In the overall population of patients with heart failure and ejection fraction of greater than or equal to 40%, placement of an atrial shunt device neither decreased the total rate of heart failure events nor improved health status.

• This randomized, international, blinded, sham-controlled trial included patients (aged ≥40 years) with symptomatic heart failure, an ejection fraction of at least 40%, and pulmonary capillary wedge pressure during exercise of at least 25 mm Hg while exceeding right atrial pressure by at least 5 mm Hg.

• A total of 626 patients were randomized to receive either the atrial shunt device (n=314) or sham procedure (n=312).

• Primary endpoint was defined as a hierarchical composite of cardiovascular death or non-fatal ischemic stroke at 12 months, rate of total heart failure events up to 24 months, and alteration in Kansas City Cardiomyopathy Questionnaire overall summary score at 12 months.

• With regard to the primary composite endpoint or the individual components of the primary endpoint, no differences were found between groups.

• A differential impact of atrial shunt device treatment on heart failure events was evident in the following prespecified subgroups: pulmonary artery systolic pressure at 20W of exercise (>70 mm Hg linked with worse outcomes), right atrial volume index (≥29·7 mL/m ² , worse outcomes]), and gender (men, worse outcomes]).