Objective: To investigate whether left ventricular hypertrophy is associated with the insulin resistance syndrome.
Methods: Fifty patients with untreated hypertension were evaluated by recording office blood pressure during regular antihypertensive treatment and 24-h ambulatory blood pressure and office blood pressure after 4-6 weeks on placebo, echocardiography with M-mode measurements of left ventricular wall thickness and pulsed-wave Doppler measurements of mitral flow in diastole and the hyperinsulinaemic euglycaemic clamp, for determination of insulin sensitivity.
Results: The left ventricular wall thickness was found to be significantly related to blood pressure [r = 0.44, P < 0.004 for 24-h ambulatory systolic blood pressure (SBP)], fasting insulin level (r = 0.32, P < 0.03) and haematocrit level (r = 0.37, P < 0.009) and inversely related to insulin sensitivity (r = -0.59, P < 0.0001). Multiple regression analysis with these relationships together with confounding factors age, sex, body mass index and waist: hip ratio as independent variables showed insulin sensitivity to be the only significant variable, explaining 43% of the variation in left ventricular wall thickness, whereas 24-h ambulatory SBP explained a further 7%. Left ventricular diastolic filling, as evaluated by the mitral Doppler early: atrial ratio, was significantly correlated with insulin sensitivity (r = 0.42, P < 0.003) and inversely related to blood pressure (r = -0.41, P < 0.02 for 24-h ambulatory SBP), left ventricular wall thickness (r = -0.34, P < 0.02) and serum fibrinogen level (r = -0.63, P < 0.0001). However, multiple regression analysis showed that insulin sensitivity was more closely related to diastolic filling than to blood pressure or left ventricular wall thickness.
Conclusion: The present study showed left ventricular wall thickness to be closely associated with insulin resistance. Because diastolic dysfunction of the left ventricle was also related to a decreased insulin sensitivity, these findings suggest that left ventricular hypertrophy and diastolic dysfunction are associated with the insulin resistance metabolic syndrome.