title: Six-minute walking test predicts long-term cardiac death in patients who received cardiac resynchronization therapy.
abstract: OBJECTIVE
  Cardiac resynchronization therapy (CRT) has been proven to be effective in patients suffering from chronic heart failure (CHF) associated with electrical dyssynchrony. However, long-term predictors of mortality in that subset have not been extensively investigated. The aim of this study was to establish baseline long-term predictors of cardiovascular mortality in CHF patients treated with CRT.
  
  
  RESULTS
  A total of 188 consecutive patients with moderate to severe CHF who had undergone a successful CRT implant were evaluated. Baseline measurements included clinical history, a 6-min walking test (6MWT), and echocardiographic parameters. Patients with cardiac or non-cardiac diseases limiting their ability to perform a 6MWT were excluded, with the final count totalling 155 patients [82% men, mean age 69 +/- 8 years, New York Heart Association (NYHA) functional class: II 22%, III 73.5%, IV 4.5%]. A total of 24 patients (15.5%) died of cardiovascular causes and one patient underwent heart transplantation during a mean follow-up of 24.4 +/- 18.1 months. Univariate analysis showed that NYHA class, distance walked in the 6MWT, left atrial diameter, digoxine and left ventricle (LV) ejection fraction were all significantly related to rates of mortality. Multivariate Cox regression after adjustment for the presence of a defibrillator showed that the LV ejection fraction [HR 0.91 (95% CI: 0.84-0.98) P = 0.008] and 6MWT distance <225 m [HR 5.6 (95% CI: 1.2-25.3) P = 0.026] were independent predictors of cardiovascular mortality.
  
  
  CONCLUSIONS
  Baseline functional capacity, measured by the 6MWT distance, and LV ejection fraction are independent predictors of mortality in moderate to severe CHF patients, despite CRT. A 6MWT distance walked of <225 m identifies patients at high risk of cardiovascular death at mid-long term.
authors.affiliation: Thorax Clinic Institute, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Villarroel 170 Barcelona 08036, Catalonia, Spain.
authors.forename: María Angeles
authors.initials: MA
authors.lastname: Castel
authors.forename: Francisco
authors.initials: F
authors.lastname: Méndez
authors.forename: David
authors.initials: D
authors.lastname: Tamborero
authors.forename: Lluís
authors.initials: L
authors.lastname: Mont
authors.forename: Santiago
authors.initials: S
authors.lastname: Magnani
authors.forename: Jose Maria
authors.initials: JM
authors.lastname: Tolosana
authors.forename: Antonio
authors.initials: A
authors.lastname: Berruezo
authors.forename: Miguel
authors.initials: M
authors.lastname: Godoy
authors.forename: Marta
authors.initials: M
authors.lastname: Sitges
authors.forename: Barbara
authors.initials: B
authors.lastname: Vidal
authors.forename: Eulàlia
authors.initials: E
authors.lastname: Roig
authors.forename: Josep
authors.initials: J
authors.lastname: Brugada
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000401:mortality*; D005080:Exercise Test / Q000706:statistics & numerical data*; D005260:Female; D006333:Heart Failure / Q000401:mortality* / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013030:Spain / Q000453:epidemiology; D016019:Survival Analysis; D015996:Survival Rate; D016138:Walking