CLCNKA (Ka Renal Chloride Channel[ClC-Ka]) Polymorphism Effects on Hypertrophy Regression

This study will consist of middle-aged Caucasian non-failing subjects with high blood pressure who are homozygous for a gene that confers increased risk of developing heart failure, the Glycine 83 variant of the Ka renal chloride channel (ClC-Ka Gly/Gly 83), or middle-aged Caucasian non-failing hypertensive subjects who lack the heart failure risk gene, the wild-type Arginine 83 Ka renal chloride channel (ClC-Ka Arg/Arg 83). Subjects on standard therapy for high blood pressure with an angiotensin converting inhibitor (ACEI) or angiotensin receptor blocker (ARB) will be randomized to additional treatment with eplerenone (an aldosterone antagonist) or placebo, and assessed for changes in echocardiographic left ventricular hypertrophy (LVMI). Secondary endpoints will assess left ventricular remodeling and other echocardiographic variables. The investigators hypothesize that subjects homozygous for the CLCNKA risk allele will have a greater response to eplerenone in terms of reductions in LVMI than those lacking the risk allele.