Pulmonary arterial hypertension (PAH) is an uncommon but serious disease characterized by severe pulmonary vascular disease and significant morbidity and mortality. PAH associated with congenital heart disease (APAH-CHD) is one etiology of PAH that has innate characteristics delineating it from other forms of PAH. The patient with APAH-CHD presents with unique challenges consisting of not only pulmonary vascular disease but also the complexity of the cardiac lesion. Eisenmenger syndrome (ES) represents the severe end of the spectrum for disease in APAH-CHD. Over time, systemic-to-pulmonary shunting through cardiac defects increases pulmonary vascular resistance to levels significant enough to reverse shunting across the defect. Historically, ES patients have been reported to have better outcomes than IPAH despite similarities in pulmonary vascular disease. However, recent studies are challenging this notion. Nonetheless, APAH-CHD survival has improved with the advent of modern PAH targeted therapies. New therapeutic options have allowed us to reconsider the dogma of inoperability in APAH-CHD patients with unrepaired defects. Certainly advances have been made, however, investigators must continue to advance the field through controlled clinical trials in both adult and pediatric APAH-CHD patients.