NEW STUDY REPORTS INCREASED MORTALITY WITH COMBINED CABG-CAROTID ENDARTERECTOMY
ARTICLE IN BRIEF
- ✓ Investigators reported a 38 percent greater chance of death or postoperative stroke when CABG and carotid endarterectomy are done together.
Patients who have a blocked carotid artery often benefit from carotid endarterectomy (CE) to increase cerebral blood flow. These patients often have major coronary artery disease as well, and may benefit from a coronary artery bypass graft (CABG). During the bypass procedure, however, blood flow through the narrowed carotid artery may diminish, resulting in hypoperfusion of the brain; in addition, blood clots may be thrown off by the cardiac surgery to clog the carotid artery or intracranial vessels, stopping blood flow altogether.
So why not perform both operations at the same time? The idea seems to make so much sense. The patient receives general anesthesia only once, and recovers from both strenuous procedures simultaneously. However, these benefits are hypothetical — no evidence demonstrates that performing both procedures at the same time produces a lower risk of stroke or death. In fact, a Jan. 16 study in Neurology (2007;68:195–197) suggests that there is a 38 percent increase in stroke and death when the procedures are performed together compared to separate operations.
In the study, Richard M. Dubinsky, MD, and Sue Min Lai, PhD, of the University of Kansas Medical Center, used hospital admissions data provided by the Nationwide Inpatient Sample to compare the incidence of mortality and postoperative stroke in patients who received CE and CABG together with those who had CABG alone. The odds ratio for death or stroke after CE and CABG together was 2.25, but dropped to 1.38 after they accounted for comorbidities and other confounders.
“Still, after this correction, there is a 38 percent greater chance of death or postoperative stroke with combined CE—CABG,” they wrote. Residual confounders such as the degree of carotid stenosis or severity of a previous stroke may account for some of the increased risk, they believe, but their results were similar to other assessments of risk for the combined procedure.
SOBERING FINDINGS FOR SURGEONS
Experts who were not involved with the current study agreed with the study's findings. These results should sober surgeons who think that there is some benefit to performing the two procedures together, said Seemant Chaturvedi, MD, professor of neurology and director of the stroke program at Wayne State University School of Medicine in Detroit, MI. “The paper shows that the risks of combining the two are clearly higher,” he said. “I think in general the message is that we should be cautious about doing the combined procedures until we have evidence that it is better than the alternatives.”
Dr. Chaturvedi, who helped write the AAN guidelines on CE (Neurology 2005;65:794–801), acknowledged that up to 3 percent of patients who undergo the CABG procedure have strokes, which is why some surgeons want to clear the carotid arteries first. “The major concern is that these patients will have low blood pressure during surgery, and if there is a blockage in the carotid artery, then there may not be enough blood flow to the brain,” he said. “Many neurologists believe that strokes following bypass surgery are related to blood clots coming from the heart, but it's not clear that fixing the carotid would reduce strokes.”
In patients who have carotid occlusion without symptoms, and need CABG, Dr. Chaturvedi said he would consider holding off on CE and treating the patient instead with cholesterol lowering medication, anti-hypertensive medication, and anti-coagulant therapy such as aspirin or prescription alternatives.
Guy M. McKhann, MD, professor of neurology and neuroscience at Johns Hopkins University School of Medicine, also emphasized the use of stents in the carotid as an alternative to CE. “There's no question that if you try to do the combined procedures, the incidence of stroke and other complications is higher,” said Dr. McKhann. “One thing that's going to come into this in the future is the role of carotid stents. It's conceivable that in three or four years we'll see more stents than carotid procedures.”
Dr. McKhann also emphasized the importance of getting brain scans of patients being considered for the combined CE-CABG surgeries. “I think you could make an argument that if you have a patient who has significant involvement of the carotid and coronary arteries, you should do imaging first to see if there is evidence of previous vascular disease such as strokes,” he said. “If you see evidence, you could make an argument for doing these as separate procedures. You have much better control of things when you do them independently. With the longer surgery, there's more stress on the patient.”
Dr. McKhann was the lead author of a study in Stroke (2006;37:562) that urged physicians to determine the extent of underlying brain problems, such as damage from small strokes, while considering a patient for these procedures.
“In high-risk patients it's worth considering getting more information with MRI with DWI (diffusion-weighted imaging),” he said. “As people get older, there's an increasing incidence of silent infarcts. You find evidence of strokes that the patient didn't recognize, but that produced evidence visible on scans. You want to know that, and if you find it, then shy away from doing both procedures at the same time.”
Pierre Fayad, MD, professor and chair of the department of neurological sciences at the University of Nebraska Medical Center in Omaha, also agreed with the conclusions of the Neurology paper. “I almost never recommend doing the two procedures together,” he said. “If someone is symptomatic from carotid stenosis, we ask to do the carotid first and then wait a couple of weeks for the heart surgery. Now we certainly do have evidence that the risk of doing the two surgeries together is much higher than doing each procedure alone.”
Still, questions remain, he said. “We still don't have a clear idea of the risk of doing CABG in someone with carotid stenosis,” Dr. Fayad said. “How much is the risk of stroke increased? There may be a subgroup of patients who could benefit from having both procedures done at the same time — perhaps those who are symptomatic from carotid stenosis and need CABG, but I don't think anyone knows this because there are not enough data.”
Providing the data would be expensive and complicated, he said, and it would require the cooperation of surgeons who are reluctant to perform CABG without fixing the carotid artery first.
Dr. Fayad agrees that carotid stenting may provide an alternative to CE. “From a hypothetical perspective, carotid stenting is much more attractive and appears to be less stressful to the heart in someone who has active coronary disease,” he said. “It's less stressful than endarterectomy, but we need specific studies in these patients.”
“The SAPPHIRE study was done in patients considered at high risk for CE (N Eng J Med 2004;351:1493–1501). That means patients with major coronary artery disease, lung disease, kidney disease — those who have anatomical risk factors that suggest that surgery would be higher risk. The study showed that stenting is not inferior, and it is less invasive and carries a lower risk of stroke, heart attack, and death.”
Although the Neurology paper provides strong evidence that combining CE and CABG is risky, Dr. Fayad does not expect it will end the debate. “The argument can go back and forth until you have a randomized study, which probably isn't going to happen because of the expense and complexity of it,” he said. “Although there are no clear data, the combined procedures are being done. And they're commonly done based on presumptions of hypothetical benefits rather than real data.”