The two-minute walk test as a measure of functional capacity in cardiac surgery patients

Objective: To examine construct validity and sensitivity of the two-minute walk test (2MWT) in cardiac surgery patients. Design: Measurements were made in patients preoperatively, during the postoperative in-hospital stay, and 6 to 8 weeks after discharge from hospital. Setting: Ambulatory and hospitalized care. Participants: Patients (N = 122; mean age +/- standard deviation, 63 +/- 9y) undergoing coronary artery bypass grafting. Interventions: Not applicable. Main Outcome Measures: The 2MWT, New York Heart Association (NYHA) functional classification for cardiac disease, the Nottingham Extended Activities of Daily Living scale, and the Medical Outcomes Survey 36-Item Short-Form Health Questionnaire (SF-36). Results: Distance walked in 2 minutes decreased significantly postoperatively (from 138 +/- 26m to 84 +/- 33m, P < .001), but increased again at follow-up (151 +/- 31 m, P < .0001). Distance walked on the 2MWT correlated significantly to SF-36 (physical function subscale) preoperatively (r = .44) and at follow-up (r = .48) (P < .001). There was a significant difference in distance walked between those with NYHA class I and II compared with those classified as III or IV (P = .04). However, there was no significant difference in distance walked in 2 minutes between those who developed cardiac or pulmonary complications postoperatively (P greater than or equal to 0.2). Conclusions: The 2MWT was sensitive to change after cardiac surgery and showed moderate correlation with measures of physical functioning in this population. However, the 2MWT could not identify those who developed complications in the postoperative period.