Combination Therapy with Aldosterone Blockade and Renin-Angiotensin Inhibitors Confers Organ Protection

Abstract

There is increasing evidence that aldosterone exerts major adverse cardiovascular effects through classical mineralocorticoid receptors (MR) in nonepithelial tissues such as the brain and heart. This nonepithelial role of aldosterone has been underscored by the recent Randomized Aldactone Evaluation Study (RALES) and the Eplerenone Post-AMI Heart Failure Efficacy and Survival Study (EPHESUS). These studies also showed that when using MR antagonist as an "organ protecting" drug, further organ protection could be derived by the addition of an angiotensin-converting enzyme (ACE) inhibitor or angiotensin II type 1 receptor blocker (ARB). The long-term effect of aldosterone was not inhibited in some subjects, so the possibility of organ damage due to so-called "breakthrough" aldosterone cannot be ignored. Nonepithelial MR-mediated effects played a major role in this aldosterone effect. These effects can be inhibited by MR antagonist at a small dose, not lower blood pressure. Therefore, the idea is now to combine a small dose of MR antagonist with an ACE inhibitor or ARB. However, warnings have been given recently due to the emergence of hyperkalemia and other adverse effects associated with inappropriate combination therapy. It is important to note that, if the eligibility criteria of RALES and EPHESUS are fulfilled, the potassium level will rarely become problematic. Therefore, the recent increase in the incidence of adverse effects can be attributed to the incorrect application of combination therapy. Elderly patients or those with dehydration, renal dysfunction, and aggravated heart failure require further close monitoring or termination of spironolactone administration. The combination of an MR antagonist and renin-angiotensin inhibitors should be a useful strategy if subjects are carefully selected, and carefully monitored. Adverse effects will occur only if the usage recommendations based on previous researches are not followed.