Background: Resistant hypertension is common in clinical practice. The aim of our study was to evaluate inappropriate aldosterone activity in causing resistance to antihypertensive therapy.
Methods: Among the patients consecutively evaluated for the first time between 1995 and 2001, we selected all those (n = 157) with an aldosterone-to-renin ratio (ARR) >or=25 (ng/dL)/(ng/mL/h), and plasma aldosterone >or=12 ng/dL. Eight patients with Conn adenoma were excluded from the study. Fifty-eight were diagnosed as idiopathic aldosteronism (IHA), the other 91 patients, who did not meet the criteria for primary aldosteronism, were operatively classified as aldosterone-associated hypertension (AAH). As a control group, we randomly chose 160 patients with essential hypertension and plasma aldosterone <12 ng/dL (EH). Antihypertensive treatment was given in accordance to World Health Organization Guidelines (1999). The study end point was blood pressure (BP) <140/90 mm Hg.
Results: During follow-up (22 +/- 2 months), 24 (41.4%) patients with IHA, 35 (38.5%) with AAH, and 72 (54.0%) with EH reached the end point. According to survival analysis, AAH and IHA patients reached the end point in a smaller fraction and in a longer time compared with EH patients, with no difference between IHA and AAH. At the end of follow-up, IHA and AAH patients had higher diastolic BP than EH patients with no difference between IHA and AAH.
Conclusions: Patients with elevated aldosterone plasma levels develop resistant hypertension, even in the absence of clinically diagnosed primary aldosteronism. Their identification will allow a targeted therapy and a more effective BP reduction.