[Lights and shadows on single and dual RAAS blockade]

Angiotensin-converting enzyme inhibitors (ACE-i) and angiotensin II receptor blockers (ARBs) are of paramount importance in everyday clinical practice. Developed as antihypertensive drugs, they soon acquired another important indication as a result of their antiproteinuric activity and capacity to delay the progression of chronic kidney disease. ACE-i and ARBs started out being used as single drugs and were subsequently combined to obtain more complete blocking of the renin-angiotensin-aldosterone system (RAAS). The most evident advantages derived from the administration of these drugs - alone or in combination - have been obtained in proteinuric nephropathies, such as chronic glomerulonephritis and diabetic nephropathy, where they have become the treatment choice. Dual RAAS blockade has been recently evaluated in a large trial of high-risk cardiovascular patients, in whom no related benefits were shown. To the contrary, a higher risk of worsening renal function emerged. It is now quite clear that patients with high proteinuria levels are the ones that benefit most from RAAS inhibition, also with combined ACE-i and ARB. It is very important to pay the utmost attention when these drugs are used in patients in whom no benefit is obtained by RAAS inhibition, such as patients with chronic kidney disease and atherosclerosis, elderly patients, and those without any significant proteinuria.