Phosphodiesterase-5A inhibitors (PDE5i) are sometimes used in patients with advanced HFrEF prior to heart transplant or LVAD to reduce RV afterload and mitigate the risk of right HF. Conflicting evidences exist regarding the impact of these drugs on right ventricular (RV) contractility. The aim of the study was to explore the acute effects of PDE5i on ventricular-vascular coupling and load-independent RV contractility.
22 patients underwent right heart catheterization (RHC) and gated equilibrium blood pool SPECT, before and after 20-mg intravenous sildenafil. SPECT and RHC-derived data were used to calculate RV loading and contractility.
PDE5i induced a reduction in RA pressure (-43%), pulmonary artery (PA) mean pressure (-26%) and wedge pressure (PAWP; -23%), with favorable reductions in PVR (-41%) and PA elastance (Ea; -40%), and increased cardiac output (+13%) (all p<0.01). RV ejection fraction increased with sildenafil (RVEF; +20%), with no change of RV contractility (RV Ees, p=0.74), indicating that the improvement in RVEF was related to enhanced RV-PA coupling (r=0.59, p=0.004) by reduction of ventricular load. RV diastolic compliance (dV/dP) increased with sildenafil. The reduction in PAWP correlated with RV EDV reduction, while no relationship was observed with the change in LV transmural pressure, suggesting decreased pericardial constraint.
Acute PDE5i administration has profound RV afterload-reducing effects, improves RV EF, reduces RV volumes and lowers PAWP predominantly through relief of pericardial constraint, without effects on RV chamber contractility. These findings support further study of PDE5i in protection of RV function in advanced HFrEF who are at risk of RV failure.

Copyright © 2020. Published by Elsevier Inc.