The Demise of EC-IC Bypass Surgery

Summary and Comment |
December 6, 2011

The Demise of EC-IC Bypass Surgery

  1. Seemant Chaturvedi, MD, FAHA, FAAN

Extracranial-intracranial bypass plus medical therapy for symptomatic carotid occlusion was no more effective than medical therapy alone at preventing stroke and early mortality in a randomized trial.

  1. Seemant Chaturvedi, MD, FAHA, FAAN

During the 1980s, a large trial showed that extracranial-to-intracranial (EC-IC) arterial bypass surgery was ineffective for stroke prevention. A lingering question was whether patients with objective evidence of hemispheric hypoperfusion would benefit from surgery. The Carotid Occlusion Surgery Study (COSS) was undertaken to study patients with symptomatic carotid occlusion and evidence on positron emission tomography of increased oxygen extraction ipsilateral to the occlusion, a marker of hemodynamic cerebral ischemia. Participants were randomized to optimal medical therapy with or without EC-IC surgery. The primary outcome was the composite of stroke or death within 30 days after either surgery or randomization, and ipsilateral stroke within 2 years of randomization.

The study was terminated early for futility, when 195 patients had been randomized. At the time of the study's termination, there was only a 2% chance for surgery to be proven effective if the trial were carried to completion. The primary outcome occurred in 21.0% of the surgical group and 22.7% of the nonsurgical group, a nonsignificant difference. Thirty-day rates of ipsilateral stroke were 14.4% in the surgical group and 2.0% in the nonsurgical group. Graft patency was 98% at 30 days and 96% at last follow-up.


In planning the study, the investigators expected a 40% rate of stroke in the nonsurgical group. The fact that the actual rate was about half that is consistent with a recent study of optimal medical therapy for intracranial stenosis (JW Neurol Sep 20 2011), in which the medically treated group did better than expected.

The current findings reinforce the need for aggressive medical therapy for optimal stroke prevention. Only 71% of the nonsurgical group had an LDL level <100 mg/dL at final follow-up, suggesting that a stroke rate even lower than that observed in these medically treated patients is achievable. This study should also stimulate a new trial to investigate aggressive medical therapy for extracranial carotid stenosis. For EC-IC bypass surgery, the door should be closed, with a padlock this time.

Dr. Chaturvedi is Professor of Neurology and Director, Stroke Program, Wayne State University, Detroit.


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