Novel Insights into Left Atrial Mechanics: Prognostic Value of Left Atrial Contractile Index in Heart Failure with Preserved Ejection Fraction

Background: Limited prognostic data exist on the relative increase of left atrial (LA) booster strain compared with reservoir strain in patients with heart failure with preserved ejection fraction (HFpEF). This study aimed to evaluate the prognostic value of a novel index derived from cardiac MRI—LA contractile index—which has the potential to detect these early changes in patients with HFpEF.

Methods: This retrospective study included 883 participants from the derivation center, comprising 803 patients with HFpEF (age, 54.8 ± 11.9 years; 72.0% male) and 80 healthy controls (age, 52.9 ± 10.1 years; 71.3% male). All patients were divided into development (70%, 562 patients) and internal validation (30%, 241 patients) cohorts. The primary endpoint was a composite of cardiovascular death and HF hospitalization. LA contractile index was calculated as the percentage of booster strain relative to reservoir strain. Results were validated in a cohort of HFpEF patients (age, 59.0 ± 13.2 years; 66.3% male) enrolled at an external validation center.

Results: Patients with HFpEF had higher LA contractile indices than healthy controls (P < .001). Over a median follow-up of 7.6 years, 211 (37.5%) patients in the development cohort reached the primary composite endpoint. LA contractile index exhibited J-shaped relationships with the primary endpoint in restricted cubic spline analysis (P nonlinear < .001). In multivariable Cox regression analysis, the abnormal LA contractile index (cut-off value, < 35.5% or > 51.5%; HRadj: 3.23 [95% CI: 2.27-4.59]; P < .001) was independently associated with the primary endpoint. The model incorporating clinical, conventional imaging variables, and abnormal LA contractile index exhibited the highest discrimination across development, internal validation, and external validation cohorts. Time-dependent receiver operating characteristic analysis showed that the addition of abnormal LA contractile index to the current risk score-based models improved prediction accuracy at the mid-term (3-year) and long-term (7-year) time points (all P < .05).

Conclusion: LA contractile index derived from cardiac MRI was associated with adverse outcomes in patients with HFpEF, and provided incremental prognostic value beyond conventional clinical and imaging variables, as well as the established risk model.

Measurements of left atrial (LA) contractile index based on cardiac MRI feature-tracking. LA contractile index was calculated as the percentage of LA booster strain relative to LA reservoir strain.
Prognostic value of left atrial (LA) contractile index in heart failure with preserved ejection fraction (HFpEF). The abnormal LA contractile index ( < 35.5% or > 51.5%) was associated with a higher risk of composite cardiovascular death or HF hospitalization.