title: Effect of continuous positive airway pressure on mitral regurgitant fraction and atrial natriuretic peptide in patients with heart failure.
abstract: OBJECTIVE
  We sought to determine the effects of continuous positive airway pressure (CPAP) on mitral regurgitant fraction (MRF) and plasma atrial natriuretic peptide (ANP) concentration in patients with congestive heart failure (CHF).
  
  
  BACKGROUND
  In patients with CHF, elevated plasma ANP concentration is associated with elevated cardiac filling pressures. Secondary mitral regurgitation may contribute to elevation in plasma ANP concentration in patients with CHF. Because CPAP reduces transmural cardiac pressures and left ventricular (LV) volume, we hypothesized that long-term CPAP application would decrease the MRF and plasma ANP concentration in patients with CHF and Cheyne-Stokes respiration with central sleep apnea (CSR-CSA).
  
  
  METHODS
  Seventeen patients with CHF and CSR-CSA underwent baseline assessments of plasma ANP concentration and left ventricular ejection fraction (LVEF) and MRF by radionuclide angiography. They were then randomized to receive nocturnal CPAP plus optimal medical therapy (n = 9) or optimal medical therapy alone (n = 8) for 3 months and were then reassessed.
  
  
  RESULTS
  In the CPAP-treated group, LVEF increased from (mean +/-SEM) 20.2 +/- 4.2% to 28.2 +/- 5.3% (p < 0.02); MRF decreased from 32.8 +/- 7.7% to 19.4 +/- 5.5% (p < 0.02); and plasma ANP concentration decreased from 140.9 +/- 20.8 to 103.9 +/- 17.0 pg/ml (p < 0.05). The control group experienced no significant changes in LVEF, MRF or plasma ANP concentration. Among all patients, the change in plasma ANP concentration from baseline to 3 months correlated significantly with the change in MRF (r = 0.789, p < 0.0002).
  
  
  CONCLUSIONS
  In patients with CHF, CPAP-induced reductions in MRF and plasma ANP concentration in association with improvements in LVEF indicate improved cardiac mechanics. Our findings also suggest that reductions in plasma ANP concentration were at least partly due to reductions in MRF.
authors.affiliation: Queen Elizabeth Hospital Sleep Research Laboratory, Toronto Hospital, Ontario, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Tkacova
authors.forename: P P
authors.initials: PP
authors.lastname: Liu
authors.forename: M T
authors.initials: MT
authors.lastname: Naughton
authors.forename: T D
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D009320:Atrial Natriuretic Factor / Q000097:blood*; D006333:Heart Failure / Q000097:blood / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000209:etiology / Q000628:therapy*; D011175:Positive-Pressure Respiration; D013318:Stroke Volume
chemical_list: D009320:Atrial Natriuretic Factor