Pathogenesis and Risk Factors for Cerebral Infarct After Surgical Aortic Valve Replacement

Abstract

Background and purpose: Stroke is a potentially devastating complication of cardiac surgery. Identifying predictors of radiographic infarct may lead to improved stroke prevention for surgical patients.

Methods: We reviewed 129 postoperative brain magnetic resonance imagings from a prospective study of patients undergoing surgical aortic valve replacement. Acute infarcts were classified as watershed or embolic using prespecified criteria.

Results: Acute infarct on magnetic resonance imaging was seen in 79 of 129 patients (61%), and interrater reliability for stroke pathogenesis was high (κ=0.93). Embolic infarcts only were identified in 60 patients (46%), watershed only in 2 (2%), and both in 17 (13%). In multivariable logistic regression, embolic infarct was associated with aortic arch atheroma (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.0-12.0; P=0.055), old subcortical infarcts (OR, 5.5; 95% CI, 1.1-26.6; P=0.04), no history of percutaneous transluminal coronary angioplasty or coronary artery bypass graft (OR, 4.0; 95% CI, 1.2-13.7; P=0.03), and higher aortic valve gradient (OR, 1.3 per 5 mm Hg; 95% CI, 1.09-1.6; P=0.004). Watershed infarct was associated with internal carotid artery stenosis ≥70% (OR, 11.7; 95% CI, 1.8-76.8; P=0.01) and increased left ventricular ejection fraction (OR, 1.6 per 5% increase; 95% CI, 1.08-2.4; P=0.02).

Conclusions: The principal mechanism of acute cerebral infarction after aortic valve replacement is embolism. There are distinct factors associated with watershed and embolic infarct, some of which may be modifiable.

Keywords: brain; carotid stenosis; cerebral infarction; embolism; magnetic resonance imaging.

Figure 1

MR Diffusion weighted imaging (DWI) and corresponding apparent diffusion coefficient (ADC) sequences. (A) Left cortical borderzone watershed infarction and right internal borderzone watershed infarction. (B) Right occipital embolic infarct. (C) Left embolic infarct, although in an area of possible watershed distribution the lesion is singular and <1.5cm.