Averaged oxygen desaturation improves the prognostic value of the six-minute walk test in elderly patients with heart failure

Abstract

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. This study aimed to assess the hypothesis that Δ[Formula: see text]-Ex, the average oxygen desaturation during the 6MWT, could enhance the prognostic value of 6MWD in elderly patients with HF for cardiovascular risk prediction. In this single-center, prospective observational study, 55 patients aged ≥65 yr with acute HF were evaluated before discharge. Patients were divided into small and large Δ[Formula: see text]-Ex groups and short and long 6MWD groups based on cutoff values of 6.7% and 220 m, respectively, obtained from the receiver operating characteristics curve analysis. Patients were followed up for 1 yr to assess major adverse cardiovascular events, including rehospitalization for heart failure or cardiovascular death. The mean Δ[Formula: see text]-Ex was 5.8 ± 4.3%, and the mean 6MWD was 237.5 ± 106.7 m. Patients with large Δ[Formula: see text]-Ex had significantly higher event rates [hazard ratio (HR) = 6.66; P < 0.001], whereas those with short 6MWD had HR of 2.40 (P = 0.03). Combining Δ[Formula: see text]-Ex with 6MWD improved predictive accuracy [area under the curve (AUC) = 0.78] compared with either marker alone (AUC = 0.72 for Δ[Formula: see text]-Ex and 0.62 for 6MWD). Importantly, patients with both large Δ[Formula: see text]-Ex and short 6MWD had the highest event rates, indicating the additive prognostic value of combining both markers. In conclusion, Δ[Formula: see text]-Ex is a complementary marker to 6MWD, improving risk stratification in elderly patients with HF.NEW & NOTEWORTHY This study evaluates the use of Δ[Formula: see text]-Ex, measured during the six-minute walk test (6MWT), as a complementary prognostic marker to the six-minute walk distance (6MWD) in elderly patients with heart failure. We hypothesize that combining Δ[Formula: see text]-Ex with 6MWD will improve the predictive accuracy for cardiovascular outcomes, offering a practical, noninvasive method for risk stratification and enhancing clinical decision-making for this patient population.

Keywords: heart failure; peripheral oxygen saturation; prognostic marker; rehospitalization; six-minute walk test.