Right ventricular function and contractile reserve in heart failure with preserved ejection fraction without severe tricuspid regurgitation

Background Right ventricular (RV) failure is associated with worse exercise capacity and prognosis in heart failure with preserved ejection fraction (HFpEF). However, markers of RV dysfunction, including RV ejection fraction (RVEF), may fail in identifying early RV failure when evaluated in resting conditions only (1,2). Additionally, even less than severe tricuspid regurgitation (TR), which frequently occurs in HFpEF, might complicate proper assessment of RV function. Aim To characterize RV function and exercise contractile reserve in HFpEF with less than severe TR. Methods HFpEF patients diagnosed by gold-standard invasive exercise hemodynamics (3) underwent simultaneous three-dimensional echocardiography (3DE) and right heart catheterization (RHC) at rest and during low-workload exercise (20 W). Patients with severe TR (i.e. TR regurgitant volume, RegVol, >45 ml or TR regurgitant fraction, RegFr, ≥50%) were excluded. The population was subdivided according to RVEF changes during exercise: 1) exhausted RV reserve, RVEF- (delta RVEF ≤ 0%); 2) preserved RV reserve, RVEF+ (delta RVEF > 0%) (4). Effective RVEF (eRVEF) was calculated as RV forward stroke volume (SV)/ RV end-diastolic volume (5). Results Sixty-five patients were included (49% with RVEF-). RVEF+ and RVEF- were not different for age, sex distribution, BMI, NTproBNP, proportion of moderate TR and clinical characteristics, except for a higher prevalence of atrial fibrillation in RVEF- (69% vs 33%, p<0.05). At rest, RVEF- had higher TR RegVol (p<0.05) and RVEF (p<0.05), than RVEF+. However, eRVEF was similar between groups (figure 1). RVEF- presented with higher pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP) and right atrial pressure (RAP) than RVEF+ (figure 2). During exercise, RVEF- dilated RV volumes and reduced RVEF by -5 (-9 - -3) % and eRVEF by -5 (-9 - -2) %. Cardiac output (CO) and SV increase was lower in RVEF- than in RVEF+ (1.68 (2.07) vs 2.79 (1.81) L/min, p=0.024, and 4 (-7 – 15) vs 17 (9-26) ml, p=0.009, respectively). During exercise, RAP and RAP/PAWP were higher in RVEF- than in RVEF+ (figure 2). Resting and exercise eRVEF, but not RVEF, was associated with resting mean PAP (r= -0.48) and with exercise RAP (r= -0.56), respectively. Conclusions Latent RV dysfunction is frequent in HFpEF. HFpEF RVEF- patients had higher RVEF at rest than RVEF+, in spite of worse cardiopulmonary hemodynamics, as well as acute RV dilation with RVEF drop during exercise, with low CO reserve and high right heart filling pressures. Even in the absence of severe TR, RVEF at rest may be deceptive in HFpEF, if not incorporating TR RegVol to calculate eRVEF.