Impaired myocardial work efficiency in heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a growing public health problem. Impairment in left ventricular (LV) diastolic function has been proposed as a key pathophysiologic determinant. However, the role of concomitant systolic dysfunction despite preserved LV ejection fraction (LVEF) has not been well characterized. To analyse LV myocardial deformation, diastolic function, and contractile reserve (CR) in patients with HFpEF at rest and while during exercise, as well as their correlation with functional capacity.

Standard echo, lung ultrasound, LV 2D speckle-tracking strain, and myocardial work efficiency (MWE) were performed at rest and during exercise in 230 patients with HFpEF (female sex 61.2%; 71.3 ± 5.3 years) in 150 age- and sex-comparable healthy controls. LV mass index and LAVI were significantly increased in HFpEF. Conversely, global longitudinal strain (GLS) and MWE were consequently reduced in HFpEF patients. During effort, HFpEF showed reduced exercise time, capacity, and VO2 peak. Increase in LVEF and LV GLS was significantly lower in HFpEF patients, while LV E/e' ratio, pulmonary pressures, and B-lines by lung ultrasound rose. A multivariable analysis outlined that LV MWE at rest was closely related to maximal Watts reached (beta coefficient: 0.43; P < 0.001), peak VO2 (beta: 0.50; P < 0.001), LV E/e' (beta: 0.52, P < 0.001), and number of B-lines during effort (beta: -0.36; P < 0.01).

The lower resting values of LV GLS and MWE in HFpEF patients suggest an early subclinical myocardial damage, which seems to be closely associated with lower exercise capacity, greater pulmonary congestion, and blunted LV contractile reserve during effort.