Background:
Half of all hospitalizations for heart failure (HF) occur in patients with normal ejection fraction (EF). Because left atrial (LA) function contributes up to thirty percent of left ventricular stroke volume, we hypothesized that LA function would predict HF hospitalization in subjects with normal EF.
Methods:
We performed resting transthoracic echocardiography in 855 patients with stable coronary heart disease (CHD) and normal EF (≥ 50%). We calculated left atrial functional index (LAFI) as [(LAEF x LVOT VTI)/(LAESVI)], where LAEF = LA emptying fraction, LAESVI = LA end-systolic volume indexed to body surface area, and LVOT VTI = left ventricular outflow tract velocity time integral. LAEF was defined as (LAESV-LAEDV)/LAESV). We used Cox proportional hazards models to evaluate LAFI as a predictor of HF hospitalization during a median follow-up of 7.9 years.
Results:
LAFI was normally distributed with a mean of 42.3 ± 18.6 units. During 5621 person-years of follow-up, 106 subjects had a HF hospitalization. Rates of HF hospitalization were inversely proportional to quartile of LAFI: Q1 (0.5-29.2): 47 per 10 person-years; Q2 (29.3-40.8): 18; Q3 (40.8-53.4): 9.5; Q4 (53.4-160): 5.3 (p<0.001). Patients with LAFI in the lowest quartile had over 8 times the risk of HF compared with those with LAFI in the highest quartile (HR 8.7, 95%CI 4.2-18.2; p<0.001). Each standard deviation decrease in LAFI was associated with an over 2-fold greater risk of HF (HR 2.6, 95% CI, 2.1-3.3, p<0.001). After adjustment for age, sex, body mass index, history of heart failure, prior revascularization, creatinine, atrial fibrillation, diastolic dysfunction, left ventricular mass index, left ventricular ejection fraction, and inducible ischemia, participants with LAFI in the lowest quartile still had over 4 times the risk of HF compared with those in the lowest quartile (HR 4.7, 95% CI, 1.7-12.5; p=0.002).
Conclusions:
Reduced left atrial function strongly predicts HF hospitalization in subjects with CHD and normal EF, even after adjustment for a wide range of clinical and echocardiographic covariates. These findings suggest that LA failure plays an important role in HF and may represent a potential target for preventative or therapeutic efforts.
489 Dynamic left ventricular dyssynchrony contributes to exercise symptoms and dynamic mitral regurgitation in heart failure patients
