Angiotensin Receptor Blocker for Stroke Prevention in Atrial Fibrillation: beyond Blood Pressure Lowering?

The renin-angiotensin system (RAS) plays an important role in the development of various cardiovascular diseases, including atrial fibrillation (AF). The arrhythmogenic effects of angiotensin II are associated with atrial fibrosis and hypertrophy, uncoupling of gap junctions, impaired calcium regulation, alteration of various ion channels, and activation of mediators of oxidative stress and inflammation. 1) Therefore, blocking the RAS with angiotensinconverting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) inhibits angiotensin II, results not only in reduced blood pressure, but also antiarrhythmic effects, which reduce the development of AF. There is robust evidence that ACEIs or ARBs reduces the new-onset of AF in patients with significant structural heart disease, such as hypertension with left ventricular (LV) hypertrophy or heart failure with reduced ejection fraction. The Losartan Intervention For Endpoint reduction in a hypertension study, which enrolled hypertensive patients with LV hypertrophy, showed a 33% reduction in the incidence of new-onset AF in the losartan group compared with the atenolol group (6.8 vs. 10.1 per 1000 person-years). Similar results were reported in a recent metaanalysis. 2) Angiotensin-II induces platelet activation by thromboxane A 2 ,