Postoperative neurological complications and risk factors for pre-existing silent brain infarction in elderly patients undergoing coronary artery bypass grafting

Abstract

Elderly patients with multiple infarctions revealed a high prevalence of postoperative stroke after coronary artery bypass grafting (CABG). However, postoperative neurological complications and characteristics of silent brain infarction (SBI) have not been evaluated in elderly patients undergoing CABG. Four hundred forty-nine patients (≥60 years old) scheduled for CABG underwent cerebral magnetic resonance imaging (MRI) and MR angiography preoperatively to assess cerebral infarctions and carotid and intracranial artery stenosis. Atherosclerosis of the ascending aorta was assessed by epiaortic ultrasound during surgery. Patients were sorted by their history of cerebrovascular disease (CVD) and the presence of infarction by MRI: SBI (infarction without CVD), BI (symptomatic brain infarction; CVD and infarction), and controls (no findings of either CVD or infarction). SBI was found in 35.5% of the 449 patients and increased with age. The prevalence of pre-existing multiple infarctions was less frequent in SBI than in BI. The incidence of postoperative stroke and cognitive dysfunction was 1.3% and 4.9% in controls (n = 225), 5.7% and 15.2% in SBI (n = 158), and 9.1% and 18.2% in BI (n = 66). Patients with SBI were older and had more renal dysfunction and preoperative cognitive impairment. Stepwise logistic regression demonstrated that age, renal dysfunction, preoperative cognitive impairment, atherosclerosis of the ascending aorta, and intracranial arterial stenosis were associated significantly with SBI. Patients with SBI were ranked at moderate risk of neurological complications after CABG between control and BI. Increased age, renal dysfunction, and preoperative cognitive impairment appeared to be strongly associated with SBI.