Current strategies to achieve further cardiac and renal protection through enhanced renin-angiotensin-aldosterone system inhibition

Abstract

An incomplete inhibition of the renin angiotensin aldosterone system (RAAS) may be responsible for the residual organ damage and event rate that still occur in spite of an apparent blood pressure control in patients with hypertension, diabetes, chronic kidney disease and heart failure treated with angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB). Additional antiproteinuric effect in diabetic and non diabetic chronic kidney disease, and reduction in hospitalizations in patients with heart failure already receiving a single RAAS antagonist, has been achieved by incremental inhibition of the RAAS with dual therapy or uptitration of an individual agent above conventional dosages. However, the synergistic increase in plasma renin activity (PRA) and the angiotensin II escape could reduce the expected benefit obtained with dual therapy. Results from ONTARGET showing a lack of additional outcome benefit over monotherapy, with a concomitant increase risk of hyperkalemia, renal impairment, and hypotension, discourage the use of the ACEI/ARB combination in patients at high risk of cardiovascular events. This occured despite a lower albumin excretion in dual versus single RAAS blockade, indicating that an incremental antiproteinuric effect is not automatically translated into clinical outcome benefits. The efficacy and safety of ACEI/ARB combination versus monotherapy in patients with overt proteinuria is currently evaluated by LIRICO and VA NEPHRON-D clinical trials. The long lasting direct renin inhibitor aliskiren, acting at the first and rate limiting step of the RAAS cascade, prevents the reactive increase in PRA when combined with ACEIs, ARBs or diuretics. The ASPIRE HIGHER programme, involving more than 35,000 patients with hypertension, heart failure, kidney disease and diabetes, is currently evaluating the efficacy and safety of aliskiren on top of standard therapy. The clinical benefit of adding mineralocorticoid receptor blockers (MRBs) in the control of resistant hypertension, proteinuric kidney diseases, and prevention of mortality in patients with heart failure on top of conventional treatment, evidences the pathogenic role of inadequately suppressed aldosterone as a cause of suboptimal response to conventional RAAS inhibition. The present review will focus on the pathophysiological ground, and the evidence provided by clinical trials assessing the efficacy and safety of recent strategies for the prevention of cardiovascular events and target organ damage progression via enhanced RAAS inhibition.