758-2 Failure of 6 Minute Walk to Predict Exercise Capacity in Patients Evaluated for Cardiac Transplantation

In patients evaluated for cardiac transplantation the measured peak oxygen consumption is an objective and powerful predictor of survival that helps to prioritize patients on the transplant list. The 6 minute walk has been shown to correlate with NYHA functional class and to predict morbidity and mortality in patients with congestive heart failure but its correlation with VO2 max has not been established. The easily performed 6 minute walk would be an ideal screening test for congestive heart failure patients if it could be shown to correlate with Vo2 max. We studied 24 patients with CHF who were undergoing cardiac transplant evaluation. Functional class assessment was obtained prior to performing the 6 minute walk and subsequent metabolic stress test. Patients were given standardized instructions for the 6 minute walk and all tests were supervised by one Exercise Physiologist. Coaching was kept to a minimum since this has been shown to effect the test results. Metabolic stress testing was performed within 1 hour of the 6 minute walk.ResultsRegression analysis showed little correlation between the 6 minute walk distance and the measured Vo2 max (R squared = 0.04, P = 0.375). The physician determined NYHA functional class correlated poorly with Vo2 max (R squared = 0.1. p = 0.151).ConclusionNeither the 6 minute walk distance nor the physician determined functional class correlates well with the measured Vo2 max obtained during metabolic stress testing and appear not to be reliable screening tests for patients considered for cardiac transplantation