Introduction: The treatment of bilateral primary aldosteronism (PA) and of patients with unilateral PA not eligible for surgery, is medical targeted therapy, with mineralocorticoid receptor antagonists (MRAs) as first choice.

Objectives: To analyze current medical treatment of PA in Spain, including efficacy, drug dose, and adverse events (AEs).

Methods: The SPAIN-ALDO registry is a national, multicenter, retrospective database including patients with PA referred to 37 tertiary centers in Spain. Data about medical treatment with MRA as first-line or as post-surgical therapy, and about antihypertensive medications used before targeted treatment (MRA or unilateral adrenalectomy) were included. We compared characteristics of surgically- and medically- treated patients at baseline and at last available follow-up, as well as clinical and biochemical responses according to PASO and PAMO criteria.

Results: The overall cohort comprised 997 patients. Before PA diagnosis, the most used classes of antihypertensive drugs were calcium-channel blockers (66%) and angiotensin-II receptor antagonists (48.4%). A total of 880 patients had at least one available visit after initiation of MRA (N = 511 as first-line therapy; N = 47 post-surgery) or adrenalectomy (N = 322). Spironolactone was more prescribed than eplerenone (58 vs. 42%). Median DDD of MRA therapy was 1.33. Eplerenone was more tolerated than spironolactone (AEs in 4 vs. 18%), especially among males. After a median follow-up of 35 and 17 months respectively for medically- and surgically-managed patients, the latter achieved a complete biochemical or clinical response (68.1-33.6%) more frequently than those under MRA as first line (48.6-15.7%, respectively; p < 0.001), or after surgery (in this case only for biochemical response: 40 vs. 68,1%; p = 0.005).

Conclusions: Our study highlights the need to optimize PA medical management to improve clinical and biochemical outcomes of these patients.