Previous studies have shown that abnormal mitral flow patterns and left atrial (LA) enlargement are independently associated with survival in patients with left ventricular (LV) dysfunction. However, it is not known whether these outcome indicators can provide different information in patients of various age groups. This study was designed to assess the prognostic value of the restrictive mitral flow pattern (RMFP) and increased LA size in patients with LV dysfunction (ejection fraction <45%) grouped into those ≤70 years old (n = 102; mean age 61) and those >70 years old (n = 105; mean age 78). Echocardiographic and Doppler indexes were recorded in patients with LV systolic dysfunction due to dilated cardiomyopathy who were followed up for 22 ± 14 months. In patients >70 years, indexed LA size (>26 mm/m²) was the single best predictor of death (hazard ratio [HR] 3.0, p = 0.018) and emerged as the most important outcome variable of the combined end point (HR 2.2, p = 0.016) on multivariate analysis. In patients ≤70 years, RMFP, characterized by an early wave deceleration time <140 ms, was independently associated with cardiac death or heart failure hospitalization (HR 5.7, p = 0.0013). When demographics, clinical, echocardiographic, and Doppler measurements were analyzed in hierarchical order, indexed LA size yielded the most valuable contribution in predicting the combined end point in older patients (global chi-square from 11.5 to 18.7). RMFP was associated with the higher additional prognostic value in younger patients (global chi-square from 14.4 to 24.1). These data suggest that LA enlargement has an independent and additional prognostic value in elderly patients with LV dysfunction.