Preoperative cognition predicts clinical stroke/TIA and mortality after surgical aortic valve replacement in older adults.

Stroke and death remain risks of surgical aortic valve replacement (SAVR). Preoperative cognitive screeners repeatedly show that reduced scores predict postoperative outcome, but less is known about comprehensive neuropsychological measures predicting risk. This study had two aims: 1) investigate whether preoperative cognitive measures predicted postoperative clinical stroke/transient ischemic attack (TIA) and mortality in older adults undergoing SAVR, and 2) identify the best predictors within a comprehensive cognitive protocol. A total of 165 participants aged 65 + with moderate-to-severe aortic stenosis completed a comprehensive cognitive test battery preoperatively. Postoperative stroke evaluations were conducted by trained stroke neurologists preoperatively and postoperatively, and mortality outcomes were obtained by report and records. Logistic regressions were conducted to evaluate preoperative cognitive predictors of clinical stroke/TIA within 1 week of surgery and mortality within 1 year of surgery. Multivariate models showed measures of delayed verbal memory recall (OR = 0.86; 95% CI 0.74-0.99) and visuospatial skills (OR = 0.95; 95% CI 0.90-1.01) predicted clinical stroke/TIA within 1 week of surgery, R2 = .41, p < .001, ƒ2 = .69. Measures of naming ability (OR = 0.88; 95% CI 0.80-0.96), verbal memory recall (OR = 1.23; 95% CI 0.99-1.51), visual memory recall (OR = 0.90; 95% CI 0.80-1.00), medical comorbidities (OR = 1.71; 95% CI 1.22-2.65), and sex (OR = 2.39; 95% CI 0.90-7.04) were significant predictors of death within 1 year of surgery, R2 = .68, p < .001, ƒ2 = 2.12. Preoperative cognitive measures reflecting temporal and parietal lobe functions predicted postoperative clinical stroke/TIA within 1 week of SAVR and mortality within 1 year of SAVR. As such, cognitive measures may offer objective and timely indicators of preoperative health, specifically vulnerabilities in cerebral hypoperfusion, which may inform intervention and/or intensive postoperative monitoring and follow-up after SAVR.

Impact of supervised exercise on skeletal muscle blood flow and vascular function measured with MRI in patients with peripheral artery disease.

Supervised exercise is a common therapeutic intervention for patients with peripheral artery disease (PAD), however, the mechanism underlying the improvement in claudication symptomatology is not completely understood. The hypothesis that exercise improves microvascular blood flow is herein tested via temporally resolved magnetic resonance imaging (MRI) measurement of blood flow and oxygenation dynamics during reactive hyperemia in the leg with the lower ankle-brachial index. One hundred and forty-eight subjects with PAD were prospectively assigned to standard medical care or 3 mo of supervised exercise therapy. Before and after the intervention period, subjects performed a graded treadmill walking test, and MRI data were collected with Perfusion, Intravascular Venous Oxygen saturation, and T2* (PIVOT), a method that simultaneously quantifies microvascular perfusion, as well as relative oxygenation changes in skeletal muscle and venous oxygen saturation in a large draining vein. The 3-mo exercise intervention was associated with an improvement in peak walking time (64% greater in those randomized to the exercise group at follow-up, P < 0.001). Significant differences were not observed in the MRI measures between the subjects randomized to exercise therapy versus standard medical care based on an intention-to-treat analysis. However, the peak postischemia perfusion averaged across the leg between baseline and follow-up visits increased by 10% (P = 0.021) in participants that were adherent to the exercise protocol (completed >80% of prescribed exercise visits). In this cohort of adherent exercisers, there was no difference in the time to peak perfusion or oxygenation metrics, suggesting that there was no improvement in microvascular function nor changes in tissue metabolism in response to the 3-mo exercise intervention.NEW & NOTEWORTHY Supervised exercise interventions can improve symptomatology in patients with peripheral artery disease, but the underlying mechanism remains unclear. Here, MRI was used to evaluate perfusion, relative tissue oxygenation, and venous oxygen saturation in response to cuff-induced ischemia. Reactive hyperemia responses were measured before and after 3 mo of randomized supervised exercise therapy or standard medical care. Those participants who were adherent to the exercise regimen had a significant improvement in peak perfusion.

Cognition and Cerebral Infarction in Older Adults After Surgical Aortic Valve Replacement.

BACKGROUND: Aortic valve replacement (AVR) for calcific aortic stenosis is associated with high rates of perioperative stroke and silent cerebral infarcts on diffusion-weighted magnetic resonance imaging (MRI), but cognitive outcomes in elderly AVR patients compared with individuals with cardiac disease who do not undergo surgery are uncertain. METHODS: One hundred ninety AVR patients (mean age 76 ± 6 years) and 198 non-surgical participants with cardiovascular disease (mean age 74 ± 6 years) completed comprehensive cognitive testing at baseline (preoperatively) and 4 to 6 weeks and 1 year postoperatively. Surgical participants also completed perioperative stroke evaluations, including postoperative brain MRI. Mixed model analyses and reliable change scores examined cognitive outcomes. Stroke outcomes were evaluated in participants with and without postoperative cognitive dysfunction. RESULTS: From reliable change scores, only 12.4% of the surgical group demonstrated postoperative cognitive dysfunction at 4 to 6 weeks and 7.5% at 1 year. Although the surgical group had statistically significantly lower scores in working memory/inhibition 4 to 6 weeks after surgery, the groups did not differ at 1 year. In surgical participants, postoperative cognitive dysfunction was associated with a greater number (p < 0.01) and larger total volume (p < 0.01) of acute cerebral infarcts on MRI. CONCLUSIONS: In high-risk, aged participants undergoing surgical AVR for aortic stenosis, postoperative cognitive dysfunction was surprisingly limited and was resolved by 1 year in most. Postoperative cognitive dysfunction at 4 to 6 weeks was associated with more and larger acute cerebral infarcts.

What Makes New Ischemic Lesions Symptomatic after Aortic Valve Replacement?

BACKGROUND: Acute cerebral infarctions on diffusion-weighted magnetic resonance imaging (MRI) are common after cardiothoracic surgery. However, most are asymptomatic and we aimed to identify features associated with clinical stroke symptoms. METHODS: Patients over 65 years of age undergoing surgical aortic valve replacement (AVR) for calcific stenosis were prospectively recruited (N = 196). All patients underwent neurological evaluation preoperatively and on postoperative days 1, 3, and 7, and MRI on planned postoperative day 5. Among those with new postoperative DWI lesions, we performed univariate and multivariable analyses to identify clinical, demographic, surgical, and imaging factors associated with clinical stroke symptoms. RESULTS: Of the 129 patients who completed a postsurgical MRI, 79 (61%) had DWI lesions and 17 (21.5%) of these had new stroke symptoms concordant with the infarct distribution. In an exploratory multivariable analysis, focal neurological symptoms were associated with increased age, a longer bypass duration, and a larger pre-existing lesion burden on fluid-attenuated inversion recovery. Limiting the analysis to the 61 patients with analyzable volume and location data, logistic regression failed to identify any location-related determinant of symptomatic lesions. CONCLUSIONS: New DWI lesions are common after AVR, but most are asymptomatic. Patients are more likely to have symptoms with longer bypass durations, increasing age, and larger pre-existing lesion burdens.

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

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.

Multiparametric assessment of vascular function in peripheral artery disease: dynamic measurement of skeletal muscle perfusion, blood-oxygen-level dependent signal, and venous oxygen saturation.

BACKGROUND: Endothelial dysfunction present in patients with peripheral artery disease may be better understood by measuring the temporal dynamics of blood flow and oxygen saturation during reactive hyperemia than by conventional static measurements. METHODS AND RESULTS: Perfusion, Intravascular Venous Oxygen saturation, and T2* (PIVOT), a recently developed MRI technique, was used to measure the response to an ischemia-reperfusion paradigm in 96 patients with peripheral artery disease of varying severity and 10 healthy controls. Perfusion, venous oxygen saturation SvO2, and T2* were each quantified in the calf at 2-s temporal resolution, yielding a dynamic time course for each variable. Compared with healthy controls, patients had a blunted and delayed hyperemic response. Moreover, patients with lower ankle-brachial index had (1) a more delayed reactive hyperemia response time, manifesting as an increase in time to peak perfusion in the gastrocnemius, soleus, and peroneus muscles, and in the anterior compartment, (2) an increase in the time to peak T2* measured in the soleus muscle, and (3) a prolongation of the posterior tibial vein SvO2 washout time. Intrasession and intersession repeatability were also assessed. Results indicated that time to peak perfusion and time to peak T2* were the most reliable extracted time course metrics. CONCLUSIONS: Perfusion, dynamic SvO2, and T2* response times after induced ischemia are highly correlated with peripheral artery disease severity. Combined imaging of peripheral microvascular blood flow and dynamics of oxygen saturation with Perfusion, intravascular SvO2, and T2* may be a useful tool to investigate the pathophysiology of peripheral artery disease.

Commissions and omissions are dissociable aspects of everyday action impairment in schizophrenia.

Prior research using performance-based assessment of functional impairment has informed a novel neuropsychological model of everyday action impairment in dementia in which omission errors (i.e., failure to complete task steps) dissociate from commission errors (i.e., inaccurate performance of task steps) and have unique neuropsychological correlates. However, this model has not been tested in other populations. The present study examined whether this model extends to schizophrenia. Fifty-four individuals with schizophrenia or schizoaffective disorder were administered a neuropsychological protocol and the Naturalistic Action Test (NAT), a performance-based measure of everyday action. A principal component analysis (PCA) was performed to examine the construct(s) comprising everyday action impairment, and correlations between the resultant component(s) and neuropsychological tests were examined. Results showed that omissions and a subset of commissions were distinct components of everyday action. However, results did not support unique associations between these components and specific neuropsychological measures. These findings extend the omission-commission model to schizophrenia and may have important implications for efficient assessment and effective rehabilitation of functional impairment, such as the potential efficacy of targeted interventions for the rehabilitation of omission and commission deficits in everyday functioning. Larger studies with prospective designs are needed to replicate the present preliminary findings.

Stroke after aortic valve surgery: results from a prospective cohort.

BACKGROUND: The incidence and impact of clinical stroke and silent radiographic cerebral infarction complicating open surgical aortic valve replacement (AVR) are poorly characterized. METHODS AND RESULTS: We performed a prospective cohort study of subjects ≥65 years of age who were undergoing AVR for calcific aortic stenosis. Subjects were evaluated by neurologists preoperatively and postoperatively and underwent postoperative magnetic resonance imaging. Over a 4-year period, 196 subjects were enrolled at 2 sites (mean age, 75.8±6.2 years; 36% women; 6% nonwhite). Clinical strokes were detected in 17%, transient ischemic attack in 2%, and in-hospital mortality was 5%. The frequency of stroke in the Society for Thoracic Surgery database in this cohort was 7%. Most strokes were mild; the median National Institutes of Health Stroke Scale was 3 (interquartile range, 1-9). Clinical stroke was associated with increased length of stay (median, 12 versus 10 days; P=0.02). Moderate or severe stroke (National Institutes of Health Stroke Scale ≥10) occurred in 8 (4%) and was strongly associated with in-hospital mortality (38% versus 4%; P=0.005). Of the 109 stroke-free subjects with postoperative magnetic resonance imaging, silent infarct was identified in 59 (54%). Silent infarct was not associated with in-hospital mortality or increased length of stay. CONCLUSIONS: Clinical stroke after AVR was more common than reported previously, more than double for this same cohort in the Society for Thoracic Surgery database, and silent cerebral infarctions were detected in more than half of the patients undergoing AVR. Clinical stroke complicating AVR is associated with increased length of stay and mortality.