Pulmonary Arterial Hypertension-Specific Therapy for Atrial Septal Defects with Severe Pulmonary Arterial Hypertension

Background Pulmonary arterial hypertension (PAH) complicates a subset of patients with atrial septal defects (ASD). Although patients with ASD-PAH and high pulmonary vascular resistance (PVR) generally do not benefit, those who demonstrate a favorable response to PAH-specific therapy, particularly a PVR of < 5 Wood units (WU) post-treatment, may be considered for shunt closure. We aimed to examine the hemodynamic characteristics of patients with severe ASD-PAH who achieved a PVR of < 5 WU with PAH-specific therapy. Methods This retrospective study evaluated 15 patients with severe ASD-PAH (PVR ≥ 5.0 WU) who underwent PAH-specific therapy. The effects of PAH-specific therapy and acute vasoreactivity testing (AVT) were examined. Patients who achieved PVR < 5 WU post-therapy were classified into the low-PVR group, and others into the high-PVR group. Results The PVR significantly decreased from 10.7 ± 5.5 to 7.0 ± 5.2 WU after oral PAH-specific therapy (p < 0.05). The maximum baseline PVR in the low-PVR group (n = 7, 47%) was 9.5 WU. The low-PVR group showed a greater change in PVR during AVT than the high-PVR group (44.9 ± 8.9% vs. 15.4 ± 15.4%, p < 0.01). Conclusions The baseline PVR of 9.5 WU was the upper threshold for achieving PVR < 5.0 WU with oral PAH-specific therapy in severe ASD-PAH. Patients who exhibited a positive response to AVT achieved greater hemodynamic improvement.