[Resistant hypertension: An update].

An estimated 10% to 20% of hypertensive patients could be considered resistant to treatment (RH). These are patients who are not controlled using three drugs, at the maximum tolerated doses, including a diuretic, as well as those with high blood pressure controlled using four or more drugs. The term is used to identify patients that might benefit from special diagnostic and/or therapeutic consideration. The term 'refractory hypertension' has recently been proposed as a novel phenotype of antihypertensive failure. It refers to patients whose blood pressure cannot be controlled with maximum treatment. The first studies of this phenotype indicate that it is rare and affects less than 5% of patients with RH. Adherence to or compliance with medical treatment is key to defining resistant hypertension. Closer attention has been paid to clinical and experimental research since the first scientific statement for the diagnosis, assessment and treatment of RH from the American Heart Association, and in the European guidelines, was published in 2008. This review will set out the concepts relating to prevalence, prognosis and compliance and cover the latest developments on this subject.