Renin-angiotensin-aldosterone System (RAAS), Inflammation, and Post-Operative Atrial Fibrillation (AF)

AF is the most prevalent, sustained type of irregular heartbeat and affects over 2 million Americans. Post-operative atrial fibrillation(AF), which leads to significant morbidity and a prolonged hospital stay, complicates 20% to 40% of CPB surgical procedures. While recent studies indicate that interruption of the renin-angiotensin-aldosterone system by either angiotensin-converting enzyme(ACE) inhibition or angiotensin II subtype 1 (AT1) receptor antagonism decreases the incidence of AF following a heart attack or cardioversion (electric shock to the heart), its effect on the incidence of post-operative AF has not been throughly studied. Studies in both animals and humans suggest that inflammation-induced atrial remodeling plays an important role in the cause of AF. Recent studies also provide evidence that activation of the renin-angiotensin-aldosterone system induces inflammation, myocyte injury, proarrhythmic electrical remodeling, and fibrosis through aldosterone. This study will evaluate the effectiveness of ACE inhibition and aldosterone receptor antagonism at decreasing inflammation and AF following cardiopulmonary bypass (CPB) surgery.