Objective assessment of the response to treatment of severe heart failure using a 9-minute walk test on a patient-powered treadmill

Abstract

Background: No previous studies have demonstrated the changes in exercise capacity thatoccur during treatment of decompensated severe heart failure. The authors assessed the efficacy and safety of using a patient-powered treadmill to objectively measure exercise capacity and its relationships, if any, to symptom scores and body weight. Methods and Results: Changes in time-limited exercise capacity on a patient-powered treadmillwere assessed during inpatient treatment of 12 patients with decompensated chronic heart failure (New York Heart Association classes III and IV). Patients performed a 9-minute walk test daily for 7 days and again at the 6-week follow-up examination. They also completed a 24-item symptom score questionnaire. After treatment, there was a rapid, significant increase in total distance walked, with the increase beginning as early as the second day after admission (mean distance walked ± SEM, 54 ± 27 m and 174 ± 54 m on admission and on day 2, respectively, P < .05). Improvement was maintained throughout the period in the hospital and at 6 weeks ( P < .001). Patients reported symptomatic improvement, but this did not reach significance until 4 days after admission ( P < .05). Weight loss was not significant. Improved exercise capacity correlated with reduced symptoms and weight loss, but preceded these by several days. Conclusions: In patients with decompensated chronic heart failure, this exercise test provides a safe, practical, inexpensive, and objective assessment of functional capacity, providing certain advantages over other indices of response to therapy, such as symptom scores and weight loss. Improvement of exercise capacity does not occur concurrently with relief of symptoms and weight loss.