Stroke Risk Not Reduced By EC-IC Bypass Surgery

Editor's Choice
Academic Journal
Main Category: Stroke
Also Included In: Neurology / Neuroscience
Article Date: 09 Nov 2011 - 9:00 PST


Patients who have had a mini-stroke to not appear to have a reduced risk of further strokes if they undergo EC-IC bypass surgery, a procedure aimed at improving blood flow in the carotid artery, researchers from University of North Carolina School of Medicine, Chapel Hill, reported in JAMA (Journal of the American Medical Association).

The authors were focusing on patients with blockage caused by thickening of the internal carotid artery and hemodynamic cerebral ischemia - the artery that supplies the brain with blood becomes blocked, causing insufficient blood flow to the brain, resulting in a sub-type of stroke. The surgical procedure aimed at improving blood flow was found not to reduce the rate of stroke after 24 months compared to those who underwent no procedure and received just medical therapy.

As background information, the researchers wrote:

"Atherosclerotic internal carotid artery occlusion (AICAO) causes approximately 10% of transient ischemic attacks [TIAs; temporary cessation or reduction of blood supply to part of the brain, resulting in brief neurologic dysfunction that usually persists for less than 24 hours; often referred to as 'mini-stroke'] and 15% to 25% of ischemic strokes in the carotid territory.

The 2-year risk of subsequent ipsilateral [on the same side of the previous stroke] ischemic stroke while a patient receives medical therapy is 10% to 15%."

EC-IC stands for extracranial-intracranial, i.e. outside, within the skull. EC-IC bypass surgery, as mentioned above, was developed to reduce the risk of stroke recurrence by improving the flow of blood to the blocked artery with revascularization. Revascularization means surgical procedure to restore or improve blood supply to a body part or organ.

A prior study revealed no benefit from the procedure. However, the authors wrote:

". . . . this trial was criticized for failing to identify the subgroup of patients with hemodynamic cerebral ischemia due to poor collateral circulation for whom surgical revascularization might be of greatest benefit."

William J. Powers, M.D., and team set out to determine whether EC-IC bypass surgery combined with best medical therapy might reduce the risk of further strokes (subsequent ipsilateral ischemic stroke) after 24 months. They focused on patients with recently symptomatic atherosclerotic internal carotid artery occlusion and hemodynamic cerebral ischemia.

195 patients were split into two groups:

• The surgery group - 97 participants
• The no surgery group - 98 participants

Risk factor intervention as well as therapy for thrombosis were recommended for all of them.

The trial was carried out from 2002 to 2010 at 49 centers and 18 PET centers in Canada and the USA.

The primary outcome for those in the surgery group was a combination of:

• All stroke and death from surgery within 30 days of the surgical procedure
• Ipsilateral ischemic stroke within 24 months of surgery

The midpoint follow-up was 723 days for those in the surgical group and 722 days for the other group. The study was stopped early because it was found that the surgery had no benefits.

The investigators found that:

• There were 20 (21%) events in the surgical group after 24 months
• There were 20(22.7%) events in the non-surgical groups after 24 months
  A difference of 1.7% between the two groups
  
  
• There were 14 (14.4%) cases of ipsilateral ischemic stroke in the surgical group after 30 days
• There were2 (2%) cases of ipsilateral ischemic stroke in the non-surgical group after 30 days
  A difference of 12.4% between the two groups

The authors wrote:

"The lower stroke risk observed in the COSS for the nonsurgical group is similar to the better outcomes observed in more recent studies of patients with medically treated asymptomatic carotid artery stenosis, ascribed to improvements in medical therapy. These observations reaffirm the hazard of using even the most carefully studied historical controls to infer therapeutic efficacy and the necessity of performing randomized controlled trials to establish clinical benefit.

Although improved hemodynamics in participants who survived EC-IC bypass surgery without perioperative stroke was associated with low risk of recurrent stroke, the better-than-expected efficacy of medical therapy in the nonsurgical group was sufficient to nullify any overall benefit of surgery."

Editorial in the same journal

Regarding reimbursement for procedures and devices in clinical practice where evidence of clinical effectiveness is lacking, Joseph P. Broderick, M.D., of the University of Cincinnati College of Medicine, and Philip M. Meyers, M.D., of Columbia University, New York, wrote:

"Clinical science and reimbursement for delivery of clinical stroke care must be balanced and aligned. Physicians who provide care for patients with stroke must recognize the current lack of evidence for clinical efficacy of endovascular therapy and enroll patients in randomized trials.

The review process of the Food and Drug Administration and Centers for Medicare & Medicaid Services (CMS) must be harmonized and should require higher standards of evidence for clinical efficacy prior to clearance or approval of devices for stroke and subsequent reimbursement.

Long-term and ongoing reimbursement should be predicated on evidence for equivalent or superior clinical efficacy, and cost-effectiveness should be an important consideration for clinically equivalent therapies. For example, if intravenous tissue plasminogen activator (IV t-PA) is clinically equivalent to endovascular therapy, society will have to weigh the substantially increased costs for equal clinical benefit. If these devices produce better clinical outcomes, appropriate reimbursement, even for more expensive endovascular interventions, should be promptly instituted so appropriate changes in delivery of care for patients with acute stroke can be expedited."

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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