Abnormalities in the brain before elective cardiac surgery detected by diffusion-weighted magnetic resonance imaging

Diffusion-weighted magnetic resonance imaging (DWI) has found ischemic lesions in the brain after cardiac surgery. However, preoperative cerebral injury has not been studied closely. In this study, we used DWI to assess the prevalence of abnormalities in patients scheduled for cardiac surgery.

We used conventional magnetic resonance imaging and DWI to study 247 consecutive patients scheduled for elective cardiac surgery. Clinical characteristics, neuropsychological test performance, and radiographic data were collected and compared with a group of patients who had normal findings on DWI.

Eleven of the 247 patients (4.5%) had cerebral ischemic lesions on DWI before surgery. Compared with patients who had normal findings on DWI, patients who had abnormalities had significantly higher rates of history of cerebrovascular disease (64% versus 12%), cardiac catheterization within 14 days before DWI (91% versus 54%), preoperative cerebral infarctions (45% versus 5%), carotid artery stenosis (36% versus 5%), and preoperative cognitive impairment (55% versus 9%). Of the 11 patients with DWI abnormalities, 5 had delayed elective surgery and follow-up image studies; of these 5, 4 showed no relevant ischemic lesion on preoperative follow-up imaging. Among the other 6 patients, 1 had an infarction due to expansion of the same lesion that was detected on the preoperative DWI. There was no significant difference with regard to the incidence of postoperative stroke and cognitive dysfunction.

In all, 4.5% of cardiac surgery patients had existing cerebral ischemic lesions on DWI without obvious neurologic defects. Further studies are required to determine whether the lesions are associated with postoperative cognitive dysfunction or stroke.