title: Matrix metalloproteinase inhibition attenuates atrial remodeling and vulnerability to atrial fibrillation in a canine model of heart failure.
abstract: BACKGROUND
  Atrial structural remodeling occurs in evolving heart failure (HF) and is an important substrate for the development of atrial fibrillation (AF). The matrix metalloproteinases (MMPs) play a role in extracellular remodeling, and recent studies have demonstrated increased atrial MMP activity in HF. Whether increased MMP activity directly contributes to atrial remodeling and AF in the setting of HF remains unclear. The current study examined the effects of MMP inhibition on atrial structural remodeling and AF vulnerability during HF progression.
  
  
  RESULTS
  Three groups of dogs (n = 5 each)--control normal dogs (controls) and 10 dogs subjected to simultaneous atrioventricular pacing (SAVP) for 2 weeks to induce HF and randomly assigned to treatment with placebo (SAVP-placebo) or a MMP inhibitor PGE-7113313, a MMP-1-sparing MMP inhibitor, 6 mg/kg orally twice daily (SAVP-MMPi)--were studied. SAVP-MMPi dogs had less AF inducibility (percent of burst attempts leading to AF episodes: 1.7 +/- 2.9 seconds vs. 23+/-19 seconds, mean +/- SD, P < .05) and maintenance (AF duration: 253 [105 to 326] vs. 1932 [1296 to 2724] seconds, median [25th-75th quartile], P < .05) than SAVP-placebo dogs. The SAVP-MMPi dogs had significantly smaller increases in atrial myocyte cross sectional area, collagen area fraction, and MMP-9 activity relative to controls than SAVP-placebo. There were, however, no significant differences in the changes in chamber dimension and function in the left atrium.
  
  
  CONCLUSIONS
  This unique finding of an attenuation of the vulnerability to AF in conjunction with reduced myocyte hypertrophy and fibrosis after MMP inhibition suggests that heightened MMP activity in the atria contributes to atrial structural remodeling and AF promotion during evolving HF.
authors.affiliation: Division of Cardiology, St. Michael's Hospital, Toronto, Ontario, Canada. moegord@attglobal.net
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Moe
authors.forename: Gabriel
authors.initials: G
authors.lastname: Laurent
authors.forename: Liia
authors.initials: L
authors.lastname: Doumanovskaia
authors.forename: Andrea
authors.initials: A
authors.lastname: Konig
authors.forename: Xudong
authors.initials: X
authors.lastname: Hu
authors.forename: Paul
authors.initials: P
authors.lastname: Dorian
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000201:enzymology* / Q000209:etiology; D004195:Disease Models, Animal; D004198:Disease Susceptibility / Q000201:enzymology / Q000209:etiology / Q000503:physiopathology; D004285:Dogs; D006333:Heart Failure / Q000150:complications / Q000188:drug therapy / Q000201:enzymology*; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors; D020782:Matrix Metalloproteinases