Impact of obesity and bariatric surgery on metabolism and coronary circulatory function

Combining body mass index with waist circumference to assess coronary microvascular function in patients with non-obstructive coronary artery disease

BACKGROUND

Coronary microvascular dysfunction (CMD) may precede clinically overt coronary artery disease (CAD). Overall and central obesity (CO) are major risk factors for CAD. This study sought to investigate the subclinical significance of body adiposity patterns based on the CMD risk.

METHODS

A total of 128 patients with non-obstructive CAD were prospectively enrolled. Patients were categorized into 4 anthropometric groups: normal weight and non-CO (NWNCO, n = 41), normal weight and CO (NWCO, n = 20), excess weight and non-CO (EWNCO, n = 26), and excess weight and CO (EWCO, n = 41). Patients underwent rest/stress electrocardiography-gated 13N-ammonia positron emission tomography to measure absolute myocardial blood flow (MBF), myocardial flow reserve (MFR), hemodynamic parameters, and cardiac function.

RESULTS

Resting MBF did not differ between groups (P = .36). Compared with the NWNCO group, hyperemic MBF and MFR were significantly lower in the NWCO and EWCO groups. Notably, patients with NWCO presented the lowest hyperemic MBF and MFR and the highest incidence of CMD. Waist circumference was an independent risk factor for CMD (OR 1.05, 95% CI 1.01 to 1.10, P = .02).

CONCLUSION

In patients with non-obstructive CAD, CO may be associated with an increased risk of CMD to better fit the study findings which did not assess management or monitoring of MBF and MFR.

Prognostic impact of coronary microvascular dysfunction assessed by caIMR in overweight with chronic coronary syndrome patients

OBJECTIVE

Coronary microvascular dysfunction (CMD) may associate with adverse cardiovascular events in obese patients. Coronary angiography-derived index of microcirculatory resistance (caIMR) is proposed as a less-invasive and pressure-wire-free index to assess CMD. We aimed to investigate the impact of coronary microvascular function assessed by caIMR in patients with overweight and chronic coronary syndrome (CCS).

METHODS

CCS patients who underwent coronary angiography between 2015 to 2018 were included. Overweight was defined as BMI≥24.0kg/m². Impaired coronary microvascular function was defined as caIMR≥25U. The patients were classified according to BMI and caIMR. The primary endpoint was major adverse cardiac events (MACE). Kaplan-Meier and Cox regression analyses evaluated the association between caIMR and MACE.

RESULTS

Two hundred and eighty-two CCS patients were enrolled. Among these, 169 (59.93%) were overweight. Impaired coronary microvascular function was higher in overweight patients than in patients with normal weight (49.70% vs. 38.05%; P=0.035). During 35 months of follow-up, 33 MACE had occurred. Among the total CCS population, MACE was higher in patients with high caIMR than in low caIMR (18.11% vs. 6.45%, P=0.003). In subgroups analysis, MACE was higher in overweight patients with high caIMR than low caIMR (20.24% vs. 7.06%, P=0.014), while there were no significant differences in normal-weight patients. Multivariate Cox analysis demonstrated that caIMR≥25 was independently associated with MACE in overweight patients (HR, 2.87; 95% CI, 1.12-7.30; P=0.027) but not in the normal-weight patients. In addition, caIMR showed a significant predictive value for adverse outcomes in overweight patients and provided an incremental prediction when added to a prediction model with BMI.

CONCLUSIONS

Impaired coronary microvascular function assessed by caIMR was common and is an independent predictor of MACE in overweight patients with CCS.

Clinical correlations and genetic associations of metabolic syndrome in the United Arab Emirates

BACKGROUND

Metabolic syndrome (MetS) contributes to increased risk of morbidity and mortality. The United Arab Emirates (UAE) has a high prevalence of MetS which may be linked to modifiable and genetic risk factors in the local population. The association between MetS as a phenotype and key genetic variants in the UAE has not been investigated. This study reports on the clinical, biochemical and genetic associations of MetS and its risk factors to improve individualized medicine outcomes.

METHODS

There were 471 subjects included in this cross-sectional study, 367 with MetS and 104 without MetS. Along with clinical and laboratory parameters, multiple risk genetic variants were tested for their association with MetS, which include 49 variants that have previously been shown to be linked with MetS development as a phenotype, 116 variants for association with waist-hip ratio (WHR), 398 variants with body-mass index (BMI), 213 variants with T2DM and insulin resistance, 307 variants with different lipid traits, 308 variants with blood pressure traits, and 64 variants with coronary and cerebrovascular accidents.

RESULTS

Patients with MetS had higher rates of type 2 diabetes mellitus (T2DM), hypertension and dyslipidemia (p < 0.0001). Waist circumference and T2DM were identified as the key risk factors for MetS development. Individuals with MetS were also found to have a higher rate of clinical complications than those without MetS (76% vs. 52%). Several gene variants including those of the FTO gene were found to be associated with a predisposition to developing MetS or some of its components (P_FTO ~0.005-0.009).

CONCLUSIONS

This study showed associations between MetS as well as clinical factors contributing to MetS and specific genetic and metabolic risk factors, providing an insight into the metabolic and genetic links to disease development. Knowledge with respect to population specific risk markers including at risk genotypes will help in early identification of individuals with increased susceptibility to MetS in the UAE and provide the opportunity for timely intervention to prevent or delay the onset of MetS.

Endothelial Function of Patients with Morbid Obesity Submitted to Roux-en-Y Gastric Bypass With and Without Obstructive Sleep Apnea-Hypopnea Syndrome

BACKGROUND

Obesity is associated with obstructive sleep apnea-hypopnea syndrome (OSA) and both induce endothelial dysfunction. However, the effect of OSA on endothelial function after bariatric surgery has not been investigated yet.

OBJECTIVES

This study aims to evaluate the impact of weight loss on endothelial function in patients with and without obstructive sleep apnea (OSA) in the first 6 months after bariatric surgery.

SETTING

This study was conducted at a university hospital, in Brazil.

METHODS

The sample consisted of 56 patients homogeneously divided into groups with and without OSA. All patients underwent Roux-en-Y gastric bypass (RYGB), and the diagnosis of OSA was performed by polysomnography. The patients were evaluated preoperatively and 6 months after surgery. The evaluations included anthropometric measures, electrical bioimpedance, clinical symptoms of OSA, and endothelial function (flow-mediated dilation). RYGB improved the anthropometric, bioimpedance, and endothelial function results in both groups.

RESULTS

Patients presented a significant clinical improvement in OSA symptoms throughout the study. However, patients with OSA had an improvement in the endothelial function 2.5% lower (p < 0.001) than patients without APNEA syndrome.

CONCLUSION

This study demonstrates that the existence of OSA prior to bariatric surgery interferes in the improvement of endothelial function.

Lifestyle recommendations for the prevention and management of metabolic syndrome: an international panel recommendation

The importance of metabolic syndrome (MetS) lies in its associated risk of cardiovascular disease and type 2 diabetes, as well as other harmful conditions such as nonalcoholic fatty liver disease. In this report, the available scientific evidence on the associations between lifestyle changes and MetS and its components is reviewed to derive recommendations for MetS prevention and management. Weight loss through an energy-restricted diet together with increased energy expenditure through physical activity contribute to the prevention and treatment of MetS. A Mediterranean-type diet, with or without energy restriction, is an effective treatment component. This dietary pattern should be built upon an increased intake of unsaturated fat, primarily from olive oil, and emphasize the consumption of legumes, cereals (whole grains), fruits, vegetables, nuts, fish, and low-fat dairy products, as well as moderate consumption of alcohol. Other dietary patterns (Dietary Approaches to Stop Hypertension, new Nordic, and vegetarian diets) have also been proposed as alternatives for preventing MetS. Quitting smoking and reducing intake of sugar-sweetened beverages and meat and meat products are mandatory. Nevertheless, there are inconsistencies and gaps in the evidence, and additional research is needed to define the most appropriate therapies for MetS. In conclusion, a healthy lifestyle is critical to prevent or delay the onset of MetS in susceptible individuals and to prevent cardiovascular disease and type 2 diabetes in those with existing MetS. The recommendations provided in this article should help patients and clinicians understand and implement the most effective approaches for lifestyle change to prevent MetS and improve cardiometabolic health.

Cardiovascular consequences of metabolic syndrome

The metabolic syndrome (MetS) is defined as the concurrence of obesity-associated cardiovascular risk factors including abdominal obesity, impaired glucose tolerance, hypertriglyceridemia, decreased HDL cholesterol, and/or hypertension. Earlier conceptualizations of the MetS focused on insulin resistance as a core feature, and it is clearly coincident with the above list of features. Each component of the MetS is an independent risk factor for cardiovascular disease and the combination of these risk factors elevates rates and severity of cardiovascular disease, related to a spectrum of cardiovascular conditions including microvascular dysfunction, coronary atherosclerosis and calcification, cardiac dysfunction, myocardial infarction, and heart failure. While advances in understanding the etiology and consequences of this complex disorder have been made, the underlying pathophysiological mechanisms remain incompletely understood, and it is unclear how these concurrent risk factors conspire to produce the variety of obesity-associated adverse cardiovascular diseases. In this review, we highlight current knowledge regarding the pathophysiological consequences of obesity and the MetS on cardiovascular function and disease, including considerations of potential physiological and molecular mechanisms that may contribute to these adverse outcomes.

Controversies in perioperative anesthetic management of the morbidly obese: I am a surgeon, why should I care?

Over the last four decades, as the rates of obesity have increased, so have the challenges associated with its anesthetic management. In the present review, we discuss perioperative anesthesia management issues that are modifiable by the early involvement of the surgical team. We sum up available evidence or expert opinion on issues like patient positioning, postoperative analgesia, and the effect of continuous positive airway pressure (CPAP) ventilation on surgical anastomosis. We also address established predictors of higher perioperative risk and suggest possible management strategies and concerns of obese patients undergoing same day procedures. Finally, a generalized pharmacological model relevant to altered pharmacokinetics in these patients is presented.

Coronary Microvascular Function and Beyond: The Crosstalk between Hormones, Cytokines, and Neurotransmitters

Beyond its hemodynamic function, the heart also acts as a neuroendocrine and immunoregulatory organ. A dynamic communication between the heart and other organs takes place constantly to maintain cardiovascular homeostasis. The current understanding highlights the importance of the endocrine, immune, and nervous factors to fine-tune the crosstalk of the cardiovascular system with the entire body. Once disrupted, this complex interorgan communication may promote the onset and the progression of cardiovascular diseases. Thus, expanding our knowledge on how these factors influence the cardiovascular system can lead to novel therapeutic strategies to improve patient care. In the present paper, we review novel concepts on the role of endocrine, immune, and nervous factors in the modulation of microvascular coronary function.

Longitudinal myocardial blood flow gradient and CAD detection

Conventional myocardial perfusion scintigraphy with SPECT/CT or with PET/CT has been established as pivotal clinical imaging modality for the identification of hemodynamically obstructive coronary artery disease (CAD) and risk stratification of patients with suspected or known CAD. While the assessment of the relative distribution of radiotracer uptake in the left-ventricular (LV) myocardium during vasomotor stress identifies the "culprit" or most severe CAD lesion in multivessel disease, flow-limiting effects of remaining but less severe epicardial lesions may be missed. This limitation principally may be overcome by the possibility of PET/CT with radiotracer-kinetic modeling to concurrently assess left-ventricular (LV) myocardial blood flow (MBF) in ml/g/min at rest and during vasomotor stress and the resulting myocardial flow reserve (MFR). While a stress-induced regional reduction in radiotracer uptake or perfusion identifies the most advanced epicardial lesion, flow-limiting effects of the other epicardial lesions may principally be identified by regional reductions in MFR. Conversely, reductions in MFR in CAD may be appreciated as suboptimal as they reflect not only the consequences of flow-limiting effects of epicardial stenosis but also of microvascular dysfunction. The relatively low specificity of a reduced therefore MFR may hamper a clear identification of the downstream hemodynamic effects of an epicardial lesion on hyperemic coronary flow increases. In this scenario, there is increasing evidence that the PET assessment of an abnormal decrease in MBF from the base to the apex of the LV during hyperemic flows, a so-called longitudinal flow gradient, is primarily related to fluid dynamic consequences of CAD-induced diffuse luminal and/or focal narrowing of the epicardial artery. The combined evaluation of the MFR and corresponding longitudinal MBF gradient could emerge as new a novel analytic concept to further optimize the identification and characterization of hemodynamic CAD burden in multivessel disease, which, however, warrants further clinical validation.