title: The time-course changes of NT-proBNP and tissue Doppler indices in patients undergoing mitral valve replacement.
abstract: BACKGROUND
  In severe mitral regurgitation, a subset of patients who are asymptomatic may develop left ventricular decompensation before changes in echocardiographic parameters become evident. Since N-terminal brain natriuretic peptide (NT-proBNP) is used to detect early heart failure, we hypothesised that NT-proBNP would be activated in patients with mitral regurgitation.
  
  
  METHODS
  Patients submitted to surgery were prospectively evaluated over eight months in the Department of Cardiology at Inkosi Albert Luthuli Central Hospital. Control patients with severe mitral regurgitation were obtained from the outpatient clinic. In order to define their value in identifying left ventricular decompensation, NT-proBNP levels and tissue Doppler imaging (TDI) indices were simultaneously measured and compared with conventional echocardiographic indices at baseline and this was repeated at one week and at six weeks after valve replacement.
  
  
  RESULTS
  Mean NT-proBNP levels were markedly elevated pre-operatively in all surgical cases compared to controls (p = 0.0001). The diastolic E-mitral/E-annulus ratio, measured using TDI, was higher in the study group, indicating higher left ventricular filling pressure present in the study group. NT-proBNP levels increased further at one week after surgery and subsided at the six-week follow-up visit to levels similar to the control group. The TDI diastolic ratio also decreased at one week, and increased slightly again at the six-week follow up. These changes were accompanied by significant reduction in left atrium and left ventricular chamber dimensions with an increase in the ejection fraction from one to six weeks.
  
  
  CONCLUSIONS
  Marked differences in mean NT-proBNP levels and TDI ratios between the study and control groups suggest that using TDI and NT-proBNP assays may detect covert left ventricular decompensation.
authors.affiliation: Department of Biomedical and Clinical Technology, Durban University of Technology, University of KwaZulu-Natal, Durban, South Africa. RosaleyPRA@dut.ac.za
authors.forename: D R
authors.initials: DR
authors.lastname: Prakaschandra
authors.forename: T
authors.initials: T
authors.lastname: Esterhuizen
authors.forename: D P
authors.initials: DP
authors.lastname: Naidoo
mesh_terms: D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D008297:Male; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000601:surgery; D008944:Mitral Valve Insufficiency / Q000097:blood / Q000000981:diagnostic imaging* / Q000601:surgery; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D011379:Prognosis; D011446:Prospective Studies; D011498:Protein Precursors; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D010446:Peptide Fragments; D011498:Protein Precursors; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain