Usefulness of medical therapy for pulmonary hypertension and delayed atrial septal defect closure

A subset of adult patients with an open atrial septal defect (ASD) have pulmonary arterial hypertension (PAH). We sought to identify predictors of response to PAH-specific medical therapy in this group. Invasive hemodynamic and clinical parameters from 12 patients with an open ASD and PAH (pulmonary vascular resistance [PVR], 8.8 ± 1.2 Wood units; mean pulmonary artery pressure, 55 ± 6 mm Hg; Qp:Qs ratio, 1.1 ± 0.1; and 6-minute walk test distance of 1,046 ± 116 feet) were analyzed. Responders (n = 5) underwent successful ASD closure at 1.3 ± 0.3 years after initiation of medical therapy and were characterized by >30% reduction in PVR (7.2 ± 1.5 to 4.6 ± 0.9 Wood units) versus <20% in nonresponders (n = 7; 9.9 ± 1.7 to 8.2 ± 1.5 Wood units, p <0.03), increased 6-minute walk test distance (1,087 ± 174 vs 1,405 ± 109 feet, p = 0.05), and higher Qp:Qs ratio after therapy (1.9 ± 0.2 vs 1.1 ± 0.2, p <0.02). Body mass index was a significant clinical predictor of response (23.3 ± 1.9 vs 30.0 ± 2.1 kg/m², p <0.05) and the change in arterial saturation with exercise correlated inversely with change in PVR (r = -0.739, p <0.01). In conclusion, medical therapy led to a significant improvement in hemodynamic and clinical parameters in a subset of patients with an open ASD and PAH, who were able to safely undergo delayed ASD closure.