REN and atrial fibrillation: Finally, in patients with prior stroke or TIA, sympathetic activation might elevate the BP either by increased catecholamine release or over-activation of the renin–angiotensin–aldosterone system.28 Two randomized trials showed that ARB use was associated with lower BP than that achieved by ACEI (0.9 mm Hg lower in ONTARGET trial, 4.0 mm Hg lower in DETAIL trial).22,29 In our patients with prior stroke, the use of ARB might have lowered the BP by more than that which was achieved by ACEI, as observed in previous clinical trials, and thus contributed to the lower AF risk.