Left atrial function index predicts long-term survival in stable outpatients with systolic heart failure

Abstract

Aims: Left atrial (LA) function index (LAFI) is a rhythm-independent index that combines LA emptying fraction (LAEF), adjusted LA volume (LAVi), and stroke volume. We evaluated LAFI as a predictor of long-term survival in outpatients with heart failure with reduced ejection fraction (HFrEF).

Methods and results: For 3 years, we followed up 203 outpatients with a left ventricular ejection fraction <40%, who were clinically stable and on optimal therapy. The endpoint was all-cause death. LAFI was calculated as LAFI = ([LAEF × left ventricular outflow tract-velocity time integral]/[LAVi]), and was categorized into quartiles (9.26/16.56/31.92) and median (16.57). Incremental Cox regression models adjusted for significant confounders were used for survival analyses. The 3-year death rate was 30%. Higher quartiles had lower death rates (43.1%/45.1%/25.5%/6%, P < 0.001). The receiver operating characteristic curve for death was associated with LAFI (area under curve = 0.695, 95% CI 0.62-0.77, P < 0.001). In the direct comparison with LAVi and LAEF, LAFI (HRcox 0.93, 95% CI 0.89-0.97, P < 0.001) was the only predictor of survival. LAFI (HRcox 0.95, 95% CI 0.88-1.01, P = 0.099), LAFI quartiles (HR 0.29, 95% CI 0.125-0.672, P=0.004), and LAFI ≥16.57 (HRcox 0.62, 95% CI 0.38-1.02, P=0.058) were adjusted predictors of survival. Subgroup analysis by heart rhythm (sinus vs. atrial fibrillation) showed that LAFI per unit increase and LAFI quartiles were independent predictors of death in both subgroups.

Conclusion: LAFI determination in HFrEF stable outpatients is a predictor of long-term survival and provides increased prognostic value over a wide range of confounder risk factors.

Keywords: atrial function; left atrial functional index; survival; systolic heart failure.