Background: High-altitude pulmonary hypertension (HAPH) is a public health problem in mountainous areas of the world. Treatment options for this condition are unsatisfactory. Recent interest in use of selective phosphodiesterase type 5 (PDE5) inhibitors for pulmonary hypertension has suggested a possible role for these agents in the treatment of HAPH. Preliminary data from several small studies have shown beneficial haemodynamic effects of empirical PDE5 treatment of HAPH but the results of these studies have been challenged.

Objective: We performed a meta-analysis to explore the potential therapeutic effects of PDE5 inhibitors for HAPH.

Methods: Randomized controlled trials were identified to test the effects of PDE5 inhibitors in HAPH by searching PubMed (inception to June 2009). A standardized protocol with predefined criteria was used to extract details on study design, Jadad score, demographic data, interventions and outcomes. The main outcomes assessed were cardiopulmonary parameters. Treatment effects for continuous variables were presented as weighted mean differences with 95% confidence intervals.

Results: Ten clinical trials were identified and included for the meta-analysis. The weighted mean difference in systolic pulmonary artery pressure post-treatment at rest in PDE5 inhibitor-treated subjects was -7.51 mmHg (95% CI -10.87, -4.16; p < 0.0001) compared with controls, whereas the analysis of systolic blood pressure and heart rate demonstrated that no significant effects were observed in the active treatment group at rest and during exercise.

Conclusions: The available evidence suggests PDE5 inhibitors can attenuate altitude-induced pulmonary hypertension without significantly affecting systemic blood pressure or heart rate.