Effect of PPAR-gamma activation and AT-II receptor blockade on electrical and structural substrate of atrial fibrillation.

Irbesartan possesses angiotensin receptor blocking and peroxisome proliferator activated receptor gamma activating properties, and has demonstrated protective effect against atrial fibrillation (AF) in various situations. The effects of irbesartan were determined in a canine atrial tachypacing model. Beagles were subjected to atrial tachypacing for 4 weeks and either placebo (control dogs) or irbesartan (irbesartan dogs) was given through the study period. After 4 weeks of tachypacing, left ventricular diastolic dimension increased and left ventricular ejection fraction decreased for similar extent in both groups. AF duration increased in control dogs, but this change was suppressed in irbesartan dogs. AF inducibility also had a tendency to be suppressed in irbesartan dogs. Atrial effective refractory period was similarly shortened in both groups. Irbesartan suppressed AF development despite similar extent of left ventricular dysfunction in a canine atrial tachypacing model.