Objective: To assess relations of left ventricular (LV) geometry and function to insulin resistance in obesity-a condition associated with volume overload and abnormal LV relaxation.
Design: Cross-sectional relational study.
Subjects: 27 healthy overweight-obese subjects (18 women, body mass index (BMI) = 35.0+/-4.0 kg/m2) and 31 age-matched normal-weight controls (21 women, BMI = 22.6+/-2.4 kg/m2).
Measurements: Subjects were studied by Doppler-echocardiography the same day and hour (08.00 h) as measurements of fasting insulin and blood glucose were made. Insulin resistance was determined by the 'Homeostasis Assessment Model'.
Results: Twelve obese subjects with insulin resistance (IR) had higher body size than 15 patients without IR and higher blood pressure than normal-weight controls (all P < 0.01). Relative IR was related to isovolumic relaxation time. This relation was not maintained after controlling for age, blood pressure, weight and height. Isovolumic relaxation time was, however, positively related to diastolic blood pressure, a measure of load, in normal controls (r=0.44) and obese without IR (r=0.62) but not in insulin resistant subjects (r=0.14).
Conclusion: IR does not independently influence myocardial relaxation in uncomplicated obesity, but modulates the effect of load on active diastole.