Abstract 12748: Continuous Measurement of Percutaneous Oxygen Saturation During 6-Minute Walk Test is Useful for Predicting the Prognostic Risk in Patients With Heart Failure

Abstract

Background: The 6-minute walk test (6MWT) is an established test to assess functional exercise performance and the 6-minute walk distance (6MWD) is strongly correlated with the functional capacity and the prognosis in patients with heart failure (HF). However, the clinical implication of sequential changes in percutaneous oxygen saturation (SpO2) during 6MWT has not been investigated in HF patients. Purpose: To prospectively clarify the association between sequential changes in SpO2 during 6MWT and prognosis in patients with HF. Methods: Fifty patients admitted with acute heart failure were enrolled. The 6MWT was performed at the time before discharge, after hemodynamic stability was confirmed. The average of SpO2 was calculated from data obtained at rest and during 6MWT by employing the wearable pulse-oximeter which is designed to record the SpO2 value every second. Alternations in SpO2 (ΔSpO2) were obtained by subtracting the average during 6MWT from that at rest. Patients were followed up to 9 months for the composite outcome of heart failure-hospitalization and death. Results: The mean age of participants was 78.8 years, and 23 (46%) were female. The mean EF was 46.1% and the number of patients with EF ≦40 was 22. The 6MWD was 250 ± 112m and the ΔSpO2 was 2.88 ± 4.3%. All cases were classified by walk distance and ΔSpO2; long- (>220m) vs. short-distance group (≦220m) and low- (<3.5%) vs. high-ΔSpO2 group (≧3.5%). There were no significant differences in cardiac parameters and respiratory function between long- and short-distance group as well as between low- and high-ΔSpO2 group. Kaplan-Meier analysis revealed that higher ΔSpO2 showed a more strong and statistically significant impact on cardiovascular outcome compared to longer 6MWD (HR=3.25, CI=1.40-7.51, p=0.006, HR=2.24, CI=0.94-5.32, p=0.067, respectively). Conclusions: This study showed that, compared to walk distance, ΔSpO2 during 6MWT was more predictive of the prognosis of heart failure patients.