Impact of obesity and bariatric surgery on cardiovascular disease

Bariatric surgeries and cardiac structure and function: Systematic review and network meta-analysis

BACKGROUND

Obesity, a global health problem, is causally implicated in the development of cardiovascular disease. Bariatric surgeries are effective treatment options for obesity; however, the effectiveness of different bariatric surgeries on cardiac structure and function is not fully understood. We undertook a systematic review and network meta-analysis to comprehensively assess this effectiveness.

DATA SOURCE

PubMed, Web of Science, and EMBASE were searched from their inception until November 11, 2023. Studies that compared bariatric surgeries vis-à-vis non-surgical treatment, placebo, and other bariatric surgeries, as well as reported changes in left ventricular mass or its index (LVM or LVMI) or left ventricular ejection fraction (LVEF), were summarized.

RESULTS

Total 19 studies (17 cohort studies and 2 randomized controlled trials) and 2012 adults were meta-analyzed. Patients receiving gastric bypass had appreciably lowered LVM (weighted mean difference [WMD]: -43.86 g, 95% confidence interval [CI] -61.09 to -26.63, p < 0.01) and LVMI (standardized mean difference: -0.67, 95% CI -1.03 to -0.32, p < 0.01) compared with other bariatric surgeries. No significant improvement in LVEF was noted across all surgeries. The drop in body mass index was most pronounced for biliopancreatic diversion with duodenal switch (WMD -16.33 kg/m2, 95% CI -21.60 to -11.05, p < 0.01).

CONCLUSIONS

Our findings of this network meta-analysis indicated that gastric bypass proved best for the improvement in cardiac structure, and there was no obvious improvement in cardiac function for all bariatric surgeries. Further studies are required to better understand the differing effectiveness of bariatric surgeries on cardiac structure and function and the underlying molecular mechanisms.

Obesity and metabolic syndrome in kidney transplantation

The epidemic of obesity and metabolic syndrome (MS) contributes to the rapid growth of chronic kidney disease (CKD) and end-stage renal disease (ESRD). There is a reverse epidemiology, known as the "obesity paradox," in ESRD patients receiving maintenance dialysis. Obese patients are routinely referred for kidney transplant, and they have more surgical and medical complications than non-obese patients. However, compared to dialysis, kidney transplant provides a survival benefit for obese patients. After kidney transplant, obese patients tend to gain more body weight, and non-obese patients can develop new-onset obesity/MS. Obesity/MS is not only associated with serious morbidities, but also compromises the long-term graft and patient survival. The immunosuppressive drugs commonly used as maintenance therapy, including corticosteroids, calcineurin inhibitors and mammalian target-of-rapamycin inhibitors, contribute to obesity/MS. Development of novel immunosuppressive drugs free of metabolic adverse effects is needed, so that the full potential and benefits of kidney transplantation can be realized.

Transplantation in obese patient

Obesity is a worldwide epidemic leading to severe comorbidity that damages end-organ function. Overall transplant outcomes in this population are inferior to those in nonobese patients. Large population studies show decreased patient and graft survival in obese kidney transplant patients. Despite the poorer outcomes, kidney transplantation is considered because of the survival benefit as compared with the wait-listed dialysis patients. In liver transplantation, the benefit to transplantation as compared with remaining on the list is obvious, as there is no viable liver dialysis at this time. Obesity in potential organ donors impacts both medical and surgical issues. Obesity-related kidney disease affects both the remaining and transplanted kidney. Pancreas donor organs are associated with decreased early graft survival. Liver donor organs with significant steatosis lead to an increased risk for delayed or nonfunction of the organ. Immunosuppressive drugs with variable lipophilicity and altered volume of distribution can greatly affect the therapeutic usefulness of these drugs. Transplant candidates benefit from a multidisciplinary team approach to their care. As the epidemic progresses and less-invasive treatments for metabolic surgery evolve, we are likely to require more patients to lose weight prior to transplantation as we continue to strive for improved outcomes.

Progressive regression of left ventricular hypertrophy two years after bariatric surgery

BACKGROUND

Obesity is a systemic disorder associated with an increase in left ventricular mass and premature death and disability from cardiovascular disease. Although bariatric surgery reverses many of the hormonal and hemodynamic derangements, the long-term collective effects on body composition and left ventricular mass have not been considered before. We hypothesized that the decrease in fat mass and lean mass after weight loss surgery is associated with a decrease in left ventricular mass.

METHODS

Fifteen severely obese women (mean body mass index [BMI]: 46.7+/-1.7 kg/m(2)) with medically controlled hypertension underwent bariatric surgery. Left ventricular mass and plasma markers of systemic metabolism, together with body mass index (BMI), waist and hip circumferences, body composition (fat mass and lean mass), and resting energy expenditure were measured at 0, 3, 9, 12, and 24 months.

RESULTS

Left ventricular mass continued to decrease linearly over the entire period of observation, while rates of weight loss, loss of lean mass, loss of fat mass, and resting energy expenditure all plateaued at 9 [corrected] months (P <.001 for all). Parameters of systemic metabolism normalized by 9 months, and showed no further change at 24 months after surgery.

CONCLUSIONS

Even though parameters of obesity, including BMI and body composition, plateau, the benefits of bariatric surgery on systemic metabolism and left ventricular mass are sustained. We propose that the progressive decrease of left ventricular mass after weight loss surgery is regulated by neurohumoral factors, and may contribute to improved long-term survival.

The neurohormonal regulation of energy intake in relation to bariatric surgery for obesity

Obesity has reached pandemic proportions, with bariatric surgery representing the only currently available treatment demonstrating long-term effectiveness. Over 200,000 bariatric procedures are performed each year in the US alone. Given the reliable and singular success of bariatric procedures, increased attention is being paid to identifying the accompanying neurohormonal changes that may contribute to the resulting decrease in energy intake. Numerous investigations of postsurgical changes in gut peptides have been conducted, suggesting greater alterations in endocrine function in combination restrictive and malabsorptive procedures (e.g., Roux-en-Y gastric bypass) as compared to purely restrictive procedures (e.g., gastric banding), which may contribute to the increased effectiveness of combination procedures. However, very few studies have been performed and relatively little is known about changes in neural activation that may result from bariatric procedures, which likely interact with changes in gut peptides to influence postsurgical caloric intake. This review provides a background in the neurohormonal regulation of energy intake and discusses how differing forms of bariatric surgery may affect the neurohormonal network, with emphasis on Roux-en-Y gastric bypass, the most commonly performed procedure worldwide. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.

Identification of cardiovascular genes in omentum from morbidly obese patients with type 2 diabetes

BACKGROUND

The metabolic syndrome describes the association between obesity and co-morbidities including insulin resistance, hypertension, dyslipidemia, and cardiovascular (CV) disease. Adipokines produced from omentum contribute to the risk of CV disease and increase the inflammatory state. This study examines the gene expression differences in the omental tissue of morbidly obese diabetic and non-diabetic patients.

METHODS

Twenty morbidly obese patients undergoing bariatric surgery were included. Ten patients were diabetic and 10 were non-diabetic. Omental samples were collected intraoperatively and snap frozen. Total RNA was extracted using the Trizol reagent and purified with the RNeasy kit (Qiagen). Microarray experiments were performed using the Affymetrix Gene 1.0 ST array and data was analyzed with the Partek 6.3 program using an unpaired t-test (P<0.05). The gene expression profiles of the diabetic group were compared with the non-diabetic group. Using the Ingenuity program, the gene list generated from the microarray analysis was evaluated and real-time quantitative PCR (qPCR) was used to validate the array data.

RESULTS

Compared with the non-diabetic group, the diabetic obese patients showed 79 upregulated genes and 4 downregulated genes with >1.4-fold difference in expression. Ingenuity analysis showed numerous dysregulated genes associated with CV disease including leptin, Von Willebrand factor, P-selectin, angiopoietin-1 (ANGPT1), phospholipase A2 (group VII), and periostin osteoblast specific factor. Microarray results for the earlier mentioned genes were confirmed with qPCR. The results were analyzed with respect to the presence or absence of hyperlipidemia, hypertension, and coronary artery disease. In patients with hyperlipidemia, ANGPT1 and P-selectin were upregulated 1.9- and 2.9-fold, respectively.

CONCLUSIONS

This microarray analysis of omental tissue from morbidly obese diabetic patients documents a host of upregulated genes related to CV disease. This study provides further evidence that diabetic status predisposes obese patients to a higher risk of developing CV disease.

Physical fitness in morbidly obese patients: effect of gastric bypass surgery and exercise training

BACKGROUND

There is a growing consensus that bariatric surgery is currently the most efficacious and long-term treatment for clinically severe obesity. However, it remains to be determined whether poor physical fitness, an important characteristic of these patients, improves as well. The purpose of this pilot study is to investigate the effect of gastric bypass surgery on physical fitness and to determine if an exercise program in the first 4 months is beneficial.

METHODS

Fifteen morbidly obese patients (BMI 43.0 kg/m(2)) were tested before and 4 months after gastric bypass surgery. Eight of them followed a combined endurance and strength training program. Before and after 4 months the operation, anthropometrical characteristics were measured, and an extensive assessment of physical fitness (strength, aerobic, and functional capacity) was performed.

RESULTS

Large-scale weight loss through gastric bypass surgery results in a decrease in dynamic and static muscle strength and no improvement of aerobic capacity. In contrast, an intensive exercise program could prevent the decrease and even induced an increase in strength of most muscle groups. Together with an improvement in aerobic capacity, functional capacity increased significantly. Both groups evolved equally with regard to body composition (decrease in fat mass and fat-free mass).

CONCLUSIONS

An exercise training program in the first 4 months after bariatric surgery is effective and should be promoted, considering the fact that physical fitness does not improve by weight loss only.

The impact of morbid obesity and bariatric surgery on comorbid conditions: a comprehensive examination of comorbidities in an employed population

OBJECTIVE

Find conditions with significantly different prevalence among employees diagnosed with morbid obesity (DMO). Examine the effect of bariatric surgery on the prevalence of all categories of comorbid conditions after surgery.

METHODS

This large employer retrospective database analysis used matching to create two cohorts: Those with a DMO and those without.

RESULTS

The DMO cohort had higher diagnosis rates in every Agency for Healthcare Research and Quality major diagnostic category except pregnancy, and it had significantly higher prevalence in 147 of 261 Agency for Health care Research and Quality specific categories. Those electing to undergo bariatric surgery experienced significant prevalence decreases in 26 of 261 specific categories.

CONCLUSION

Employees DMO are at higher risk for many serious diseases. Bariatric surgery has been effective in promoting weight loss and decreasing the rates of many serious comorbidities.

Body weight, insulin resistance, and serum adipokine levels 2 years after 2 types of bariatric surgery

OBJECTIVE

Bariatric surgery reverses obesity-related comorbidities, including type 2 diabetes mellitus. Several studies have already described differences in anthropometrics and body composition in patients undergoing Roux-en-Y gastric bypass compared with laparoscopic adjustable gastric banding, but the role of adipokines in the outcomes after the different types of surgery is not known. Differences in weight loss and reversal of insulin resistance exist between the 2 groups and correlate with changes in adipokines.

METHODS

Fifteen severely obese women (mean body mass index [BMI]: 46.7 kg/m(2)) underwent 2 types of laparoscopic weight loss surgery (Roux-en-Y gastric bypass=10, adjustable gastric banding=5). Weight, waist and hip circumference, body composition, plasma metabolic markers, and lipids were measured at set intervals during a 24-month period after surgery.

RESULTS

At 24 months, patients who underwent Roux-en-Y were overweight (BMI 29.7 kg/m(2)), whereas patients who underwent gastric banding remained obese (BMI 36.3 kg/m(2)). Patients who underwent Roux-en-Y lost significantly more fat mass than patients who underwent gastric banding (mean difference 16.8 kg, P<.05). Likewise, leptin levels were lower in the patients who underwent Roux-en-Y (P=.003), and levels correlated with weight loss, loss of fat mass, insulin levels, and Homeostasis Model of Assessment 2. Adiponectin correlated with insulin levels and Homeostasis Model of Assessment 2 (r=-0.653, P=.04 and r=-0.674, P=.032, respectively) in the patients who underwent Roux-en-Y at 24 months.

CONCLUSION

After 2 years, weight loss and normalization of metabolic parameters were less pronounced in patients who underwent gastric banding compared with patients who underwent Roux-en-Y gastric bypass. Our findings require confirmation in a prospective randomized trial.

The metabolic syndrome

The "metabolic syndrome" (MetS) is a clustering of components that reflect overnutrition, sedentary lifestyles, and resultant excess adiposity. The MetS includes the clustering of abdominal obesity, insulin resistance, dyslipidemia, and elevated blood pressure and is associated with other comorbidities including the prothrombotic state, proinflammatory state, nonalcoholic fatty liver disease, and reproductive disorders. Because the MetS is a cluster of different conditions, and not a single disease, the development of multiple concurrent definitions has resulted. The prevalence of the MetS is increasing to epidemic proportions not only in the United States and the remainder of the urbanized world but also in developing nations. Most studies show that the MetS is associated with an approximate doubling of cardiovascular disease risk and a 5-fold increased risk for incident type 2 diabetes mellitus. Although it is unclear whether there is a unifying pathophysiological mechanism resulting in the MetS, abdominal adiposity and insulin resistance appear to be central to the MetS and its individual components. Lifestyle modification and weight loss should, therefore, be at the core of treating or preventing the MetS and its components. In addition, there is a general consensus that other cardiac risk factors should be aggressively managed in individuals with the MetS. Finally, in 2008 the MetS is an evolving concept that continues to be data driven and evidence based with revisions forthcoming.

Obesity and vascular dysfunction

One of the most profound challenges facing public health and public health policy in Western society is the increased incidence and prevalence of both overweight and obesity. While this condition can have significant consequences for patient mortality and quality of life, it can be further exacerbated as overweight/obesity can be a powerful stimulus for the development of additional risk factors for a negative cardiovascular outcome, including increased insulin resistance, dyslipidemia and hypertension. This manuscript will present the effects of systemic obesity on broad issues of vascular function in both afflicted human populations and in the most relevant animal models. Among the topics that will be covered are alterations to vascular reactivity (both dilator and constrictor responses), adaptations in microvascular network and vessel wall structure, and alterations to the patterns of tissue/organ perfusion as a result of the progression of the obese condition. Additionally, special attention will be paid to the contribution of chronic inflammation as a contributor to alterations in vascular function, as well as the role of perivascular adipose tissue in terms of impacting vessel behavior. When taken together, it is clearly apparent that the development of the obese condition can have profound, and frequently difficult to predict, impacts on integrated vascular function. Much of this complexity appears to have its basis in the extent to which other co-morbidities associated with obesity (e.g., insulin resistance) are present and exert contributing effects.

Proinflammatory cytokines in obesity: impact of type 2 diabetes mellitus and gastric bypass

BACKGROUND

Obesity and obesity-associated type 2 diabetes mellitus (T2DM) are frequently related to a low-grade chronic inflammatory state, which increases the risk of developing cardiovascular diseases. The aim of the present work was to evaluate the effect of obesity and T2DM on the concentrations of pro-inflammatory factors and to study the effect of weight loss after Roux-en-Y gastric bypass (RYGBP).

METHODS

Plasma concentrations of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-alpha), serum amyloid A (SAA) and sialic acid (SA) were measured in 25 female volunteers. The concentrations of these cytokines were determined in 14 female obese patients before and after weight loss following RYGBP. Additionally, visceral adipose tissue (VAT) obtained from 15 females was used to quantify expression levels of MCP-1 and CD68 by Real-Time PCR.

RESULTS

Both obese normoglycemic (NG) and T2DM groups exhibited significantly higher MCP-1 (P < 0.05), TNF-alpha (P < 0.01), SAA (P < 0.05) and SA (P < 0.05) concentrations, compared to the lean group. No differences were found between obese NG and obese T2DM subjects. A significant positive correlation was found between body fat percentage (BF) and all inflammatory markers (P < 0.05) studied. MCP-1 expression levels in VAT were upregulated in obese NG (P = 0.008) and obese T2DM (P = 0.032) patients compared to lean subjects, but no additional detrimental effect of T2DM was observed between both obese groups. After weight loss, SAA (P < 0.001) and SA (P < 0.05) concentrations diminished, whereas circulating levels of MCP-1 showed a tendency to decrease (P = 0.093) and TNF-alpha did not change.

CONCLUSION

The present findings suggest that elevated pro-inflammatory cytokine levels found in obese patients relate mainly to obesity rather than to T2DM. Moreover, surgery-induced weight loss reduces circulating concentrations of key pro-inflammatory factors, which contribute to the improvement in the cardiovascular co-morbidity following excess weight loss.