Load-Independent Systolic and Diastolic Right Ventricular Function in Heart Failure With Preserved Ejection Fraction as Assessed by Resting and Handgrip Exercise Pressure-Volume Loops

BACKGROUND: Although systolic right ventricular (RV) dysfunction has been shown to be a potent predictor for adverse outcomes in patients with heart failure with preserved ejection fraction (HFpEF), RV functional abnormalities in the course of the syndrome are not well characterized. We, therefore, sought to assess load-independent and load-dependent systolic and diastolic characteristics of RV function in stable outpatients with HFpEF. METHODS AND RESULTS: We invasively obtained RV and left ventricular pressure-volume loops in 24 HFpEF patients and 9 patients without heart failure symptoms with a conductance catheter during basal conditions and handgrip exercise. Transient preload reduction was used to extrapolate the RV end-systolic elastance and diastolic stiffness constant. HFpEF patients and controls showed similar left ventricular and RV dimensions and ejection fractions with elevated left ventricular filling pressures. In HFpEF patients, invasively determined load-independent RV contractility (P=0.04) and load-independent passive RV stiffness constant beta (P<0.01) were elevated. Although RV relaxation and cardiac output were similar at baseline, HFpEF patients demonstrated a blunted increase in cardiac output under exercise (P=0.01) associated with prolonged RV relaxation (P=0.01), decrease in stroke volume (P<0.01), higher RV-filling pressures (P<0.01), and a marked increase in the end-diastolic pressure-volume relationship (P<0.01). CONCLUSIONS: In compensated stages of the HFpEF syndrome, systolic RV function is preserved, but diastolic abnormalities with intrinsic RV stiffness and prolonged RV relaxation are already present. Impaired diastolic RV reserve contributes to a blunted increase in cardiac output during exertion. Because impairments in diastolic function seem to be a biventricular phenomenon, RV diastolic dysfunction warrants further consideration when characterizing HFpEF patients.