Obesity and preclinical changes of cardiac geometry and function

[Heart failure and obesity]

Obesity is an independent predictor of cardiovascular diseases (CVD), including heart failure (HF). Nevertheless, numerous studies have shown that patients with CVD who are overweight and slightly obese have a better short-term and moderate prognosis than thinner patients with CVD. This phenomenon has been called the obesity paradox. Understanding the obesity paradox is important in patients with HF, given the high prevalence of obesity in patients with HF. The article presents an overview of clinical studies devoted to the study of obesity as a risk factor for HF, the pathogenesis of HF in obesity, and highlights the issues of the obesity paradox and the treatment of obesity in this category of patients.

Interactions of hypertension, obesity, left ventricular hypertrophy, and heart failure

PURPOSE OF REVIEW

Hypertension (HTN) and obesity are major risk factors for cardiac remodeling and dysfunction, leading to left ventricular hypertrophy (LVH) and heart failure (HF). In this review, we discuss the complex mechanisms and effects of HTN and obesity, and their treatments in LVH, ventricular function, and HF.

RECENT FINDINGS

Obesity and HTN impact the heart through overlapping neurohormonal pathways. However, the relationship between obesity and cardiomyopathy is more complex, and additional metabolic and hemodynamic pathways seem to contribute to cardiac dysfunction in these patients. Weight loss and blood pressure (BP) control help to prevent and reverse at least some of the damage caused by obesity and HTN even beyond what would be expected from solely the hemodynamic changes.

SUMMARY

Obesity and HTN cause maladaptive changes in the heart that can lead to LVH and HF. Weight loss and BP control help to, at least partially, reverse some of these changes and improve clinical outcomes in patients with HF.

Understanding the molecular mechanisms and role of autophagy in obesity

Vital for growth, proliferation, subsistence, and thermogenesis, autophagy is the biological cascade, which confers defence against aging and various pathologies. Current research has demonstrated de novo activity of autophagy in stimulation of biological events. There exists a significant association between autophagy activation and obesity, encompassing expansion of adipocytes which facilitates β cell activity. The main objective of the manuscript is to enumerate intrinsic role of autophagy in obesity and associated complications. The peer review articles published till date were searched using medical databases like PubMed and MEDLINE for research, primarily in English language. Obesity is characterized by adipocytic hypertrophy and hyperplasia, which leads to imbalance of lipid absorption, free fatty acid release, and mitochondrial activity. Detailed evaluation of obesity progression is necessary for its treatment and related comorbidities. Data collected in regard to etiological sustaining of obesity, has revealed hypothesized energy misbalance and neuro-humoral dysfunction, which is stimulated by autophagy. Autophagy regulates chief salvaging events for protein clustering, excessive triglycerides, and impaired mitochondria which is accompanied by oxidative and genotoxic stress in mammals. Autophagy is a homeostatic event, which regulates biological process by eliminating lethal cells and reprocessing physiological constituents, comprising of proteins and fat. Unquestionably, autophagy impairment is involved in metabolic syndromes, like obesity. According to an individual's metabolic outline, autophagy activation is essential for metabolism and activity of the adipose tissue and to retard metabolic syndrome i.e. obesity. The manuscript summarizes the perception of current knowledge on autophagy stimulation and its effect on the obesity.

Healthy Weight and Obesity Prevention: JACC Health Promotion Series

Overweight and obesity have reached epidemic levels in the United States and worldwide, and this has contributed to substantial cardiovascular and other health risks. However, controversy exists concerning the causes of obesity and effective modalities for its prevention and treatment. There is also controversy related to the concept of metabolically healthy obesity phenotype, the "obesity paradox," and on the importance of fitness to protect individuals who are overweight or obese from cardiovascular diseases. In this state-of-the-art review, the authors focus on "healthy weight" with the emphasis on the pathophysiologic effects of weight gain on the cardiovascular system; mechanistic/triggering factors; and the role of preventive actions through personal, education/environment, and societal/authoritative factors, as well as factors to provide guidance for caregivers of health promotion. Additionally, the authors briefly review metabolically healthy obesity, the obesity paradox, and issues beyond lifestyle consideration for weight loss with medications and bariatric surgery.

Targeting Autophagy in Obesity-Associated Heart Disease

Over the past three decades, the increasing rates of obesity have led to an alarming obesity epidemic worldwide. Obesity is associated with an increased risk of cardiovascular diseases; thus, it is essential to define the molecular mechanisms by which obesity affects heart function. Individuals with obesity and overweight have shown changes in cardiac structure and function, leading to cardiomyopathy, hypertrophy, atrial fibrillation, and arrhythmia. Autophagy is a highly conserved recycling mechanism that delivers proteins and damaged organelles to lysosomes for degradation. In the hearts of patients and mouse models with obesity, this process is impaired. Furthermore, it has been shown that autophagy flux restoration in obesity models improves cardiac function. Therefore, autophagy may play an important role in mitigating the adverse effects of obesity on the heart. Throughout this review, we will discuss the benefits of autophagy on the heart in obesity and how regulating autophagy might be a therapeutic tool to reduce the risk of obesity-associated cardiovascular diseases.

High sodium intake in women with metabolic syndrome

Background and Objectives

Metabolic syndrome and high sodium intake are associated with frequent cardiovascular events. Few studies have estimated sodium intake in subjects with metabolic syndrome by 24-hour urine sodium excretion. We evaluated sodium intake in individuals with metabolic syndrome.

Subjects and Methods

Participants were recruited by random selection and through advertisement. Twenty four-hour urine collection, ambulatory blood pressure measurements, and blood test were performed. Sodium intake was estimated by 24-hour urine sodium excretion. Participants receiving antihypertensive medications were excluded from analysis.

Results

Among the 463 participants recruited, subjects with metabolic syndrome had higher levels of 24-hour urine sodium excretion than subjects without metabolic syndrome (p=0.0001). There was a significant relationship between the number of metabolic syndrome factors and 24-hour urine sodium excretion (p=0.001). The proportion of subjects with metabolic syndrome was increased across the tertile groups of 24-hour urine sodium excretion (p<0.0001). The association of high sodium intake and metabolic syndrome was significant only among women. Among the factors related to metabolic syndrome, body mass index had an independent association with 24-hour urine sodium excretion (p<0.0001).

Conclusion

Women with metabolic syndrome exhibited significantly higher sodium intake, suggesting that dietary education to reduce sodium consumption should be emphasized for women with metabolic syndrome.

Asymptomatic obese hypertensives and need of routine echocardiography for left ventricular mass assessment and treatment

BACKGROUND

Echocardiographic determination of Left Ventricle Mass (LVM) - an important marker of cardiovascular disease, has been given a lot of importance in clinical diagnosis and in planning of treatment. Clinically asymptomatic compensated hypertensives show some pathological findings which are indicative of left ventricular dysfunction.

METHODS

The study population of 106 males, after a detailed clinical examination, were evaluated by echocardiography and were classified as per the body mass index classification of WHO Western Pacific Region in 2000 for Asian population. Fasting blood samples were taken to estimate blood sugar and lipid profile.

RESULTS

It was observed that subjects in normal range of body mass index <45 years (23.68%) and >45 years (16.1%), subjects of overweight <45 years (15.7%) and >45 years (10.29%) and obese I and II<45 years (60.52%) and >45 years (73.52%). The comparison between left ventricular mass which was indexed to height(2.7) in subjects who were <45 years and >45years was observed to be statistically significant (p<0.03). On comparing LVM/ht(2.7) of normal BMI group with that of those with higher BMIs, it was noted to be significantly different (p<0.009), which was suggestive of adverse effects of increasing BMI on LVM. It was also observed that persons with increased BMIs showed changes in left ventricular geometry - 30.13% had concentric hypertrophy, 17.80% had concentric remodeling, 8.21% had eccentric hypertrophy and that 38.35% had normal left ventricle geometry.

CONCLUSION

The present study therefore, indicated that it was better to do an echocardiographic screening of asymptomatic subjects who had even a marginal increase in blood pressure and BMI, to diagnose potential cardiac dysfunction.

Impact of obstructive sleep apnea on left atrial functional and structural remodeling beyond obesity

BACKGROUND

To evaluate the left atrial (LA) volume and function of obese patients with/without obstructive sleep apnea (OSA) and its association with left ventricular (LV) diastolic function independent of obesity.

METHODS

LA volumetric and functional parameters were measured by 2-dimensional and strain echocardiography in 49 obese (body mass index ≥ 25 kg/m(2)) subjects (24 non-OSA and 25 OSA).

RESULTS

OSA group showed larger maximal LA volume indexed for body surface area, larger volume before atrial contraction, a reduction in the LA passive emptying fraction, and an increase in the LA active emptying fraction with no significant change in LA total emptying fraction. Mitral annular early diastolic velocity (Ea) was significantly reduced, whereas the ratio of mitral valve early diastolic velocity (E) to Ea (E/Ea) and late diastolic velocity (Aa) were significantly increased in OSA group. Although the mean peak late diastolic strain rate had not shown any differences, the LA mean peak systolic strain/strain rate, and mean peak early diastolic strain rate were significantly lower in the OSA group. Apnea-hypopnea index (AHI) of the OSA patients was significantly correlated with E/Ea (r=0.67, p<0.001). There is a significant correlation between LA active emptying volume index and E/Ea (r=0.77, p<0.001), and between LA passive emptying volume index and E/Ea (r=-0.51, p=0.009).

CONCLUSION

LA structural and functional remodeling was significantly correlated with the severity of OSA and LV diastolic filling pressure. OSA impaired LA wall compliance and passive contraction independent of obesity.

Impact of obstructive sleep apnea on the global myocardial performance beyond obesity

We aimed to assess the impact of obstructive sleep apnea (OSA) on the left ventricular (LV) function independent of obesity using the myocardial performance index (Tei index) and the global longitudinal LV strain (GLS) and its reversibility after surgery. Twenty-five newly diagnosed OSA patients, normal weight (n = 15) and obese (body mass index [BMI] ≥ 25; n = 20) controls without OSA were enrolled and underwent transthoracic echocardiographic evaluation. The OSA and obese groups had a significantly comparable increased BMI and LV chamber dimension, prolonged isovolumic relaxation time, reduced early mitral filling velocity, and increased late mitral filling velocity and Tei index as compared to the normal weight group. However, GLS was significantly reduced only in the OSA group (-16.5 ± 1.9%) as compared to the normal weight group (-20.6 ± 2.0%, P < 0.001) and obese group (-19.1 ± 2.5%, P < 0.001). As a treatment, 13 of 25 patients underwent surgical modification, and the follow-up echocardiogram revealed significantly improved Tei index and GLS as compared to baseline (0.37 ± 0.06 and -18.9 ± 3.3% vs. 0.42 ± 0.04 and -16.3 ± 2.4%, P = 0.006 and 0.031, respectively), which was comparable to the obese controls. A reduction in the apnea-hypopnea index had a significant effect on the improvement in the GLS (r = 0.73, P < 0.001). LV systolic and diastolic function significantly deteriorated in the patients with OSA beyond obesity, and an improvement in the LV function was observed within 6 months after the surgical modification. GLS is considered to be one of the parameters that can be used in the early detection of LV systolic dysfunction in patients with OSA and a normal ejection fraction.