Pulmonary arterial hypertension is a serious complication of adult congenital heart disease associated with systemic-to-pulmonary shunts. Although early shunt closure restricts development of pulmonary arterial hypertension, patients remain at risk even after repair. The development of pulmonary arterial hypertension is associated with a markedly increased morbidity and mortality. It is important to identify patients with a poor prognosis using disease specific markers. Echocardiography and biomarkers arise as practical tools to determine the risk of mortality. Although pulmonary arterial hypertension cannot be cured, four classes of disease-targeting therapies are currently available and several promising therapies are being studied. There is a shift in drug studies towards more clinically relevant endpoints such as time to clinical worsening and morbidity and mortality events.