Surgery to prevent stroke. High hopes and deep disappointment

Carotid endarterectomy and EC/IC bypass grafting have been widely adopted for patients considered at risk from stroke, without good evidence of efficacy. Unjustified claims for surgery usually derive from overestimating the dangers of the disease without surgery, while perioperative risks are underestimated. Inadequate follow-up and choosing irrelevant outcome measures often add to the confusion. All these factors apply to surgery for stroke. A trial of EC/IC bypass in 1,377 patients from three continents took 8 years to complete and showed no benefit in patients randomized to surgery. Reluctance to accept this result led to detailed critiques of this trial in several journals, largely based on the discovery that many patients had been operated on in some centers without having been randomized. In reply, the investigators showed that these cases did not affect the "resounding negativity of the results." Lack of good data about the prognosis of patients with TIAs or minor strokes was the fundamental reason for so much misplaced surgical effort. This applies equally to carotid endarterectomy, for which large trials are currently being completed. Had there been a reliable data base of patients at risk of stroke, prospectively collected and followed, the efficacy of these two operations could have been determined much sooner, and inappropriate diffusion might have been prevented.