Paradoxical low-flow phenotype in hospitalized heart failure with preserved ejection fraction

Low flow (LF) in heart failure with preserved ejection fraction (HFpEF) is a paradox but is associated with worse prognosis. Determinants of LF in HFpEF have not been clarified but their assessment could corroborate recognition and definition of such a paradoxical condition.

A cohort of 193 patients hospitalized with HFpEF was retrospectively studied and divided in a group with LF (N = 45), defined by a left ventricular (LV) stroke volume index (SVI) < 30 ml/m², and a group with normal flow (N = 148). A small LV cavity was pre-defined as LV end diastolic diameter index (EDDI) below median values (<25 mm/m² for males and <26 mm/m² for females). Right ventricular dysfunction (RVD) was defined as the ratio between tricuspid annular plane systolic excursion and systolic pulmonary artery pressure < 0.36 mm/mmHg. An endpoint of all-cause mortality was evaluated after a median follow-up of 2.4 years.

RVD (OR = 7.4; P < 0.001), atrial fibrillation (AF) during echocardiography (OR = 3.26; P = 0.008), and small LV cavity (OR = 3.81; P = 0.003) were independently associated with LF. After adjusting for age, body mass index, systolic blood pressure, renal function, chronic obstructed pulmonary disease, use of ACE inhibitors/angiotensin receptor blockers, moderate tricuspid regurgitation, RVD), LF was associated with mortality (HR = 3.69; P < 0.001) whereas the combination of the determinants of LF was not.

Paradoxical LF in HFpEF is associated with small LV cavity, AF and RVD. None of the combination of different factors associated with LF could substitute direct assessment of LF status in predicting prognosis in this cohort.