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

The screening phase will involve identifying Caucasian hypertensive patients who are homozygous for the ClC-Ka Gly/Gly83 and the ClC-Ka Arg/Arg 83 allele. All patients will be on background therapy with an angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) at least mid range dosing. If patient is not at recommended dose of ACE or ARB they must be titrated up and be stable on a midrange dose of ACEI or ARB for at least 4 weeks before they can be entered into the study. There will be 2 treatment phases. Phase 1 will be up to 4 weeks in duration and will consist of randomization to one table of eplerenone (25 mg) or matching placebo. On week 2 the patient will be up titrated to two tablets of eplerenone (50 mg) or matching placebo, to achieve a target dose of 50 mg of eplerenone. If the patient cannot tolerate two tablets of eplerenone or matching placebo they can be down titrated to one tablet of eplerenone or matching placebo. The target BP on study medication is \< 130/80 mmHg. After the patients have been up titrated to the maximally tolerated dose of study medication, the background hypertension therapy can be adjusted to reach the target BP of \< 130/80 mmHg by the end of week 4. Phase 2 will be 52 weeks in duration to assess the effects of placebo or eplerenone on LV hypertrophy. Serum potassium will be monitored throughout the study, and if necessary, doses of eplerenone will be titrated down as necessary.