HFpEF and HFmrEF in acute heart failure: isolated diastolic dysfunction or alternative cardiac pathologies?

A significant proportion of acute heart failure (AHF) hospitalizations involve patients with heart failure with preserved or mildly reduced ejection fraction (HFpEF or HFmrEF). According to the current Guidelines, these HF phenotypes exclude patients with major cardiac pathologies, such as severe valvular disease, cardiomyopathies, or isolated precapillary pulmonary artery hypertension, and their aetiology is attributed to diastolic dysfunction alone. However, whether HFpEF or HFmrEF-when defined in this way-can independently cause fluid overload remains unproved. We retrospectively analyzed 773 consecutive cardiology admissions for AHF between January 2022 and November 2023. Of these, 323 patients presented with left ventricular ejection fraction (LVEF) > 40% were included. Systemic venous congestion was defined as an inferior vena cava diameter > 21 mm with reduced inspiratory collapse. A structured diagnostic approach was used to identify the prevalence of major cardiac structural abnormalites and rhythm abnormalities, classified as HFpEF mimics, in patients with preserved or mildly reduced LVEF and peripheral congestion. Among 323 patients with LVEF>40%, 252 (78%) showed systemic congestion. Of these, 206 (81.7%) had severe valvular dysfunction, 26 (10.3%) had other relevant structural or rhythmic cardiac pathology (such as cardiomyopathy) or had V stage renal failure, and only 20 patients (8%) had no identifiable HFpEF mimic, thereby fulfilling the strict guideline-based definition of these entities. In patients with LVEF >40%, systemic venous congestion was almost invariably associated with significant structural or rhytm heart disease or advanced renal failure. Cases without such alternative explanations were extremely rare, suggesting that guideline-defined HFpEF/HFmrEF, as an independent cause of acute decompensation, may represent an uncommon or even non-existent clinical entity. These findings challenge the validity of current definitions and support a more comprehensive diagnostic approach in this patient population.