Running on empty: Factors underpinning impaired cardiac output reserve in heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFpEF) is frequently attributed etiologically to an underlying left ventricular (LV) diastolic dysfunction, although its pathophysiology is far more complex and can exhibit significant variations among patients. This review endeavours to systematically unravel the pathophysiological heterogeneity by illustrating diverse mechanisms leading to an impaired cardiac output reserve, a central and prevalent haemodynamic abnormality in HFpEF patients. Drawing on previously published findings from our research group, we propose a pathophysiology-guided phenotyping based on the presence of: (1) LV diastolic dysfunction, (2) LV systolic pathologies, (3) arterial stiffness, (4) atrial impairment, (5) right ventricular dysfunction, (6) tricuspid valve regurgitation, and (7) chronotopic incompetence. Tailored to each specific phenotype, we explore various potential treatment options such as antifibrotic medication, diuretics, renal denervation and more. Our conclusion underscores the pivotal role of cardiac output reserve as a key haemodynamic abnormality in HFpEF, emphasizing that by phenotyping patients according to its individual pathomechanisms, insights into personalized therapeutic approaches can be gleaned.