Role of Renin Angiotensin System Inhibitors in Cardiovascular and Renal Protection: A Lesson from Clinical Trials

Beneficial effects of angiotensin converting enzyme inhibitors (ACEI) and angiotensin type 1 receptor (AT1) blockers in patients with cardiovascular and renal diseases have been clearly demonstrated in numerous large outcomes studies. In patients with heart failure (HF), ACEI have been shown to reduce overall mortality, mortality from cardiovascular causes, to increase life expectancy, as well as to preserve the renal function (CONSENSUS, SAVE, TRACE, AIRE, AIREX, CATS trials). In addition, in the PROGRESS study ACEI substantially decreased the risk of stroke and transient ischemic attacks in patients with cerebrovascular disorders. The HOPE and EUROPA studies confirmed that long term therapy with ACEI provides significant survival benefit in patients with broad range of atherosclerotic cardiovascular diseases. After these large and well designed clinical studies, ACEI have become standard therapy for routine secondary prevention in all patients with cardiovascular diseases, unless contraindicated. AT1 receptor blockers have been recently added to the cardiovascular therapeutic armamentarium. They are believed to provide additional protection by inhibition of locally synthesized angiotensin II on the level of AT1 receptor. The ELITE II, ValHeFT and CHARM studies have shown that AT1 receptor blockers are equally effective as ACEI in reduction of mortality and morbidity in patients with HF. Importantly, they may be used together with ACEI, or as alternative treatment in ACEI intolerant patients. Renal protection is another important effect of both ACEI and AT1 blockers that has been confirmed in several large clinical trials. The North American Microalbuminemia Study group and EUCLID group demonstrated significant reduction in progression of diabetic nephropathy in patients with insulin dependent diabetes mellitus (IDDM) treated with ACEI. AT1 receptor blockers are mainly studied in the non-insulin dependent diabetes mellitus (NIDDM) nephropathy. Four recent clinical trials (IRMA-2, DETAIL, RENAAL and IDNT) examined the effect of AT1 receptor blockers in patients with NIDDM nephropathy. These studies confirmed the beneficial effect of AT1 receptor blockers in patients with NIDDM nephropathy that was extended beyond the blood pressure reduction. Ongoing studies (ONTARGET, TRANSCEND and PROTECTION) should provide us with additional insights about cardiovascular, renal and other end-organ protective effects of these therapeutics.