Background:A therapeutic strategy in patients with atrial septal defect (ASD) and significant pulmonary arterial hypertension (PAH) remains controversial. This study aimed to assess the effect of PAH-specific medications and subsequent transcatheter shunt closure (ie, a treat and repair strategy) in these patients.Methods and Results:Among 646 patients with ASD, 22 patients (mean age of 56±20 years) who had PAH [mean pulmonary artery pressure ≥25 mmHg and pulmonary vascular resistance (PVR) ≥3 Wood units] underwent successful transcatheter ASD closure. Prior to the procedure, 8 patients received PAH-specific medications (PHM group) and 14 patients did not (non-PHM group). Initially, the PHM group had higher PVR compared with non-PHM group (9.6±3.8 vs. 4.2±1.0 Wood units, P<0.01). After treatment with PAH-specific medications, PVR in this group decreased to 4.0±0.8 Wood units (P<0.01). No adverse events were observed in either the PHM or non-PHM group during or after the transcatheter procedure. In the PHM group, during a treatment period of 52±48 months, the World Health Organization Functional Classification significantly improved (3.0±0.5 to 2.0±0.0, P<0.01), as well as in the non-PHM group (2.1±0.6 to 1.5±0.5, P<0.01).Conclusions:Treat and repair strategy provided substantial improvement and no worsening of the WHO-FC, even in patients with ASD and significant PAH. Long-term hemodynamic follow-up is mandatory to evaluate the ultimate efficacy and safety of this new strategy. (Circ J 2016; 80: 227–234)