Resistant hypertension is defined as hypertension not controlled (i.e. blood pressure not below 140/90 mmHg) with the use of adequate doses of at least three different anti-hypertensives including a diuretic. Resistant hypertension is abundant. In the ALLHAT trial 34% of patients did not reach the blood pressure goal of 140/90 mmHg. One possible mechanism of resistance is the aldosterone-escape phenomenon.

During aldosterone escape, aldosterone plasma levels are normal or even elevated despite therapy with ACEIs or ARBs. The prevalence is about 30-50%. Possible reasons for aldosterone escape are alternative ways of aldosterone stimulation (hyperkalemia, adrenomedullin, ACTH), local aldosterone production or primary aldosteronism. Aldosterone has deleterious blood pressure independent effects on cardiac, vascular and renal damage.

Hypothesis: Eplerenone is effective to improve hypertensive target organ damage in patients with resistant hypertension.

Inclusion Criteria:

• Casual blood pressure >=140/90 despite effective triple therapy including an ACEI/ARB and a diuretic

Exclusion Criteria:

• Contraindication for eplerenone
• Creatinine-Clearance < 60 ml/min (Cockroft-Gault formula)
• Diabetes mellitus