A shuttle walk test for assessment of functional capacity in chronic heartfailure

Background Peak oxygen uptake (peak VO2) is a reference parameter in the as sessment of functional capacity of patients with chronic heart failure, but the procedure for cardiopulmonary exercise testing with expired gas analys is is complex and expensive, so more simple and available methods are desir able. Methods We compared the usefulness of a time-limited walk lest, the 6-minut e walk test (6-MT), with that of a symptom-limited walk test, the shuttle w alk test (SWT), in the evaluation of patients with moderate to severe chron ic heart failure. We prospectively studied 46 clinically stable patients in New York Heart Association class II to IV heart failure with left ventricu lar ejection fraction <40% (aged 53 +/- 10 years, election fraction 23% +/- 8%, New York Heart Association functional class 2.8 +/- 0.7). Each patient performed two 6-MT, two SWT and a cardiopulmonary exercise testing within 2 weeks. Results We found a close correlation between distance walked in SWT and pea k VO2 (r = 0.83, P <.001) and a moderate correlation between distance in 6- MT and peak VO2 (r = 0.69, P <.001). Both walk tests showed to be reproduci ble after just one practice walk. All patients who walked > 450 m in SWT ha d a peak VO2 >14 mL/kg/min. The overall discriminatory accuracy for SWT dis tance was greater than that for 6-MT distance for predicting a peak VO2 <14 mL/kg/min (area under receiver operator characteristic curves 0.97 and 0.8 3 respectively, P =.02). Stepwise multivariate regression analysis, includi ng clinical, exercise testing, echocardiographic, radionuclide-angiographic , and rest hemodynamic date, showed that distance walked in SWT was the onl y independent predictor of peak VO2 (P <.001) and the strongest predictor o f percent achieved of age- and sex-predicted peak VO2 (%PVO2) (P <.001), wi th only age offering additional information (P =.02). Conclusions The SWT shows to be a feasible and safe method to evaluate pati ents with chronic heart failure that strongly and independently predicts pe ak VO2 and %PVO2. This symptom-limited walk test seems to be more useful th an 6-MT in the assessment of functional capacity in these patients.