Modulation of the renin-angiotensin-aldosterone system for the secondary prevention of stroke.

Recurrent stroke is a major public health concern and new treatment strategies are needed. While modulation of the renin angiotensin aldosterone system (RAAS) has proven effective in reducing recurrent cardiac events, its role in preventing recurrent cerebrovascular events remains unclear. RAAS is both a circulating and tissue based hormonal system that regulates homeostasis and tissue responses to injury in both the CNS and the periphery, via the activity of angiotensin II (Ang II). Vascular and hematologic effects induced by Ang II including endothelial dysfunction, vascular structural changes, inflammation, hemostasis, and fibrinolysis are increasingly linked to the occurrence of cerebrovascular events. Animal models have shown that RAAS modulation may be protective in cerebrovascular disease. The HOPE and LIFE trials support the role of blood pressure independent mechanisms of RAAS modulation for improving outcomes in a broad range of patients with cardiovascular disease but do not specifically address recurrent stroke prevention. PROGRESS, a trial of secondary stroke prevention, demonstrates that blood pressure reduction with a combination strategy including the routine use of ACE inhibitors prevents recurrent stroke. Current evidence suggests that the RAAS plays an important role in the development and progression of cerebrovascular disease. Modulation of the RAAS holds promise for the secondary prevention of stroke, however, ongoing clinical trials will better define the exact role of ACE inhibitor and angiotensin II Type 1 receptor blocker therapy in stroke survivors.