Averaged Oxygen Desaturation Improves the Prognostic Value of the Six-Minute Walk Test in Elderly Patients with Heart Failure.

Abstract

Background: Heart failure (HF) is a major cause of hospitalization, and exercise capacity is a key prognostic marker. The six-minute walk test (6MWT) is widely used to assess exercise capacity, but six-minute walk distance (6MWD) varies among individuals, especially the elderly.

Aim: This study aimed to assess the hypothesis that ΔSpO₂-Ex, the average oxygen desaturation during the 6MWT, could enhance the prognostic value of 6MWD in elderly HF patients for cardiovascular risk prediction.

Methods: In this single-center, prospective observational study, 55 patients aged ≥ 65 years with acute HF were evaluated before discharge. Patients were divided into small and large ΔSpO₂-Ex groups and short and long 6MWD groups based on cut-off values of 6.7% and 220 m, respectively, obtained from the Receiver Operating Characteristics curve analysis. Patients were followed for one year to assess major adverse cardiovascular events, including rehospitalization for heart failure or cardiovascular death.

Results: The mean ΔSpO₂-Ex was 5.8 ± 4.3%, and the mean 6MWD was 237.5 ± 106.7 m. Patients with large ΔSpO₂-Ex had significantly higher event rates (HR 6.66, p < 0.001), while those with short 6MWD had HR of 2.40 (p = 0.03). Combining ΔSpO₂-Ex with 6MWD improved predictive accuracy (AUC 0.78) compared to either marker alone (AUC 0.72 for ΔSpO₂-Ex and 0.62 for 6MWD). Importantly, patients with both large ΔSpO₂-Ex and short 6MWD had the highest event rates, indicating the additive prognostic value of combining both markers.

Conclusion: ΔSpO₂-Ex is a complementary marker to 6MWD, improving risk stratification in elderly HF patients.