Background Maximal left atrial (LA) volume is reported by most echocardiography laboratories and is associated with clinical outcomes in patients with heart failure (HF). Recent studies suggest that minimal LA volume may better reflect left ventricular filling pressure and may be more prognostic than maximal LA volume. This study assessed the prognostic value of indexed minimal LA volume (LAVImin) in patients with HF with preserved ejection fraction. Methods and Results We assessed the relationship of LAVImin with a primary composite end point of cardiovascular death, aborted cardiac death, or HF hospitalization in 347 patients with HF with preserved ejection fraction enrolled from the Americas region in TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist Trial). We compared LAVImin with indexed maximal LA volume with respect to their prognostic values. In addition, we assessed if LA functional parameters provide additional prognostic information over LAVImin. During a median follow‐up of 2.5 years, 107 patients (31%) experienced a primary composite end point. LAVImin was associated with increased risk of a primary composite outcome (hazard ratio [HR], 1.35; 95% CI, 1.12–1.61) and HF hospitalization alone (HR, 1.42; 95% CI, 1.17–1.71) after adjusting for clinical confounders and ejection fraction. In contrast, indexed maximal LA volume was not related to the primary composite outcome, but related to HF alone (HR, 1.25; 95% CI, 1.02–1.54). In comparison with indexed maximal LA volume, LAVImin was significantly more prognostic for primary composite outcome ( P for comparison=0.032). Both LA emptying fraction and LA strain were prognostic of primary outcome independent of LAVImin (all P <0.05). Conclusions In patients with HF with preserved ejection fraction, LAVImin was more predictive of cardiovascular outcome than indexed maximal LA volume, suggesting this measure may be more physiologically relevant and might better identify patients at high risk for cardiovascular events. LA functional parameters provide prognostic information independent of LAVImin. Registration URL: https://www.clinicaltrials.gov ; Unique identifier: NCT00094302.