Angiotensin receptor blockers in heart failure: a work in progress.

The concept that the renin–angiotensin system (RAS) plays a major role in the development, progression and clinical manifestations of heart failure has become widely accepted over the past several decades. The importance of the angiotensin (Ang) II Type 1 (AT1) receptor in mediating most of the pathophysiologic effects of Ang II has also been well established. Nonetheless, finding a role for the angiotensin receptor blockers (ARBs) in the treatment of heart failure has not been an easy task, nor is it by any means complete at this time. Much of the difficulty is related to the fact that by the time the ARBs became available in clinical practice, a substantial body of evidence demonstrating that the angiotensin-converting enzyme inhibitors (ACEIs) improved the natural history of patients with heart failure had already been accumulated (1). Based on the consistency of beneficial effects that were seen in clinical trials encompassing a broad spectrum of patients ranging from individuals