Stroke risk after coronary artery bypass graft surgery and extent of cerebral artery atherosclerosis

Abstract

Objectives: We aimed to define the relationship between cerebral atherosclerosis and stroke after coronary artery bypass grafting (CABG).

Background: 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.

Methods: Pre-operative magnetic resonance angiography was performed on 1,367 consecutive CABG patients to assess intracranial and extracranial cerebral atherosclerosis. Disease severity was evaluated by atherosclerosis score, as determined by the number of steno-occlusions of cerebral arteries and the degree thereof. Post-CABG strokes (within 14 days) were classified as atherosclerotic (strokes attributable to pre-defined atherosclerosis) or other (strokes caused by other mechanisms). Associations between post-CABG stroke and each type of atherosclerotic disease (extracranial carotid artery disease, intracranial, extracranial, or extracranial and/or intracranial cerebral atherosclerosis), differentiated according to the involved arteries, were analyzed.

Results: Stroke occurred in 33 patients, and the atherosclerosis score was independently associated with stroke development (odds ratio: 1.35; 95% confidence interval: 1.16 to 1.56). Atherosclerotic stroke was defined in 15 (45%), and constituted >40% of both immediate (within 24 h) and delayed strokes. Intracranial, extracranial, and extracranial and/or intracranial cerebral atherosclerosis were significantly associated with stroke.

Conclusions: Cerebral atherosclerosis was closely related to the occurrence of post-CABG stroke, being both an independent risk factor for and the cause of a significant proportion of strokes. Pre-operative evaluation of intracranial and extracranial cerebral arteries, apart from the extracranial carotid artery, may be useful to predict the likelihood of post-CABG stroke.