Paradoxical preservation of vascular function in severe obesity

Relation of body mass index to late survival after valvular heart surgery

Limited data have suggested that an "obesity paradox" exists for mortality and cardiovascular outcomes in patients undergoing coronary artery bypass grafting. Much less is known about the role of the preoperative body mass index (BMI) in patients undergoing valve surgery. We evaluated 2,640 consecutive patients who underwent valve surgery between April 2004 and March 2011. The patients were classified by the World Health Organization standards as "underweight" (BMI 11.5 to 18.4 kg/m(2), n = 61), "normal weight" (BMI 18.5 to 24.9 kg/m(2), n = 865), "overweight" (BMI 25 to 29.9 kg/m(2), n = 1,020), and "obese" (BMI 30 to 60.5 kg/m(2), n = 694). Mortality was ascertained using the Social Security Death Index. Hazard ratios (HRs), adjusted for known preoperative risk factors, were obtained using Cox regression models. The mean follow-up was 31.9 ± 20.5 months. The long-term mortality rate was 1.21, 0.52, 0.32, and 0.44 per 10 years of person-time for underweight, normal, overweight, and obese patients, respectively. Compared to the normal BMI category, overweight patients (adjusted HR 0.60, 95% confidence interval 0.46 to 0.79, p <0.001) and obese patients (adjusted HR 0.67, 95% confidence interval 0.50 to 0.91, p = 0.009) were at a lower hazard of long-term all-cause mortality. Underweight patients remained at a greater adjusted risk of long-term mortality than normal weight patients (adjusted HR 1.69, 95% confidence interval 1.01 to 2.85, p = 0.048). Similar patterns of mortality outcomes were noted in the subset of patients undergoing isolated valve surgery. In conclusion, overweight and obese patients had greater survival after valve surgery than patients with a normal BMI. Very lean patients undergoing valve surgery are at a greater hazard for mortality and might require more rigorous preoperative candidate screening and closer postoperative monitoring.

Endothelial dysfunction, inflammation, and oxidative stress in obese children and adolescents: markers and effect of lifestyle intervention

With an increasing prevalence, pediatric obesity is often a prelude to adulthood obesity, and represents a major public health issue. Comorbidities are very common and severe in obese adults, justifying the search for earlier markers or risk factors for cardiovascular diseases in obese children. Endothelial dysfunction has been found to be present in the early stages of atherosclerosis, and can be non-invasively assessed with widely accepted and well-standardized techniques at the macrocirculation level. Endothelial dysfunction at the microcirculation level is less documented in obese children. Obesity in children has been repeatedly and independently correlated to endothelial dysfunction, inflammation and oxidative stress markers, although the relationship between these factors remains to be investigated. However, this would not only allow substantial improvements in risk stratification, but also provide essential data regarding the evolution of endothelial dysfunction in childhood obesity, especially during puberty when pro-inflammatory and pro-oxidative changes, with relative insulin resistance, occur. Therapeutic strategies such as lifestyle interventions in early childhood obesity appear all the more necessary, optimally including both exercise and diet because of their known effects on inflammatory and oxidative stress markers, potentially reversing endothelial dysfunction.

Obesity paradox in amputation risk among nonelderly diabetic men

The association between BMI and amputation risk is not currently well known. We used data for a cohort of diabetic patients treated in the US Department of Veterans Affairs Healthcare System in 2003. Men aged <65 years at the end of follow-up were examined for their amputation risk and amputation-free survival during the next 5 years (2004-2008). Compared to overweight individuals (BMI 25-29.9 kg/m(2)), the risks of amputation and treatment failure (amputation or death) were higher for patients with BMI <25 kg/m(2) and were lower for those with BMI ≥30 kg/m(2). Individuals with BMI ≥40 kg/m(2) were only half as likely to experience any (hazard ratios (HR) = 0.49; 95% confidence interval (CI), 0.30-0.80) and major amputations (HR = 0.53; 95% CI, 0.39-0.73) during follow-up as overweight individuals. While the amputation risk continued to decrease for higher BMI, amputation-free survival showed a slight upturn at BMI >40 kg/m(2). The association between obesity and amputation risk in our data shows a pattern consistent with "obesity paradox" observed in many health conditions. More research is needed to better understand pathophysiological mechanisms that may explain the paradoxical association between obesity and lower-extremity amputation (LEA) risk.

Obesity phenotype and cardiovascular changes

OBJECTIVE

Healthy obese phenotype with favorable metabolic profiles is proposed. However, whether healthy obesity leads to target organ changes is controversial. We investigated the impact of a healthy obesity on cardiovascular structure and function.

METHODS

A total of 2540 participants without known cardiovascular disease were enrolled. According to BMI and the metabolic syndrome (MetS) component, the participants were divided into six groups: healthy (none of five MetS components) normal weight (BMI <23 kg/m²), unhealthy (one or more of five MetS components) normal weight, healthy overweight (BMI 23-24.9 kg/m²), unhealthy overweight, healthy obesity (BMI ≥25 kg/m²), and unhealthy obesity. The cardiovascular changes were assessed by echocardiography, tissue Doppler imaging (TDI), carotid ultrasonography, and pulse wave velocity (PWV).

RESULTS

In a multivariate analysis after adjusting for age, sex, heart rate, high-sensitivity C-reactive protein, and medication for hypertension and diabetes mellitus, the unhealthy overweight and obese groups showed statistically significant changes in the left ventricular mass index, mitral E/A ratio, E/Ea ratio, TDI Ea velocity, common carotid artery intima-media thickness (CCA-IMT), and brachial-ankle PWV (P < 0.001), compared with the healthy normal weight individuals. In the healthy overweight and obese groups, CCA-IMT and brachial-ankle PWV values were similar, but left-ventricular mass index and TDI Ea velocity were significantly different (P < 0.001).

CONCLUSION

Healthy obesity was associated with subtle changes in left ventricular structure and function. These data provide evidence that metabolically healthy phenotypes with excess weight may not be a benign condition.

Cardiovascular risk in obesity: different activation of inflammation and immune system between obese and morbidly obese subjects

BACKGROUND

Both inflammation and immunity are involved in the development and progression of atherosclerosis. Obesity is considered a major modifiable cardiovascular risk factor, however, the correlation between increasing degrees of obesity and cardiovascular risk is not clear yet. Aim of our study was to investigate how different degrees of obesity are associated with inflammation and immune system responses.

METHODS

One-hundred healthy individuals were divided into 3 groups according to body mass index (BMI): 22 overweight (OW), 26 obese (O) and 52 morbidly obese (MO). High-sensitivity C-Reactive Protein (hs-CRP, immunonephelometry), leptin (radio-immunoassay) and CD4+CD28nullT-lymphocytes (flow-cytometry), a particular subset of T-lymphocytes with pro-atherogenic and plaque-destabilizing properties, were assessed.

RESULTS

hs-CRP levels were significantly higher in O vs OW (p=0.036), in MO vs OW (p<0.001) and in MO vs O (p=0.012). Similarly, leptin levels were higher in O vs OW (p=0.02), in MO vs OW (p<0.001) and in MO vs O (p<0.001). CD4+CD28nullT-lymphocytes were higher in O vs OW (p<0.001), in O vs MO (p=0.03) and in MO vs OW (p=0.01). hs-CRP and leptin levels significantly correlated each other (r=0.39; p<0.001) and with waist circumference (r=0.52; p<0.001; r=0.64; p<0.001) and BMI (r=0.60; p<0.001; r=0.74; p<0.001).

CONCLUSIONS

Our study demonstrates that, notwithstanding higher levels of inflammation, MO are characterized by less detrimental immune activation, as shown by the reduced CD4+CD28nullT-cells expansion as compared to OW and O, which might translate in less immune vascular injury. These findings suggest that MO might represent a particular population, in which different pathophysiological mechanisms take part if compared with "classic" obesity.

Thromboxane production in morbidly obese subjects

Postmortem studies have demonstrated that morbidly obese subjects, surprisingly, have less coronary atherosclerosis than obese subjects. However, the reasons for this apparent protection from atherosclerosis are not yet clear. Thromboxane A2, a marker of platelet activation, is greater in obese subjects than in lean subjects, and this might be a clue to their increased cardiovascular risk. However, data on thromboxane A2 in morbidly obese subjects are lacking; therefore, we hypothesized that lower levels of thromboxane A2 in morbidly obese subjects might play a role in their lower atherothrombotic burden. We measured the serum levels of thromboxane B2 (TxB2), a stable metabolite of thromboxane A2, high-sensitivity C-reactive protein (hs-CRP) and leptin in 17 lean subjects (body mass index [BMI] 22.9 ± 1.6 kg/m(2)), 25 obese subjects (BMI 32.6 ± 2.4 kg/m(2)), and 23 morbidly obese subjects (BMI 48.6 ± 7.1 kg/m(2)), without insulin resistance, diabetes, or overt cardiovascular disease. The serum TxB2 levels were lower in the lean subjects than in the obese subjects (p = 0.046) and in the morbidly obese subjects than in the lean and obese subjects (p = 0.015 and p <0.001, respectively). In contrast, the hs-CRP and leptin levels were greater in the obese than in the lean subjects (hs-CRP, p <0.001; leptin, p <0.001) and in the morbidly obese subjects than in the lean subjects (p <0.001 for both). Leptin was also higher in the morbidly obese subjects than in the obese subjects (p <0.001). TxB2 negatively correlated with leptin and BMI. hs-CRP correlated with leptin, and both also correlated with waist circumference, BMI, and homeostasis model assessment of insulin-resistance. In conclusion, insulin-sensitive morbidly obese subjects had lower levels of TxB2 than the obese subjects and lean subjects, suggesting that reduced platelet activation could play a role in the paradoxical protection of morbidly obese subjects from atherosclerosis, despite the greater levels of leptin.

Cardiovascular dysfunction in obesity and new diagnostic imaging techniques: the role of noninvasive image methods

Obesity is a major public health problem affecting adults and children in both developed and developing countries. This condition often leads to metabolic syndrome, which increases the risk of cardiovascular disease. A large number of studies have been carried out to understand the pathogenesis of cardiovascular dysfunction in obese patients. Endothelial dysfunction plays a key role in the progression of atherosclerosis and the development of coronary artery disease, hypertension and congestive heart failure. Noninvasive methods in the field of cardiovascular imaging, such as measuring intima-media thickness, flow-mediated dilatation, tissue Doppler, and strain, and strain rate, constitute new tools for the early detection of cardiac and vascular dysfunction. These techniques will certainly enable a better evaluation of initial cardiovascular injury and allow the correct, timely management of obese patients. The present review summarizes the main aspects of cardiovascular dysfunction in obesity and discusses the application of recent noninvasive imaging methods for the early detection of cardiovascular alterations.