New brain infarcts on magnetic resonance imaging after coronary artery bypass graft surgery: lesion patterns, mechanism, and predictors.

OBJECTIVE: New brain infarcts after coronary artery bypass graft (CABG) are markedly more frequent than clinically evident stroke and have been proposed as a surrogate marker of postprocedural stroke. We sought to investigate the lesion patterns, mechanisms, and predictors of new brain infarction after CABG surgery.

METHODS: This was a prospective pre- and postoperative brain magnetic resonance imaging (MRI) study in consecutive patients who underwent isolated CABG. Preoperative MRI included diffusion-weighted imaging (DWI) and magnetic resonance angiography. DWI was repeated on postoperative day 3. Clinical variables, intraoperative findings, and laboratory findings were compared between patients with and without new brain infarcts on DWI.

RESULTS: Of a total of 127 included patients, 35 (27.6%) showed new brain infarcts on DWI. Most lesions were clinically silent, located in the cortical territory (80%), small (<1.5cm) in diameter (89%), and not related to the underlying cerebral arterial abnormality (80%). Old age (odds ratio [OR] = 1.09, 95% confidence interval [CI] = 1.03-1.15), use of cardiopulmonary bypass (OR = 3.12, 95% CI = 1.13-8.57), a moderate to severe aortic plaque (OR = 21.17, 95% CI = 2.01-222.58), and high levels of high-sensitivity C-reactive protein (OR = 1.35, 95% CI = 1.08-1.70) were independent predictors of new brain infarction.

INTERPRETATION: Post-CABG new brain infarcts are mostly silent and cortically located. Old age, aortic arch atherosclerosis, use of cardiopulmonary bypass, and systemic inflammatory response may contribute to the pathogenesis of post-CABG new brain infarcts.