Kerstyn C. Zalesin

Impact of Obesity on Cardiovascular Disease

Obesity promotes a cascade of secondary pathologies including diabetes, insulin resistance, dyslipidemia, inflammation, thrombosis, hypertension, the metabolic syndrome, and OSA, which collectively heighten the risk for cardiovascular disease. Obesity may also be an independent moderator of cardiac risk apart from these comorbid conditions. Rates of obesity and cardiac disease continue to rise in a parallel and exponential manner. Because obesity is potentially one of the most modifiable mediators of cardiovascular morbidity and mortality, effective treatment and prevention interventions should have a profound and favorable impact on public health.

Impact of obesity on cardiovascular disease.

The epidemiology of cardiovacular disease risk factors is changing rapidly with the obesity pandemic. Obesity is independently associated with the risks for coronary heart disease, atrial fibrillation, and heart failure. Intra-abdominal obesity is also unique as a cardiovascular risk state in that it contributes to or directly causes most other modifiable risk factors, namely, hypertension, dysmetabolic syndrome, and type 2 diabetes mellitus. Obesity can also exacerbate cardiovascular disease through a variety of mechanisms including systemic inflammation, hypercoagulability, and activation of the sympathetic and renin-angiotensin systems. Thus, weight reduction is a key strategy for simultaneous improvement in global cardiovascular risk, with anticipated improvements in survival and quality of life.

Relation between degree of weight loss after bariatric surgery and reduction in albuminuria and C-reactive protein.

BACKGROUND Bariatric surgery achieves long-term weight loss in obese adults with amelioration of diabetes and hypertension. Improvement in albuminuria and high-sensitivity C-reactive protein (hs-CRP) has also been reported. We investigated, at a weight control center in a community hospital setting, the relation between degree of surgical weight loss and reduction in the cardiovascular risk markers, albuminuria and hs-CRP. METHODS We performed a retrospective study of 62 obese adults who had undergone Roux-en-Y gastric bypass surgery and had a median follow-up of 15 months. RESULTS The baseline (preoperative) mean age was 46 years, 82% were women, 26 had a blood pressure of > or =140/90 mm Hg, and 25 had type 2 diabetes. During follow-up (postoperative), a decrease occurred in the body mass index (mean +/- standard deviation 49.2 +/- 8.7 kg/m(2) to 34.1 +/- 8.1 kg/m(2); P <.0001), excess body weight (mean +/- SD 76.1 +/- 23.6 kg to 34.9 +/- 21.7 kg; P <.0001), hemoglobin A1c (mean +/- SD 6.5% +/- 1.3% to 5.6% +/- 0.8%; P <.0001), systolic blood pressure (mean +/- SD 133.7 +/- 14.3 mm Hg to 112.9 +/- 14.6 mm Hg; P < .0001), urine albumin creatinine ratio (from a median of 8.0 mg/g [interquartile range 5.0-29.3] to a median of 6.0 mg/g [interquartile range 3.3-11.5]; P <.0001), and hs-CRP (mean +/- SD 11.2 +/- 9.8 mg/L to 4.7 +/- 5.9 mg/L; P <.0001). The study sample was divided into tertiles of the percentage of excess body weight loss; the mean percentage of excess body weight loss was -37.1% +/- 5.5% in the first tertile, -54.3% +/- 6.8% in the second tertile, and -75.8% +/- 10.9% in the third tertile. The median percentage of change in albuminuria was greatest (median -52.8%, interquartile range -79.1% to -17.5%) in the third tertile, intermediate (median -45.5%, interquartile range -72.4% to 0%) in the second tertile, and lowest (-42.6%, interquartile range -80.5% to 16.7%) in the first tertile (P = .953). The mean percentage of change in hs-CRP was greatest (-72.4% +/- 30.4%) in the third tertile, intermediate (-55.4% +/- 31.9%) in the second tertile, and lowest (-44.8% +/- 30.6%) in the first tertile (P = .037). CONCLUSION The results of our study have shown that obese adults experience a reduction in albuminuria and hs-CRP after bariatric surgery, with a greater reduction in hs-CRP observed with more surgical weight loss.

Cardiorespiratory fitness and obstructive sleep apnea syndrome in morbidly obese patients.

BACKGROUND Conflicting data exist regarding the effects of obstructive sleep apnea syndrome (OSAS) on cardiorespiratory fitness in morbidly obese individuals with normal resting left ventricular function. METHODS Ninety-two morbidly obese subjects without any prior diagnosis of OSAS underwent cardiorespiratory fitness testing, two-dimensional echocardiography, and overnight polysomnography. Using the results of the polysomnogram, comparisons were made between subjects with (n = 42) and without (n = 50) OSAS. RESULTS Mean body mass index (BMI) for the study population (n = 92) was 48.6 +/- 9.3 kg/m(2) (+/- SD); mean age was 45.5 +/- 9.8 years, and approximately 69% were female. Despite having a higher resting, exercise, and resting mean arterial pressures, the OSAS cohort had a maximum oxygen consumption that was lower than the cohort without OSAS (21.1 mL/kg/min vs 17.6 mL/kg/min; p < 0.001). There was no difference in BMI, age, gender, waist circumference, and neck circumference between those with and without OSAS. Differences were observed between the cohorts in systolic BP, diastolic BP, and heart rate during rest, exercise, and recovery periods. There was no difference in ejection fraction, diastolic dysfunction, and treadmill test duration between cohorts. CONCLUSIONS Morbidly obese individuals with OSAS demonstrate reduced cardiorespiratory fitness and differing hemodynamic responses to exercise testing as compared with their counterparts without this disorder. These data suggest chronic sympathetic nervous system activation negatively influences aerobic capacity in OSAS.

Differential loss of fat and lean mass in the morbidly obese after bariatric surgery.

BACKGROUND Bariatric surgery has become a common treatment for morbid obesity. The relative changes in body tissue that comprise the substantial weight loss over time are not completely understood. METHODS We evaluated the differential rates of fat and lean tissue losses in morbidly obese patients who underwent Roux-en-Y gastric bypass surgery. Body composition was assessed using whole-body dual energy X-ray absorptiometry (DXA) performed at two timepoints in the postoperative period. Patients were stratified by the tertile of rapidity of weight loss expressed as percent reduction in body mass index per month. RESULTS Thirty two patients (25 women, 7 men) with a mean age of 46.7 +/- 10.4 years and an average initial body weight of 141.4 +/- 29.4 kg experienced a 52.3 +/- 16.6 kg (36.5 +/- 5.5%) weight loss over 13.9 +/- 6.0 months. The incremental rates of lean body mass loss by tertiles were 0.3 +/- 0.6, 0.5 +/- 0.2, and 1.0 +/- 0.8 kg/month (P = 0.02), whereas the rates of fat loss were 1.2 +/- 0.9, 1.8 +/- 0.4, and 2.9 +/- 1.0 kg/month (P = 0.0001). The ratios for lean to fat loss among the respective tertiles were 1:4.0, 1:3.6, and 1:3.0. The correlation between rates of lean and fat mass loss was r = 0.37 (P = 0.04). Only three of the 32 patients (9.4%) patients maintained or gained lean mass following Roux-en-Y gastric bypass surgery. CONCLUSIONS After bariatric surgery, those patients losing weight at the greatest rate appear to have accelerated losses of both lean and fat mass. Few patients maintain lean body mass after bariatric surgery, despite self-reported participation in conventional exercise programs. These data suggest the need for more aggressive interventions to preserve lean body mass during the weight loss phase after Roux-en-Y gastric bypass surgery.

Preventing weight regain after bariatric surgery: an overview of lifestyle and psychosocial modulators.

Bariatric surgery is being increasingly used as a treatment for obesity. With this weight loss intervention, obesity-specific disease remission and mortality reduction benefits are undeniable. After surgical weight loss is complete, one of the greatest challenges becomes long-term weight loss maintenance, which is largely behavior-ally based. The fundamental behavioral components to maintaining surgical weight loss include dietary control, commitment to regular physical activity, and behavior modification. Changing these longstanding lifestyle habits, however, is a serious challenge and, unfortunately, many formerly obese individuals ultimately experience weight regain due to noncompliance. Further research is needed to identify optimal treatment strategies for postoperative bariatric surgery patients to minimize weight regain.

Treating type 2 diabetes: incretin mimetics and enhancers

As a consequence of excess abdominal adiposity and genetic predisposition, type 2 diabetes is a progressive disease, often diagnosed after metabolic dysfunction has taken hold of multiple organ systems. Insulin deficiency, insulin resistance and impaired glucose homeostasis resulting from beta-cell dysfunction characterize the disease. Current treatment goals are often unmet due to insufficient treatment modalities. Even when combined, these treatment modalities are frequently limited by safety, tolerability, weight gain, edema and gastrointestinal intolerance. Recently, new therapeutic classes have become available for treatment. This review will examine the new therapeutic classes of incretin mimetics and enhancers in the treatment of type 2 diabetes.

Audiocardiography in the cardiovascular evaluation of the morbidly obese

Morbid obesity is believed to limit cardiovascular auscultation. We compared audiocardiography to senior attending physicians using conventional stethoscopes in 190 individuals with morbid obesity. Overall, there were 128 (67·4%) women and 62 (32·6%) men with mean ages of 44·9 ± 12·3 and 51·3 ± 10·8 , respectively (P = 0·001). The overall body mass index (BMI) was 47·3 ± 8·5 kg m−2. Of those with an S3 by audiocardiography (n = 7), one had a history of coronary artery disease (CAD), none had a history of heart failure, and one had a left ventricular ejection fraction (LVEF) <45%. The mean LVEF was 58·6 ± 9·9 versus 61·6 ± 5·3 for those with and without an S3 by audiocardiography (P = 0·16). By contrast, of those (n = 6) with an S3 by stethoscope, one had a history of CAD, two had histories of heart failure, and 3 had LVEF < 45%. The mean LVEF of those with and without S3 by stethoscope was 53·7 ± 2·3 and 61·6 ± 5·5%, respectively (P = 0·02). There were 40 (21·1%) patients with an S4 (S4 strength >5) identified by acoustic cardiography while there were 42 (22·1%) heard by the stethoscope and it was heard with both methods in nine patients (21·4% concordance). There were no significant correlations between BMI or peak oxygen consumption and S3 or S4 strength by audiocardiography. Acoustic cardiography performed with an electronic device was not helpful in assisting the cardiovascular examination of the morbidly obese. These data suggest the careful clinical exam with attention to traditional cardiac auscultation using a stethoscope in a quiet room should remain the gold standard.

Nutraceutical meal replacements: more effective than all-food diets in the treatment of obesity

The prevalence of obesity continues to increase in many developed countries throughout the world and is now referred to as a pandemic. Obesity is a chronic, relapsing disease, with neurochemical changes that influence energy balance, often rendering traditional treatment interventions ineffective at restoring normal body weight. Therefore, obesity treatment interventions, including dietary strategies, are receiving increasing attention by investigators and clinicians. Hundreds of randomized, controlled trials examining various food diet interventions have found modest long-term weight loss. Meal replacements in the form of drinks, bars and entrees work to replace food, restrict caloric intake and blunt the rise of postprandial blood sugar, fatty acids and the resultant secretion of incretins, insulin and other factors. Thus, these agents have a significant neurohormonal impact that enables weight reduction and have therefore been referred to as nutraceuticals – nutrition with a pharmaceutical effect. There is accumulating evidence that meal-replacement dietary approaches are superior to all-food approaches for short- and long-term weight loss, as well as improvement of obesity comorbidities.