The purpose of this study was to clarify whether changes in cardiopulmonary haemodynamics induced by pharmacological therapy correlate with exercise capacity and clinical events in patients with pulmonary arterial hypertension. 16 randomised trials including 2353 patients, followed up for 16.4±10.6 weeks, measuring cardiopulmonary haemodynamics by right heart catheterisation and reporting clinical events were included. Meta-analysis and meta-regression analysis were performed to assess the effects of treatments on clinical events and the relationship between haemodynamic changes (pulmonary artery pressure, pulmonary vascular resistance, cardiac index and right atrial pressure) and clinical events. Treatments significantly reduced all-cause death (OR 0.5, 95% CI 0.3-0.7; p<0.01), hospitalisation for pulmonary arterial hypertension (OR 0.4, 95% CI 0.2-0.7; p<0.01), initiation of rescue therapy (OR 0.3, 95% CI 0.2-0.6; p<0.01) and the composite outcome (OR 0.3, 95% CI 0.3-0.5; p<0.01). No relationship was found between changes of haemodynamic parameters and clinical events, whereas changes of cardiac index and pulmonary vascular resistance significantly correlated with changes in the 6-min walking distance (r = 0.64, p = 0.03; r = -0.55, p = 0.04, respectively). In patients with pulmonary arterial hypertension, improvements of cardiopulmonary haemodynamics observed in randomised clinical trials correlate with exercise capacity changes but do not predict clinical events in a short-term follow-up.