title: The 6-minute walking test and all-cause mortality in patients undergoing a post-cardiac surgery rehabilitation program.
abstract: BACKGROUND
  The 6-minute walking test (6mWT) is used to prescribe physical activity in cardiac surgery patients. The clinical value of a pre-discharge 6mWT and its association with outcome is not well defined.
  
  
  METHODS
  We retrospectively analyzed data from 313 patients (age 66 ± 11 years, 23% females, left ventricular ejection fraction (LVEF) 52 ± 11%, Hb 10.5 ± 1.3 g/dl, serum albumin 3.9 ± 0.4 mg/dl) who were admitted to our rehabilitation institute following cardiac surgery. A 6mWT was performed at entry and at discharge and expressed as % of theoretical predicted values calculated on the basis of individual age, height, weight and sex. The endpoint was represented by all-cause mortality. The predictive value of 6mWT was tested in univariate and multivariate analysis.
  
  
  RESULTS
  A pre-discharge 6mWT was completed by 284 out of 313 patients. Two patients died in hospital. During a median of 23 months, mortality was 9% (26/284) and 44% (12/27) (p < 0.0001) in patients who did or did not perform the pre-discharge 6mWT. The distance covered at the pre-discharge 6mWT as a continuous variable of % predicted values was a significant predictor of subsequent mortality (Hazard Ratio (HR) 0.97 (95% CI 0.96-0.99), p = 0.0019). After adjustment for all preselected covariates, the pre-discharge 6mWT (HR 0.97 (95% CI 0.95-0.99), p = 0.0038) and LVEF (HR 0.93 (95% CI 0.90-0.96), p < 0.0001) remained significantly associated with the outcome.
  
  
  CONCLUSIONS
  In recent cardiac surgery patients, the pre-discharge 6mWT is not only a valid measurement of the impact of cardiac rehabilitation but also provides outcome information offering the possibility to identify patients who may need more intensive follow-up.
authors: Department of Cardiology, Fondazione "Salvatore Maugeri", IRCCS, Montescano (Pavia), Italy mariateresa.larovere@fsm.it.
authors: Maria Teresa
authors: MT
authors: La Rovere
authors: Department of Biomedical Engineering, Fondazione "Salvatore Maugeri", IRCCS, Montescano (Pavia), Italy.
authors: Gian Domenico
authors: GD
authors: Pinna
authors: Department of Biomedical Engineering, Fondazione "Salvatore Maugeri", IRCCS, Montescano (Pavia), Italy.
authors: Roberto
authors: R
authors: Maestri
authors: Department of Cardiology, Fondazione "Salvatore Maugeri", IRCCS, Montescano (Pavia), Italy.
authors: Francesca
authors: F
authors: Olmetti
authors: Department of Cardiology, Fondazione "Salvatore Maugeri", IRCCS, Montescano (Pavia), Italy.
authors: Vincenzo
authors: V
authors: Paganini
authors: Department of Cardiology, Fondazione "Salvatore Maugeri", IRCCS, Montescano (Pavia), Italy.
authors: Giorgio
authors: G
authors: Riccardi
authors: Department of Cardiology, Fondazione "Salvatore Maugeri", IRCCS, Montescano (Pavia), Italy.
authors: Roberto
authors: R
authors: Riccardi
authors: Division of Cardiac Surgery, Policlinico San Matteo, IRCCS, Pavia, Italy.
authors: Claudio
authors: C
authors: Goggi
authors: Department of Cardiothoracic-Vascular Anesthesia and Intensive Care, Policlinico San Donato, IRCCS, Milano, Italy.
authors: Marco
authors: M
authors: Ranucci
authors: Department of Cardiology, Fondazione "Salvatore Maugeri", IRCCS, Montescano (Pavia), Italy.
authors: Oreste
authors: O
authors: Febo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006348:Cardiac Surgical Procedures / Q000009:adverse effects / Q000401:mortality* / Q000534:rehabilitation*; D002423:Cause of Death; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D016138:Walking
keywords: 6-minute walking test; cardiac rehabilitation; cardiac surgery; functional capacity; left ventricular ejection fraction; mortality