Weerts J, Aizpurua AB, Henkens MTHM, et al. - In heart failure with preserved ejection fraction (HFpEF), a likely greater prognostic role of mechanical atrial dysfunction exists than atrial fibrillation (AF) status alone. Mechanical atrial dysfunction can not only predict adverse outcome (independently of AF presence or stage), but it could also be an underlying mechanism (mediator) for the worse outcome linked with AF in HFpEF. This implies an important role of mechanical atrial dysfunction in disease progression in HFpEF cases with AF, and probably also in HFpEF cases without AF.

• This study included 258 HFpEF patients, who were divided based on rhythm and stages of AF: 112 with no history of AF (no AF), 56 with paroxysmal AF (PAF), and 90 with sustained (persistent/permanent) AF (SAF).

• Mechanical atrial function reduction was progressive: left atrial reservoir strain (LASr) 30.5 ± 10.5% (no AF), 22.3 ± 10.5% (PAF), and 13.9 ± 7.8% (SAF).

• Following were revealed as independent predictors for lower LASr values: AF, absence of chronic obstructive pulmonary disease, higher N-terminal-pro hormone B-type natriuretic peptide, left atrial volume index, and relative wall thickness, lower left ventricular global longitudinal strain, and echocardiographic signs of increased left ventricular filling pressure.

• Adverse outcome was independently predicted by LASr (hazard ratio per 1% decrease =1.049), but not by AF when LASr was incorporated into the multivariable model.

• Moreover, the adverse outcome related to AF in HFpEF was mediated by LASr.