CONGRESS ABSTRACT

Background: Heart failure with preserved or mildly reduced ejection fraction (HFpEF/HFmrEF) accounts for a large share of acute heart failure (AHF) admissions. However, it remains uncertain how often decompensation is attributable to isolated diastolic dysfunction, without relevant structural or arrhythmic disease, as required by guideline-based definitions. Although HFmrEF is classified separately in guidelines, we included patients with LVEF >40%, consistent with major HFpEF trials and registries. Objective: To assess the prevalence ofAHF driven solely by diastolic dysfunction in patients with LVEF >40% and congestion. Methods: We retrospectively analyzed 773 consecutive AHF admissions (January 2022–November 2023) with complete echocardiography at entry. Of these, 323 had LVEF >40%. Systemic congestion was defined as inferior vena cava (IVC) diameter >21 mm with reduced inspiratory collapse. A structured algorithm identified significant cardiac pathology (severe valvular disease, precapillary pulmonary hypertension, cardiomyopathy, arrhythmias with hemodynamic impact) and stage V kidney disease. Patients without these conditions were classified as guideline-defined HFpEF/HFmrEF. This variable was tested in multivariable logistic regression against systemic congestion. Results: Among 323 patients with LVEF >40%, 252 (78%) had systemic congestion. Of these, 206 (81.7%) had severe valvular disease, 26 (10.3%) had other significant cardiac disease or stage V renal failure, and only 20 (8%) had no identifiable cause and thus fulfilled guideline-defined HFpEF/HFmrEF. Guideline-defined HFpEF/HFmrEF was inversely associated with congestion (OR 0.037, 95% CI 0.017–0.078, p<0.001). Conclusions: In LVEF >40%, systemic congestion is rarely due to isolated diastolic dysfunction. Guideline-defined HFpEF appears uncommon as a cause of acute decompensation, underscoring the need for comprehensive diagnostic evaluation