Researchers from South Korea found a strong linkage between pre-operative cerebral atherosclerosis and occurrence of stroke post-CABG, and suggested that pre-operative evaluation of intracranial and extracranial cerebral arteries could help predict post-CABG stroke, according to study results published in the May 3 issue of the Journal of the American College of Cardiology.
“Although cerebral atherosclerosis may play a crucial role in the advent of post-CABG stroke, only extracranial carotid artery disease has been extensively studied, and the effects of atherosclerosis on the mechanisms underlying post-CABG stroke remain unclear,” Eun-Jae Lee, MD, of the Asan Medical Center and University of Ulsan College of Medicine in Seoul, South Korea, and colleagues wrote.
The authors also noted that post-operative stroke is greater post-CABG compared with general surgery; these rates ranged from 1.4 percent to 3.8 percent to 0.08 percent to 0.7 percent, respectively.
To bolster existing data on atherosclerosis and post-CABG stroke, Lee and colleagues enrolled 1,367 CABG patients to evaluate intracranial and extracranial cerebral atherosclerosis.
Lee et al performed post-op MR angiography and evaluated disease severity by atherosclerosis score, which was determined by the number and degree of steno-occlusions of the cerebral arteries.
The researchers classified stroke that occurred within 14 days after CABG as atherosclerotic. During the study the researchers also evaluated associations between post-CABG stroke and the various types of atherosclerotic disease including extracranial carotid artery disease, intracranial, extracranial or extracranial and/or intracranial cerebral atherosclerosis.
The results showed that stroke occurred in 33 patients and that atherosclerosis score was independently associated with stroke development. Fifteen strokes were defined as atherosclerotic and accounted for more than 40 percent of immediate (within 24 hours) and delayed stroke cases. The authors found intracranial, extracranial and extracranial and/or intracranial cerebral atherosclerosis to be significantly associated with stroke.
“We found that the atherosclerotic burden of cerebral arteries was closely related to the risk of post-CABG stroke, with the risk of stroke increasing about 1.3-fold for every one-point increase in the atherosclerosis score,” Lee et al wrote.
While the researchers found that extracranial carotid artery (ECCA) disease was present in 46.7 percent of the atherosclerotic stroke population, only ischemic lesions in three patients could be explained by ECCA disease alone, and ECCA disease did not have a significant association with post-CABG stroke. Consequently, the researchers said that pre-operative evaluation of cerebral arteries could better predict the risk of post-CABG stroke in patients.
“Intriguingly, intracranial cerebral disease showed a closer association with stroke than did other atherosclerotic diseases,” the authors wrote. “However, the predisposition to intracranial atherosclerosis in Asian populations may have magnified the importance of intracranial cerebral atherosclerosis in the onset of post-CABG stroke in our patients.”
“The risk of post-CABG stroke was increased as the atherosclerotic burden of the cerebral arteries increased,” the authors concluded. “Pre-operative evaluation of both intracranial and extracranial cerebral arteries, apart from the ECCA, may be useful to predict post-CABG stroke.”
In an accompanying editorial, Steven Shea, MD, and Marco Di Tullio, MD, both of the Columbia University Medical Center in New York City, wrote that some aspects of the current study “should be interpreted with caution. “Although Lee et al mention aortic arch atherosclerosis as possibly implicated in otherwise unexplained strokes with apparent embolic features, they did not report on the presence of aortic arch atherosclerosis, a major offender in post-CABG stroke,” Shea and Di Tuillio offered.
“In summary, this paper adds new information about an important and feared complication of CABG surgery,” the authors wrote.
“It is also possible that the emboli causing these strokes originated in the aorta or heart and that these patients had coexistent but not causally implicated atherosclerosis on MRA in the cerebral arteries,” the authors concluded. They noted that additional studies will be useful to confirm the findings.