THE RELATION BETWEEN INSULIN-RESISTANCE AND LEFT VENTRICULAR MASS IN HYPERTENSIVE PATIENTS

Abstract

Both left ventricular hypertrophy (LVH) and insulin resistance (IR) have often been demonstrated in
patients with essential hypertension (EH). Insulin may exert a direct growth promoting effect on
cardiomyocytes rather than affecting the left ventricular internal diameter.The aim of this work was
to examine the effect of IR on LV geometry in newly diagnosed arterial hypertension (NDAH), non
diabetic patients not taking any antihypertensive medication. One hundred and eight subjects (66
males and 42 females) with mean age of 48.9±4.67 years were enrolled in the study; including 88
newly diagnosed hypertensive patients (54 males and 34 females) and 20 healthy control subjects.
Hypertension was defined as elevation of blood pressure 6 140 mmHg for systolic, and/or 6 90 mmHg
for diastolic blood pressure as the mean of 3 different measurements in at least 3 different visits at 1-
week intervals. Fasting glucose, insulin levels, total cholesterol, (HDL-C), and triglyceride (TG)
levels. HOMA-index was calculated for the assessment of insulin resistance by the formula: Fasting
Blood Glucose (mg/dL) × Fasting Insulin (μU/mL)/405. Two-dimensional guided M-mode
echocardiography for measurements of left ventricular end-diastolic dimension (LVEDD), interventricular
septum thickness (IVST), posterior wall thickness (PWT), left atrial diameter (LAD),
fraction of shortening (FS) and ejection fraction (EF). Left ventricular mass (LVM) and LV mass
index (LVMI) was calculated .According to LVMI, hypertensive patients were classified into two
groups; normal LV dimensions and LVH. So, we had three groups on our study: Hypertensive
patients with normal LV dimensions included 46 patients (28 males and 18 females) with mean age
48.6±3.55 years, Hypertensive patients with LVH included 42 patients (26 males and 16 females) with
mean age 49.8±3.72 years and Healthy control subjects included 20 subjects (12 males and 8 females)
with mean age 47.7±7.74 years. Fasting blood insulin and HOMA-index were significantly higher in
patients with LVH than patients with normal LV dimensions and than control subjects. PWT, IVST,
LVM and LVMI were significantly higher in patients with LVH than in patients with normal LV
dimensions and than control subjects. Other echocardiographic measures showed no significant
difference between the study groups. We found highly significant positive correlations between insulin
levels and IVS, PWT, LVM, and LVMI. Also, we found highly significant positive correlations
between HOMA-index and IVS, PWT, LVM, and LVMI. There was no significant correlation
between insulin level or HOMA-index and other echocardiographic parameters. We concluded that
cardiac changes in hypertensive patients including increased wall thickness, LVM and LVMI. The
concentric LV geometry seen in hypertensive patients might be mediated, at least in part, by increased
insulin levels and the HOMA index.
Key words: Insulin resistance, HOMA index, Hypertension, Left ventricular hypertrophy.