Prolonged heart rate recovery time after 6-minute walk test is an independent risk factor for cardiac events in heart failure: a prospective cohort study

Abstract Objectives To determine whether the time for peak exercise heart rate to return to resting heart rate after the 6-minute walk test (6MWT) can predict cardiac events in patients with heart failure (HF) within 2 years. Design Prospective cohort study. Setting HF outpatient facility at a tertiary teaching hospital. Participants Seventy-six patients with HF, New York Heart Association functional classification II and III, and left ventricular ejection fraction Main outcome measures Patients used a heart rate monitor to measure the time for peak exercise heart rate to return to resting heart rate after the 6MWT. Data were analysed using Polar Pro-Trainer 5 software (Kempele, Finland). Patients were followed for >2 years for cardiac events (hospitalisations and death). Results Thirty-four patients had cardiac events during the 2-year follow-up period. There was a significant difference in time to return to resting heart rate between the groups with and without cardiac events {with 3.6 [standard deviation (SD) A] vs without 2.8 (SD B) minutes; mean difference C; 95% confidence interval (CI) of the difference D to E; P = 0.003}. No significant differences between patients with and without cardiac events were found for mean walking distance, mean heart rate recovery at 1 minute and mean heart rate recovery at 2 minutes. The receiver operating curve discriminated between patients with and without cardiac events (area under the curve 0.71, 95% CI 0.61 to 0.81; P  Conclusions Prolonged time to return to resting heart rate (≥3 minutes) after the 6MWT was an independent predictor of cardiac events in patients with HF.