title: Pirfenidone prevents the development of a vulnerable substrate for atrial fibrillation in a canine model of heart failure.
abstract: BACKGROUND
  Atrial fibrosis is an important substrate in atrial fibrillation (AF), particularly in the setting of structural heart disease. In a canine model, congestive heart failure (CHF) produces significant atrial fibrosis and the substrate for sustained AF. This atrial remodeling is a potential therapeutic target. The objective of the present study is to evaluate the effects of the antifibrotic drug pirfenidone (PFD) on arrhythmogenic atrial remodeling in a canine CHF model.
  
  
  RESULTS
  We studied 15 canines, divided equally into 3 groups: control, CHF canines not treated with PFD, and CHF canines treated with PFD. CHF was induced by ventricular tachypacing (220 bpm for 3 weeks), and oral PFD was administered for the 3-week pacing period. We performed electrophysiology and AF vulnerability studies, atrial fibrosis measurements, and atrial cytokine expression studies. Only canines in the untreated CHF group developed sustained AF (>30 minutes, 4 of 5 canines; P<0.05). Treatment of CHF canines with PFD resulted in an attenuation of arrhythmogenic left atrial remodeling, with a significant reduction in left atrial conduction heterogeneity index (median [25% to 75% interquartile range] 4.96 [3.53 to 5.64] versus 2.52 [2.11 to 2.82], P<0.01; pacing cycle length 300 ms), left atrial fibrosis (16.0% [13.0% to 17.5%] versus 8.7% [5.7% to 10.6%], P<0.01), and AF duration (1800 [1020 to 1800] seconds versus 6 [5 to 22] seconds, P<0.01). Immunoblotting studies demonstrated the drug's effects on multiple cytokines, including a reduction in transforming growth factor-beta1 expression.
  
  
  CONCLUSIONS
  Treatment of CHF canines with PFD results in significantly reduced arrhythmogenic atrial remodeling and AF vulnerability. Pharmacological therapy targeted at the fibrotic substrate itself may play an important role in the management of AF.
authors.affiliation: Cardiac Electrophysiology and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA.
authors.forename: Ken W
authors.initials: KW
authors.lastname: Lee
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Everett
authors.forename: Dulkon
authors.initials: D
authors.lastname: Rahmutula
authors.forename: Jose M
authors.initials: JM
authors.lastname: Guerra
authors.forename: Emily
authors.initials: E
authors.lastname: Wilson
authors.forename: Chunhua
authors.initials: C
authors.lastname: Ding
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Olgin
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D004285:Dogs; D006333:Heart Failure / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control*; D011728:Pyridones / Q000627:therapeutic use*
chemical_list: D011728:Pyridones; C093844:pirfenidone