Influence of dietary sodium on the renin-angiotensin-aldosterone system and prevalence of left ventricular hypertrophy by EKG criteria.

Abstract

We investigated the interplay of dietary sodium and renin-angiotensin-aldosterone system (RAAS) activity with the prevalence of left ventricular hypertrophy (LVH) in essential hypertension. Electrocardiograms (EKG) were reviewed for the presence of LVH in 160 hypertensive patients. We then compared the rate of LVH to levels of plasma renin activity (PRA) and serum aldosterone under high and low sodium diet conditions. On high sodium diet, serum aldosterone was significantly higher (7.7+/-0.93 vs 5.7+/-0.35 ng/dl, P=0.02) in participants with LVH. With low sodium diet and upright posture, PRA was significantly lower in subjects with LVH vs those without (5.6+/-1.1 vs 7.6+/-0.56 ng/ml/h, P=0.026). Aldosterone levels on low sodium diet were not different between those with and those without LVH. PRA was then dichotomized at the lowest quartile under low sodium/upright posture conditions to define a 'low renin' group. In a multivariate logistic regression containing renin status (low renin vs normal/high renin), aldosterone on a high sodium diet, age, body mass index, gender, race, duration of hypertension, systolic and diastolic blood pressure and salt-sensitivity only low-renin status on a low sodium diet (P=0.019) and serum aldosterone on a high sodium diet (P=0.04) were significant predictors of LVH. Thus, reduced modulation of renin activity in response to sodium restriction and an increased aldosterone on a high sodium diet appear to identify characteristics of hypertensive patients predisposed to abnormal cardiac remodelling.