Obesity and Recurrent Vascular Risk After a Recent Ischemic Stroke

The obesity paradox in stroke: impact on mortality and short-term readmission

BACKGROUND

The aim of the present study was to assess the association of obesity with the mortality of hospitalized patients with acute stroke and the risk of readmission in less than 30 days.

METHODS

A retrospective chart review of a cohort of consecutive patients admitted with stroke as the primary reason for discharge in Spain between January 1, 2005, and December 31, 2011, was performed. Patients with a diagnosis of obesity were identified. The mortality and readmittance indexes of obese patients were compared against the subpopulation without theses diagnosis.

RESULTS

A total of 201,272 stroke admittances were analyzed, and 14,047 (7.0%) diagnosis of obesity were identified. In-hospital global mortality reached 14.9%, and readmittance risk was 5.9%. Obese patients showed a lower in-hospital mortality risk (odds ratio [OR], .71; 95% confidence interval [CI], .67-.76) and early readmittance risk (OR, .89; 95% CI, .82-.96) than the nonobese even after adjusting for possible confounding factors.

CONCLUSIONS

Obesity in those hospitalized for stroke is associated with reduced in-hospital mortality risk and early readmittance.

The effects of obesity on the cerebral vasculature

The incidence of obesity in the population is increasing at an alarming rate, with this comes an increased risk of insulin resistance (IR). Obesity and IR increase an individual's risk of having a stroke and they have been linked to several forms of dementia. Stroke and dementia are associated with, or exacerbated by, reduced cerebral blood flow, which has recently been described in obese patients. In this review we will discuss the effects of obesity on cerebral artery function and structure. Regarding their function, we will focus on the endothelium and nitric oxide (NO) dependent dilation. NO dependent dilation is impaired in cerebral arteries from obese rats, and the majority of evidence suggests this is a result of increased oxidative stress. We will also describe the limited studies showing that inward cerebral artery remodeling occurs in models of obesity, and that the remodeling is associated with an increase in the damage caused by cerebral ischemia. We will also discuss some of the more paradoxical findings associated with stroke and obesity, including the evidence that obesity is a positive factor for stroke survival. Finally we will discuss the evidence that links these changes in vascular structure and function to cognitive decline and dementia.

Etiology and treatment of arterial ischemic stroke in children and young adults

OPINION STATEMENT

Stroke is the second leading cause of death worldwide (Go et al. Circulation 129:e28-292, 2014) and is a major cause of morbidity and mortality. Compared with older adults, arterial ischemic stroke (AIS) is relatively uncommon in children and young adults, comprising 5-10 % of all stroke (Biller Nat Rev Cardiol 6:395-97, 2009), but is associated with significant cost. In contrast to the declining overall incidence of stroke, some early studies suggest that the rate of stroke hospitalizations in children and young adults is rising (George et al. Ann Neurol 70:713-21, 2011; Kissela et al. Stroke 41:e224, 2010; Nguyen-Huynh et al. Stroke 43, 2012), emphasizing the importance of understanding the similarities and differences in etiology and treatment of AIS across the age spectrum. Among the most common causes of AIS in children are cardioembolism (often related to congenital heart disease), cervicocephalic arterial dissections, focal arteriopathy of childhood and several genetic and metabolic disorders, such as sickle cell disease (SCD). AIS in young adults is less well understood, but likely overlaps in etiology with both children and older adults. Young adults with AIS often have classic atherosclerotic risk factors similar to older adults, but are also more likely to have thrombophilias, cervicocephalic arterial dissections and cardioembolism, similar to children with AIS. Since little evidence exists regarding both acute treatment and secondary prevention after AIS in children and young adults, standard treatment practices are mainly extrapolated from research done in older adults. In most cases we recommend treating young adults per the guidelines published by the American Heart Association for adults with stroke (Jauch et al. Stroke 44:870-947, 2013; Kernan et al. Stroke 45:2160-2236, 2014) and children per the equivalent guidelines regarding pediatric stroke (Roach et al. Stroke 39:2644-91, 2008). It is also important in children and young adults to consider less common structural, metabolic and genetic risk factors for stroke, which may require more specific treatment. Other standard risk factors for stroke, including hypertension, hyperlipidemia and diabetes mellitus should also be addressed, but are less likely in children and young adults. Given the lack of data and possibility of rare underlying etiologies such as Antiphospholipid Antibody Syndrome or Ehlers-Danlos syndrome, we recommend including multiple specialists in the care of these patients, such as hematologists and vascular neurologists.

Guidelines for the prevention of stroke in patients with stroke and transient ischemic attack: a guideline for healthcare professionals from the American Heart Association/American Stroke Association

The aim of this updated guideline is to provide comprehensive and timely evidence-based recommendations on the prevention of future stroke among survivors of ischemic stroke or transient ischemic attack. The guideline is addressed to all clinicians who manage secondary prevention for these patients. Evidence-based recommendations are provided for control of risk factors, intervention for vascular obstruction, antithrombotic therapy for cardioembolism, and antiplatelet therapy for noncardioembolic stroke. Recommendations are also provided for the prevention of recurrent stroke in a variety of specific circumstances, including aortic arch atherosclerosis, arterial dissection, patent foramen ovale, hyperhomocysteinemia, hypercoagulable states, antiphospholipid antibody syndrome, sickle cell disease, cerebral venous sinus thrombosis, and pregnancy. Special sections address use of antithrombotic and anticoagulation therapy after an intracranial hemorrhage and implementation of guidelines.

Association of cardiovascular risk factors with disease severity in cerebral cavernous malformation type 1 subjects with the common Hispanic mutation

BACKGROUND

Cerebral cavernous malformations (CCM) are enlarged vascular lesions affecting 0.1-0.5% of the population worldwide and causing hemorrhagic strokes, seizures, and neurological deficits. Familial CCM type 1 (CCM1) is an autosomal dominant disease caused by mutations in the Krev Interaction Trapped 1 (KRIT1/CCM1) gene, and is characterized by multiple brain lesions whose number and size increase with age. The number of lesions varies widely for unknown reasons, even among carriers of similar ages with the same mutation. The purpose of this study was to investigate whether cardiovascular (CV) risk factors influence potential markers of familial CCM1 disease severity, such as lesion count and history of intracerebral hemorrhage.

METHODS

We analyzed baseline data from 185 Hispanic subjects, enrolled in the Brain Vascular Malformation Consortium study between June 2010 and March 2013. All subjects were carriers of the founder Q455X 'Common Hispanic Mutation' (CHM) in the KRIT1 gene, and had a clinical diagnosis of CCM or had an affected first- or second-degree relative with CCM. We performed a cross-sectional study, collecting detailed clinical information of CCM1-CHM subjects and cerebral susceptibility-weighted magnetic resonance imaging to assess lesion count. Linear or logistic regression analysis of log-lesion count or history of intracerebral hemorrhage and CV risk factors (age, gender, obesity, diabetes, hypertension, hyperlipidemia and smoking status) and related quantitative traits (body mass index, glycosylated hemoglobin levels, blood pressure, lipids levels and pack-years of cigarette smoking) was performed accommodating familial clustering.

RESULTS

CCM1-CHM subjects were mainly female (63.8%) and symptomatic at presentation (63.2%). Lesion count was highly variable (mean ± SD: 57.7 ± 110.6; range: 0-713); 90% of CCM1-CHM subjects had multiple lesions at enrollment. Age (p < 0.001) was positively correlated with lesion count and male gender (p = 0.035) was associated with a greater number of lesions. Obesity (p = 0.001) and higher body mass index (p = 0.002) were associated with fewer lesions. No association with hypertension was detected, however, systolic blood pressure (p = 0.002) was associated with fewer lesions. No significant association with lesion count was observed for diabetes, hyperlipidemia, smoking status or for related quantitative traits. History of intracerebral hemorrhage was not significantly associated with any CV risk factors, however, we found borderline associations of hemorrhage with obesity (p = 0.062), systolic blood pressure (p = 0.083) and pack-years of cigarette smoking (p = 0.055). After correction for multiple testing, age and obesity remained significantly associated with lesion count in CCM1-CHM subjects.

CONCLUSIONS

These results suggest that several CV risk factors explain some of the variability in lesion count in Hispanic CCM1-CHM subjects. Although age, gender, obesity, body mass index and systolic blood pressure may influence familial CCM1 disease severity, further longitudinal studies in larger sample sizes are essential to confirm these findings.

Association of body mass index and mortality after acute ischemic stroke

BACKGROUND

The prevalence of severe obesity is rising in the United States. Although mild to moderately elevated body mass index (BMI) is associated with reduced mortality after acute ischemic stroke, less is known about severe obesity.

METHODS AND RESULTS

Patients with acute ischemic stroke (n=1791) ≥45 years were identified from the biethnic population-based Brain Attack Surveillance in Corpus Christi (BASIC) study from June 1, 2005, to December 31, 2010. Median follow-up was 660 days. BMI was abstracted from the medical record. Survival was estimated by BMI category (underweight, normal weight, overweight, class 1 obesity, class 2 obesity, and severe obesity) using Kaplan-Meier methods. Hazard ratios for the relationship between BMI modeled continuously and mortality were estimated from Cox regression models after adjustment for patient factors. The median BMI was 27.1 kg/m(2) (interquartile range, 23.7-31.2 kg/m(2)), and 56% were Mexican American. A total of 625 patients (35%) died during the study period. Persons with higher baseline BMI had longer survival in unadjusted analysis (P<0.01). After adjustment for demographics, stroke severity, and stroke and mortality risk factors, the relationship between BMI and mortality was U shaped. The lowest mortality risk was observed among patients with an approximate BMI of 35 kg/m(2), whereas those with lower or higher BMI had higher mortality risk.

CONCLUSIONS

Severe obesity is associated with increased poststroke mortality in middle-aged and older adults. Stroke patients with class 2 obesity had the lowest mortality risk. More research is needed to determine weight management goals among stroke survivors.

Favorable functional recovery in overweight ischemic stroke survivors: findings from the China National Stroke Registry

BACKGROUND

Obesity paradox has been reported because of the inverse relationship between the body mass index (BMI) and mortality in stroke patients. The relationship between BMI and functional recovery in stroke survivors is less well established. We explored the impact of BMI on functional recovery and mortality in stroke patients in the China National Stroke Registry (CNSR).

METHODS

Patients were consecutively recruited based on a standard protocol and prospectively followed up for outcomes at 3 months after disease onset. Patients were divided into 5 groups according to their BMI: underweight (<18.5 kg/m(2)), normal weight (18.5-22.9 kg/m(2)), overweight (23-27.4 kg/m(2)), obese (27.5-32.4 kg/m(2)), or severely obese (≥32.5 kg/m(2)). Multivariate logistic regression was performed to analyze the association between BMI and functional recovery or mortality.

RESULTS

CNSR enrolled 22,216 patients hospitalized for acute cerebrovascular events, and 10,905 eligible acute ischemic stroke patients were analyzed in our study. Favorable functional recovery (modified Rankin Scale score 0-1) was seen in 52.4% of underweight, 55.0% of normal weight, 61.0% of overweight, 59.2% of obese, and 60.3% of severely obese stroke survivors (P < .001). Overweight was independently associated with favorable 3-month functional recovery (odds ratio [OR] 1.24; 95% confidence interval [CI] 1.12-1.38). Mortality rate was 14.9% in underweight, 7.8% in normal weight, 7.1% in overweight, 7.2% in obese, and 11.5% in severely obese patients (P < .001). Severe obesity was independently associated with higher 3-month mortality (OR 2.01; 95% CI 1.10-3.69).

CONCLUSIONS

The stroke obesity paradox can be extended to include functional recovery but should not be interpreted as the fatter the better.

Body Mass Index and Acute Ischemic Stroke Outcomes

Background The impact of body mass index on acute ischemic stroke outcomes is unclear. Aims and/or hypothesis We sought to determine the effect of body mass index on short-term (90 days) acute ischemic stroke outcomes. Methods Data were extracted for patients with acute ischemic stroke and records of body mass index at baseline from the Virtual International Stroke Trials Archive database. Multivariate logistic regression and Cox proportional hazard analysis were used to analyze effect of body mass index on poor functional outcome (modified Rankin Scale >2) and mortality, respectively, within 90 days of stroke's onset. Results Of the 4811 patients (mean age 68·8 ± 12·2 years) included in the study, 2002 (41·6%) were overweight, and 1095 (22·8%) were obese. Overweight (body mass index 25-29·9 kg/m2) was associated with decreased mortality (hazard ratios 0·59; 95% confidence interval 0·51-0·68; P < 0·01) and decrease in poor functional outcome (odds ratio 0·74; 95% confidence interval 0·64-0·85; P < 0·01) following acute ischemic stroke. The association of body mass index with stroke outcomes was dependent on age, gender, and use of thrombolytic therapy. Conclusions Being overweight or obese is associated with a better functional outcome and reduced mortality in patients of acute ischemic stroke. However, the definition of an 'optimal' body mass index, in relation to stroke outcomes, may be affected by age, gender, and use of thrombolytic therapy.

Coronary artery calcification is inversely related to body morphology in patients with significant coronary artery disease: a three-dimensional intravascular ultrasound study

AIMS

Emerging data have indicated unexpected complexity in the regulation of vascular and bone calcification. In particular, several recent studies have challenged the concept of a universally positive relationship between body morphology [weight, height, body mass index (BMI), body surface area (BSA)] and the extent of vascular calcification. We sought to clarify these discrepancies and investigated the relationship between index lesion coronary artery calcification (CAC) and body morphology in patients undergoing percutaneous coronary intervention (PCI) using three-dimensional intravascular ultrasound (IVUS).

METHODS AND RESULTS

We analysed CAC in patients who underwent PCI with pre-intervention IVUS imaging. The main outcome measure was the calcium index (CalcIndex); a three-dimensional IVUS-derived measure of total calcification per obstructive coronary lesion. A total of 346 patients (65.3 ± 10.6 years; 29.5% females) underwent PCI with IVUS-based CAC assessment. CalcIndex was categorized as zero-low (0-0.1399; n = 152) or intermediate-high (0.1400-1.2541; n = 194). All measures of body morphology were lower in patients with intermediate-high CalcIndex (height, P = 0.024; weight, P = 0.008; BMI, P = 0.064; BSA, P = 0.005). In adjusted multivariable models, weight and BSA were independent inverse predictors of intermediate-high CalcIndex [weight: odds ratio (OR) 0.986, P = 0.017; BSA: OR 0.323, P = 0.012] while CalcIndex also trended towards an inverse association with both height (P = 0.068) and BMI (P = 0.064). These independent inverse associations were consistent across multiple clinical subgroups, including stratification by age, race, gender, diabetes, and renal impairment.

CONCLUSION

Using three-dimensional IVUS to assess vascular calcification, these data confirm an independent, inverse relationship between body size and index lesion CAC in patients with obstructive coronary artery disease.

Body mass index and stroke: overweight and obesity less often associated with stroke recurrence

BACKGROUND

Although obesity is associated with excess mortality and morbidity, mortality is lower in obese than in normal weight stroke patients (the obesity paradox). Studies now indicate that obesity is not associated with increased risk of recurrent stroke in the years after first stroke. We studied the association between body mass index (BMI) and stroke patient's risk of having a history of previous stroke (recurrent stroke).

METHODS

A registry designed to collect data on all hospitalized stroke patients in Denmark 2000-2010 includes 61,872 acute stroke patients with information on BMI in 38,506. Data include age, sex, civil status, stroke severity (Scandinavian Stroke Scale), computed tomography, and cardiovascular risk factors. There were 28,382 patients with complete covariate information. We used multiple logistic regression models on this data set to compare the risk of stroke being recurrent in the 4 BMI groups: underweight (BMI<18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25.0-29.9), and obese (BMI≥30.0).

RESULTS

Of the patients with complete covariate information, 22,811 (80.1%) had first-ever stroke; in 5571 patients (19.6%), stroke was recurrent. Multiple logistic regression analysis adjusting for age, stroke severity, sex, BMI, civil status, and cardiovascular risk factors showed that being obese and overweight in comparison with normal weight was associated with a significantly lower risk of stroke being recurrent (obese: odds ratio [OR]=.90, confidence interval [CI] .82-.98; overweight: OR=.89, CI .83-.96). Being underweight was associated with a significantly higher risk of stroke being recurrent (OR=1.23; CI 1.06-1.43).

CONCLUSIONS

The obesity paradox in stroke can be extended to include also stroke recurrence. Obese and overweight stroke patients had experienced less previous strokes than normal weight stroke patients.

Paradoxical association of smoking with in-hospital mortality among patients admitted with acute ischemic stroke

BACKGROUND

Compared to those who never smoked, a paradoxical effect of smoking on reducing mortality in patients admitted with myocardial ischemia has been reported. We sought to determine if this effect was present in patients hospitalized with ischemic stroke.

METHODS AND RESULTS

Using the local Get with the Guidelines-Stroke registry, we analyzed 4305 consecutively admitted ischemic stroke patients (March 2002-December 2011). The sample was divided into smokers versus nonsmokers. The main outcome of interest was the overall inpatient mortality. Compared to nonsmokers, tobacco smokers were younger, more frequently male and presented with fewer stroke risk factors such as hypertension, hyperlipidemia, diabetes, coronary artery disease, and atrial fibrillation. Smokers also had a lower average NIH Stroke Scale (NIHSS) and fewer received tissue plasminogen activator (tPA). Patients in both groups had similar adherence to early antithrombotics, dysphagia screening prior to oral intake, and deep vein thrombosis (DVT) prophylaxis. Smoking was associated with lower all-cause in-hospital mortality (6.6% versus 12.4%; unadjusted OR 0.46; CI [0.34 to 0.63]; P<0.001). In multivariable analysis, adjusted for age, gender, ethnicity, hypertension, diabetes mellitus, hyperlipidemia, CAD, atrial fibrillation, NIHSS, and tPA, smoking remained independently associated with lower mortality (adjusted OR 0.64; CI [0.42 to 0.96]; P=0.03).

CONCLUSIONS

Similar to myocardial ischemia, smoking was independently associated with lower inpatient mortality in acute ischemic stroke. This effect may be due to tobacco-induced changes in cerebrovascular vasoreactivity, or may be due in part to residual confounding. Larger, multicenter studies are needed to confirm the finding and the effect on 30-day and 1-year mortality.

Body mass index is inversely associated with mortality in patients with peripheral vascular disease

BACKGROUND

Current guidelines contain no advice on how to manage obesity and underweight in patients with peripheral vascular disease (PVD).

OBJECTIVES

The aim of this study was to assess the association of underweight, overweight and obesity with mortality in patients with PVD.

PATIENTS AND METHODS

We recruited 1472 patients with a broad range of presentations of PVD. Underweight, overweight and obesity were defined by body mass index (BMI) and associated with mortality using Kaplan Meier and Cox proportional hazard analyses.

RESULTS

Survival at 3 years was 37.5, 78.1, 86.8 and 87.0% for patients that were underweight, normal weight, overweight and obese at recruitment, respectively, p<0.001. Patients that were underweight had approximately twice the risk of dying (RR 2.15, 95% CI 1.31-3.55, p=0.003), while patients that were overweight (RR 0.67, 95% CI 0.49-0.91, p=0.011) or obese (RR 0.59, 95% CI 0.41-0.85, p=0.005) had approximately half the risk of dying, after adjustment for other risk factors and using normal weight subjects as the reference group. 823 patients had waist circumference measured at recruitment. Patients with waist circumference in the top quartile had half the risk of dying (RR 0.50, 95% CI 0.26-0.98, p=0.045). In 267 patients we assessed the relationship between BMI and abdominal fat volumes using computed tomography. BMI was highly correlated with both intra-abdominal and subcutaneous fat volumes.

CONCLUSIONS

Obesity whether assessed by BMI or central fat deposition is associated with reduced risk of dying in patients with established PVD. Underweight is highly predictive of early mortality in patients with PVD.

Adipose tissue biology and cardiomyopathy: translational implications

It is epidemiologically established that obesity is frequently associated with the metabolic syndrome and poses an increased risk for the development of type 2 diabetes mellitus and cardiovascular disease. The molecular links that connect the phenomenon of obesity, per se, with insulin resistance and cardiovascular disease are still not fully elucidated. It is increasingly apparent that fully functional adipose tissue can be cardioprotective by reducing lipotoxic effects in other peripheral tissues and by maintaining a healthy balance of critical adipokines, thereby allowing the heart to maintain its full metabolic flexibility. The present review highlights both basic and clinical findings that emphasize the complex interplay of adipose tissue physiology and adipokine-mediated effects on the heart exerted by either direct effects on cardiac myocytes or indirect actions via central mechanisms through sympathetic outflow to the heart.

Dahl salt-sensitive rats are protected against vascular defects related to diet-induced obesity

Obesity increases plasma renin activity and angiotensin II levels, leading to vascular damage, elevated blood pressure, diabetes mellitus, and renal damage. Because genetic deletion of crucial parts of the renin-angiotensin system protect against obesity-related cardiovascular defects, we hypothesized that Dahl salt-sensitive (SS) rats, a model of chronically low plasma renin activity and angiotensin II levels, would be protected against vascular defects during diet-induced obesity compared with SS.13(BN) consomic rats showing normal renin-angiotensin system regulation. We evaluated vascular function in middle cerebral arteries of SS or SS.13(BN) rats fed high-fat (45% kcal from fat) versus normal-fat diet for 15 to 20 weeks from weaning. Endothelium-dependent relaxation in response to acetylcholine (10(-8) to 10(-4) mol/L) was restored in middle cerebral arteries of high-fat SS rats versus normal-fat diet controls, whereas vasodilation to acetylcholine was dramatically reduced in high-fat SS 13(BN) rats versus normal-fat diet controls. These findings support the hypothesis that physiological levels of angiotensin II play an important role in maintaining normal vascular relaxation in cerebral arteries and suggest that the cerebral vasculature of the SS rat model is genetically protected against endothelial dysfunction in diet-induced obesity.