SAN DIEGO – A surgical procedure or intervention with a perioperative stroke risk of less than 9% would advance the treatment of chronic carotid artery occlusive disease, according to Dr. Colin P. Derdeyn.
If such a procedure existed, "we’d have an intervention that would provide a benefit in a very high-risk population," he said at the annual meeting of the Society of Neurointerventional Surgery.
Dr. Colin P. Derdeyn
The Carotid Occlusion Surgery Study, a recently completed randomized trial of surgical bypass for complete atherosclerotic carotid artery occlusion, failed to show a benefit for surgery. The risk of stroke in patients who had surgery, but did not suffer a complication from the surgery, was much lower than the risk of stroke in the medically treated patients. If the perioperative complication rate had been less than 9%, surgery might have shown a benefit in the trial, explained Dr. Derdeyn, director of the stroke and cerebrovascular center and professor of radiology, neurology, and neurologic surgery at Washington University, St. Louis.
Dr. Derdeyn and his colleagues are trying to take the perioperative complication rate of endovascular recanalization below 9% by organizing a pilot trial of its use in patients with subacute or chronic carotid occlusion. PET scans will be used "to identify patients whom we know are going to have a high 2-year risk of stroke, and examine safety and 2-year stroke rates," he said. "There have been a number of case series, primarily from Asia, with very high recanalization rates and very low perioperative complication rates for going through a chronic occlusion and stenting it open."
Another important area for future research in chronic occlusive disease may involve exploration of a theory known as reversible cognitive impairment. "The idea here is that there is a metabolic downregulation secondary to chronic oligemia, and that this reduced metabolic activity reduces the blood flow needs," Dr. Derdeyn said. "The second part of this theory is that there is cognitive impairment related to this metabolic downregulation, and the third part of the theory is that if you revascularize, it all gets better."
He emphasized that reversible cognitive impairment has not been proven. "We’ve certainly had anecdotal cases that make us think that it’s true, but we have no proof yet that this exists," he said. "There have been a lot of case series, but the problem is that many of them include stroke patients who recovered from their strokes. We expect stroke patients to get better in terms of their neurocognition, so there is no good control [group]."
Dr. Derdeyn is one of the investigators in the National Institute of Neurological Disorders and Stroke–sponsored Randomized Evaluation Carotid Occlusion and Neurocognition (RECON) trial. For this blinded clinical study, researchers set out to test the hypothesis that patients who have symptomatic, unilateral carotid artery occlusion and increased oxygen extraction fraction will have better cognitive function following extracranial to intracranial bypass, compared with an identical group of patients treated with best medical therapy alone. The results of the trial are expected to be presented at the 2013 International Stroke Conference.
Baseline data from RECON published earlier this year demonstrated an association of increased oxygen extraction fraction with cognitive impairment in 44 patients who suffered a transient ischemic attack (Neurology 2012;78:250-5).
Dr. Derdeyn said that he had no relevant financial disclosures.