Left ventricular function response to exercise in normotensive obese subjects: influence of degree and duration of obesity.

This study has been designed to evaluate whether duration and severity of obesity can influence left ventricular function response to exercise in obese subjects without other known cardiovascular risk factors such as hypertension, diabetes or hyperlipoproteinemia. A total of 29 obese subjects were included and they were divided, according to their body mass index and to Garrow's criteria as follows: Overweight or mildly obese subjects: body mass index from 25 to 30 kg/m2; moderately obese subjects: body mass index > 30 and < 40 kg/m2. Both obese groups were further subdivided according to their duration of obesity evaluated by accurate anamnesis in subgroup A (duration of obesity less than 120 months) and subgroup B (duration of obesity more than 120 months). Left ventricular ejection fraction was detected by blood pool gated radionuclide angiocardiography both at rest and after symptom-limited bicycle ergometer procedure. At peak exercise left ventricular ejection fraction increased significantly (p < 0.05) only in overweight subjects. Exercise produced an increase of left ventricular ejection fraction in 14 overweight and in 5 moderately obese subjects and a decrease in 2 moderately obese subjects. At peak exercise mean heart rate and mean blood pressure increased significantly (p < 0.001) in both groups. When obese subjects were subgrouped according to duration of obesity, left ventricular ejection fraction increased significantly (p < 0.05) only in overweight subjects with duration of obesity less than 120 months. Duration of obesity correlated inversely with percent change in left ventricular ejection fraction (EF) at peak exercise (delta EF) (r = -0.59; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of increased body mass index on accuracy of two-dimensional echocardiography for measurement of left ventricular volume, ejection fraction, and mass

We used 2- and 3-dimensional echocardiography to determine left ventricular volume, mass, and ejection fraction in overweight (body mass index [BMI] > or = 25 kg/m2), obese (BMI > or = 30 kg/m2), and control (BMI < 25 kg/m2) subjects. Compared with corresponding magnetic resonance imaging measurements, 3-dimensional echocardiography is more accurate than 2-dimensional echocardiography in all patients, but particularly in overweight and obese subjects.     

A weight reduction and weight maintenance program with long-lasting improvement in left ventricular mass and blood pressure.

Obesity is a major risk factor for cardiovascular disease and is associated with hypertension and increased left ventricular mass (LVM). Maintenance of reduced weight has been a matter of recent concerns in the treatment of obese subjects. This study was conducted to confirm the effect of the addition of exercise to diet on maintenance of body weight in a weight reduction program. In addition, this study was conducted to estimate whether LVM changes in parallel with a change in body weight during a long-term follow-up after a weight-reduction program. Twenty-two normotensive (NT) obese subjects and 14 mild hypertensive (HT) obese subjects ranging in age from 22 to 51 years participated in a 12-week supervised weight-reduction program involving mild exercise and a mild hypocaloric diet. After this 12-week intervention, they were advised to maintain their modified lifestyle during a 1-year follow-up period. After the 12-week intervention, the mean reductions in body weight (BW) in the NT and HT groups were 4.1 kg (P < .0001) and 5.8 kg (P < .0001), respectively. LVM in the NT and HT groups was significantly reduced from 154 g to 136 g (P < .005) and from 169 g to 152 g (P < .002), respectively. One year after intervention, the mean gains in BW in the NT and HT groups were 2.3 kg (not significant, NS) and 0.4 kg (NS), respectively. The mean gains in LVM in the NT and HT groups were 8 g (NS) and 7 g (NS), respectively. It was also shown that blood pressures in the HT group were significantly decreased after the 12-week intervention and there was no significant change in blood pressure in the HT group 1 year after intervention. In conclusion, reduced body weight was maintained for 1 year after a 12-week supervised weight-reduction program in both normotensive and mild hypertensive obese subjects. Reduced left ventricular mass was maintained for a long period in both normotensive and mild hypertensive obese subjects and lowered blood pressure was maintained in the mild hypertensive obese subjects.     

Randomized comparison of reduced fat and reduced carbohydrate hypocaloric diets on intrahepatic fat in overweight and obese human subjects

Obesity-related hepatic steatosis is a major risk factor for metabolic and cardiovascular disease. Fat reduced hypocaloric diets are able to relieve the liver from ectopically stored lipids. We hypothesized that the widely used low carbohydrate hypocaloric diets are similarly effective in this regard. A total of 170 overweight and obese, otherwise healthy subjects were randomized to either reduced carbohydrate (n = 84) or reduced fat (n = 86), total energy restricted diet (-30% of energy intake before diet) for 6 months. Body composition was estimated by bioimpedance analyses and abdominal fat distribution by magnetic resonance tomography. Subjects were also submitted to fat spectroscopy of liver and oral glucose tolerance testing. In all, 102 subjects completed the diet intervention with measurements of intrahepatic lipid content. Both hypocaloric diets decreased body weight, total body fat, visceral fat, and intrahepatic lipid content. Subjects with high baseline intrahepatic lipids (>5.56%) lost ≈7-fold more intrahepatic lipids compared with those with low baseline values (<5.56%) irrespective of diet composition. In contrast, changes in visceral fat mass and insulin sensitivity were similar between subgroups, with low and high baseline intrahepatic lipids. CONCLUSION: A prolonged hypocaloric diet low in carbohydrates and high in fat has the same beneficial effects on intrahepatic lipid accumulation as the traditional low-fat hypocaloric diet. The decrease in intrahepatic lipids appears to be independent of visceral fat loss and is not tightly coupled with changes in whole body insulin sensitivity during 6 months of an energy restricted diet.     

Contemporary strategies for weight loss and cardiovascular disease risk factor modification

Because of the overweight/obesity epidemic and attendant increase in risk of chronic disease worldwide, there is a pressing need to identify effective weight loss strategies. Current recommendations for weight loss advocate a reduced-calorie dietary pattern (lower in total fat) in conjunction with regular physical activity and behavior change. This combined approach is important for long-term adherence and weight maintenance. Several large-scale clinical trials implementing different reduced-calorie dietary patterns have shown that 4 to 10 kg of weight is typically lost. The different hypocaloric dietary patterns shown to be effective include reduced-fat diets (10%–30% of calories from fat), a Mediterranean-style diet, and diets that are reduced in energy density. The weight loss achieved is accompanied by beneficial changes in cardiovascular disease risk, including the lipid and lipoprotein profile and blood pressure. This article summarizes our current understanding of effective weight loss programs.     

Contemporary strategies for weight loss and cardiovascular disease risk factor modification

Because of the overweight/obesity epidemic and attendant increase in risk of chronic disease worldwide, there is a pressing need to identify effective weight loss strategies. Current recommendations for weight loss advocate a reduced-calorie dietary pattern (lower in total fat) in conjunction with regular physical activity and behavior change. This combined approach is important for long-term adherence and weight maintenance. Several large-scale clinical trials implementing different reduced-calorie dietary patterns have shown that 4 to 10 kg of weight is typically lost. The different hypocaloric dietary patterns shown to be effective include reduced-fat diets (10%–30% of calories from fat), a Mediterranean-style diet, and diets that are reduced in energy density. The weight loss achieved is accompanied by beneficial changes in cardiovascular disease risk, including the lipid and lipoprotein profile and blood pressure. This article summarizes our current understanding of effective weight loss programs.     

Comparison of 4 diets of varying glycemic load on weight loss and cardiovascular risk reduction in overweight and obese young adults: a randomized controlled trial

BACKGROUND: Despite the popularity of low-glycemic index (GI) and high-protein diets, to our knowledge no randomized, controlled trials have systematically compared their relative effects on weight loss and cardiovascular risk. METHODS: A total of 129 overweight or obese young adults (body mass index, > or =25 [calculated as weight in kilograms divided by the square of height in meters]) were assigned to 1 of 4 reduced-fat, high-fiber diets for 12 weeks. Diets 1 and 2 were high carbohydrate (55% of total energy intake), with high and low GIs, respectively; diets 3 and 4 were high protein (25% of total energy intake), with high and low GIs, respectively. The glycemic load was highest in diet 1 and lowest in diet 4. Changes in weight, body composition, and blood chemistry profile were studied. RESULTS: While all groups lost a similar mean +/- SE percentage of weight (diet 1, -4.2% +/- 0.6%; diet 2, -5.5% +/- 0.5%; diet 3, -6.2% +/- 0.4%; and diet 4, -4.8% +/- 0.7%; P = .09), the proportion of subjects in each group who lost 5% or more of body weight varied significantly by diet (diet 1, 31%; diet 2, 56%; diet 3, 66%; and diet 4, 33%; P = .01). Women on diets 2 and 3 lost approximately 80% more fat mass (-4.5 +/- 0.5 [mean +/- SE] kg and -4.6 +/- 0.5 kg) than those on diet 1 (-2.5 +/- 0.5 kg; P = .007). Mean +/- SE low-density-lipoprotein cholesterol levels declined significantly in the diet 2 group (-6.6 +/- 3.9 mg/dL [-0.17 +/- 0.10 mmol/L]) but increased in the diet 3 group (+10.0 +/- 3.9 mg/dL [+0.26 +/- 0.10 mmol/L]; P = .02). Goals for energy distribution were not achieved exactly: both carbohydrate groups ate less fat, and the diet 2 group ate more fiber. CONCLUSION: Both high-protein and low-GI regimens increase body fat loss, but cardiovascular risk reduction is optimized by a high-carbohydrate, low-GI diet.     

Effects of olmesartan on blood pressure and insulin resistance in hypertensive patients with sleep-disordered breathing

The increased risk of cardiovascular morbidity and mortality among patients with sleep-disordered breathing (SDB) has been linked to arterial hypertension and insulin resistance. However, an effective antihypertensive agent for patients with SDB has not been identified. We investigated the effect of the angiotensin II subtype 1 receptor blocker olmesartan in hypertensive patients with SDB. This prospective, one-arm pilot study included 25 male patients with untreated SDB (mean age, 52.7 ± 11.4 years). We measured blood pressure, oxygen desaturation index (ODI), cardiac function using echocardiography, and insulin resistance using the homeostasis model assessment (HOMA) before and after 12 weeks of olmesartan therapy (mean dose, 17.6 ± 4.4 mg/day). Olmesartan significantly decreased systolic blood pressure (151.4 ± 8.0 vs. 134.0 ± 7.4 mmHg; P < 0.001), diastolic blood pressure (93.4 ± 7.1 vs. 83.9 ± 6.3 mmHg; P < 0.001), and HOMA index (3.7 ± 2.9 vs. 2.8 ± 1.9; P = 0.012). Furthermore, left ventricular ejection fraction significantly increased at 12 weeks (68.1 ± 5.1 vs. 71.6 ± 5.4%; P = 0.009). However, body mass index (BMI) and degree of SDB did not change (BMI, 26.6 ± 4.0 vs. 26.6 ± 4.2 kg/m2, P = 0.129; 3% ODI, 29.5 ± 23.1 vs. 28.2 ± 21.0 events/h, P = 0.394). Olmesartan significantly reduced blood pressure and insulin resistance in hypertensive patients with SDB without changing BMI or SDB severity.     

Orlistat in hypertensive overweight/obese patients: results of a randomized clinical trial

OBJECTIVE: To assess the effect of orlistat plus diet compared with diet alone in promoting weight loss and blood pressure reduction in hypertensive, overweight/obese patients. DESIGN: A pragmatic randomized, controlled trial. SETTING: Hypertension clinic of a university hospital. PATIENTS: Hypertensive patients aged 18-75 years with a body mass index greater than 25 kg/m(2). INTERVENTIONS: Orlistat 360 mg/day combined with a hypocaloric diet (treatment group), or a calorie-restricted diet alone (control group). MAIN OUTCOME MEASURES: Primary outcomes were reductions in weight and blood pressure. Secondary outcomes were decreases in lipid and glucose concentrations. A subgroup analysis of the main outcomes among diabetic and non-diabetic patients was also performed. RESULTS: A total of 204 patients were included in the intention-to-treat analysis. After 12 weeks the orlistat group lost, on average, 3.7 kg and the control group lost 2.0 kg in weight (P < 0.001). Systolic (SBP) and diastolic (DBP) blood pressures decreased by 15.3 and 11.4 mmHg, respectively, in the group given orlistat plus a hypocaloric diet and by 11.6 and 5.2 mmHg, respectively, in the control group given the calorie-restricted diet alone (P = 0.25 and P = 0.0004, respectively). Fasting glucose (0.82 and 0.17 mmol/l, P = 0.01) and total cholesterol (0.85 and 0.56 mmol/l, P = 0.05) were reduced to a greater extent with orlistat than with diet alone. The mean reduction in triglycerides with orlistat plus the hypocaloric diet was 0.75 mmol/l and that in the control group was 0.30 mmol/l (P = 0.28); the increases in high-density lipoprotein cholesterol were 0.05 and 0.00 mmol/l, respectively, in the two groups (P = 0.17). Treatment improved blood pressure and glucose control in the individuals with diabetes, but not in those without diabetes. CONCLUSION: In both groups there was a reduction in weight, blood pressure and metabolic parameters. The orlistat group performed better in reducing weight, DBP, glucose and cholesterol. Results show that even a small reduction in weight helps to control blood pressure and glucose. The cost-benefit of the use of orlistat should be evaluated for hypertensive obese patients.     

饮食控制对肥胖老年女性心功能的影响

目的 采用组织多普勒成像(TDI)技术评价饮食控制的无全身疾病的老年肥胖女性左心功能的效果. 方法入选100例无全身疾病肥胖老年女性,随机分为饮食控制组47例(3例退出)和非饮食控制组50例.另选健康正常体质量老年女性40例为对照组.饮食控制6个月(饮食给予相当于自身基础代谢率70%的低卡路里食物).以TDI技术测量其在二尖瓣瓣环6个取样点的收缩期、舒张早期和晚期峰值运动速度(Sm、Em和Am)及Em和Am比值(Era/Am),并计算各指标平均值(MSm、MEm、MAm和MEm/Am). 结果 6个月后饮食控制组较非饮食控制组体质指数(BMI)下降[两组分别为(28.4±1.7)kg/m~2、(30.7±1.4)kg/m~2,P<0.05].收缩压和心率降低.饮食控制前后3组二尖瓣瓣环各取样点Sm、Em、Am和Em/Am及Mm、MEm、MAmt MEm/Am均差异有统计学意义(均P<0.05);但6个月后饮食控制组较非饮食控制组增加,MSm分别为(8.3±1.5)cm/s与(7.4±1.4)cm/s(P<0.05);饮食控制组基线自身比较,MSm(7.5±1.5)cm/s降低(P<0.05). 结论饮食控制有助于无全身疾病肥胖老年女性左心室收缩功能的改善.TDI技术是左心室局部和整体功能早期评价的理想检测手段.     

N-3 polyunsaturated fatty acids in coronary heart disease: a meta-analysis of randomized controlled trials

PURPOSE: Observational studies have shown an inconsistent association between n-3 polyunsaturated fatty acids and the risk of coronary heart disease. We investigated the effects of dietary and non-dietary (supplemental) intake of n-3 polyunsaturated fatty acids on coronary heart disease. SUBJECTS AND METHODS: We searched the literature to identify randomized controlled trials that compared dietary or non-dietary intake of n-3 polyunsaturated fatty acids with a control diet or placebo in patients with coronary heart disease. Studies had to have at least 6 months of follow-up data, and to have reported clinical endpoint data. We identified 11 trials, published between 1966 and 1999, which included 7951 patients in the intervention and 7855 patients in the control groups. RESULTS: The risk ratio of nonfatal myocardial infarction in patients who were on n-3 polyunsaturated fatty acid-enriched diets compared with control diets or placebo was 0.8 (95% confidence interval [CI]: 0.5 to 1.2, P = 0.16; Breslow-Day test for heterogeneity, P = 0.01), and the risk ratio of fatal myocardial infarction was 0.7 (95% CI: 0.6 to 0.8, P <0.001; heterogeneity P >0.20). In 5 trials, sudden death was associated with a risk ratio of 0.7 (95% CI: 0.6 to 0.9, P <0.01; heterogeneity P >0.20), whereas the risk ratio of overall mortality was 0.8 (95% CI: 0.7 to 0.9, P <0.001; heterogeneity P >0.20). There was no difference in summary estimates between dietary and non-dietary interventions of n-3 polyunsaturated fatty acids for all endpoints. CONCLUSION: This meta-analysis suggests that dietary and non-dietary intake of n-3 polyunsaturated fatty acids reduces overall mortality, mortality due to myocardial infarction, and sudden death in patients with coronary heart disease.     

The cardiovascular risk of young women with polycystic ovary syndrome: an observational, analytical, prospective case-control study

To evaluate the cardiovascular risk of polycystic ovary syndrome (PCOS), we investigated lipid profile, metabolic pattern, and echocardiography in 30 young women with PCOS and 30 healthy age- and body mass index (BMI)-matched women. PCOS women had higher fasting glucose and insulin levels, homeostasis model assessment score of insulin sensitivity, total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels, and TC/high density lipoprotein cholesterol (HDL-C) ratio and lower HDL-C levels than controls. Additionally, PCOS women had higher left atrium size (32.0 +/- 4.9 vs. 27.4 +/- 2.1 mm; P < 0.0001) and left ventricular mass index (80.5 +/- 18.1 vs. 56.1 +/- 5.4 g/m(2); P < 0.0001) and lower left ventricular ejection fraction (64.4 +/- 4.1 vs. 67.1 +/- 2.6%; P = 0.003) and early to late mitral flow velocity ratio (1.6 +/- 0.4 vs. 2.1 +/- 0.2; P < 0.0001) than controls. When patients and controls were grouped according to BMI [normal weight (BMI, >18 and <25 kg/m(2)), overweight (BMI, 25.1-30 kg/m(2)), and obese (BMI, >30 kg/m(2))], the differences between PCOS women and controls were maintained in overweight and obese women. In normal weight PCOS women, a significant increase in left ventricular mass index and a decrease in diastolic filling were observed, notwithstanding no change in TC, LDL-C, HDL-C, TC/HDL-C ratio, and TG compared with controls. In conclusion, our data show the detrimental effect of PCOS on the cardiovascular system even in young women asymptomatic for cardiac disease.     

Dietary intervention increases n-3 long-chain polyunsaturated fatty acids in skeletal muscle membrane phospholipids of obese subjects. Implications for insulin sensitivity

OBJECTIVE: Cross-sectional studies suggest that the fatty acid (FA) composition of phospholipids in skeletal muscle cell membrane may modulate insulin sensitivity in humans. We examined the impact of a hypocaloric low-fat dietary intervention on membrane FA composition and insulin sensitivity. DESIGN Muscle membrane FA profiles were determined in muscle (vastus lateralis) biopsies from 21 obese subjects before and after 6 months of dietary restriction. Diet instructions emphasized low intake of FA of marine origin by recommending lean fish and prohibiting fatty fish and fish oil supplements. Insulin resistance was estimated by the homeostasis model assessment (HOMA-IR). RESULTS The mean weight loss was 5.1 kg (range -15.3 to +1.3 kg). BMI decreased from 36.5 to 34.9 kg/m(2) (P=0.003). Saturated FA (SFA) decreased 11% (P=0.0001). Polyunsaturated FA (PUFA)n-6 increased 4% (P =0.003). Long-chain PUFAn-3 increased 51% (P= 0.0001), mainly due to a 75% increase (P<0.0001) in docosahexaenoic acid. Changes in HOMA-IR correlated significantly with changes in long-chain PUFAn-3 (R=-0.57, P< 0.01), SFA (R=0.58, P<0.01) and waist circumference (R=0.46, P<0.05). A multivariate linear regression analysis that included changes in weight, fat mass, waist circumference, plasma lipids, PUFA, SFA and long-chain PUFAn-3 indicated that SFA and long-chain PUFAn-3 were independent predictors of HOMA-IR (R(2)=0.33, P<0.01). CONCLUSIONS: A hypocaloric low-fat dietary intervention programme increased incorporation of long-chain PUFAn-3 and reduced SFA in skeletal muscle membrane phospholipids of obese subjects, a setting that may impact on insulin action.     

Effects of insulin on left ventricular function during dynamic exercise in overweight and obese subjects.

AIMS: We designed this study in order to determine the effect of insulin on cardiac function in overweight and obese subjects during exercise. METHODS AND RESULTS: The cardiac function of 62 normal glucose tolerant subjects, aged 30-40 and divided into normal weight (group 1, n=22, BMI 20-24.9 kg/m(2)), overweight (group 2, n=20, BMI 25-29.9 kg/m(2)), and obesity (group 3, n=20, BMI 30-35 kg/m(2)) was evaluated at rest and during dynamic exercise through angiocardioscintigraphy, when on hyperinsulinaemic euglycaemic clamp (test A) and when on normal saline infusion (test B). Left ventricular function at rest was statistically greater (P<0.05) in both tests in overweight and obese subjects compared with normal weight controls, with no statistical difference (P=0.057) within groups between insulin and normal saline infusion. During exercise, cardiac function improved in all the subjects in both tests. The increase was lower in overweight and obese patients, even if statistically significant only in obese vs. control subjects in both tests (P<0.05). Insulin sensitivity showed a significant correlation (P< or =0.001) with left ventricular ejection fraction (LVEF) at rest and with change in LVEF during clamp. CONCLUSION: Our findings suggest a metabolic pathogenesis for the impaired LV function in obesity.     

超重和肥胖对心房颤动导管消融复发的影响

目的探讨超重和肥胖对心房颤动(简称房颤)导管消融复发的影响。方法回顾性分析连续入院在三维标测系统指导下行环肺静脉线性消融的患者369例,复发定义为消融1个月后发生持续30s以上的房性快速性心律失常,以体重指数≥25.0kg/m2做为超重和肥胖的诊断标准。结果369例中超重和肥胖199例,左房前后径和左室舒张末径在超重和肥胖组显著大于非超重和肥胖组(40.2±6.0mmvs36.6±6.5mm,P<0.001;49.1±7.1mmvs46.9±6.6mm,P=0.003)。随访459±181天,超重和肥胖组复发率为40.2%,非超重和肥胖组的复发率为25.9%,两组间差异有显著性(P=0.004)。单因素分析发现超重和肥胖、持续性/永久性房颤、左房前后径、左室舒张末径是导管消融复发的预测因素。经校正房颤病程、房颤类型、高血压、器质性心脏病,Cox多因素分析显示超重和肥胖是房颤复发的独立危险因素(危险比=1.67,95%可信区间1.13～2.46,P=0.009)。进一步校正左房前后径和左室舒张末径,Cox多因素分析发现只有左房前后径是复发的独立预测因素(危险比=1.04,95%可信区间1.01～1.08,P=0.010)。结论超重和肥胖是影响房颤导管消融复发的重要因素,其机制可能是通过左房增大介导的。     

Effect of body weight changes on 24-hour blood pressure and left ventricular mass in hypertension: a 4-year follow-up

BACKGROUND: Few data are available on the long-term effects of weight loss on 24-h blood pressure (BP) and left ventricular mass in overweight hypertensive patients. METHODS: A total of 181 never-treated overweight hypertensive subjects (body mass index, 25 to 39 kg/m(2), office BP 145/94 +/- 12/7 mm Hg) had 24-h BP monitoring and echocardiography twice, at baseline and after 3.8 +/- 2 years (minimum 1 year). None of the subjects received antihypertensive drugs during the follow-up. Main outcome measures were changes in 24-h BP and in left ventricular mass. RESULTS: Percent change in body weight had a direct relationship with 24-h BP changes (r = 0.35 and 0.31 for systolic and diastolic BP, respectively; both P <.001). The associations with office BP changes (r = 0.13, P =.10 for systolic BP; r = 0.15, P =.06 for diastolic BP) were significantly weaker (both P <.01, z test). The patients who lost weight during follow-up (n = 106) had a significantly lower increase in 24-h BP (+0.6 +/- 9/ +0.2 +/- 6 v +4.9 +/- 9/ +2.7 +/- 7 mm Hg for systolic/diastolic BP, both P <.01) and in left ventricular mass (-3 +/- 30 g v +9 +/- 32 g, P <.02) than the remaining subjects. In a multiple linear regression, a 10% weight loss independently predicted a 4.3/3.8 mm Hg decrease in 24-h systolic/diastolic BP. CONCLUSIONS: Long-term weight loss determines a sustained BP reduction during the 24 h and a decrease in left ventricular mass in overweight hypertensive subjects. The relation of weight loss with ambulatory BP changes is closer than that with office BP.     

Effects of dietary weight loss on sympathetic activity and cardiac risk factors associated with the metabolic syndrome

CONTEXT: Weight reduction, the first line treatment for the metabolic syndrome, improves insulin sensitivity and associated metabolic and cardiovascular abnormalities, but there is a paucity of data regarding its effect on sympathetic nervous system (SNS) activity in this clinical setting. OBJECTIVES: The objectives of this study were to test the hypothesis that dietary weight loss attenuates both insulin resistance and SNS activity and to examine the relationships between SNS activity and metabolic syndrome (MetS) components. DESIGN: This was a single-sample, repeated measures design study. SETTING: This study was performed at a tertiary referral center. PARTICIPANTS: Twenty-three MetS subjects (age, 58 +/- 2 yr; body mass index, 33.3 +/- 0.8 kg/m2; mean +/- sem) were studied. INTERVENTION: A hypocaloric modified Dietary Approaches to Stop Hypertension diet (26% fat, 22% protein, and 51% carbohydrate; 100 mmol/d sodium) was consumed for 3 months. MAIN OUTCOME MEASURES: The main outcome measures were postganglionic muscle sympathetic nerve activity (microneurography at a peroneal nerve), whole-body plasma norepinephrine spillover rate, spontaneous cardiac baroreflex function, and insulin sensitivity. RESULTS: The hypocaloric diet significantly reduced body weight by 7% and improved all MetS components. Norepinephrine spillover decreased from 877 +/- 180 to 503 +/- 39 ng/min (P = 0.005), and muscle sympathetic nerve activity decreased from 40.6 +/- 2.1 to 34.6 +/- 2.4 bursts/min (P = 0.01), whereas cardiac baroreflex sensitivity increased by 23.0 +/- 8.0% (P = 0.02). The change in the norepinephrine spillover rate correlated positively and independently with the change in plasma leptin concentration (r = 0.49; P = 0.03). CONCLUSION: Weight loss by a hypocaloric diet with moderate sodium restriction diminishes SNS activity in MetS subjects. This may be due to the consequences of decreased leptin concentration, enhanced insulin sensitivity, or improvements in cardiac baroreflex function.     

Differences in insulin resistance do not predict weight loss in response to hypocaloric diets in healthy obese women

The current study was initiated to determine whether insulin resistance and/or hyperinsulinemia affected the ability of obese individuals to lose weight in response to hypocaloric diets. Thirty-one obese, nondiabetic women, with values for body mass index ranging from 28.0-35.0 kg/m2, volunteered for this program. Resistance to insulin-mediated glucose disposal was assessed by determining their steady state plasma insulin and glucose concentration during the last 30 min of a 180-min infusion of somatostatin, insulin, and glucose. The total integrated insulin response to breakfast and lunch was also determined. After the baseline measurements, volunteers were placed on a hypocaloric diet calculated to lead to a minimum weekly loss of 1% of ideal body weight. Individuals who met the criteria after 30 days of dieting were defined as weight loss successes (n = 20) and continued on the diet for another 30 days. Individuals not meeting the criteria were designated as weight loss failures (n = 12) and were discharged from the study. There was a mean (+/-SEM) weight loss at 60 days of 9.2 +/- 0.4 kg in the 20 individuals defined as weight loss successes, but there was no correlation between weight loss and either steady state plasma glucose or the total integrated insulin response (r < 0.1; P > 0.83). Furthermore, using the same criteria to define insulin sensitivity and insulin resistance as those for therapeutic successes, the therapeutic failures comprised six insulin-sensitive and five insulin-resistant subjects. In summary, insulin-mediated glucose disposal varied widely in nondiabetic, obese women, and there was no relationship between baseline insulin resistance or total integrated insulin response and weight loss. It is concluded that the ability to lose weight on a calorie-restricted diet over a short time period does not vary in obese, healthy women as a function of insulin resistance or hyperinsulinemia.     

Obesity as a risk factor for sustained ventricular tachyarrhythmias in MADIT II patients

Background: Obesity, as defined by body mass index ≥30 kg/m², has been shown to be a risk factor for cardiovascular disease. However, data on the relationship between body mass index (BMI) and the risk of ventricular arrhythmias and sudden cardiac death are limited. The aim of this study was to evaluate the risk of ventricular tachyarrhythmias and sudden death by BMI in patients after myocardial infarction with severe left ventricular dysfunction.
Methods : The risk of appropriate defibrillator therapy for ventricular tachycardia or ventricular fibrillation (VT/VF) by BMI status was analyzed in 476 nondiabetic patients with left ventricular dysfunction who received an implantable cardioverter defibrillator (ICD) in the Multicenter Automatic Defibrillator Implantation Trial-II (MADIT II).
Results : Mean BMI was 27 ± 5 kg/m². Obese patients comprised 25% of the study population. After 2 years of follow-up, the cumulative rates of appropriate ICD therapy for VT/VF were 39% in obese and 24% in nonobese patients, respectively (P = 0.014). In multivariate analysis, there was a significant 64% increase in the risk for appropriate ICD therapy among obese patients as compared with nonobese patients, which was attributed mainly to an 86% increase in the risk of appropriate ICD shocks (P = 0.006). Consistent with these results, the risk of the combined endpoint of appropriate VT/VF therapy or sudden cardiac death (SCD) was also significantly increased among obese patients (Hazard Ratio 1.59; P = 0.01).
Conclusions : Our findings suggest that in nondiabetic patients with ischemic left ventricular dysfunction, a BMI ≥30 kg/m² is an independent risk factor for ventricular tachyarrhythmias.     

Insulin sensitivity after a reduced-fat diet and a monoene-enriched diet in subjects with elevated serum cholesterol and triglyceride concentrations

BACKGROUND AND AIMS: To investigate the effect of a reduced-fat diet and a monoene-enriched diet (MUFA diet) on serum lipids, glucose and insulin metabolism in subjects with elevated cholesterol and triglyceride concentrations. METHODS AND RESULTS: Eighteen subjects with elevated serum cholesterol and triglyceride concentrations consumed the MUFA diet (39% of energy (E%) as fat and 21 E% monoenes) and the reduced-fat diet (34 E% fat, 16 E% monoenes) for 4 weeks according to a randomized cross-over design. Both periods were preceded by consumption of a standardized baseline diet for 2 weeks. Serum lipid and lipoprotein concentrations were determined at the beginning and end of each diet period. A frequently sampled intravenous glucose tolerance test was performed after the MUFA diet and the reduced-fat diet. Insulin sensitivity index (SI) was 40% higher after the reduced-fat diet than after the MUFA diet (2.42 +/- 0.42 vs 1.73 +/- 0.24 10(-4) min-1 U-1 ml-1, p = 0.018). This change in insulin sensitivity was seen in 13 subjects and was most evident in those who began with the MUFA diet. Compared to the baseline diet (high in saturated fat), both experimental diets lowered serum total and LDL cholesterol concentrations (6.6-6.9%, p < 0.05 and 7.4-8.0%, p < 0.05 respectively). CONCLUSIONS: Both diets were equally effective in lowering serum lipid concentrations, but the reduced-fat diet resulted in better insulin sensitivity.