REN and Abnormal renal physiology: Only the Additive Renin Inhibition with Aliskiren on Renal Blood Flow and Neurohormonal Activation in Patients with Chronic Heart Failure and Renal Dysfunction (ARIANA-CHF-RD) trial enrolled patients with mild to severely increased plasma renin activity (PRA) at baseline [219]; aliskiren successfully lowered PRA in the treatment group after 26 weeks compared to placebo controls.