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.