Lessons from ONTARGET

Are ACE-inhibitors or ARB's still needed for cardiovascular prevention in high risk patients? Insights from profess and transcend

The HOPE and EUROPA clinical studies have shown that treatment with the angiotensin-converting enzyme (ACE) inhibitors, ramipril and perindopril, may reduce the occurrence of major cardiovascular events in patients with proven atherosclerotic disease. The recently published results of the PRoFESS and TRANSCEND trials completed the much needed information concerning the use of an angiotensin receptor blocker for patients at high risk of cardiovascular events. PROFESS compared a therapy of telmisartan 80 mg daily with placebo in patients with a recent ischemic stroke. The difference in the primary outcome of first recurrent stroke was not statistically significant between telmisartan and placebo. The secondary outcome of major cardiovascular events showed a relative risk reduction (RRR) of 7% in favour of telmisartan. This tended to be significant (p = 0.06) despite a rather short follow-up period of only 28 months. In TRANSCEND 5926 patients at high risk for cardiovascular events were randomized to a treatment with telmisartan 80 mg daily or placebo for a mean duration of follow-up of 56 months. The primary composite outcome of cardiovascular death, myocardial infarction, stroke or hospitalization for heart failure showed a non-significant 8% RRR in favour of the telmisartan treated patients. The main secondary outcome of cardiovascular death and myocardial infarction or stroke as used in the HOPE trial showed a non-significant RRR of 13% in favour of telmisartan treated patients (p = 0.068 adjusted for multiplicity of comparisons). In comparing the Kaplan-Meier curves for the endpoint of major cardiovascular events used in HOPE, EUROPA, TRANSCEND and PRoFESS, the trends are similar. Results of most of the recently published trials have been neutral.This could partly be explained by major improvements in the optimal background therapy of the patients included. Nevertheless, the results of PRoFESS and TRANSCEND do not contradict the results from previous studies with theACE inhibitors ramipril and perindopril and the ARB telmisartan.

Newer Insights into the Biochemical Physiology of the Renin–Angiotensin System: Role of Angiotensin-(1-7), Angiotensin Converting Enzyme 2, and Angiotensin-(1-12)

Knowledge of the mechanisms by which the rennin–angiotensin system contributes to cardiovascular pathology continues to advance at a rapid pace as newer methods and therapies uncover the nature of this complex system and its fundamental role in the regulation of blood pressure and tissue function. The characterization of the biochemical pathways and functions mediated by angiotensin-(1-7) [Ang-(1-7)], angiotensin converting enzyme 2 (ACE2), and the mas receptor has revealed a vasodepressor and antiproliferative axis that within the rennin–angiotensin system opposes the biological actions of angiotensin II (Ang II). In addition, new research expands on this knowledge by demonstrating additional mechanisms for the formation of Ang II and Ang-(1-7) through the existence of an alternate form of the angiotensinogen substrate [angiotensin-(1-12)] which generates Ang II and even Ang-(1-7) through a non-renin dependent action. Altogether, this research paves the way for a better understanding of the intracellular mechanisms involved in the synthesis of angiotensin peptides and its consequences in terms of cell function in both physiology and pathology.