Calgary, AB - Results from a new Canadian study have revealed an unusually high risk of stroke and death in patients undergoing a combined carotid endarterectomy (CEA) and coronary artery bypass graft (CABG) surgery procedure.[1] The study showed that the adjusted rate of stroke and death is 2.7 times greater in the combined CEA-CABG groups compared with patients undergoing bypass alone.

Regarding the combined procedure, lead investigator Dr Michael Hill (University of Calgary, AB) told heartwire, "The risk is high and the indication is unproven. If we really want to know more about it, we're going to have to do a big trial to see whether we're making a difference."

The results of the study are published in the May 2005 issue of Neurology.

The combined CEA-CABG procedure is typically performed to reduce the risk of stroke and cerebral injury. During bypass surgery, explained Hill, blood pressure is lowered to approximately 60 or 70 mm Hg and the thinking has been that if pressure is reduced, the patient is hemodynamically compromised and at an increased risk of stroke. Also, combining CEA and CABG under one anesthesia has the theoretical potential to decrease perioperative risk.

To assess outcomes of the combined CEA-CABG procedure, Hill and colleagues obtained data from the Canadian Institute for Health Information database on all patients who underwent bypass surgery at a Canadian hospital, excluding Quebec, between 1992 and 2001. Of the 131 762 patients who had bypass graft surgery, just 0.51% underwent combined CEA-CABG. Although Canadian surgeons perform the procedure less frequently than their US counterparts, the number of combined procedures performed is on the rise in Canada, doubling since 1992.

Over the nine-year period the adjusted combined rate of stroke or death in patients undergoing CEA-CABG was 13.0%, compared with 4.9% in patients who had bypass surgery only. Although the risk of death was not statistically different between the two groups after adjusting for confounding variables, an excess risk of stroke remained in the CEA-CABG group (6.8%) compared with patients who underwent bypass surgery only (1.8%).

Hill told heartwire that the rationale for performing the surgeries simultaneously to reduce the risk of stroke caused by blood-pressure reductions might be incorrect. With spontaneous stroke in the setting of carotid stenosis, most strokes are embolic rather than hemodynamic, he said. While removing the plaque in the carotid artery can reduce the risk of stroke occurring in the immediate perioperative period, the benefit is still uncertain. Hill added that based on data from the asymptomatic carotid surgery trials, there is a benefit to patients only if the procedure carries a less than 3% risk of surgical morbidity and mortality.

"If you're going to operate on these people, you're probably not doing it to prevent perioperative stroke but to prevent long-term stroke, five years down the road," said Hill. "If that's the case, then you have to operate on them with the chance of stroke-related morbidity at less than 3%. That's not happening."

Hill noted the data are observational and there is the potential for selection bias. However, he said the paper raises the idea that the risk of the combined strategy is quite high, and clinicians must be careful about selecting patients for the CEA-CABG procedure. Further randomized trials will be necessary to demonstrate the appropriateness of combining the two surgeries, he said.

In an editorial accompanying the study, Drs Patrick Pullicino (University of Medicine and Dentistry of New Jersey, Newark) and Jonathan Halperin (Mount Sinai Medical Center, New York, NY) suggest that it is possible that patients undergoing the combined procedure have more severe vascular disease.[2] Data from the New York State Cardiac Database showed CEA-CABG patients had a greater burden of vascular disease than CABG patients, and this intrinsic vascular risk might be a more powerful determinant of outcome than the surgical procedure.

The editorialists add that the Canadian data also differ from the New York database, pointing out that the US data do not suggest an increased risk of stroke and death when CEA is combined with CABG surgery. Nevertheless, they write, there is still a further need to reduce the risk of death and stroke. The recent Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) study has shown that stenting can be performed with a low combined stroke and death rate in high-risk patients with carotid stenosis.

"As a result, pre-CABG carotid angioplasty with or without stenting has replaced CEA-CABG at several centers in the US," write Pullicino and Halperin. "The onus is now on surgeons who perform CEA-CABG to show that it can be performed with acceptable risks."