Introduction: Pulmonary arterial hypertension (PAH) therapies have vasodilator effects that could induce or aggravate hypoxemia in patients with portopulmonary hypertension (PoPH)

Aims: To investigate effect of PAH therapies on gas exchanges in patients with PoPH

Methods: Patients with newly diagnosed PoPH and available room air arterial blood gases measurements at both baseline and first follow-up after PAH treatment initiation were analyzed. Change in alveolar-arterial oxygen gradient (A?aDO2) on PAH therapy was analyzed, as well as usual variables such as NYHA functional class (FC), 6-min walk distance (6MWD), and cardiopulmonary haemodynamics.

Results: Gas exchanges were analyzed in 107 newly diagnosed PoPH patients (70% males, mean age 55±8 years). Baseline mean A-aDO2 was 37±3.0 mmHg. No correlation was found between A?aDO2 and 6MWD.  Eighty-three patients received initial oral monotherapy (PDE-5 inhibitor, n=59; endothelin-receptor antagonist, n=24) and 24 oral dual combination therapy. At four months, there was no significant change in A?aDO2 (median -0.92 mmHg, 95%CI [- 3.2; +1.3], p=0.42). Change in A?aDO2 was neither correlated with change in 6MWD nor with change in FC. In multivariate models, cardiac index or pulmonary vascular resistance (PVR) assessed at first follow-up were independently associated with change in A?aDO2 (-3.69mmHg decreased 95%CI [-6.15; -1.22] per 1 incremental L/min/m2 of cardiac index p=0.004, or 1.88mmHg CI95% [0.30; 3.48] per 1 incremental Wood Unit of PVR, p=0.02)

Conclusion: Overall, we did not find negative impact of PAH therapies on gas exchanges in PoPH. Haemodynamic improvement on therapy was not associated with worsening in gas exchanges.