Investigators anticipate that the stroke rate in COSS will turn out to be 40% in the medically treated group and 24% in the surgically treated group, even taking into account a 12% perioperative stroke and mortality rate, as reported in the original EC/IC trial, said Dr. Powers, codirector of the Stroke Center at Barnes-Jewish Hospital and the Washington University School of Medicine.
Even if these reduced stroke rates are borne out by the study, EC/IC bypass surgery is unlikely to become as common as coronary artery bypass; elevated OEF occurs in only 30% of patients with carotid occlusion. The study's $21-million price tag over the next 5-7 years may prove to be money well spent if it settles the question of patient selection once and for all. A similar trial, the Japanese EC/IC Trial (JET), is also working on the question of patient selection. A third trial, the Randomized Evaluation of Carotid Occlusion and Neurocognition (RECON) study, was recently funded by NIH to examine the hotly debated question of whether carotid bypass surgery affects cognitive function.
Stroke is more likely in brains that respond to reduced perfusion (left) with higher OEF (right) in order to support normal oxygen metabolism (middle), some say. Courtesy Dr. Colin Derdeyn