OBJECTIVES: This study aimed to assess left atrial (LA) structure and phasic function in patients with heart failure (HF) with preserved ejection fraction (HFpEF), HF with mid-range ejection fraction (HFmrEF), and HF with reduced ejection fraction (HFrEF) as well as to explore abnormal atrioventricular interaction in HF patients. METHODS: The LA structure and function of 49 controls without HF (24 males, mean age, 57 ± 7 years) and 142 HF patients (98 males, mean age, 59 ± 13 years) were evaluated by LA volumetric and strain analysis using cardiac magnetic resonance, complemented by T1 and left ventricular (LV) strain measurements. Reservoir, conduit, and booster pump LA function was analyzed by LA strain, strain rate, and emptying fraction. RESULTS: The HF patients included 50 HFpEF, 31 HFmrEF, and 61 HFrEF cases. Compared with controls, HF patients displayed increased LA volumes. LA phasic functions were impaired in all HF groups, even in patients with normal LA size. The LA reservoir strain and strain rate decreased from HFpEF through HFmrEF to HFrEF (all p <
0.05). The worse LA strain parameters were associated with worse LV strains, higher native T1, higher extracellular volume, and higher brain natriuretic peptide levels (all p <
0.05). LA phasic strains and strain rates showed better performance in differentiating HF categories compared to LA volumetric analysis. CONCLUSIONS: LA phasic function was impaired to varying degrees in HFpEF, HFmrEF, and HFrEF patients compared to controls. LA strain plays a valuable role in identifying early LA function alterations and different LA function states in HF entities. KEY POINTS: Question Information left atrial (LA) structure and phasic function changes across the heart failure spectrum, especially alterations in LA strains before LA enlargement, remain limited. Findings Compared to controls, LA phasic strains assessed by cardiac MR were impaired to varying degrees in all heart failure subtypes, even with normal LA size. Clinical relevance LA strain plays a valuable role in identifying early LA function alterations and different LA function states in heart failure entities, with implications for monitoring dynamic LA function changes in routine practice.