Mild to moderate atheromatous disease of the thoracic aorta and new ischemic brain lesions after conventional coronary artery bypass graft surgery

Abstract

Background and purpose: The presence of new ischemic brain infarcts, detected by diffusion-weighted magnetic resonance imaging (DW-MRI), have been reported in considerable number of patients after cardiac surgery. We sought to determine the role of proximal thoracic aortic atheroma in predicting embolic events and new ischemic brain lesions in patients undergoing conventional coronary revascularization surgery.

Methods: Transesophageal echocardiography and epiaortic scanning was performed to assess the severity of aortic atherosclerosis in the ascending aorta and the aortic arch. Patients were allocated to either low-risk group, (intimal thickness < or =2mm), or high-risk group (intimal thickness >2mm). Transcranial Doppler was used to monitor the middle cerebral artery. DW-MRI was performed 3-7 days after surgery. The NEECHAM Confusion Scale was used for assessment and monitoring patient consciousness level.

Results: Patients in the high-risk group were considerably older; 71+/-6 (n=38) versus 67+/-6 (n=72) years, P=0.004 and were more likely to have impaired left ventricular function. Confusion was present in 6 (16%) patients in the high-risk group and 5 (7%) patients in the low-risk group. Patients in the high-risk group had a three-fold increase in median embolic count, 223.5 versus 70.0, P=0.0003. DW-MRI detected brain lesions were only present in patients from high-risk group, 61.5 versus 0%, P<0.0001. There was significant correlation between the NEECHAM scores and embolic count in the high-risk group; r=0.63, P<0.001.

Conclusions: The findings of this investigation suggest that mild to moderate atheromatous disease of the ascending aorta and the aortic arch (intimal thickness >2mm) is a major contributor to ischemic brain injury after cardiac surgery.