of <5% and even more recently, in the region of 2%. But we must always remember that single centre series always report better results than multicentre trials. Why is this? Highest quality data are those of multicentred trials. When single centres report they seem to get better results than the multicentre trials. It is possible that only the better centres report or those that report only report their better results? It is as if the truth comes out in the multicentre trial and this is true as far as the whole population is concerned. Nevertheless there is very considerable evidence of improvement of carotid surgical results at centres like Leicester and Charing Cross in Britain which have noted an improvement since the rigorous application of transcranial Doppler. These centres would be surprised to see results declared much greater than 3% and would often hope for better results than that. Carotid stenting is now poking over the horizon. It is seen by the carotid surgeon as another potential hazard in the performance of an operation that is achieving good results. Why cannot referring doctors accept this?
What about carotid angioplasty? Results of the original CAVATAS report were slow to be published and when they eventually were, 9 and 10% stroke rate was declared and the good carotid centres were quick to emphasise the superiority of their own carotid surgery over angioplasty. These surgeons simply could not understand how the radiologists could have assembled such a poor group of surgeons to perform the carotid surgery for the CAVATAS trial etc etc! Another advance has occurred. Cerebral protection has now been introduced with the carotid angioplasty devices. The proponents now argue that it is unethical not to use cerebral protection when using carotid angioplasty. These systems catch the debris and are removed and this prevents cerebral embolization, they argue, and this should be used all the time. Why was carotid angioplasty without cerebral protection introduced then? On what basis was it ever a good idea to blow up a balloon in a carotid artery and send off all of the small debris into the brain? It now seems that was never a good idea although the pioneers did it and some still do it!
Carotid surgeons need to bear in mind these historical occurrences but not to be completely overwhelmed by them. Cerebral protection is now available and there is the possibility that carotid angioplasty with cerebral protection will have substantially better results than the earlier angioplasties. What then? Well, carotid surgeons need to reckon that every patient would prefer to have carotid angioplasty rather than carotid endarterectomy if results of the two are approximately the same. This is the crux of the problem. We do not currently know whether the results are going to be in the same order, but if they are, carotid surgeons had better reckon that patients will prefer the lesser procedure. However, patients certainly will not prefer the lesser procedure if that lesser procedure (angioplasty) is associated with a higher stroke rate or mortality. They would surely tolerate carotid endarterectomy with a better stroke and mortality outcome than a hazardous angioplasty.
What next? You may say this is crystal clear and a random control trial is required. Certainly the Leicester and Charing Cross groups have called for serious thinking on this matter. If we can assume that an asymptomatic carotid stenosis has approximately 1% per year stroke risk for a stenosis <70% and a 3% per year stroke risk for a stenosis of >70% then at this stage, the use of carotid stenting for asymptomatic patients is surely wrong, even in the context to the random controlled trial. In other words, there should be no intervention until the proven track record of a procedure is known to be in the same ballpark in terms of expected morbidity and outcome as a natural history, and one would always hope that the intervention would improve the natural history. The chances of improving the natural history for asymptomatic patients is very very low and at this stage, carotid angioplasty must be thought of as highly novel. Surely the way to go is to support the asymptomatic carotid surgical trial. For those who feel that intervention is appropriate, let us first of all know if there is any benefit in terms of carotid surgery against the natural history.
As far as symptomatic lesions are concerned, a multicentred trial seems inevitable. The issue must surely be that centres should be included whose track record of carotid endarterectomy is of a stroke and death rate of under 5%. If this cannot be achieved in the centre, then those carotid surgeons ought not to be taking part in a multicentred trial. Instead patients should be referred from the occasional carotid surgeon to the experienced carotid surgeon with results of combined morbidity and mortality well under 5%. For those that can achieve this, any random controlled trial must beat those results. If these results are beaten by carotid angioplasty with cerebral protection, then we can expect a sudden massive increase in enthusiasm for carotid angioplasty. We should remember that the EVEM Panel data suggest that the total number of carotid procedures in Europe is around 107,000 (2001) of which only 8% are performed by carotid angioplasty. Incidentally, in any trial, the answer will not be achieved if almost all of the patients are not randomised. It is absolutely no good leaving the difficult ones for carotid endarterectomy and just choosing the simple ones for angioplasty.
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