The influence of obesity and consequent insulin resistance on coronary risk factors in medically treated patients with coronary disease.
OBJECTIVE
Obesity promotes the development and progression of coronary heart disease (CHD), in part, through its association with hyperlipidemia, hypertension, clotting abnormalities and insulin resistance. We assessed whether these relationships persist in patients with established CHD treated with evidence-based preventive pharmacologic therapies.


METHODS
We performed a cross-sectional study of 74 adults with CHD and a body mass index (BMI) of >27 kg m(-2) (mean 32+/-4). The mean age of subjects was 64+/-9 years (range 44-84 years).


METHODS
Obesity measures included weight, BMI, waist, fat mass, intra-abdominal fat and subcutaneous fat. Risk factor measures included insulin sensitivity, fasting insulin level, lipid profiles, blood pressure, C-reactive protein (hs-CRP), plasminogen activator inhibitor (PAI-1) and platelet reactivity. Medication use included aspirin (99%), statin (84%), beta-blocker (71%), ACE inhibitor or blocker (37%) and clopidogrel (28%).


RESULTS
There was no direct relationship between obesity parameters and risk factor measures of lipid concentrations, blood pressure, clotting abnormalities or platelet reactivity except for a modest relationship between visceral fat and hs-CRP (r=0.30, P=0.02). However, increased BMI, waist circumference, fat mass, total abdominal fat and abdominal subcutaneous fat all correlated with insulin sensitivity (r-values -0.30 to -0.45, P-values 0.01 to <0.001) and insulin concentrations. Insulin sensitivity, in turn, was the best predictor of PAI-1, triglycerides, high-density lipoprotein (HDL) levels, cholesterol/HDL levels (all P<0.01) and platelet reactivity (R=0.34, P=0.02).


CONCLUSIONS
Use of preventive pharmacologic therapies obviated the expected relationship between adiposity and CHD risk factors. However, a residual effect of insulin resistance is left untreated. Total adiposity and central adiposity were strong predictors of insulin sensitivity, which in turn predicted cardiac risk factors such as lipid concentrations, PAI-1 and platelet reactivity. Thus, while evidence-based pharmacologic treatments may diminish the statistical relationship between obesity and many cardiac risk factors, adiposity negatively impacts CHD risk by reducing tissue insulin sensitivity.
Ades
P A
PA
Division of Cardiology, University of Vermont College of Medicine, Burlington, VT 05403, USA. Philip.Ades@vtmednet.org
Savage
P D
PD
Toth
M J
MJ
Schneider
D J
DJ
Audelin
M C
MC
Bunn
J Y
JY
Ludlow
M
M
D050154:Adiposity / Q000502:physiology; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D003327:Coronary Disease / Q000209:etiology* / Q000517:prevention & control; D003430:Cross-Sectional Studies; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D019317:Evidence-Based Medicine; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D012307:Risk Factors
D000319:Adrenergic beta-Antagonists; D001786:Blood Glucose; D004791:Enzyme Inhibitors; D007328:Insulin; D010975:Platelet Aggregation Inhibitors