Background: According to the 2016 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure, the term "HFpEF" (heart failure with preserved ejection fraction) is reserved for patients with left ventricular ejection fraction (LVEF) =50%, and the new term "HFmrEF" denotes those with LVEF 40-49%. Possible differences in exercise hemodynamic profile between these two entities are unknown to date.
Methods: Results of exercise right-heart catheterization performed from 2009 to 2017 were screened for patients with HFpEF or HFmrEF, and 233 patients were determined to be suitable for further analysis. Differences between hemodynamic variables in the two groups were analyzed, and the ratio of tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure estimated by Doppler echocardiography (PASP) compared for the two groups. Each group was then subdivided according to whether the TAPSE/PASP ratio was greater than or less than the median, and the hemodynamic variables were compared in the resulting four groups.
Results: The cohort of 180 patients with HFpEF and 53 with HFmrEF had the following baseline characteristics: 53% men, median age 73 years (IQR 67-77), median NTproBNP 1132 pg/ml (IQR 570-2255), 27% in NYHA class II and 69% in class III, and 66% with atrial fibrillation. Key resting hemodynamic parameters, expressed as mean mmHg (SD) or l/min/m2 (SD) for cardiac index (CI), were: mean right atrial pressure 7.55 (4.29) in HFpEF and 7.4 (5.15) in HFmrEF; mean pulmonary artery pressure (mPAP) 25.71 (7.60) in HFpEF and 25.98 (11.43) in HFmrEF; mean pulmonary artery wedge pressure (PAWP) 16.02 (5.44) in HFpEF and 15.85 (7.50) in HFmrEF; CI 2.54 (0.63) in HFpEF and 2.44 (0.60) in HFmrEF. Multiple hemodynamic exercise parameters showed no significant differences between the two groups at comparable workload, maximum heart rate, and final mixed venous oxygen saturation. However, the TAPSE/PASP ratio was significantly different (p=0.001) between HFpEF and HFmrEF patients. Subgrouping according to median TAPSE/PASP ratio showed significant differences between the four groups: the increase in cardiac output during exercise (p=0.001), maximum total pulmonary resistance (p=0.000), maximum pulmonary artery compliance (p=0.000), and maximum transpulmonary gradient (p=0.003), whereas the rise in PAWP was not different.
Conclusions: Standard hemodynamic parameters at rest and during exercise did not differ significantly between patients with HFpEF and HFmrEF. Instead, partitioning of the two entities using an echocardiographic parameter of the right ventricular-pulmonary circulation unit showed marked differences in the exercise hemodynamic profile between the different subgroups. Thus, LVEF may be not the appropriate parameter to stratify heart failure patients with an EF >40%, but parameters of the right ventricular-pulmonary circulation unit, including exercise hemodynamics, may be helpful for profiling.