Combining coronary bypass and plaque removal from the main arteries serving the brain has become standard care for heart and stroke prevention over the past 15 years. The theory is that combining the two will lower the risk of a stroke during heart bypass as well as minimize the time a patient is under anesthesia. But patients who undergo this combination therapy may significantly increase their risk of stroke or death, according to a new study.

"We need to be cautious, because this shows that [combining the surgeries] might not be as risk-free as thought," says study author Richard Dubinsky, a neurologist at the University of Kansas Medical Center in Kansas City, Kans. "We need tighter clinical trials ... before we say this is the best thing to do, because we don't know if [performing the procedures together] is safer or has a better outcome than separating them by a few weeks."

The report, appearing in the January 16 issue of Neurology, found that patients who undergo both surgeries at the same time have a 38 percent greater chance of suffering postoperative stroke or death, compared with the risk of death or stroke from heart bypass surgery alone.

The study was based on the discharge records of 657,877 patients admitted to U.S. hospitals for carotid endarterectomy (clearing out blocked carotid arteries) and coronary artery bypass surgery from 1993 to 2002.

Dubinsky says more study is needed that takes into account factors that might affect the outcome that were not revealed by his data, such as severity of symptoms, the degree of carotid artery narrowing or blockage and whether a patient previously suffered a stroke. He notes that carotid endarterectomy, the most common stroke prevention surgery, is only performed if a carotid artery (we have two in our necks) is more than 70 percent blocked.

"The benefit of this combined procedure is controversial," he says. "Given this significant increase in postoperative stroke and death, a randomized clinical trial of the combined surgery is needed to determine the benefit, if any, compared to performing the operations in separate hospitalizations."