Left ventricular hypertrophy and insulin resistance in adults from an urban community in The Gambia: cross-sectional study

Objective

To determine the association between left ventricular hypertrophy and insulin resistance in Gambians.

Design

Cross-sectional study.

Setting

Outpatient clinics of Royal Victoria Teaching Hospital and Medical Research Council Laboratories in Banjul.

Participants

Three hundred and sixteen consecutive patients were enrolled from outpatient clinics. The data of 275 participants (89 males) were included in the analysis with a mean (± standard deviation) age of 53.7 (±11.9) years.

Interventions

A questionnaire was filled and anthropometric measurements were taken. 2-D guided M-mode echocardiography, standard 12-1ead electrocardiogram, fasting insulin and the oral glucose tolerance test were performed.

Main Outcome Measures

The Penn formula was used to determine the left ventricular mass index, 125 g/m² in males and 110 g/m² in females as the cut-off for left ventricular hypertrophy. Using the fasting insulin and fasting glucose levels, the insulin resistance was estimated by the homeostatic model assessment formula. Logistic regression analysis was used to determine the association between left ventricular hypertrophy and insulin resistance.

Results

The mean Penn left ventricular mass index was 119.5 (±54.3) and the prevalence of Penn left ventricular mass index left ventricular hypertrophy was 41%. The mean fasting glucose was 5.6 (±2.5) mmol/l, fasting insulin was 6.39 (±5.49) μU/ml and insulin resistance was 1.58 (±1.45). There was no association between Penn left ventricular mass index left ventricular hypertrophy and log of insulin resistance in univariate (OR = 0.98, 95% CI = 0.80 – 1.19, p = 0.819) and multivariate logistic regression (OR = 0.93, 95% CI = 0.76–1.15, p = 0.516) analysis.

Conclusion

No association was found in this study between left ventricular hypertrophy and insulin resistance in Gambians and this does not support the suggestion that insulin is an independent determinant of left ventricular hypertrophy in hypertensives.

Adiponectin: anti-inflammatory and cardioprotective effects

Adipose tissue is an endocrine organ that plays an essential role in regulating several metabolic functions through the secretion of biological mediators called "adipokines". Dysregulation of adipokines plays a crucial role in obesity-related diseases. Adiponectin (APN) is the most abundant adipokine accounting for the 0.01% of total serum protein, and is involved in a wide variety of physiological processes including energy metabolism, inflammation, and vascular physiology. APN plasma levels are reduced in individuals with obesity, type 2 diabetes and coronary artery disease, all traits with low-grade chronic inflammation. It is has been suggested that the absence of APN anti-inflammatory effects may be a contributing factor to this inflammation. APN inhibits the expression of tumor necrosis factor-α-induced endothelial adhesion molecules, macrophage-to-foam cell transformation, tumor necrosis factor-α expression in macrophages and adipose tissue, and smooth muscle cell proliferation. It also has anti-apoptotic and anti-oxidant effects, which play a role in its cardioprotective action. This review will focus on APN as an anti-inflammatory, anti-atherogenic and cardioprotective plasma protein.

Association of adiponectin with left ventricular mass in blacks: the Jackson Heart Study

BACKGROUND

Blacks have a higher prevalence of left ventricular hypertrophy than whites. Several population-based studies have reported an inverse association between adiponectin and left ventricular mass (LVM); however, the relationship between adiponectin levels and LVM has yet to be defined in blacks. The Jackson Heart Study cohort provides an opportunity to test the hypothesis that the inverse association between adiponectin and LVM may be modified by risk factors common among blacks.

METHODS AND RESULTS

The study population included 2649 black Jackson Heart Study participants (mean age 51±12 years, 63% women, 51% obese, 54% with hypertension, and 16% with diabetes). Multiple linear and spline regression was used to assess the association, with adjustment for demographic, clinical, and behavioral covariates. Among all the participants, there was a statistically significant but modest inverse association between adiponectin and LVM index. Hypertension and insulin resistance emerged as statistically significant effect modifiers of this relationship. The inverse association present among the normotensive participants was explained by obesity measures such as the body mass index. Among participants with both hypertension and insulin resistance, there was a significant direct association between adiponectin and the LVM index after multivariable adjustment (β=1.55, P=0.04, per 1-SD increment in the adiponectin log value).

CONCLUSIONS

The association between serum adiponectin and LVM among blacks in the Jackson Heart Study cohort was dependent on hypertension and insulin resistance status. Normotensive blacks exhibited an inverse adiponectin-LVM association, whereas participants with hypertension and insulin resistance had a direct association.

Plasma adiponectin levels are associated with left ventricular hypertrophy in a random sample of middle-aged subjects

BACKGROUND

A low adiponectin level is associated with high blood pressure which, in turn, often results in left ventricular hypertrophy. We evaluated the association between plasma adiponectin concentrations and echocardiographic measurements, including left ventricular mass index (LVMI), in 933 middle-aged subjects consisting of 453 hypertensives and 480 controls.

METHODS

Plasma adiponectin concentrations were measured with an enzyme-linked immunosorbent assay (ELISA) method. One experienced cardiologist performed echocardiographic examinations, and LVMI was calculated according to Devereux's method.

RESULTS

Low plasma adiponectin levels were independently associated with increased intraventricular septum thickness, posterior ventricular wall thickness, and left ventricular mass index (P<0.001) in the whole cohort. In the subgroup analysis, the association between these echocardiographic parameters and adiponectin concentrations was observed only in the hypertensive cohort although fractional shortening revealed an association with adiponectin levels also in the control cohort (P=0.021). Findings remained significant after adjustment for the major risk factors for LVMI, such as age, sex, smoking, and systolic blood pressure.

CONCLUSIONS

This study in a large population sample detected an association between low plasma adiponectin concentration and LVMI, a marker of left ventricular hypertrophy. This association may be one of the factors that could explain the reported increased cardiovascular risk in subjects with low adiponectin levels.

Resistin is associated with biomarkers of inflammation while total and high-molecular weight adiponectin are associated with biomarkers of inflammation, insulin resistance, and endothelial function

OBJECTIVE

Adiponectin and resistin have been linked to inflammation, endothelial dysfunction, and/or insulin secretion or resistance. It remains to be elucidated which of these adipokines is associated primarily with biomarkers of all or only some of these categories, i.e. biomarkers of inflammation, endothelial dysfunction, and/or insulin secretion or insulinemia.

DESIGN AND METHODS

We studied 1065 healthy women, Nurses' Health Study participants, who provided blood samples in 1989-1990. A cross-sectional analysis was conducted to assess the relationships between total and high-molecular weight (HMW) adiponectin and resistin with inflammatory markers and biomarkers of endothelial dysfunction, insulin secretion, and insulinemia.

RESULTS

Resistin was positively associated with the inflammatory markers soluble tumour necrosis factor-alpha receptor II and interleukin-6 but not with any biomarkers of endothelial function, glycemia, insulinemia, or markers of insulin secretion after multivariate adjustment for age and body mass index (BMI). In both crude and multivariate analyses, total adiponectin was inversely associated with insulin, proinsulin, C-peptide, HbA1c, sE-selectin, and C-reactive protein (CRP) levels. HMW adiponectin was inversely associated with circulating insulin, proinsulin, C-peptide, HbA1c, sE-selectin, and CRP concentrations, even after adjustment for age, BMI, lifestyle factors, exercise, the use of medications as well as the other biomarkers of interest. Total and HMW adiponectin demonstrated negative associations with soluble intercellular adhesion molecule-1, which became nonsignificant after adjustment for confounders, whereas positive associations between soluble vascular cell adhesion molecule-1 and total adiponectin became significant only after multivariate adjustment.

CONCLUSIONS

Total and HMW adiponectin are inversely associated with markers of insulin secretion/insulinemia, endothelial function, and inflammation. Resistin is positively associated only with markers of inflammation.

Adiponectin and left ventricular structure and function in healthy adults

CONTEXT

Adiponectin inhibits protein synthesis in cardiac myocytes, thereby opposing the effect of cardiac workload and trophic factors (in particular, insulin) on left ventricular (LV) mass and wall thickness (WT).

OBJECTIVE

We tested whether adiponectin and its isoforms are related to LV mass, WT, and function independently of metabolic factors.

DESIGN

This was a cross-sectional study.

SUBJECTS

The study included 77 healthy volunteers (42 men) aged 30-59 yr with normal LV structure and function.

MAIN OUTCOME MEASURES

Insulin response and insulin sensitivity were assessed by oral glucose tolerance test and euglycemic hyperinsulinemic clamp. LV mass, WT, stroke work, chamber function, and myocardial longitudinal function were evaluated by standard Doppler echocardiography and tissue Doppler imaging. Total and molecular isoforms of adiponectin were measured in plasma.

RESULTS

By multivariate analysis, independent factors affecting LV mass were sex, body mass index, stroke work, and current smoking (R(2) = 0.66). Independent correlates of LV WT were age, stroke work, and plasma adiponectin (standardized r = 0.28, 0.41, and -0.26, P at least < 0.005, R(2) = 0.48). LV longitudinal late diastolic velocity was independently related to age, body mass index, and adiponectin (standardized r = 0.20, 0.26, -0.33, P at least < 0.05, R(2) = 0.30). High-molecular-weight adiponectin (47% of total), but not lower molecular-weight isoforms, insulin sensitivity, or other metabolic factors, was inversely and independently related to WT (standardized r = -0.27, P < 0.01) and myocardial longitudinal late diastolic velocity (standardized r = -0.28, P < 0.05).

CONCLUSION

In healthy subjects, circulating total and high-molecular-weight adiponectin are related to LV WT and diastolic function, independently of age and metabolic factors.