To Catch a Thief

New rules predict stroke risk and death from stroke-preventive surgery

(RxWiki News) Carotid-artery surgery can cause stroke, but so can asymptomatic carotid disease if left untreated. It's a catch-22 that has rattled medical science -- until now.

University of Texas Southwestern Medical Center researchers have now developed a clinical-risk prediction rule that looks at factors such as sex, race and health history to assess the surgery's dangers. A modified version of the rule will help patients make a more fully informed choice about whether to have the procedure.

"It may take a thief to catch a thief, but physicians don't want to cause stroke while trying to prevent stroke, so being able to carefully weigh an individual's benefits and risk from carotid surgery is critically important," said Dr. Ethan Halm, chief of the William T. and Gay Solomon Division of General Internal Medicine and senior author of the study.
Carotid arteries run along the sides of the neck. They are the main blood vessels that supply oxygen to the brain. Over time, these arteries narrow because of plaque (fatty cholesterol deposits). If pieces of plaque break free, they can lodge in the brain, causing stroke.

In one of the most common types of vascular surgeries -- carotid endarterectomy (CEA) -- surgeons open the artery and remove the plaque. Symptom-free carotid artery disease usually is found by chance during unrelated medical tests. Asymptomatic patients achieve only a modest benefit from CEA – decreasing their chance of stroke from their chance of stroke from 2 percent annually to 1 percent annually – because they have a lower chance of having a stroke in the first place, according to Halm.

"For patients with several other medical risk factors, the upfront risk of surgery can outweigh any potential long-term benefits," Halm said.

Halm and cohorts reviewed cases from the New York Carotid Artery Surgery study (NYCAS), which includes the evaluated outcomes of carotid surgeries performed on elderly patients in 167 hospitals in New York state between January 1998 and June 1999. About 6,553 of the 9,308 surgeries were performed on asymptomatic patients. Researchers found eight factors to be independent predictors of death or stroke: being female, a minority, or severely disabled, or having a history of stroke, having arteries narrowed more than 50 percent, coronary artery disease, congestive heart failure or valvular heart disease.

As a result of the study, the authors are working on an interactive educational initiative that helps patients better understand the different risks and benefits of surgical versus medical management of asymptomatic carotid disease.

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Review Date: 
December 13, 2010