Left Atrial Structure and Function and the Risk of Death or Heart Failure in Atrial Fibrillation

AIMS: The present study aimed to assess the association between left atrial (LA) structure and function and the risk for cardiovascular (CV) death or heart failure (HF) hospitalization in a population with atrial fibrillation (AF). METHODS AND RESULTS: In a prospective echocardiographic substudy of the Effective Anticoagulation with Factor Xa Next Generation in AF-Thrombolysis in Myocardial Infarction 48 (ENGAGE AF-TIMI 48) study, 971 patients underwent transthoracic echocardiography. The associations between LA structure (LA volume index [LAVi]) and function (LA emptying fraction [LAEF] and LA expansion index [LAEi]) and risk for the composite endpoint of CV death or HF hospitalization, and its components, were assessed. Over a median follow-up of 2.5 years, 142 patients (14.6%) experienced CV death or HF hospitalization. Higher LAVi and lower LAEF and LAEi were each associated with a higher unadjusted risk for the composite outcome and its components. After adjustment for clinical and echocardiographic confounders, only measures of impaired LA function were predictive of the composite outcome (hazard ratio [HR] per 1 standard deviation [SD] decrease in LAEF: 1.35; 95% confidence interval [CI] 1.09-1.67 [P = 0.005]; HR per 1 SD decrease in LAEi: 1.34; 95% CI 1.06-1.69 [P = 0.012]). These findings were similar regardless of left ventricular ejection fraction, history of HF or whether patients were in AF or sinus rhythm at the time of the echocardiographic examination. CONCLUSIONS: In patients with AF, LA dysfunction was significantly associated with an increased risk for CV death or HF hospitalization and was more predictive of these outcomes than LA size. These parameters may help to identify AF patients at greatest risk for the development of HF. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT00781391.